FEDERAL STATE BUDGETARY EDUCATIONAL INSTITUTION OF HIGHER EDUCATION «BASHKIR STATE MEDICAL UNIVERSITY» OF THE MINISTRY OF HEALTHCARE OF RUSSIA DEPARTMENT OF NORMAL PHYSIOLOGY PHYSIOLOGY PRACTICAL Education Guidance for Students of General Medicine Faculty Part II Physiology of Special Functions of CNS, Respiration, Digestive System, Metabolism and Nutrition, High Nervous Activity and Special Senses. A.F. Kayumova, O.S. Kiseleva, K.R. Ziyakaeva, I.R.Gabdulkhakova UFA 2022 УДК 612.8 ББК 28.903я73 G 36 Printed by the decision of“Federal State Budgetary Educational Institution of Higher Education BSMU” (document № ______ 2021) Normal physiology. Part II. Physiology of special functions of CNS, respiration, digestive system, metabolism and nutrition, high nervous activity and special senses.: education guidance for students of General Medicine faculty /A.F.Kayumova, O.S. Kiseleva, K.R. Ziyakaeva., I.R. Gabdulkhakova- Ufa: BSMU, 2022. pages. The Physiology practical was compiled on the basis of the work program (2021), the current curriculum (2021) and in accordance with the requirements of the Federal State Educational Standard of Higher Education 3 ++, in the specialty 31.05.01.–General Medicine. It presents the physiology of special functions of CNS, respiration, digestive system, metabolism and nutrition, high nervous activity and special senses. The manual contains the techniques and theory necessary for the study of students of the faculty of General Medicine. Illustrations are taken from open Internet resources. Recommended for publication by the Coordination Scientific and Methodological Council and approved by the decision of the Editorial and Publishing Council of the FSBEI HE BSMU of the Ministry of Health of Russia work. For English speaking students of General Medicine faculty. УДК 612.8 ББК 28.903я73 G 36 © Kayumova A.F., Kiseleva O.S., Ziyakaeva K.R,Gabdulkhakova I.R. © BashkirState Medical University, 2022 2 CONTENTS THEME 1. Special Physiology of Central Nervous System (CNS)……………1 Lesson 1. Role of Different CNS Parts in the Regulation of Movements and Muscle Tone.…………………………………………………………………5 Exercise 1.Positional-tonic Reflexes in Guinea Pig. ………………………….…15 Exercise 2.Straightening reflexes in Guinea Pig. ……………………………....15 Exercise 3. “Lifting” and ”Landing” Reflexes in Guinea Pig ……………..……16 Lesson 2.Physiology of Vegetative Nervous System. Investigation of Some Human Vegetative Reflexes.…………………………………………….17 Exercise1. Investigation of Vegetative Tone by Index Kerdo.………………..24 Exercise 2.Investigation of Vegetative Tone by Questionnaire Design Method.……………………………………………………………………24 Exercise 3.Investigation of Vegetative Reactance by Extracardial Reflexes.…………………………………………………………………………...26 Exercise 4. Analysis of Vegetative Reactance by Cold Test. ………….………..27 Exercise 5. Other Vegetative Tests.………………………………………………28 THEME2. Physiology of Respiration.…………………………………………....29 Lesson 1.External respiration. Gas Exchange. Research of Parameters of External Respiration. Control of Respiration …………………………………..29 Exercise 1.Spirometry. …………………………………………………………….40 Exercise 2.Lung Volumes and Capacities. Spirography. ……………………….....42 Exercise 3. Pneumography………………..………………………………………..43 THEME3. Digestive System. …………………………………………….………46 Lesson 1. Digestion in Oral Cavity and Stomach. ………………………….…….46 Exercise 1. Influence of Saliva on Starch. ………………………………….……54 Exercise 2. Determination of Mucin in Saliva. …………………………….……55 Exercise 3. Influence of Gastric Juice on Milk. …………………………….....…56 Lesson 2. Digestive System. Digestion in Intestine. Role of Bile in Digestion…....57 Exercise 1. Role of Bile in Digestion……………………………………….…....63 Exercise 2. Identification Test on Bile Pigments and Bile Salts. ……………...…64 Exercise 3. Gmelin’s Test on Bile Pigments. ………………………………..…..65 THEME4. Metabolism and Nutrition.…………………………………...………..66 Exercise 1. Methods for Determination of Energy Output.……………..………….69 Exercise 2.The Basal Metabolism Calculation by Garris - Benedict’s Tables……74 Exercise3. Determination of Energy Output by Reed’s Nomogram and Hemodynamic index.…..…………………………………………………………….74 Exercise 4. Analysis of Energy Value of Daily Student’s Diet.…………………....77 3 Exercise 5.Composing of the proper food diet with calculation of rational nourishment principals..……………………………………………………………77 THEME 5: Highest Nervous Activity. ......................................................................82 Lesson 1. Methods of Investigation of Cerebral Hemispheres. Cortex Functions. Investigation of Active Bioelectrical Processes in Brain. Functional Asymmetry of Hemispheres Performing Sensor and Motor functions.…………………………….82 Exercise 1. Determination of Individual Profile of Functional Asymmetry……..88 Lesson 2. Conditioned Reflexes. Conditioned Inhibitory Reflexes Methods of Making Reflexes and Methods of Formation of Conditioned Inhibitory Reflexes. ……………………………………………………………………………91 Exercise 1. Making of Defensive Conditioned Reflex on Human. ……………….95 Exercise 2. Making the Conditioned Wink Reflex on Human. ………………….95 Lesson 3. Spatiality of Human Mental Activity. Types of Highest Nervous Activity. Analytical-synthesis Functions of Cerebral Cortex. ………………………………..94 THEME 6. Sensory System…….. ………………………………………………..100 Lesson 1. The Special Senses. Physiology of Visual System.……………………100 Exercise 1. Determination of Visual Acuity by Using Rot’s Apparatus and Sivcev’s Table. ………………………………………………………..104 Exercise 2. Determination of Visual Fields. ………………………………107 Lesson 2. The Sense of Hearing. ………………………………………………....109 Exercise 1. Determination of Auditory Acuity……………………………111 Exercise 2. Determination of Bone and Air Conductivity of Sound. ….....113 Exercise 3. …………………………………………………………………113 4 THEME 1.SPECIAL PHYSILOGY OF CENTRAL NERVOUS SYSTEM Lesson 1.Role of different CNS parts in the regulation of movements and muscle tone. Questions for studying. 1. Organization of the spinal cord in motor functions. Role of the muscle spindles in motor control. The descending and ascending spinal cord tracts. 2. Medulla oblongata. The nuclei of the cranial nerves. The vital centers: the vasomotor center, the cardiac control center and the respiratory center. Midbrain. Functions of the cerebral peduncles, the red nucleus and the substantianigra. Static and statokinetic reflexes. 3. The reticular formation. Reticular activating system. Excitatory and inhibitory function of thereticular formation. 4. Thalamus. The generalized thalamocortical system: role of sensory information on cortical activity. Function of the thalamus in attention and in mechanisms of pain. 5. Physiologic anatomy of the basal ganglia. Motor functions of the basal ganglia. Function of the different basal ganglia. Clinical syndromes resulting from damage of the basal ganglia. 6. The cerebellum and its motor functions. Functions of the cerebellum in controlling movements. Clinical abnormalities of the cerebellum The spinal cord consists of 31-32 segments and 31 pairs of spinal nerves. It is symmetrically divided into two lateral halves. The spinal cord contains motor nuclei (motoneurons) in anterior horn and intermedial (inserted) nuclei in posterior horn. Lateral horn cells are autonomic (intermediolateral) cell group. Each segment of the spinal cord includes posterior - sensory and anterior - motor roots. The anterior roots consist of efferent fibers of motor neurons and preganglionic autonomic neurons (fig.1). 5 Figure 1.The spinal roots. Functions of spinal cord: 1.Conductive function. The spinal cord consists of the main conductive parts to the higher centers of the spinal cord and brain and back. The ascending pathways: - transfer information from muscular, tendinous receptors and tactile receptors of skin;are formed by axons of spinal ganglion, and send information to cerebral cortex and cerebellum. The descending pathways: - Pyramidal: cortical-spinal tract. It originates from the neurons of the motor areas of the cortex and ends on the motor neurons of the spinal cord. This is a conscious regulation of motor activity. - Extrapyramidal pathways: rubro-spinal, tegmental-spinal, reticulo-spinal, vestibulospinal, olivospinal (fig.2). 6 Figure 2.The spinal pathways. 2. Reflex function - the spinal cord is the main center of the reflex action of the trunk and limbs. Classification of spinal reflexes I. Somaticreflex 1. Tone reflex (myotatic reflex) 2. Phasic reflex (flexor reflex, II. Vegetative reflex 1. vasomotor reflex 2. urinary reflex 3. defecation reflex 4. sexual reflex ect., crossed extensor reflex) Spinal vegetative reflexes are important to control activity of viscera.Reflex arcs of skin-visceral reflexes have a segmental structure. These reflexes begin with skin receptors and end with a change in the functioning of internal organs. The essence of this structure is that each segment of the spinal cord innervates the corresponding metamere of the body (fig. 3). The therapeutic effect of acupressure, acupuncture, local warming and cooling is based on the segmental principle of skin-visceral reflexes. The intersegmental principle of spinal reflexes is that each metamere of the body receives innervation not only from the segment, but also from the overlying and underlying segments. Spinal somatic reflexes are important to motor activity and regulation muscle tone and 7 posture. Figure 3.The segment of spinal cord. Myotatic or stretch reflex. Muscle tone is purely a reflex process.Thus muscle tone is maintained by impulse activity of afferent nerves whose endings lie in the muscle spindles. Muscle spindle is an organ, which lies between regular or extrafusal muscle fibres and richly innervated both by sensory and motor axons. Muscle spindle is composed of a bundle of modified muscle fibres, called intrafusal muscle fibres. Intrafusal muscle fibers are divided into 2 groups: nuclear bag and nuclear chain fibers.Proprioreceptors are found inside the nuclear bag - these are stretch receptors. They are excited when the nuclear bag or nuclear chain is stretched. Impulses from them are sent to the spinal cord to the alpha motor neurons of the anterior horns, which innervate the extrafusal muscle fibers (fig. 4). 8 Figure 4.The myotatic reflex. Extra- and intrafusal fibers. When the muscle tone decreases, its muscle lengthens and the greater the stretching of the proprioreceptors of the intrafusal fibers and, consequently, the impulses to the motor neurons of the anterior horns of the spinal cord. This means that more stimuli go to the muscles and their tone increases. This is the principle of operation of the gamma loop, which regulates muscle tone (fig. 5). 9 Figure 5.The myotatic reflex or gamma loop. The tone of the skeletal muscles is established at the level of the spinal cord, but it is regulated (increased or decreased) due to the descending influences of the overlying centers (tab. 1). Table 1. Influence of supraspinal centers on the muscle tone. CorticoRubroReticuloReticulospinal spinal tract spinal spinal (pyramidal) medial lateral tract (from pons) tract (from medulla) Alfa, gamma motoneurons of flexors Alfa, gamma motoneurons of extensors Vestibulospinal lateral tract + + - + - - - + - + Myotatic or stretch reflex: 1.makes the movement smooth and accurate 2. maintains the line of gravity constant (equilibrium). 10 The posture is not the active movement itself (which in most cases is a voluntary process) but is the associated redistribution of tone in the different groups of related muscles. Brainstem includes medulla oblongata, pons, midbrain. Brainstem has refectory and conduction functions. All cranial nerves exceptI and II pairs are based in the brainstem (tab. 2). Table 2. Number of the nerve III Name of cranial nerve Cranial nerves Includes fibers Efferent (motor and vegetative) Efferent V Oculomotor nerve Nervous trochlearis Trigeminal nerve VI Adducent nerve Efferent VII Facial nerve Efferent (motor and vegetative) VIII Vestibulocochlear nerve Glossopharyngeal nerve Afferent IV IX Afferent and efferent Afferent and efferent (motor and vegetative) X Nervous Vagus Afferent and efferent (motor and vegetative) XI Accessories nerve Efferent (motor) XII Hypoglossal nerve Efferent (motor) Functions Accommodation, movement of eyes The movement of eye muscle Chewing and sensitivity of the person Movement of eyes The movement of mimic face muscles, salivation and tears. Flavoring sensitivity of tongue Hearing, sense of equilibrium Flavoring sensitivity of tongue, sky. Salivation, swallowing Signals from internals, regulation of inhibitions of smooth muscle, secretion the exocrine of glands Movement of the head, neck, shoulders. Information transfer from neck muscles Movement of tongue. Information from tongue muscles Thedescending ways from brain to a spinal cord pass through a midbrain, pons and medulla oblongata. All ascending pathways which bring sensory information from 11 proprio- receptors of muscles, tactile, temperature receptors and receptors of pain also pass through brainstem to cerebellum and cerebral cortex. Reflex function of brainstem. A lot of vital reflexes are based in the level of medulla and pons. They are: respiratory and vascular-motor centers. Reflexes of salivation and swallowing, vomiting and sneezing, coughing, lachrymal and blinking locate here. Midbrain as well as medulla oblongata and pons relate to stem structures (fig.6). Primary visual area and primary auditory area a quadrigeminal (superior and inferior colliculus); red nucleus, substantianigra, nuclei of nerves reticular formation are parts of the midbrain. Figure 6.The brainstem (medulla oblongata, pons and midbrain). Primary visual area regulates orientative visual reflexes. The animal without cerebral cortex turns its head and changes pupillary width to light. Primary auditory area regulates orientative auditory reflexes. Primary visual and primary auditory areas regulate protect reflex. It arises at sudden action of non-identified incentive and includes change of a tone of skeletal muscles. A red nucleus activates motor-neurons of flexor. The condition of a decerebrate rigidity arises at a section of a rubrospinal tract. At the same time, the tone of the extensor muscles sharply increases. The limbs of the animal are strongly elongated, the head is thrown back, the tail is raised.It’s happens 12 after cutting the midbrain in experiment between superior and inferior colliculi. The red nucleus is cut off. The result is: activation of vestibular lateral nucleus which was inhibited by red nucleus before cut (fig. 7). Figure 7.The decerebrate rigidity The substantianigra is a collection of nerve cells containing the pigment melanin. The black substance regulates the acts of chewing and swallowing, precise movements of the fingers. Neurons of the substantia nigra synthesize the neurotransmitter dopamine. This neurotransmitter travels along the axons to the basal ganglia. Cerebellum and its functions. The cerebellum is the highest subcortexcentre coordinating motive, vegetative and behavioral reactions. The functional structures of the cerebellum:the ancient cerebellum consists of a flocculus, nodule and the bottom of a vermis(fig. 8). It has an entrance from vestibular nuclei. The old cerebellum consists of parafloccular section and superior of vermis. It has afferent entrances from a spinal cord. The neocerebellum consists of hemispheres. It receives afferent entrances from cerebral cortex and from muscle receptor through the inferior olive. Corpus medullare contains three pairs of nuclei (a fastigii, dentate and intermediate). It is the main efferent exit of the cerebellum to the motor centers of the brain. Functions of the cerebellum: - Muscle tone and equilibrium regulation; - Pose and targeted movement coordination; - Targeted movement programming. The cerebellum has activating and inactivating impacts on the vegetative centers (breath, digestive) and activity of internals. 13 Figure 8.The Cerebellum. Tonic reflexes of a brainstem arereactions aimed at maintaining a normal body position in space. They are divided into two big groups: static and stato-kinetic reflexes. Static reflexes are the reflexes of posture (positional-tonic) and straightening reflexes. Positional-tonic reflexes occur as a result of changes of head position in relation to the trunk. Under these conditions as the body gravity center is shifted there is a danger of balance disturbance. In this case the receptors of otolithic body of the vestibular apparatus, proprioceptors of muscles and tendons and skin receptors of neck are stimulated. Stimulation reaches the nuclei of back brain (medulla oblongata and pons Varolii) and the midbrain taking part in redistribution of neck muscles, trunk and limbs and providing the support of the part of a body in the direction of gravity center shift (fig. 9). 14 Figure 9. Posture reflexes: changing head position affects muscle tone. Straightening reflexes - occur as a result of head turnings and body inclinations. They are directed to the returning a normal position. They represent series of tonic reflexes started by irritation of otolithic body of the vestibular apparatus and skin receptors of a trunk, leading to redistribution of neck muscles and returning to the normal position of a head. Turning of a head is followed by overwinding of neck muscles and tendons that causes their proprioceptors irritation. It gives rise to a new part of a straightening reflex providing consecutive redistribution of muscles tone of the forepart and then the back part of a trunk that leads to the returning to a normal position. Statokinetic reflexes, - depending on the character of movements, are subdivided into the reflexes occurring under influence of linear and angular accelerations. The first ones are reflexes of descent and rise ("lifting"), and also reflexes of "landing". These reflexes result from irritation of otolithic receptors of the vestibular apparatus, and partially of semicircular canals. In the beginning of rise under the action of positive acceleration there comes involuntary bending of limbs, lowering of a head and a trunk. In the end of rise under action of negative acceleration extension of limbs occurs, thus raising a head and a trunk. When descending, the given reactions occur in the reverse sequence. The reflex of “landing” occurs during an unsupported phase of a vertical jump. In the air animal’s limbs become straighten and move forward. Falling down, the animal springs its limbs to protect its head and trunk from impacts against the ground. Statokinetic reflexes occurring under the influence of angular accelerations (rotations of a body in various planes), develop owing to irritation of semicircular canals receptors and are directed on returning of a body and its parts to a normal position. The example of statokinetic reflexes is the vestibular nystagmus representing movement of eyes in the direction opposite to the direction of rotation. The study of the vestibular nystagmus is of great importance for the characteristic of the vestibular apparatus in clinical picture. 15 Exercise 1.Positional-tonic reflexes in the guinea pig. Purposes: - to study the static and stato-kinetic reflexes in the guinea pig; - to study the positional-tonic reflexes in the guinea pig; - to study the straightening reflexes in the guinea pig; - to study the “lifting” reflexes in the guinea pig; Procedure. The guinea pig is placed on a napkin and its natural position is studied (fig. 10, a).The animal is taken by its snout, its head is lifted upwards (fig. 10, b). It is marked that in these conditions forelegs of an animal are straighten, while back legs remain bent. Figure 10.The extension of forelegs with lifting of the head. Exercise2. Straightening reflexes in the guinea pig: a) The animal is lifted upwards by the shoulder girdle and by the head, then the trunk is turned by 180 degrees and the head is directed downwards. When the head is released - it is returned to the normal position, i.e. the crown of the head is directed upwards (fig.11 a). 16 Figure 11.Returning the head to the natural position after turning the trunk by 180 degrees a-the head is fixed, b- the head is released. Returning the natural position after turning the trunk by 90 degrees. c- the trunk is transferred to the horizontal position, the head and trunk is fixed by the hand, d- the head is released, it is returned to the normal position e- the trunk is released, it is returned to the normal position b) When taking the guinea pig by the pelvis, its trunk is transferred to the vertical position with the head downwards. It is marked that in these conditions the head of the animal keeps normal position - is focused upwards(fig.11 b). c) When trying to lay the animal on its side (by 90 degrees), the posture is restored in two stages: placing the head with the top of the head up and then straightening the body(fig.11 c, d, e). Exercise 3. “Lifting reflexes” and the reflex of “landing” in the guinea pig. a) The guinea pig is placed on a plate and its position is studied - its forelegs and back legs are bent, the head is raised. (fig. 12, a). The platform with the animal is quickly 17 moved upwards and downwards. It is observed that in the beginning of the fast descending its forelegs and back legs are straightened, the trunk and the head are lifted up (fig. 12, b). At the moment of a sudden stop, in the end of descending, the legs are bent; the head and the trunk are pressed to the supporting plane (fig. 12, c). When lifting, reflex reactions change in the reverse sequence. Figure 12.Change the position of the guinea pig during the fast descending: a - the initial position b - the position of the guinea pig at the beginning of the fast descending c - the position of the guinea pig at the moment of sudden stop b) The guinea pig is lifted up by the pelvis and by the shoulder girdle; - its legs are halfbent and are hung down. The animal is quickly moved to the ground. It is marked that during the movement its forelegs and back legs are unbent and straightened forward; its fingers are fan-shaped. Observations, results and conclusion. Lesson 2. Physiology of vegetative nervous system. Investigation of some human vegetative reflexes. Questions for studying. 1. Physiology of vegetative nervous system. Structural and functional properties of somatic and vegetative nervous system. 2. Properties of reflex arch of somatic and vegetative nervous system. 3. Sympathetic and parasympathetic divisions of vegetative nervous system. 4. Adrenergic and cholinergic structures of vegetative nervous system. 18 5. Synergism and relative antagonism ofinfluenceofsympatheticandparasympatheticdivisionsofvegetativenervoussystem. 6. Vegetative centers. Hypothalamus, its nuclei and their significance in regulation of vegetative functions. 7. Participation of vegetative nervous system in the fusion of functions. Purposes: Investigation of reflexes, characterizing status sympatheticandparasympatheticdivisionsofvegetativenervoussystem. of Principle. The autonomic nervous system is a motor system concerned with the regulation of smooth muscle, cardiac muscle, and glands. It is not directly accessible to voluntary control. Instead, it operates in an automatic fashion on the basis of autonomic reflexes and central control. Anatomically, the autonomic outflow is divided into two components: the sympathetic and parasympathetic divisions of the autonomic nervous system. In the gastrointestinal tract, these both communicate with the enteric nervous system, and this is sometimes called a third division of the autonomic nervous system. Sympathetic preganglionic neurons are located in the intermediolateral (and intermediomedial) cell columns of the CVIII to LII segments of the spinal cord. Their axons leave the spinal cord through ventral roots and enter the sympathetic chain through white communicating rami. Sympathetic preganglionic neurons synapses are located on postganglionic neurons in the paravertebral or prevertebral ganglia. Postganglionic axons synapse in target organs. Parasympathetic preganglionic neurons synapses are located in cranial nerve nuclei and the sacral preganglionic nucleus. Postganglionic axons synapses are located in target organs. The enteric nervous system is in the wall of the gastrointestinal tract in the myenteric and submucosal plexuses. It coordinates the movements and glandular secretions of the gut. The sympathetic and parasympathetic nervous systems regulate the activity of smooth muscle, cardiac muscle, and glands. These components of the autonomic nervous system often act in a reciprocal fashion. Preganglionic sympathetic and parasympathetic neurons release acetylcholine as their neurotransmitter. This neurotransmitter acts on nicotinic cholinergic receptors (and also on muscarinic receptors) on postganglionic neurons. Nicotinic receptors are blocked by curare. 19 Parasympathetic and some sympathetic postganglionic neurons (sudomotor and vasodilator neurons) also release acetylcholine. The postsynaptic receptors on target cells in this case are muscarinic and can be blocked by atropine. Most sympathetic postganglionic neurons release norepinephrine, which acts on α- and β-adrenergic receptors. The adrenal medulla receives sympathetic preganglionic input and releases epinephrine and norepinephrine into the general circulation (fig. 13). Figure 13. Autonomic nervous system The autonomic nervous system operates reflexly and in response to descending control systems, especially the hypothalamus and other parts of the limbic system. The hypothalamus regulates homeostasis, motivation, and emotional behavior through control of the autonomic nervous system, endocrine system, and somatic nervous system. Some of the functions regulated include body temperature, cardiovascular activity, appetite, water intake, and immune responses. The hypothalamus controls endocrine function both by the direct release of hormones in the posterior pituitary gland and by the release of peptides into the portal circulation of the anterior pituitary gland. 20 The limbic system comprises not only the hypothalamus but also a number of forebrain structures, including the hippocampus, amygdaloid nuclei, and several nuclei in the midbrain. Functions of the limbic system include the regulation of aggressive behavior and sexuality. The hippocampus is involved in the storage of recently acquired memories and in memory consolidation. Cholinereceptors. Acetylcholine cooperates with М-and N-cholinereceptors. They are named so because possess according to high sensitivity poison of a fly agaric -muscarine or to alkaloid to the nicotine containing in leaves of tobacco. М-and N-choline receptors basically are located postsynaptic. The M-cholinereceptors are localized on membranes of automatically functioning cells of myocardium, atria- ventricular node, glands of external secretion, innervated by postganglionic parasympathetic nerves, and also on membranes of cells smooth muscles of a stomach, uterus, and sweat- glands, innervated by the some postganglionic sympathetic nerves. 5 variants of M-cholinereceptors are distinguished. Distinguish also different N-cholinereceptors. Some of the mare localized on postsynaptic neuron’s membrane of vegetative ganglions, ganglia similar educations (brain substance of adrenal glands, sleepy glomerule, neurohypophysis), and others are localized on postsynaptic membranes of fibers of skeletal muscles. There are N-and Mcholinereceptors in CNS. Besides postsynaptic structures, cholinereceptors are localized in presynaptic membrane. Stimulation N-cholinereceptors promotes releasing acetylcholine, and stimulation of M-cholinereceptors inhibit this process. Adrenoreceptors. Epinephrine and norepinephrine cooperate with adrenoreceptors. Adrenoreceptors divide into two basic groups –α -and β-receptors, there are several types of each group of receptors (tab. 3, 4). Table 3 Comparative characteristics of the autonomic and somatic nervous system. Properties Somatic nervous system 1.Higher centers 4-5 layer of cells of the precentral gyrus of the frontal lobe of the cerebral Vegetative nervous system Parasympathetic Sympathetic part Some areas of the cerebral cortex Anterior nuclei the hypothalamus 21 Posterior nuclei the hypothalamus 2. Executive centers cortex motor neurons of the anterior horns of the spinal cord 3. The presence of peripheral ganglia along the efferent part of the reflex arc No 4. Characteristic of efferent neural fibers long uninterrupted, type A (speed 70120 m/s) 5.Transmitters and receptors 6.Innervated organs 7. Effect on the organs 8. Activation conditions Acetylcholine N-cholinergic receptors Skeletal muscles Rising activity Control activity of skeletal muscles Cranial part: nuclei of cranial nerves: III, autonomic nuclei of VII, IX, X the lateral horns of Sacral part: the spinal cord CVIII autonomic nuclei of to LII the lateral horns of the spinal cord SII-SIV Intramural ganglia Paravertebral (in the walls of the ganglia innervated organs) (sympathetic trunk) and extramural and prevertebral ganglia near the ganglia- (superior innervated organ and inferior (submandibular, mesenteric plexus sublingual, parotid..) and celiac trunk) Preganglionic type B Preganglionic type (3-18 m/s), long B (3-18 m/s), short postganglionic type postganglionic type C (0,5-3 m/s) – C (0,5-3 m/s) – unmyelinated, short unmyelinated, long Preganglionic fibers: Preganglionic Acetylcholine fibers: N-cholinergic Acetylcholine receptors N-cholinergic recep. Postganglionic Postganglionic: fibers: Noradrenalin Acetylcholine α, β- adrenergicM-cholinergic receptors receptors All organs, except: All organs sweat glands, adrenal gland, CNS, uterus, most of the vessels Inhibitory effect activation dominates at rest, controls normal 22 dominates during times of stress, only physiological processes physical activity Influence of autonomic nervous system on the organs (fig. 14). Figure 14.Autonomic nervous system – innervation of the inner organs. Table 4 Localization ofα, β -adrenoreceptors and results of their activation Type of receptor Localization Smooth muscles vessels Myocardium Result of activation blood Narrowing Increase in force of contraction * 23 α1 α2 Type receptor Spleen Circular muscle of iris Liver CNS Adrenergic axon`s endings Blood vessels Adrenergic neurons CNS Adipose tissue Islet tissue of pancreas of Localization Sinus node β1 Increase of excitability, increase of frequency of heart contractions Increase the force of contractions Increase conductivity Increase automatism Myocardium Atrioventrycular node Bundle of His Liver, skeletal muscles Arterioles, especially arterioles of skeletal muscles Smooth muscles ofbronchi Pregnant uterus β2 β1and β2 Contraction Distension of pupil glycogenolysis increases Increase in impellent activity Decrease secretion of catecholamines Narrowing Decrease activity Calming; analgesia, oppression of the structures activating cardiovascular system Oppression of lipolysis Decrease of secretion of insulin Result of activation Increase glycogenolysis Relaxation Relaxation Weakening and stoppage of contractions Islet tissue of pancreas Increase of secretion of insulin Sympathetic nerves` ending Increase of secretion of neurotransmitter Cholinergic nerves` ending Increase of secretion of acetylcholine Adipose tissue Increase of lipolysis Juxtoglomerular tissue of Increase of secretion of renin kidneys 24 Research the functional status of vegetative nervous system of the person. Research of functional status vegetative nervous systemhas huge diagnostic valueina clinical practice. Status of reflexes and also results of some special functional tests characterize tone of vegetative system. Methods of clinical research of vegetative nervous system may be conditionally divided into following groups: 1. questioning the patient: presence of burning pains;sleep disturbance, urinationabnormalities, disturbances of functions of intestines; recurring decrease and increase of arterial pressure; bradycardia or tachycardia, pain of death, etc.; 2. research of dermographism (white, red, elevated, reflex); 3. research of painful vegetative points; 4. cardiovascular tests: capillaroscopy, research of reaction of skin on the influence of ultra-violet irradiation, adrenalinic and histamine skin tests, hygrophilous test, oscillography, plethysmography, measuring skin temperature, some reflexes (oculocardiac, clinostatic, orthostatic, etc.); 5. electrophysiological tests - research of electroskin resistance ; 6. measuringamount of biologically active substances - catecholamine (adrenaline, noradrenalin) and others in urine and blood, definition of choline esterase activity in blood. Research of functional status vegetative nervous system also includes examination of sweating, sensitivity of zones by Zaharyne-Ged. Exercise1.Investigation of vegetative tone of the person by index Kerdo. Index Kerdo allows estimating a status of vegetative tone by the parameters describing a status of cardiovascular system (arterial pressure (AP) and heart rate). Equipment: monometer with phonendoscope, a stop watch. Procedure. Measure arterial pressure at the person in sitting position after 5 mines of rest. Examine the AP (mm hg) and a pulse rate (heart rate). Registration of the results. 1. Using these parameters calculate vegetative index Kerdo (VIK, %) by the formula: VIK = (1 - AP/heart rate) •100 (%) 2. Make estimation of your own initial vegetative tone: normotonia: VIKfrom-10 to+10 %, sympaticotonia: VIK more + 10 %, vagotonia: VIK less-10 %. Observations, results and conclusion. Exercise2.Investigation of vegetative tone by methodof questionnaire design. Equipment: the table-questionnaire. 25 Procedure. Following questions of tab 15. At each positive answer put a sign "+", that will correspond to one point. After filling the table-questionnaire count up sumunder corresponding columns and formulate one of three conclusionsby prevalence of a sum in one of three columns: eitoniaor normotonia (relative vegetative balance); vagotonia (prevalence parasympathetic influences); sympaticotonia ( prevalence of sympathetic influences). Make the conclusion about your initial vegetative tone and compare it to the conclusion from the previous problems. Observations, results and conclusion. Table 5 A questionnaire for reference estimation of an initial vegetative tone in human* Symptoms and clinical indexes Skin: Color Dermographism Body temperature Body weight Appetite Cardiovascular functions: Frequency of heart beats Arterial pressure The sensation heartbeats in rest Pains in the heartregions Respiratory parameters: Frequency of breath The volume of breath Physical efficiency, activity Dream Sympaticotonia Normotonia Vagotonia Pale Normal Pink, white Propensity to raise Red Normal Propensity to grow thin Normal Increase Propensity to tachycardia Normal Normocardia Propensity to reddening Red, towering Propensity to decrease Propensity to obesity Decrease Propensity to bradycardia Propensity to raise Propensity to hypotension Is not characteristic Are often Is raised Accordingly toage Is not characteristic Is not characteristic Normal Is raised Normal Is decreased Is raised Normal Is decreased Restless Quiet Deep Is characteristic Are possible 26 Is decreased Psychoemotialfeatures Absent-mindedness, often hyperexcitability Steadiness Apathy Amount of points * The table is presented in a reduced variant. Exercise 3. Investigation of vegetative reactance of the person by extracardial reflexes. Some cardiac reflexes have important diagnostic, and sometimes medical, value. Reflex by Danini-Ashner, sinocardial (Goering-Chermaac), solar (Tome-Ru) are most well known reflexes. All of them arise during irritation corresponding reflexogenic zones and conduct to stimulation of vagus nerves influences on heart. Centripetal ways of these reflexes reach nuclei of these nerves in medulla oblongata; centrifugal ways to heart begin from them. Equipment: a stop watch. Researchis carried out on the human being. Procedure. Consistently carry out research of three reflexes. 1. Oculocardiac (Daniini-Ashner) reflex. Tested personsits on a chair, having relaxed, during 5-6 minutes. Count up the initial pulse at the tested person. Then ask him to close his eyes. Put four fingers of hands to temporal surface of person's head and press on his eyes with the thumbs slowly during 10-20 sec. Do not use very strongly press on both closed eyes, then quickly stop pressing. Again count up frequency of pulse. Pulse is counted up right after with pressings on eyeballs and through 5 minutes after the termination of influence. The maximal delay of pulse is registered on 15-30-thto second and lasts 20-60 second after the termination of pressure.At healthy people the number of intimate reductions is slowed down on 4-10 beats /minute (normal type).If thedelay of pulsewill be more than on 10 beats /minute reaction is considered strengthened (vagothonic type). Ifpulse becomes frequent,it is the perverted reaction; atabsence of shifts -reaction is negative (sympaticothonic type). 2. Cervical vegetative (carotid sinus) reflex; test by Chermac. Make this test through 8-10 minutes after previous exercise. Wait for initial pulse value will be recovered. Define a pulsation in the field of forward border of theuppertierce of sternocleidomastoid muscle (a zone of projection of carotid bifurcating). Carry out easy constant pressing on it during 20-30 seconds. With other hand count up frequency of pulse for 30 seconds. Writedown results in the table. Delay of pulse on 6-12 beats /minute is characteristic for normal parasympatheticreactions (vagotonia); delay over 12 beats /minute testifies to increase of tone of vagus nerve. 27 Table 6 Test Oculo-cardiac reflex Carotid sinus reflex Results of research of vegetative reflexes Initial value of pulse, Size of change of pulse in test per min Normal test Norm al test 60-65 from -2,0 to -10,0 60-65 from -4,0 to -10,0 60-65 -4,0 --10,0 Observations, results and conclusion. Exercise 4. The analysis of vegetative reactance of the person by cold test method Cold test allows investigation of vegetative reactance. Equipment: a tonometer with a phonendoscope, a stop watch, a glass with very cold water. Research is carried out on the human being. Procedure. Define arterial pressure (the AP, mm hg) and a pulse rate (heart rate, /mines) at the tested person in sitting position. Then ask him to dip his right hand into the glass with cold water for1 minute. In 0, 5 and 1 minutes from the beginning of test, and also every minute after the hand is taken from a glass with cold water, the AP (mm hg) and heart beats are investigated repeatedly. 1. Write your results into the table 7. Table 7 Parameter SP, (systolic pressure)mm Hg DP, (diastolic pressure)mm Hg Hear rate, per min VIK, % Initial values Vegetative reactivity (minute of inspection) 1-st 2-nd 3-rd 4-th 0,5 28 5-th 2. Estimate size of vegetative reactance by change the AP (mm Hg) and heart rate, using formula Kerdo. VIK = (1 - AP/heart rate) •100 (%) (VIK – vegetative index Kerdo). Observations, results and conclusion. Exercise5. Other vegetative tests Simple tests may be made in any conditions. In spite of a seeming simplicity of these methods, they give the important information about status of vegetative regulation at the person. Equipment: a stop watch, a couch, a wooden stick with the sharp end. Procedure. Two students participate in exercise - one is investigated, another performs tests. Carry out following manipulations consistently. A. Clinostaticreflex (test by Daniepolopol) Investigated slowly passes from vertical position in horizontal. In response pulse is slowed down on 4 - 6 beats per minute (positive reaction) or on 8-12 beats per minute(sharply positive reaction) that depends on reflex increase of a tone of vagus center. B. Orthostatic reflex (test by Prevel) Investigated, being in horizontalposition, slowlystands up. In response pulse will be increase on 6-24 beats /min (positive reaction); more than on 24 beats /min - sharply positive. It depends on reflex increase of a tone of sympathetic system. C. Dermographism-a parameter of a tone of precapillars of skin. White dermographismis causedby fast drawing of an easy stroke on a skin (with the sharp end of a wooden stick). In 8 -20 sec after irritation there will be a white strip which is kept from 1 up to 5-10 minutes(in norm). Red dermographismis caused by a slow drawing strong stroke on a skin with the blunt end of a stick. Through 5-15 sec there will be red strip which is kept from 1,5 minutes up to 1- 2 hours(in norm). Toweringdermographism.Make stroke on a skin by strong pressure with the holeof stick. Through 1-2 minutes there will bepalecylinder, which in norm is kept for a long time. Unlike two previouskinds of dermographisms, it occurs in healthy people, toweringdermographism is characteristic only for sickpeople. Reflex dermographism.Make stroke on a skin with strong pressurewith sharp end of the stick. Through 5-30 sec there will appear pink -red (rare white) spots. There sizes may be about 1-6 sm. Contours are rough. These changes are kept in norm from 30 sec up to 10 minutes. 29 Hair (pilomotor) reflex (test byToma). This reflex is caused by mechanical irritation: tingle skin, friction, a touch of an ice, ether and chloroaethyle irritation. In response there will be a goose-pimples in the area of irritation. Observations, results and conclusion. THEME 2. PHYSIOLOGY OF RESPIRATION Lesson 1. Physiology of breathing. External breathing. Control of Respiration. The questions for studying: 1. Functions of respiration. 2. Pleural cavity and intrapleural pressure. Surface tension of the intraalveolar fluid. 3. Mechanics of breathing. 4. Pulmonary volumes and capacities. Respiratory dead space. 5. Composition of gases in air. Gases exchange in the lungs. 6. Oxygen and carbon dioxide transport by blood. 7. Dissociation curve of haemoglobin. Factors influencing the shape of the curve. Gases exchange in the tissues. 8. Oral and nasal breathing, their peculiarity and connection. 9. Nervous control of respiration. Respiratory control center. Its localization and composition. 10. Mechanism of rhythmic respiration. 11. Central chemoreceptors, peripheral chemoreceptors. Their significance in regulation of breathing. 12. Pulmonary mechanoreceptors. Their significance in regulation of breathing. 13. The importance of the hypothalamus and cerebral cortex in the regulation of respiration. 1. Functions of respiration. Respiration is a chemical reaction that happens in all living cells, including plant cells and animal cells. It is the way that energy is released from glucose so that all the other chemical processes needed for life can happen. The major functions of the respiratory system are: supplying our bodies with oxygen from cellular respiration as well as disposing of the carbon dioxide waste product that comes from cellular respiration.The respiratory system and the circulatory system are very intimately coupled with each other in this process.Other functions of the respiratory system also include our sense of smell or olfaction as well as speech (fig. 15). 30 The term respiration includes three functions: 1) ventilation(breathing); 2) gas exchange, which occurs between the air and blood in the lungs and between the blood and other tissues of the body; 3) oxygen utilizationby the tissues in the energy-liberating reactions of cell respiration. Figure 15. Major functions of the respiratory system The respiratory system is divided into a conducting zone, which conducts the air to the alveolus and a respiratory zone, which is the site of gas exchange between air and blood (fig. 16). The exchange of gases occurs across the walls of respiratory alveoli.The conducting zone structures: pharynx, larynx, trachea, right and left mainstem bronchi and bronchioles. The respiratory zone consists of respiratory bronchioles and alveoli. Figure 16. Organs of respiratory system 31 Breathing is a process as a result of which the organism receives oxygen and emits carbon dioxide. We distinguish five stages of breath. 1. Exchange of gases between environment and alveoli of lungs. 2. Exchange of gases between alveoli and blood. Gas exchange in lungs. 3. Blood transport of gases. 4. Gas exchange in tissue. 5. Actual tissue respiration. Ventilation and the exchange of gases (oxygen and carbon dioxide) between the air and blood are collectively called external respiration. Gas exchange between the blood and other tissues and oxygen utilization by the tissues are collectively known as internal respiration. 2. Pleural cavity and intrapleural pressure. Surface tension of the intraalveolar fluid. The pleural cavity is formed by visceral and parietal pleura. Negative (below atmospheric) pressure in this cavity is caused by elastic draft of a lung and a superficial tension of surfactant. Elastic draft is caused by elasticity of pulmonary fabric and directed to a lung root (fig. 17). Surfactant is a proteinaceous and lipidic complex. If pressure in a pleural cavity becomes equal to atmospheric (for example, at an injury) there is pneumothorax. At the same time lungs are tightened to a root and cease to participate in breath. Figure17. Pulmonary pressure 3. Mechanism of breath and exhalation. At a breath of and ribs rise outside and upward. The dome of a diaphragm is flattened. Lungs follow the thorax increasing in volume. It occurs because between an external surface of lungs and an internal surface of a thorax there is a pleural cavity. Pressure in 32 this cavity is lower than a mercury column at 6-9 mm. The exhalation occurs passively. At the same time the dome of a diaphragm rises and ribs fall. The volume of a thorax decreases (fig.18). Figure18. Mechanism of breath and exhalation 4. Pulmonary volumes and capacities. Respiratory dead space The maximal volume of all the airways in an adult is typically 5 to 6 liters. This volume includes those of the nasopharynx, the trachea, and all airways down to the alveolar sacs (tab. 8). Table 8 Lung’s volumes Volume and capacities: Typical ranges IRV= Inspiratory reserve volume 1,0-2,5L TV= Tidal volume ERV= Expiratory reserve volume 0,3-0,9 L 1,0-1,5 L RV = Residual volume 0,5 L TLC = Total lung capacity 3,5-7,0 L IC= Inspiratory Capacity (TV+IRV) 2,5-3,5 L FRC = Functional residual capacity (RV+ERV) 2,3-2,7 L VC= Vital capacity 4,0-7,0 L (male); 3,0-5,0L (female) 6,0-8,0 L/min Minute ventilation Rate of breathing (RB) 12-18 breaths per minute 33 1. Tidal Volume (TV) – is the volume of air breathed in and out during quiet respiration (about 500 ml). 2. Inspiratory Reserve Volume (IRV) – the volume of air that can be breathed in by maximum inspiratory effort after an ordinary inspiration. 3. Expiratory Reserve Volume (ERV) – the volume of air that can be breathed out by maximum expiratory effort after an ordinary expiration. 4. Residual Volume (RV) – is the amount of air which remains in the lungs after maximal expiration. It can only be expelled out from the lungs by opening the chest and allowing the lungs to collapse. 5. Inspiratory Capacity (IC) – maximum volume of air that can be inspired from the end-expiratory position, i.e. TV+IRV. 6. Vital Capacity (VC) – it is the volume of air that can be breathed out by maximal expiratory effort after a maximum inspiration. It equals TV+IRV+ERV. Respiratory dead space The air which remains confined in the upper respiratory tract with each inspiration and is not available for gaseous interchange constitutes what is known as “dead space air”. It amounts roughly to 150 ml. Functions of anatomical dead space: 1. Inspired air is saturated by water vapour before it reaches the alveoli of the lungs. 2. To remove the particulate matter in sizes more than 2,0 mm from the inspired air before it is delivered to the alveoli. 5. Composition of gases in air. Gases exchange in the lungs. The alveolar air differs in composition from that of the inspired (atmospheric) air. The reasons for this difference are: 1. Only a part of the alveolar air is replaced by inspired air as explained previously. 2. There is continuous absorption of O2 from the alveolar air by pulmonary venous blood – the alveolar air, therefore, is poorer in oxygen. CO2 is added continuously to the alveolar air by the pulmonary venous blood – the alveolar air, therefore, is richer in CO2.The inspired air is dry but gets saturated with water vapour during its passage through the respiratory tract.Since some of the space in the alveoli is now occupied by water vapour – the space available for other gases is diminished (tab. 9). Expired air. It has been noted that part of the expired air (“dead space” air) is atmospheric air rich in O2 and poor in CO2. As expiration progresses the expired air becomes a mixture of “dead space” air and that the last part of the expired air is pure 34 alveolar air. The expired air, therefore, is richer in O2 but poorer in CO2 as compared to alveolar air. Table 9 Composition of the inhaled, exhaled and alveolar air Gases Inspired air (%) Alveolar air (%) Expired air (%) 𝐎𝟐 20,93 14,0 16,0 С𝐎𝟐 0,03 5,5 4,5 Diffusion.Diffusion means movements of a substance from an area of high concentration to an area of low concentration.In the present context the diffusion of O 2 from alveoli to pulmonary capillaries and of CO2in the reverse direction is to be considered N2 being metabolically inert may be left out of discussion. The following points are to be noted in this connection: 1) Gases in the alveoli are dissolved in small quantity of alveolar fluid and are in equilibrium with partial pressure of the respective gases in alveolar air. 2) Gases in the blood of pulmonary capillaries are also dissolved in water of the plasma where these exert a tension. 6. Oxygen and carbon dioxide transport by blood The average values of tension of O2 and CO2 in these two areas are given below (tab. 10): Table 10 Average values of tension of O2and CO2 O2, mm Hg P CO2, mm Hg Alveoli 100 40 Venous blood 40 46 Diffusion, therefore, takes place in the direction shown by the arrows through the alveolo-capillary membrane which consists of:alveolar epithelium – thin epithelial cells together with its basement membrane; thin interstitial space between above and below; capillary endothelium together with its membrane.Alveolo-capillary membrane is freely permeable to respiratory gases and thus ensure rapid diffusion of O2 and CO2 through them in the direction shown by the arrows from the point of high pressure to the point of low pressure (fig. 19). 35 Figure 19. Blood transport of carbondioxide. Oxygen comes to tissue. Carbon dioxide comes out of tissue. One part of it is just dissolved in blood. It is the first form of transport of carbon dioxide. The other part of carbon dioxide comes to an erythrocyte and contacts hemoglobin. Carbohemoglobin is formed. It is the second form of transport. In erythrocytes carbon dioxide contacts water forming an coal acid. Reaction is catalyzed by enzyme of a carbanhydrase. Coal acid dissociates on ions H+ + HCO3-. HCO3-leaves an erythrocyte and forms bicarbonates of sodium and potassium in plasma. It is the third form of transport. In plasma there is also a reaction CO2+H2O↔H2CO3. The coal acid which is formed at the same time is the fourth form of transport. 36 7. Dissociation curve of haemoglobin. Factors influencing the shape of the curve Blood in the systemic arteries, at a PO2, of 100 mmHg, has a percent oxyhemoglobin saturation of 97% (which means that 97% of the hemoglobin is in the form of oxyhemoglobin). This blood is delivered to the systemic capillaries, where oxygen diffuses into the cells and is consumed in aerobic respiration.Blood leaving in the systemic veins is thus reduced in oxygen; it has a PO2 of about 40 mmHg and a percent oxyhemoglobin saturation of about 75% . A graphic illustration of the percent oxyhemoglobin saturation at different values of PO2 is called an oxyhemoglobin dissociation curve.Theoxyhemoglobin dissociation curve is S-shaped, or sigmoidal. The fact that it is relatively flat at high PO2 values indicates that changes in PO2 within this range have little effect on the loading reaction. One would have to ascend as high as 10,000 feet, for example, before the oxyhemoglobin saturation of arterial blood would decrease from 97% to 93%. At more common elevations, the percent oxyhemoglobin saturation would not be significantly different from the 97% value at sea level (fig.20). Figure 20. The oxyhemoglobin dissociation curve Blood transport of oxygen. Oxyhemoglobin dissociation curve (fig.21).Oxygen is transferred by blood in two forms: in physical dissolution and in the form of oxyhemoglobin [Hb(O2)4] S= ----------------------------------[Hb] + [Hb (O2)4] Oxyhemoglobin dissociation curve shows that the main condition of development and dissociation of oxyhemoglobin is the partial tension of oxygen in blood. 37 Figure 21. Oxyhemoglobin dissociation curve 8. Nervous control of respiration. Respiratory control center Inspiration and expiration are produced by the contraction and relaxation of skeletal muscles in response to activity in somatic motor neurons in the spinal cord. The activity of these motor neurons is controlled, in turn, by descending tracts from neurons in the respiratory control centers in the medulla oblongata and from neurons in the cerebral cortex (fig. 22). Figure 22. Regulation of breathing The I neurons project to and stimulate spinal motoneurons that innervate the respiratory muscles. Expiration is a passive process that occurs when the I neurons are inhibited, presumably by the activity of the E neurons. 38 The inspiratory neurons are located primarily in the dorsal respiratory group, and the expiratory neurons in the ventral respiratory group. The dorsal group of neurons regulates the activity of the phrenic nerves to the diaphragm, and the ventral group controls the motor neurons to the internal intercostal muscles.The activity of the I and E neurons varies in a reciprocal way to produce a rhythmic pattern of breathing. The activity of the medullary rhythmicity center is influenced by centers in the pons. As a result of research in which the brain stem is destroyed at different levels, two respiratory control centers have been identified in the pons. One area—the apneustic center —appears to promote inspiration by stimulating the I neurons in the medulla. The other area—the pneumotaxic center —seems to antagonize the apneustic center and inhibit inspiration (fig. 23). Figure 23. Pons. The rhythmicity center in the medulla oblongata directly controls breathing, but it receives input from the control centers in the pons and from chemo-receptors. 9. Central chemoreceptors, peripheral chemoreceptors The automatic control of breathing is also influenced by input from receptors sensitive to the chemical composition of the blood. There are two groups of chemoreceptors that respond to changes in blood PCO2, pH, and PO2. These are the central chemoreceptors in the medulla oblongata and the peripheral chemoreceptors. The peripheral chemoreceptors include the aortic bodies, located around the aortic arch, and the carotid bodies, located in each common carotid artery at the point where it branches into the internal and external carotid arteries (fig. 24). Chemoreceptors in the medulla most sensitive to changes in the arterial PCO2 and H+ arе located in the ventral area of the medulla oblongata. The chemoreceptors in the medulla are ultimately responsible for 70% to 80% of the increased ventilation that occurs in response to a sustained rise in arterial PCO2. 39 Figure 24. The peripheral chemoreceptors (aortic and carotid bodies) regulate the brain stem respiratory centers by means of sensory nerve stimulation. 10. Mechanism of rhythmic respiration. The automatic control of breathing is regulated by nerve fibers that descend in the lateral and ventral white matter of the spinal cord from the medulla oblongata. The voluntary control of breathing is a function of the cerebral cortex and involves nerve fibers that descend in the corticospinal tracts. The separation of the voluntary and involuntary pathways is dramatically illustrated in the condition called Ondine's curse (the term is taken from a German fairy tale). In this condition, neurological damage abolishes the automatic but not the voluntary control of breathing. People with Ondine's curse must remind themselves to breathe and they cannot go to sleep without the aid of a mechanical respirator (fig. 25). 40 Figure 25. The automatic and voluntary control of breathing. 11. Pulmonary mechanoreceptors. Effects of pulmonary receptors on ventilation. The lungs contain various types of receptors that influence the brain stem respiratory control centers via sensory fibers in the vagus nerves. Irritant receptors in the wall of the larynx, and receptors in the lungs identified as rapidly adapting receptors, can cause a person to cough in response to components of smoke and smog, and to inhaled particulates The Hering-Breuer reflex is stimulated by pulmonary stretch receptors. The activation of these receptors during inspiration inhibits the respiratory control centers, making further inspiration increasingly difficult. The Hering-Breuer reflex appears to be important in maintaining normal ventilation in the newborn. Exercise 1. Spirometry. Principle. The functional condition of lungs depends on age, sex, size, physical development and other factors. The most widespread characteristic of a condition of lungs is measurement of pulmonary volumes. They testify to development of organs of breath and functional reserves of respiratory system. Spirometry is a method of determination of vital capacity of lungs and volumes of air making it. It is possible to measure volume of inspired and expired air by means of a spirometer. Equipment. Spirometer (fig. 26), spirit cotton wool. 41 Figure 26. Spirometer Procedure: 1. Measurements make standing. 2. Take a spirometer; establish a scale of the spirometer on zero position. 3. Clean a mouthpiece of spirometer with the spirit cotton wool. 4. First make the maximal breath, after that make as much as possible deep expiration into the spirometer. On a scale of spirometer it is defined vital capacity lungs. 5. For measurement of respiratory volume make a quiet breath through a nose and then easy expire air into spirometer. On a scaleof spirometer it is defined tidal volume (size of respiratory volume). 6.Compare size of vital capacity of lungs to due or proper vital capacity which calculate with nomogram (fig. 27). The exact amount of vital capacity depends on age, sex and size of the individual. Observed VC may show a variation of 10% from the predicted VC in normal subjects. Pulmonary ventilation = Tidal volume x Respiratory rate. 42 Calculate parameters of Vital Capacity of lungs (percentage) by the formula: X = 100 - (Vital capacity [measure] / Vital capacity [proper]) x 100%. Norm of parameter is 12-15%. Men age VC height Women age VC height Figure 27. Nomogram Normal ventilation in an adult (75 kg) is about 6 L per minute with a respiratory rate of 12 breaths per minute and Tidal volume of 0,5 L. Observations, results and conclusion. Exercise 2. Spirography. Principle. If the spirometer is equipped with a recording device (spirograph), it can be also used for graphic measurement of the total ventilation per unit time (fig. 28). Purpose. To record the changes in lung volume during quiet and maximal effort respirations. Equipment. Spirograph, spirit cotton wool. Procedure. 1. The spirographmust be turned on. The mouth-piece and the nose-clip must be sterilized. 2. Sit in a relaxed position. 3. Take the mouth-piece in your mouth and put on the nose-clip. 4. Breathe quietly into the mouth-piece. The Spirograph records tidal lungvolume. 5. Make the maximal inspiratory and expiratory effort into the mouth-piece, the Spirograph records inspiratory and expiratory reserve volumes. 43 6. At the end of the spirographic recording make a maximal inspiratory effort and then exhale all air very fast. The volume of air exhaled in one second under these conditions is called the forced-expiratory volume in one second (FEV). In healthy young adults, FEV is about 80% of VC. 7. Calculate the value of lung volumes and capacities. Pay attention that one point on vertical channel of the recording paper equals 200 ml of air and one point on horizontal line is corresponding to 12 sec (5 points equals 1 min). Figure 28. Spirogram. Observations, results and conclusion. Exercise 3.Pneumography. Principle. Pneumography is registration of the respiratory movements. It allows to determine the frequency and depth of respiration, as well as to determine the ratio of duration of inhalation and exhalation. In adults the frequency of respiratory movements is amount 12-18 per minute, children have more rapid breathing. The frequency and depth of respiration are changed during muscular work. Change the frequency and depth of respiration is observed during swallowing, conversation, after delay the breathing etc. Pneumography may be determine with different methods. Pneumosensor with Mare’s capsule is the most simple and available method for registration of the respiratory movements. Strain gage transducer, rheostatatic and induction sensors may be used for 44 pneumography, but these methods need in use electronic intensive and registering apparatus (fig. 29). Equipment. Kymograph, cuff from sphygmomanometer, Mare’s capsule, tripod, Tjoint, rubber tubing, time controller, liquid ammonia. Figure 29. Pneumography. A - graphic registration of respiration by means of Mare’s capsule. 1. wide cuff, 2.rubber tube, 3. Mare’s capsule, 4.kymograph, 5. time marker, 6. T-joint, 7. universal tripod. Pneumograms:а- quiet breathing, b- at inhalation ammonia, c- during speech, d- after hyperventilation, e- after voluntarydelay the breathing, f- during physical exercises. Procedure. 1. Assemble the apparatus for registration respiratory movements as itdemonstrated in figure 28. Cuff from sphygmomanometer must be fixed on the chest of person. Then join the cuff from sphygmomanometer with capsuleby means of T-joint and rubber tubing. Bring in registering apparatus a small quantity of air through the T-joint. Engage kymograph and time controller. 2. Record the respiration: 45 а) at rest condition (quiet breathing); b) at maximum inhalation and at maximum exhalation (lung vital capacity); c) during the conversation; d) at swallowing; e) at inhalationammonia (cotton wool which is wetted with ammonia is carried to the nose of person; f) after voluntarydelay of respiration; h) after hyperventilationof lungs; i) during muscles exercise. 3. Draw the curve of pneumograms into your copy-book. Determine the phase when swallowing and speech are realized. Compare nature of respiration changes under influence from different factors. Observations, results and conclusion. 46 THEME 3. DIGESTIVE SYSTEM Lesson 1. Digestion in Oral Cavity and Stomach. Questions for studying. 1. Function of digestive system: motility, secretion, digestion, absorption, storage, elimination. 2. Mouth. Secretion of saliva. 3. Mastication. Deglutition. Swallowing center. 4. Esophagus. Peristalsis in esophagus. Lower esophageal sphincter. 5. Stomach. Gastric glands. Gastric juice. 6. Digestion and absorption in stomach. 7. Regulation of gastric secretion by nervous and hormonal mechanisms. 1. Function of digestive system The main functions of the digestive system include: 1. Ingestion of food. 2. Digestion of food. 3. Secretion of various digestive juices. 4.Absorption of water, salts, vitamins and end productions of food digestion. 5. Excretion – heavy metals, toxins, certain alkaloids etc. 6. Movement. 7. Erythropoiesis – in stomach – intrinsic faсtor, extrinsic factor – vitamin B12. Maturation of the erythroid cells (pernicious anaemia). 8. Regulates blood reaction. 9. Regulates blood sugar. 10. Maintains water balance. Motility. Food moves through the digestive tract due to a process called peristalsis, which is the movement of muscles in the GI tract that move the food through the digestive system. This involves the breakdown and mixing of ingested nutrients all the way through the elimination of undigested waste from the body. Secretion. This is the release of enzymes, hormones, and other substances that help the body digest the food that is eaten. Hormones tell the body when to produce digestive juices and signal the brain when you are hungry or full. Digestion. Ingested nutrients including proteins, fats, carbohydrates, vitamins, minerals, and water are reduced into molecules small enough to pass through the lining of the gut and so they can enter the bloodstream. The digestive system breaks down foods we consume so the body can use them for energy, growth, and cell repair. Proteins 47 break down to amino acids. Fats break down to fatty acids and glycerol. Carbohydrates break down to simple sugars. Absorption. The digested nutrients pass from the gut into the blood so the circulatory system or lymph system can pass them on to the rest of the body to use or store. The lymph system absorbs fatty acids and vitamins. The blood carries simple sugars, amino acids, glycerol, and some vitamins and salts to the liver. The liver stores, processes, and delivers these nutrients to the body when needed. There are five digestive juices:saliva;gastric juice;pancreatic juice;intestinal juice;bile.One juice does not contain all the enzymes necessary for digesting all the different types of blood stuff.Saliva contains only carbohydrate – splitting enzymes; gastric juice contains both fat-and protein-splitting enzymes.One digestive juice cannot digest a particular type of food up to completion.Gastric juice digests protein up to the stage of peptone;pancreatic juice carries the digestion of peptone further up to lower peptide;the latter is digested completely up to amino acids by succusentericus.Reactions of the digestive juice are not all same (acid and alkaline). 2. Mastication. Mastication (chewing), in which food is crushed and mixed with saliva to form a bolus for swallowing, is a complex mechanism involving opening and closing of the jaw, secretion of saliva, and mixing of food with the tongue. Mastication is programmed in the lower brainstem. Masticatory movements comprise exceedingly complex and coordinated neuromuscular events. The masticatory activities require the coordinated activity of several groups of muscles attached primarily to the mandible. During mastication, there is an opening phase, a closing phase, and an occlusal phase. Figure 30. Teeth anatomy 48 3. Deglutition. Swallowing center. Regulation of deglutition Deglutition is the process of swallowing any food stuff into the body, particularly passing from the mouth, to the pharynx, and down through the esophagus. The food stuff ingested and swallowed is called a bolus.There are three stages of deglutition. The first stage is the voluntary closure of lips and tooth approximation. The second stage is the involuntary peristalsis so that the bolus would be propelled down the esophagus. At this stage, the nasal passage and pharyngeal airway are shut. The third stage is the passing of the bolus along the length of the esophagus and then into the stomach, again, through involuntary peristalsis. Chewing and initial phase of swallowing are carried out by skeletal musculature (fig. 31). The center of swallowing is located in a medulla. The innervation is provided with the trigeminal, glossopharyngeal and vagus nervous. The food lump is forced back by the tongue that starts a swallowing reflex through mechanoreceptors. The lump gets into a throat, the nasal cavity and airways are reflexively closed. Stretching of the top part of a gullet starts a peristaltic reflex which promotes the food down. Both ends of a gullet have sphincters: upper and lower. The lower sphincter protects mucous of a gullet from gastric juice. Figure31. Phases of swallowing 5. Mouth. Secretion of saliva. In a mouth the nutrition is split, moistened and there is an initial stage of splittng of carbohydrates with the participation of a saliva amylase (fig. 32).Saliva is formed in three larger paired salivary glands: parotid gland, submandibular gland, sublingual gland and in glands mucous checks, a palate and a pharynx. 49 Figure 32. Digestion in the oral cavity Salvia is formed in two stages. At first lobes of special cells make the isotonic primary saliva similar to the structure of blood plasma. At the second stage during passing across the removing canals of gland its ionic structure changes. pH saliva changes from subacidic to alkalescent. 6. Composition and functions of saliva. Total amount of saliva is 1200-1500 ml in 24 hours. Consistency of saliva is slightly cloudy (presence cells and mucin). Reaction of saliva is usually slightly alkaline (pH – 6,02-7,05). Composition of saliva:Water – 99,5%, Solids – 0,5%. 1) cellular constituents (epithelial cells); 2) inorganic salts(0,2%), NaCl, KCl, Ca2+ phosphate; 3)organic (0,3%): a) enzymes – amylases (ptyalin); lipase, lysozyme;b) mucin;c) urea, amino acids,ets.; 4) gases (O2, CO2); 5) kallikrein (vasodilatation). Functions of saliva. I. Mechanical functions. 1. It keeps the mouth moist and helps speech. 2. It helps in the process of mastication of the food stuff and in preparing it into a bolus, suitable for deglutition. 3. It dilutes hot and irritant substances and thus prevents injury to the mucous membrane. 4. Constant flow of saliva washes down the food debris and there by does not allow the bacteria to grow. II. Digestive functions.Amylase (ptyalin) and maltase (in traces) converts maltose into glucose. III. Excreted functions.Saliva excretes urea, heavy metals and antibiotics, ets. 50 IV. Helps in the sensation of taste.Saliva acts as a solvent and it thus essential for taste. V. Helps water balance.Saliva keeps the mouth moist. VI. Buffering action.Mainly bicarbonate and to a lesser extent phosphate and mucin present in saliva act as buffers. VII. Bacteriolytic action. Lysozyme – it dissolves the cell wall of many bacteria and finally kills them. 7. Regulation of saliva secretion by sympathetic and parasympathetic nervous Salivation is controlled by salivary center in medulla through autonomic nervous system. The salivation reflex under the influence of smell and taste of food is stimulated. Big salivary glands have a sympathetic and parasympathetic innervation. Salivary secretion is the only digestive secretion that controlled only neural factors (fig. 33). Figure 33. Salivation is regulated by central nervous system At increase of a tone of sympathetic nerves it is allocated with a little viscous and rich organic substance of saliva. At increase of a tone of parasympathetic nervous a lot of liquid saliva is emitted (fig. 34). 51 Figure 34. Parasympathetic nervous regulation of salivary secretion Parotid gland is located below the ear and over the masseter. Submandibular is under lower edge of mandible. Sublingual is deep to the tongue in floor of mouth. All salivary glands have ducts that empty into the oral cavity (exocrine glands). Serous glands –cell secrete a watery fluid – e.g. parotid. Mixed glands secrete both mucus and a serous fluid – e.g. submandibular and sublingual. Chemical digestion begins with enzyme salivary amylase and lingual lipase. 8. Stomach. Gastric glands. Gastric juice The stomach is a hollow organ that is part of the gastrointestinal system, and it is responsible for functions including the formation of chyme, synthesis of proteins necessary for vitamin absorption, microbial defenses, and propagates the peristaltic reflex. Contrary to popular thought, the stomach does not contribute to the absorption of any nutrients. This organ can is in the peritoneal cavity, located in the left upper abdominal quadrant or in the epigastric abdominal region that acts to relay ingested food between the nervous system and the endocrine system. Gastric acid secretion, peristaltic propulsion, and other physiologic functions of the stomach are finely controlled by the integration of the enteric nervous system, parasympathetic nervous system, and the secretion of various neurohormonal molecules (i.e., gastrin, HCl acid, intrinsic factor, bicarbonate, mucus, etc.) As a component of the alimentary canal (i.e., the tubal passageway for ingested food to be digested, absorbed, then excreted as waste), the stomach’s physiological function is structured around creating an environment where the food ingested can be safely acted on by proteolytic enzymes and acidic solutions. There are pathologic consequences that can develop with the failure of the gastric mucosa to isolate the lumenal contents from the surrounding peritoneal cavity. 52 The gastric juice is produced by stomach glands, located in its mucosa. The main cells secrete pepsinogens. These are proteases, proteolytic. Acid cells secret the hydrochloric acid and Kastl’s factor. Roles of the hydrochloric acid: activation of pepsinogen, that turns into pepsin; possesses bactericidal action; promotes opening of a pyloric sphincter; Kastl’s factor is a B12 vitamin carrier. Mucoid cells produce slime (mucin).The mucosa is composed of surface epithelial cells and glands. The basic structure of the stomach wall is similar to that of other regions of the gastrointestinal (GI) tract, therefore, the wall of the stomach consists of both mucosal and muscle layers. The stomach can be divided, based on its gross anatomy, into three major segments (fig. 35): 1) A specialized portion of the stomach called the cardia is located just distal to the gastroesophageal junction and is devoid of the acid-secreting parietal cells. 2) The body or corpus is the largest portion of the stomach; its most proximal region is called the fundus. 3) The distal portion of the stomach is called the antrum. The surface area of the gastric mucosa is substantially increased by the presence of gastric glands, which consist of a pit, a neck, and a base. These glands contain several cell types, including mucous, parietal, chief, and endocrine cells; endocrine cells also are present in both corpus and antrum. The surface epithelial cells, which have their own distinct structure and function, secrete image and mucus. Figure 35. Anatomy of the stomach Gastric juice is a thin watery acid digestive fluid secreted by glands in the mucous membrane of the stomach (fig. 36). 53 Figure 36. Composition of gastric juice 2. Regulation of gastric secretion by nervous and hormonal mechanisms A small amount of a gastric juice is developed at rest. It is basal secretion. At meal there is a stimulated secretion. There are three phases of gastric secretion (fig. 37): I. Complex-reflex (cerebral) phase. In this phase the gastric juice is allocated at a sight and flavor of food and at getting food into a mouth. It is appetite juice. II. Gastric phase of gastric secretion begins with the moment of getting of a food lump into a stomach. It includes nervous and humoral components. Nervous component: the food lump irritates the stomach mechanoreceptors. An impulse from them comes to a medulla to cores of a vagus and to intramural nervous plexuses. From there impulses go to a stomach. The terminations of these nerves allocate acetylcholine which strengthens secretion of the hydrochloric acid and pepsinogen. Humoral component: at getting of a food limp into a stomach a hormone gastrin is emitted. It contacts the receptors on the acid cells and strengthens the secretion of hydrochloric acid. Hormone gastron, on the contrary, slows down the secretion of hydrochloric acid. 54 Figure 37. Regulation of gastric secretion by nervous and hormonal mechanisms III. Intestinal phase of gastric secretion. It begins with the moment of a chymus getting into intestinal. This phase also includes nervous and humoral components. Thus, there is mainly inhibition of gastric secretion. Nervous component: the chymus irritates mechanoreceptor of intestine and an impulse comes to a medulla to cores of a vagus and intramural ganglion. From them impulses come to a stomach to fundic glands. Humoral component: getting of a chymus into a duodenum gut stimulates allocation of secretin and enterogastrone which slow down secretion of hydrochloric acid. Exercise 1. Influence of Saliva on Starch. Principle. Saliva contains chiefly salivary amylase orptyalin and traces of maltase. Salivary amylase (α-type) whose origin in the saliva, acts on starch (which is mostly amylopectin type) and contains straight chains held by l,4'-a-glucosidic linkages and branch chains whose branch points are l,6'-a-glucosidic linkages. Maltase acts on maltose. Salivary amylase (ptyalin) acts on boiled starch only. It cannot penetrate the intact cellulose covering of the unboiled starch particle. Optimum reaction is slightly acid (pH 6,5), but it can also act in neutral or slightly alkaline medium. Strong acid (such 55 as HC1 of gastric juice) destroys ptyalin. Optimum temperature is about 45°C. At 60°C it is destroyed. Ptyalin digests starch up to the maltose stage only. Equipment. Glass test tubes, marker, crude and boiled starch, saliva, dropping pipette, water, water bath, thermometer, a spirit-lamp, matchbox, solution of iodine, ice cubes. Procedure. Experience spends under the following scheme. Collect saliva in test tubes, preliminary to rinse a mouth pure water. Take 5 test tubes. 1 test tube – 2ml of saliva + 1 ml of boiled starch (paste). 2 test tube - 2 ml of saliva + crude starch. 3 test tube - 2 ml of boiled saliva (boil it above a spirit-lamp) + 1 ml of boiled starch. 4 test tube - 2 ml of saliva + 1 ml of boiled starch. 5 test tube - 2 ml of dog’s saliva + 1 ml of boiled starch. Place 1, 2, 3, 5 test tubes into the water bath with temperature +38-40°C, 4 test tube in a glass with ice for 30 minutes. After 30 minutes take out all test tubes and add a solution of iodine (do reaction of iodine and starch). The color of solution becomes dark blue if there is some starch in the solution (tab. 10). Table 10 Influence the saliva on the starch. №№ tube 1 2 3 4 5 Content of a test tube Reaction with iodine 2ml of saliva + 1 ml of boiled starch 2 ml of saliva + crude starch 2 ml of boiled saliva + 1 ml of boiled starch 2 ml of saliva + 1 ml of boiled starch (put in a glass with ice) 2 ml of dog’s saliva + 1 ml of boiled starch Observations, results and conclusion. Exercise 2. Determination of Mucin in Saliva. Equipment. Glass test tube, saliva, dropping pipette, water, 10 % solution of an acetic acid (CH3COOH). Procedure: 56 1. Pour 1 ml of 10 % solution of an acetic acid (CH3COOH) into the test tube with saliva. 2. Observe acid mucin in the form of white deposit settles on a test tube bottom. Observations, results and conclusion. Exercise 3. Influence of Gastric Juice on Milk. Principle. The main protein of milk is casein, a complex phosphoprotein. The enzyme rennin causes clotting of milk. It liberates paracasein from casein which is precipitated as calcium paracaseinate. Although rennin is absent in human stomach, but chymosin is present in infant stomach which does the same action of rennin of ruminants. Chymosin is distinct from pepsin. Other proteases presented in the stomach can convert casein to paracasein. Trypsin and chymotrypsin digestions convert it to phosphopeptones containing phosphoserine. Digestion of milk. Three constituents of milk require digestion: 1) Protein – Caseinogen. Lactalbuminand Lactglobulin are digested in the same way as proteins successively by pepsin, trypsin and erepsin. 2) Fats. They undergo the same process of digestion as other fats. 3) Lactose is digested by lactase to glucose and galactose. Equipment. Glass test tubes, marker, dropping pipette, water, water bath, thermometer, a spirit-lamp, matchbox, solution of gastric juice, milk, СаСО3. Procedure. Take 3 test tubes. 1 test tube - 2 ml of gastric juice + 2 ml of milk. 2 test tube - 2 ml of boiled gastric juice (boil it above a spirit-lamp) + 2 ml of milk. 3 test tube - 2 ml of gastric juice neutralized by СаСО3 + 2 ml of milk. Place all test tubes into the water bath at temperature + 40оС for 15 minutes. After 15 min. take out test tubes and observe the effect of clotting milk under influence of gastric juice (tab. 11). Table 11 Influence of gastric juice on milk. №№ tube 1 2 3 Content of a test tube 2 ml of gastric juice + 2 ml of mi 2 ml of boiled gastric juice + 2 ml of milk 2 ml of gastric juice neutralized by CaCO3 + 2 ml of milk 57 Result Observations, results and conclusion. Lesson 2. Digestive System. Digestion in Intestine. Role of Bile in Digestion. Questions for studying. 1. Stomach. Gastric glands. Gastric juice. 2. Digestion and absorption in the stomach. 3. Regulation of gastric secretion by nervous and hormonal mechanisms. 4. Pancreas. Pancreatic secretion. Regulation of pancreatic secretion. 5. Liver. Functions of the liver. Secretion of bile by the liver. 6. Small intestine. The regions of the small intestine. Secretion of the small intestine (mucus and intestinal digestive juices). Regulation of small intestinal secretion. 7. Intestinal contractions and motility. Peristalsis, segmentation. Slow waves. Function of small intestine. 8. Large intestine. Function of large intestine. The act of defecation. Digestion of carbohydrates, fats and proteins in gastrointestinal tract. 9. Anatomical basis and basic mechanisms of absorption. Fluid and electrolyte absorption in the intestine. 10. Regulation of the gastrointestinal tract. Autonomic nervous system, enteric nervous system, paracrine regulation, hormonal regulation. Pancreas. Pancreatic secretion. Regulation of pancreatic secretion Pancreatic juice has alkaline reaction due to bicarbonates (pH = 8-8,3). Enzymes are a part of pancreatic juice – proteolytic (trypsinogen, chemotrypsinogen, elastase, procarboxypeptidase A and B). They are developed by gland in an inactive form and activated only in a duodenum gleam by enzyme of enterokinase. - Lipase, splits fats; - Amylase (amylolytic enzyme), splits amylum and glycogen. There are two ways of pancreatic secretion regulation: Nervous (vagus strengthens secretion, sympathetic nerves block it) and humoral (hormones secretin and pancreozymin), (fig. 38). 58 Figure 38. Pancreatic juice and bile are secreted into the duodenum On the figure 39 is given a scheme of regulation of pancreatic juice secretion. Figure 39. Regulation of pancreatic juice secretion Liver. Secretion of bile by the liver Liver produces and releases bile (fig. 40). Components of bile secretin hepatocytes and epithelial cells come into bilious channels. Out of digestion process bile gathers in a gall 59 bladder. In the course of digestion bile sphincter is removed through Odi’sin a duodenum. One liter of bile is allocated per a day. The bile includes bilious acids. They emulsify fats, participate in absorption the long-chain of fatty acids.Also cholesterine, bilirubin, bicarbonates are a part of the bile. pH of bile is equal to seven point eight. Bilious acids from intestines are soaked up in blood, through a portal vein come back to a liver and there they secrete into bile again. It is a hepatoenteric circulation.Bile secretion is regulated: 1) Secretion by hypatocytes (parenchymal) depends on concentration of bilious acids in blood of a portal vein. 2) Ductal secretion is stimulated by hormone secretin. Also cholesterine, bilirubin, bicarbonates are a part of the bile, bile’s pH = 7,8. Bilious acids from intestines are soaked up in blood, through a portal vein come back to a liver and there they secrete into bile again. It is a hepatoenteric circulation. Bile secretion is regulated by: 1) hepatocytessecretion(parenchymal). It depends on concentration of bilious acids in blood of a portal vein; 2) Ductal secretion is stimulated by hormone secretin. Figure 40. The role of liver in digestion Small intestine There are two types of digestionin a small intestine: abdominal digestion and parietal digestion. Abdominal digestion happens in a gut cavity with the participation of enzymes of pancreatic juice, intestinal juice and bile. At the same time polymers of food are split to oligomer (fig. 41). Parietal digestion happens with the participation of enzymes of intestinal juice on a brush border of a small intestine. At the same time 60 oligomers are split to monomers and monomers are absorbed up.Components of intestinal juice are produced by Brunnerov and Lieberkuhn glands, enterocytes, epitheliocytes and beaker cells. In a small intestine there is a final digestion and absorption of food. Enterokinase, peptidase (the leucine amino-peptidase, nuclease and others split peptides to amino acid), amylase, lactase, sucrose, maltose, lipase are a part of intestinal juice. Cations and anions are also a part of intestinal juice. Intestinal juice pH is from 7.8 to 8.0.Regulation of intestinal secretion is carried out by local reflexes (with participation of a gastroenteric nervous system), a nervous system with participation of a CNS (stimulationof n. Vagus and sympathetic nerves block) and with participation of hormones (secretin, gastric inhibitory peptide). Figure 41. Two types of digestion in a small intestine: abdominal digestion and parietal digestion Intestinal contractions and motility The peristalsis of small intestine can be divided into propulsive (pushing) and nonpropulsive segmental movement (fig. 42). Nonpropulsive peristalsis movement promotes the best mixing of chymus and digestive juice. We distinguish nonpropulsive segmental activity, tonic contraction, pendular movements and fluctuation of fibers. At the end of digestion process one or two powerful waves of contraction of longitudinal muscles move the remain of contents of small intestine to large intestine. It is propulsive peristalsis. Motility of small intestinal is locally regulated with participation of gastroenteric nervous system, sympathetic nerves (block) also parasympathetic nervous (vagus stimulates) and with participation of hormones (gastrin, secretin, 61 glucagon).Motility of colon carries out two function: moving the fecal masses forward and storage the fecal masses. Normal antiperistalsis happens here (from an anus). Figure 42. Motility of a small and thick intestine Anatomical basis and basic mechanisms of absorption The product of food digestion is not absorbed in a mouth cavity because it is not split completely (fig. 43). In stomach water, mineral salts, a small amount of amino acids, weak solutions of alcohol are absorbed. The main absorption of products of splitting happens in a small intestine. After full digestion of the carbohydrates arriving with food there are formed monosaccharide: glucose, fructose and galactose. Fructose is absorbed passively into the blood. Glucose is absorbed in two stages: secondary active transport (symport with sodium ions) in enterocyte also from enterocyte in blood on the mechanism lite diffusion. The galactose is also transferred by secondary active transport. Proteins are split into amino acids, di- and tripeptide. Amino acids are absorbed by secondary active transport (symport with sodium ions) by means of special protein-carriers. Di- and tripeptide are also absorbed by secondary active transport (symport with hydrogen ions) by means of nonspecific carrier (transports various peptides) – protein. Fats are split into monoglycerides and fatty acids. Short- and medium – chain – length fatty acids are absorbed passively in blood. Long chain fatty acids with bilious acids form micelles in gut gleam. Micelles come into contact with a membrane of enterocyte. Bilious acids remain in a gut gleam.In enterocyte triglycerides are formed from fatty acids which with apoprotein form chylomicrons. Get to the lymph by an exocytosis. Fat – soluble vitamins A, D, E and K are similarly absorbed. 62 Water-soluble vitamins are absorbed by active transport with participation of special carriers. Figure 43. Absorption in various departments of a digestive tract Regulation of the gastrointestinal tract Gastrointestinal tract, gastroenteric nervous system includes bodies of neurons which lie in a wall digestive tubes and form full reflex arches. These reflex arches can work without CNS’ influence(fig.44). There are two big plexuses can be distinguished: intermuscular (Auerbac’s plexus, plexusmyentericus). It is located between layers of longitudinal and ring muscles and proceeds along all gastrointestinal tract. The second one is submucous nervous plexus (Meyssner`s` plexux, plexux submucosus). It lies in a 63 submucous layer. Both plexuses innervate a smooth, blood vessels and cells of an epithelium of a digestive tube. Value of own nervous system of a gastrointestinal tract is visible on the example of illness of Girshprung – congential defect of both plexuses. Babies with this pathology arenot capable of empting an intestine independently. The gastrointestinal tract innervation is also carried out by means of a vegetative nervous system (a parasympathetic a sympathetic innervation – efferent nerves) and a visceral afferent innervation. Parasympathetic preganglionic fibers come in structure of Nerves Vagus from a medulla and as a part of pelvic nerves from sacrum department of a spinal cord. The parasympathetic system sends fibers to exciting and inhibitory cells of an intermuscular nervous plexus. Preganglionic sympathetic fibers begin from cells in side horns of sternal-lumbar department of a spinal cord. Their axons innervate blood vessels and approach cells of nervous plexuses, inhibiting their exciting neurons.Visceral afferent begin in a wall of a gastrointestinal tract and as a part of the n.vagus, n.splanchnice and n.pelvici go to a medulla, sympathetic ganglia and a spinal cord. Figure 44. The innervation of the gastrointestinal tract. Exercise 1. Role of Bile in Digestion. Principle. The most abundant substance secreted in the bile is bile salts, but there are also bilirubin, cholesterol, lecithin and the usual electrolytes of plasma, secreted or excreted in large concentrations. In concentrating process in gallbladder, water and large portions of electrolytes are reabsorbed by gallbladder mucosa, but essentially all other constituents, including especially bile salts and lipid substances cholesterol and lecithin, are not reabsorbed and therefore become highly concentrated in gallbladder bile. 64 It is very important that bile contains no digestive enzyme because of the presence of bile salts which 1) have a detergent action on the fat particles in food and in other words help to emulsify fat globules so that they can be digested by the intestinal lipases, 2) increases the activity of intestinal lipase and other proteolytic enzymes, and 3) help in the absorption of fatty acids, monoglycerides, cholesterol, and other lipids from intestinal tract. Bile is secreted continually by the liver and then the bile is stored in the gallbladder until it is needed in the gut. The gallbladder then empties the bile into the intestine in response to cholecystokinin. Purpose. To investigate the emulsifying or detergent function of bile and to observe the influence of bile by the filtration of oil. Equipment. Glass test tubes, glass funnels, glass slides, dropping pipettes, paper filters, bile, vegetative oil, water. Procedure. 1. Moisten thoroughly one of the paper filter with bile, another – with water. 2. Put both paper filters into glasses funnels. 3. Pour 2 ml vegetable oil on the paper filters and after 45 min study the filtration of oil through the paper filters. Observations, results and conclusion. Exercise 2. Identification Test on Bile Pigments and Bile Salts. Principle. Bile consists of salts of bilious acids and bile acids: taurocholic and glycocholic acids. Equipment. Glass test tubes, dropping pipettes, bile, 10% solution of sugar,H2SO4, water. Procedure. 1. Pour 0,5 ml of bile into the test tube and add 5-6 drops 10% solution of sugar. 2. Add to the test solution very carefully 2 ml H2SO4. 3.Put the test tube into the glass with cold water. 4. Observe the color of mixture becomes red in some minutes. It is positive reaction of presence of taurocholic and glycocholic acids in the bile. Observations, results and conclusion. Exercise 3. Gmelin’s Test on Bile Pigments. Principle. The bile pigments are porphyrin compounds and constitute about 15-20% of the total solids of the liver bile. They can be detected by Gmelin’s test. 65 Equipment. Glass test tubes, dropping pipettes, bile, HNO3 (Nitric acid), water. Procedure. 1. Pour 1 ml HNO3 in one test-tube and pour 2 ml bile to another test tube. 2. Add very carefully bile to Nitric acid avoiding mixing of liquids. 3. Observe formation of multi-colored rings on border of two liquids. The mixture has positive reaction, which shows different degree of oxidation of bilirubin. Observations, results and conclusion. 66 THEME 4. METABOLISM AND NUTRITION Questions for studying. 1. Metabolism and interchange of energy in human being. Plastic and energy role of nutrients. 2. Laws of thermodynamics in living organisms. 3. Energy storage (anabolism) and energy liberation (catabolism). 4. Energy balance. Positive energy balance, negative energy balance. 5. Methods of determine energy expenditure. 6. Direct calorimetry. 7. Indirect calorimetry. Complete and incomplete gas analysis. 8. Respiratory quotient (RQ) and its significance for calculation energy expenditure. Respiratory quotient during physical activity. 9. Basal metabolism, conditions for its determination, significance. Factors which influence on level of basal metabolism. 10. Positive energy balance, negative energy balance. Basal metabolic rate. 11. Labor exchange energy consumption during different kinds of labor. 12. Irreplaceable componentry of food. 13. Plastic and energy value of nutrients. 14. Role of trace elements and vitamins in nutrition. 15. Ballast substances – kinds, physiological significance. 16. Replaceable componentry of food. 17. Food intake. Regulation of food intake. 18. Energy equivalents of the carbohydrate, protein and lipid. Nutritional equipment. Nitrogenous balance. 19. Physiological fundamentals of clinical nutrition. The specific function of cell metabolism is energy transformation subordinated to laws of thermodynamics. Fermentative breaking up organic substances (catabolism) is accompanied with discharge of energy. And fermentative synthesis (anabolism) is accompanied with consumption of energy. Metabolism of carbohydrate and lipids is primary process formative energy. The definition metabolism with meaning literally “change” is used to refer to all the chemical and energy transformations that occur in the body. The body’s metabolism encompasses all of the chemical processes involved in energy production, energy release, and growth. These processes can be anabolic (formation of substances) or catabolic (breakdown of substances). 67 The animal organism oxidizes carbohydrates, proteins, and fats, producing principally CO2, H2O and the energy necessary for life processes. CO2, H2O, and energy are also produced when food is burned outside the body. However, in the body, oxidation is not a one-step, semiexplosive reaction but a complex, slow, stepwise process called catabolism, which liberates energy in small, usable amounts. Energy can be stored in the body in the form of special energy – in rich phosphate compounds and in the form of proteins, fats, and complex carbohydrates synthesized from simpler molecules. Formation of these substances by processes that take up rather than liberate energy is called anabolism. Both anabolism and catabolism are reversible chemical reactions but growth and loss of tissue mass (breakdown of tissue) depends on predominance of one over the opposite reaction. Metabolism may be broadly defined as the sum of all chemical and physical processes involved in producing and expending energy from exogenous and endogenous sources, in synthesizing and degrading structural and functional tissue components, and in disposing of resultant waste products. These processes are of fundamental importance to all cells, tissues, organs, and systems. Cells of internal organs consume about 25% of all chemical energy for their needs. It can be spent, for example, for active transport, protein synthesis, contraction of smooth and skeletal muscles. Subsequently, this energy is converted into heat. The intensity of energy exchange is usually estimated in units of thermal energy. In the international SI system of units, the joule (J) or kcal is adopted as the basic unit of energy, 1kcal = 4.19 kJ. From 100% of the food energy of a modern person, its consumption can be represented as follows: 1. 50-60% - spent on life support 2. 10-15% - for the assimilation of the food itself (specific-dynamic effect of food) 3. 30-40% - to ensure human activity, including: work in production, at home, outdoor activities, physical education. The energy balance of the body is calculated as the difference between the incoming and outgoing energy. Energy exchange in an adult is considered balanced if the income is equal to the consumption. If the income is higher than the consumption, the energy balance is called positive. If the expense exceeds the income - negative. The body's energy consumption depends on: I. Individual typological factors: 1. Surfaces of the body and masses. 2. Age (the child is 4 times higher). 68 3. Gender (women are 5% lower than men, except for pregnancy). 4. Genetic features (severity of non-phosphorylating oxidation - insensitivity to cold, hyperthyroidism). 5. Body temperature (an increase in body temperature by 1 ° C, accelerating chemical reactions, increases energy exchange by 5%). II. Environmental conditions: 1. Climate (high temperature in the tropics does not require large energy consumption; in a cold climate, energy exchange increases by 5-7 times). 2. Biorhythms: daily - during the day energy exchange is higher than at night; seasonal - summer and winter. 3. Psycho-emotional environment: the modern standard of beauty (fashion) and food consumption; food traditions. Energy consumption is determined by the value of the main exchange. Basal metabolic rate (BMR) is the amount of energy expended to maintain the vital activity of the body and the constancy of body temperature under conditions of physiological rest. The basal metabolism in an adult is about 1 kcal per 1 kg of body weight per hour (1 kcal / kg / hour) and is equal to - 1,700 kcal / day for men, and 1,500 kcal / day for women, which is 10-15% less than in men. Factors affecting basal metabolism are from gender, age, weight and body length. The same person from 20 to 40 years old can have fluctuations in basal metabolism from ± 7 to ± 10% (normal). The purpose of determining the basal metabolic rate is to clarify the type of exchange, that is, to clarify the question of the presence of deviations from an energetically balanced state. Research is carried out under standard conditions: - at a comfortable temperature (18-20°С); - in a calm state, because emotional stress increase metabolism; - lie down, but do not sleep, because sleep reduces energy metabolism by about 10%; - on an empty stomach, at least 12 hours after the last meal. Energy consumption per day (total metabolism) consists of the following values: 1. Basic exchange - BMR 2. The specific dynamic action of food (DAF) is the cost of energy for motility, secretion and absorption processes in the gastrointestinal tract. 3. Working increase - energy consumption during labor activity. During physical exertion, the metabolic rate increases depending on the degree of physical exertion. The more intense the work, the greater the value of the work 69 exchange. The acceleration of metabolism also occurs during mental stress, although this is not only related to the needs of the brain. Predominantly, the increase in metabolism during the period of mental work is a reflex increase in muscle tone. Accounting for energy output 1. Determination of the BMR 2. Definition of general exchange. Accounting for the arrival of energy 1. Accounting for the amount of nutrients, consumed per day. 2. Calculation of the caloric value of nutrients substances, i.e. the total amount of energy, obtained with various nutritional substances. According to the obtained values of energy income and consumption, the energy balance is estimated. Methods for determining energy consumption (output). I. Direct calorimetry. II. Indirect calorimetry: 1. Method of complete gas analysis. 2. Method of incomplete gas analysis. 3. Calculation of the proper basal metabolism according to tables and formulas. Exercise 1. Methods for determination of energy output. Principle. Energy output can be determined by measuring the heat production of an individual over a measured amount of time. I. Direct calorimetry. A biocalorimeter is a completely sealed and heat-insulated chamber, into which oxygen is supplied from special cylinders and excess carbon dioxide and water vapor are removed. Inside the chamber are pipes filled with water. During the movement of water through the pipes, it gradually heats up due to the heat generated by the test subjects in the chamber (fig. 45). Taking into account the amount of water flowing through the pipes and accumulating in a special tank, as well as measuring its temperature with a special thermometer, the amount of heat that was released over a certain period of time (per hour, day) is calculated. Food and waste products are fed and removed through a special window. The pump allows air to be removed and driven through the soda lime to remove excess CO2, and also through sulfuric acid to absorb excess water. This method is the most accurate, since it directly takes into account the amount of heat released by the body. 70 Figure 45. Biocalorimeter Benedict II. Indirect calorimetry. The process of heat generation can be judged indirectly, based on the amount of oxygen consumed and carbon dioxide released, since the formation of heat in the body is based on redox processes involving these gases. 1.Method of complete gas analysis. The subject inspires atmospheric air. The expired air is collected in special air-tight bag known as Douglas bag (fig. 46). Figure 46. Douglas bag The total volume of expired air collected in the bag at the end of experiment is measured and the samples are analyzed for CO2 and O2 in Haldane gas-analysis apparatus or in Scholander's micro-gas analysis apparatus. The amount of oxygen consumed and carbon dioxide given off is calculated from the difference of percentage of O2 and CO2 71 between the atmospheric and expiratory air. The RQ and the caloric value of O 2 can then be determined. The Douglas bag method can conveniently be used to measure the energy output during different types of activities. Respiratory quotient (RQ) It is the ratio of the volume of CO2 produced by the volume of O2 consumed during a given time. In healthy adult it is 0, 85 for a mixed diet. This is done by measuring the volume of O2 consumed and CO2 produced during a given time with the help of Douglas bag and other similar instruments. Factors affecting RQ. 1. Role of diet. a) In case of carbohydrate diet the RQ is unity. Because in carbohydrate diet the volume of CO2 produced is same as the volume of oxygen consumed. This is due to the fact that, in the carbohydrate molecule, the amount of O2 present is just sufficient to oxidize the H present in the same molecule. Hence, external oxygen is necessary only to convert the C of the molecule into CO2 . So that the volume of O2 consumed and the volume of CO2 produced will the same. This is represented in the following equation: C6H12O6 +6CO2=6CO2+6H2O RQ=6CO2 / 6O2=1,0 b) In case of fats the RQ will be lowest and is about 0,7; because fat is an oxygenpoor compound. The oxygen present in it cannot fully oxidize the H of the molecule. So that, oxygen consumed from outside, is used for two purposes: first, for oxidizing C and producing CO2 and secondly, for oxidizing H giving H2O. Consequently, the volume of CO2 produced will be less than the volume of O2 utilized. Hence, RQ will fall and will be about 0, 7. c) In case of proteins the RQ is about 0, 8. In any condition where fats are burnt chiefly (starvation, advanced diabetes, etc.), the RQ is about 0,7. Whereas with a predominant carbohydrate combustion the RQ is approach 1,0. 2. Effect of interconversion in the body. When carbohydrates are converted into fats in the body, RQ will rise. Because in the process an oxygen-rich substances converted into an oxygen-poor compound. So that some amount of O2 liberated from carbohydrate, will be utilized for purposes of oxidation. Consequently, less oxygen will be needed from outside. Hence, the amount of CO2 produced will be more than the amount of O2 consumed. So that RQ will rise. When fat is converted into carbohydrate just the opposite effects will be produces and RQ will fall. 72 It is therefore evident that RQ value will indicate the following: 1. the type of foodstuff burning in the body or 2. the nature of conversion of one foodstuff into another in the body. 3. Acidosis. During acidosis CO2 output is greater than O2 consumption so RQ rises. 4. Alkalosis. Here the RQ will fall, because respiration is depressed and CO2 will be retained in the body (i.e., less CO2 is produced). 5. Rise of body temperature will cause increased breathing and thereby will wash out more CO2. It may increase RQ as in acidosis. 6. Diabetes. Little carbohydrate is burning; energy is supplied mainly by oxidation of fats. Hence, RQ will fall. In such cases, if insulin is injected, carbohydrates will start burning and RQ will rise. 7. Muscular exercise. Value of determining RQ. 1. RQ acts as a guide, as to the type of food burning or the nature of synthesis taking place in the whole body as well as a particular organ. 2. RQ is very helpful in determining metabolic rate. 3. Non-protein RQ helps in finding-out the proportion of the three foodstuffs that are being utilized in the body. 4. Determination of RQ helps in the diagnosis of various pathological conditions, such as acidosis, etc. Table 12 Amount of heat produced per liter of O2 consumed at different RQ. RQ 0,71 0.75 0,80 0,85 0,90 0,95 1,0 Calories evolved per liter of O2 consumed 4,795 4,829 4,875 4,921 4,967 5,012 5,058 Example. 1. The probationer expired 30 liters of air during 5 minutes. This amount of air contains about 17% of O2 and 3, 5 % of CO2. The atmospheric air consists of 73 about 215 of O2; the expired air consists of 17% of O2. Consequently, organism takes up (21-17) 4 ml of O2 and excrete 3, 5 ml of CO2. Determine the RQ: RQ = O2 consumed / CO2 produced RQ = 3,5 /4.0 = 0,87. 2. Than determine the oxygen calorific equivalent using the table 1. It is 4, 88. 3. Determine the Respiratory Minute Volume (RMV): RMV = 30 litres / 5 min = 6 liters per minute. 4. Calculate oxygen using per minute: 4 ml of O2 are used from 100 ml of air X ml of O2 are used from 6000 ml of air So: X = (6000x4):100 = 240 ml = 0, 24 litters. 5. Calculate the consumption of energy per minute by equalization: oxygen using per minute multiply by oxygen calorific equivalent: 0, 24 x 4, 88 = 1б17 kcal. 6. Calculate the consumption of energy per hour: 1,17 х 60 = 70,2 kcal. 7. Calculate the consumption of energy per 24 hours: 70,2 x 24 = 1684 kcal. Due to complications involved in direct calorimetry, heat output is calculated indirectly from O2 consumption and CO2 output. 2. Method of incomplete gas analysis. Various apparatus may be used for this purpose, such as Benedict – Roth apparatus and other apparatus of similar type. Benedict – Roth apparatus is very useful for clinical purposes as the heat production can be calculated in this type of apparatus by the oxygen consumption only without determination of CO2 elimination. The subject is allowed to breathe from O2 reservoir through a mouthpiece, the nose being clipped. The CO2 eliminated in expiration is absorbed by soda lime to keep the O2 reservoir pure. The fall in the level of O2 during the experiment is recorded which gives the value of CO2 consumption at the specified time. In this method, respiratory quotient (RQ) of the subject is not determined and the average RQ is taken as 0, 82. 4,825 Cal of heat is liberated at this RQ when 1 liter of O2 consumed. The energy output during the experiment is calculated by multiplying liters of O2 consumed at that time with 4,825. 74 The following table shows the amount of heat produced per liter of O 2 consumed, at different RQ. Exercise 2. The Basal metabolism calculation by Garris – Benedict’s tables. Equipment: auxanometer, floor scales, standard tables for determination the BMR amounts. Procedure. 1. Determine probationer’s body weight and growth. Starting from sex, body weight, age and growth determine the BMR amounts by appropriate tables. Computational exercise. Man is 25 years old, growth - 180 сm, body weight - 75 kg. Calculation table consists of two parts: table A and table B. Find out the probationer's weight in table A (75 kg) and against it find number (1098 kcal). 2. Find out probationer’s age across on table B (25 years), on vertical line - growth (180 cm) and find number (732 kcal) at the intersection of lines. Sum up the number from table A (1098 kcal) and table B (732 kcal). The sum is 1830 kcal / day, average statistical level of the probationer’s BMR. 3. Calculate your own BMR by tables. Observations, results and conclusion. Exercise 3. Determination of Energy Output Diversion by Reed’s nomogram and hemodynamic index. Principle. The intensity of the metabolic processes which are proceeding in the organism is accompanied with some changes in the internal organs activity, in case, from the heart-vascular system side. This relation was investigated by researcher Reed. His formula and nomogram allow estimate the percentage of deviation of probationer’s main exchange (energy output) from normal level. If you know the probationer’s pulse frequency and AD value, you can find out a diversion percent of energy output from normal level by Reed’s formula and Reed’s nomogram. Procedure. 75 1. It is necessary follow some conditions: probationer is lying on a medical couch; he has an empty stomach, he has not any physical and psychical stress, comfortable temperature in the room. 2. Determine a probationer’s pulse, measure diastolic and systolic AD. Count a pulse pressure (PP = AD systolic – AD diastolic). 3. Counting method of diversion percent (DP) with Reed’s formula: DP = 0,75 x ( HBF + PP*0,74)-72; The result shows a divergence percent of energy output (the main exchange) from normal level. 4. Counting method of diversion percent (DP) with Reed’s Nomogram Match amounts of pulse frequency on the left scale and pulse pressure on the right scale on the Reed’s nomogram (fig. 47). The crossing point on the middle line shows the main exchange divergence value from normal in percent. Divergence till 10% - is normal. Figure 47. Reed’s Nomogram. Observations, results and conclusion. Make a conclusion about taken results of your diversion percent of energy output to the normal level. 76 Nutritional requirements. Regulation of food intake. The aim of the science of nutrition is the determination of the kinds and amounts of foods that promote health and well-being. This includes not only the problems of undernutrition but those of overnutrition, taste, and availability. However, certain substances are essential constituents of any human diet. Essential Dietary Components An optimal diet includes, in addition to sufficient water, adequate calories, protein, fat, minerals, and vitamins Caloric Intake and Distribution. The caloric value of the dietary intake must be approximately equal to the energy expended if body weight is to be maintained. In addition to the 2000 kcal/d necessary to meet basal needs, 500-2500 kcal/d (or more) are required to meet the energy demands of daily activities. The distribution of the calories among carbohydrate, protein, and fat is determined partly by physiologic factors and partly by taste and economic consideration. A daily protein intake of 1 g/kg body weight to supply the eight nutritionally essential amino acids and other amino acids is desirable. The source of the protein is also important. Grade I proteins, the animal proteins of meat, fish, and eggs, contain amino acids in approximately the proportions required for protein synthesis and other uses. Some of the plant proteins are also grade I, but most are grade II because they supply different proportions of amino acid and some lack one or more of the essential amino acids. Protein needs can be met with a mixture of grade II proteins, but the intake must be large because of the amino acid wastage. Fat is the most compact form of food, it supplies 9,3 kcal/g. However, it is also the most expensive food. Indeed, internationally there is a reasonably good positive correlation between fat intake and standard of living. In the past, Western diets have contained large amounts (100 g/d or more). The evidence indicating that a high unsaturated/saturated fat ratio in the diet is of value in the prevention of atherosclerosis and the current interest in preventing obesity may change this. In Central and South American Indian communities where corn (carbohydrate) is the dietary staple, adults live without ill effects for years on a very low fat intake. Therefore, provided that the needs for essential fatty acids are met, a low fat intake does not seem to be harmful, and a diet low in saturated fats is desirable. Carbohydrate is the cheapest source of calories and provides 50% or more of the 77 calories in most diets. In the average middle-class American diet, approximately 50% of the calories come from carbohydrate, 15% from protein, and 35% from fat. When calculating dietary needs, it is usual to meet the protein requirement first and then split the remaining calories between fat and carbohydrate, depending upon taste, income, and other factors. For example, a 65-kg man who is moderately active needs about 2800 kcal/d. He should eat at least 65 g of protein daily, supplying 267 (65 × 4.1) kcal. Some of this should be grade I protein. A reasonable figure for fat intake is 50-60 g. The rest of the caloric requirement can be met by supplying carbohydrate. Exercise 4. Analysis of the energy value of the daily student’s diet Principle. Caloric value of the daily diet must cover all energy wishes of the person with a registration of the food adaptation. Procedure. 1. Compose approximate diet for one day for your own. 2. Calculate the energy value of your daily diet using the tables 13,14. Observations, results and conclusion. Make a conclusion about accordance or discrepancy of normal data, common energy wastes (also with calculation of the work groups, age and etc.). Exercise 5. Composing of the proper food diet with calculation of rational nourishment principals. Principle. During the constitution of the diet, next indicators are calculated: Proportion between proteins, lipids, carbohydrates is taken: 1:1,1:4,1 – For men and women , who are occupied with a intellectual work; 1:1,3:5 – heavy physical work. Daily energy value of the diet, taken as 100%, must supply proteins by 13%, lipids – by 33%, carbohydrates – by 54%. Animal’s origin proteins must constitute 55% of the common proteins number. Vegetative oils as indispensable fat acids source must compose till 30% of the common lipids number. Carbohydrates: starch – 75-80%, easily adoptable carbohydrates – 15-20%, cellulose and pectin – 5%. Proportion of calcium, phosphorus and magnesium must be 1:1,5:0,5. Nourishments norms – daily dozes of the nutritious substances, which are indicating balanced keeping in the food diet of proteins, lipids, carbohydrates, and also vitamins, 78 mineral substances and water. These foods must provide a great self feeling, health and working ability of a person in the normal conditions. Nourishment norms depends on the gender, age, physical and mental working and other factors. Due to this data, adult man with a lesser muscular loading must gain daily with food: proteins 100-120 g, lipids 100g, carbohydrates 400-500g. Energy waste in this state is 50-60 kcal due to 1 kg of the body weight daily. Procedure. 1. Compose students’ diet, due to the next data: A student is listening lections during 6 hours, works by his own 4 hours, free of studying 6 hours sleeps 8 hours. He is 20 years old, 165 cm height, 65 kg weight. Energy wastes during the lections 145%, during self studying 160%, during free time – 220% of the main exchange value. 2. Identify the main exchange value by the Benedickt’s formula: a) formula for men: K=66,473+ (13,752xW) + (5,003 x S) – (6,755 x a). b) formula for women: К = 655,096 + (9,563 x W) + (1,850 x S) - (4,676 . а), where К — common warmth production, kcal; W — body weight, kg; S — height, cm; а — age. 3. Put the meanings of the height and weight to the formula due to the gender of the probationer. 4. Identify energy wastes during the lections listening, during the self studying, relaxation and sleeping 5. Gained results add between each other and get a daily energy wastes. 6. Count the amount of proteins, lipids and carbohydrates (g), which is necessary to add into the daily student’s diet, to compensate his energy wastes. 7. With the help of chemical composition table compose the diet for three nourishments. Table 13 Nutritious substances and their energy value (kcal) 79 Products proteins lipids wheat flour cereals: • buckwheat • semolina • millet rice macaroni marrowfat bread loaf of bread water-melon green peas cabbage • white cabbage • cauliflower • sauerkraut potatoes potato starch bulb onion carrots cucumber garden radishes red beet tomato orange grape cranberries apple fungi: • fresh • dried fungi honey sugar chocolate cocoa shortcake 5,6 1,3 carbohy drates 36,0 13,4 11,2 11,8 7,5 11,0 32,8 5,9 9,0 0,3 5,0 2,5 0,8 2,4 1,0 0,9 2,3 0,8 1,3 - 66,5 73,3 68,4 74,4 74,2 52,0 47,3 51,4 4,8 13,3 351 354 352 346 358 329 326 260 21 75 1,4 1,5 0,3 1,4 2,5 1,1 0,8 0,9 1,0 0,5 0,7 0,4 0,5 0,3 - 4,3 2,8 2,3 14,7 84,7 8,1 6,0 2,8 3,1 8,1 3,6 6,3 14,9 4,7 10,0 23 18 17 66 351 43 29 15 16 37 19 33 66 33 44 4,2 36,0 0,4 6,3 23,6 12,8 0,4 4,0 37,2 20,2 9,0 2,3 23,5 81,3 99,9 53,2 40,2 69,5 30 281 335 410 590 449 421 80 kcal 160 sponge-cake plum jam • butter • vegetable oil • cow milk curdled milk sour cream cottage cheese Dutch cheese mutton beef pork boiled sausage chicken-meat small sausage hen's egg fluvial perch pike perch cod herring 5,6 0,2 39,1 - 40,5 74,7 553 310 0,5 3,3 3,5 33 2,5 13,2 21,7 12,6 14,2 14,2 12,3 9,7 14,7 10,7 8,9 9,7 13,7 83,5 99,8 3,7 3,5 3,7 30,0 20,0 28,4 13,1 8,3 18,5 14,8 6,3 10,0 10,3 0,4 0,4 0,3 0,5 4,7 16,4 3,9 2,3 2,4 1,2 — 2,4 0,4 — — — 781 928 77 144 67 203 253 361 173 135 230 193 98 159 142 40 43 59 Table 14 Energy value of some food. rations Portion, g. 150 150 150 1 piece (115 g) 1 piece (125 g) 1 slice (9 g) 1 slice (30 g) 150 1/2 of fish, 60 g 1 glass (250 g) 1. steak 2. rich pork 3. pigeon-chest 4. beef small sausage 5. milk sausage 6. boiled sausage 81 Energy value of one portion, kсal. 357 528 168 350 466 15 257 138 110 92 7. lard 1/ glass (80 g) 1 slice (30 g) 1 piece (30 g) 1 table-spoon (30 g) 1 piece (60 g) 1 table-spoon. (12 g) 1 table-spoon (10 g) 1 table-spoon (15 g) 1 table-spoon (15 g) 1 portion (25 g) 1 portion (60 g) 1 slice 1 slice (40 g) 8. filleted perch 9. freshly-saltedherring 10. milk 3,5 % 11. kefir 1,5 % 12. Edam 45 % 13. processed cheese 14. rich cottage cheese 15. hen's egg 16. butter 17. vegetable oil 18. mayonnaise 19. buckwheat 20. corn flakes 21. cooked rice 22. rye-bread 23. pizza Observations, results and conclusion. THEME 5. HIGHEST NERVOUS ACTIVITY 82 90 102 103 55 90 95 75 54 94 73 82 106 Lesson 1. Methods of Investigation of Cerebral Hemispheres. Cortex Functions. Investigation of Active Bioelectrical Processes in Brain. Functional Asymmetry of Hemispheres Performing Sensor and Motor Functions. Questions for studying. 1. Structure of cerebral cortex and functions of its different layers. 2. Functions of cerebrum. 3. Cerebral lateralization. 4. Areas in brain which control motor, sensory and other activities. 5. Association areas of cerebrum. 6. Methods of studying the cortex functions. 7. Electrical activity of the cerebral cortex. Electroencephalography. 8. Clinical use of the electroencephalogram (EEG). 9. The different types of brain waves (alpha, beta, theta and delta waves). 10.Physiological basis of EEG. Mechanism of desynchronization and synchronization. 11.Cortical evoked potential. 12.Cerebral Dominance. Electrical activity of the cerebral cortex. The electrical activity of the brain and cerebral cortex is the summary activity of different types of neurons and nerve fibres. A large number of neurons, synapses and various properties of synapses, such as inhibition, summation, facilitation- etc., are integrated together to give rise rhythmic electrical potential changes which can be recorded by electroencephalograph. The electrical activity of the cerebral cortex is divided into two types- spontaneous and evoked. The spontaneous electrical activity of the brain is the electroencephalogram (EEG) which is described below. Electroencephalography Like other cells, nerve cells also show changes of electrical potential during activity. With an instrument called electroencephalograph the waves can be detected, amplified and recorded. Such record is called electroencephalogram. Hans Berger, who was a German scientist, first introduced the term electroencephalogram (EEG). Berger in 1929 recorded changes in the electrical potential by placing electrodes on the scalp of the human beings. These electrical potentials were later investigated by Adrian and Matthews. Electroencephalogram (EEG) I. Spontaneous electrical activity. 83 The spontaneous electrical activity from the brain is recorded by the electroencephalographic machine with the help of scalp electrodes through the lead is called electroencephalogram which has been most effectively studied in human beings. Electroencephalographic records may be bipolar or unipolar and consists of different types of rhythmic waves. Bipolar is the record of potential fluctuations between two cortical electrodes, whereas the unipolar electrode is the record of potential differences between a cortical electrode and an indifferent electrode placed on some part of the body. Alpha, beta, theta and delta waves. In normal human subjects four types of waves are recorded, e.g., alpha, beta, theta and delta (fig 48). Figure 48. Diagrammatic representation of normal electroencephalographic α-alpha, β-beta, θ- theta and Δ-delta waves. Alpha waves. Alpha waves (rhythm) are the most prominent synchronised rhythmic potential changes, found with eyes closed or in dark, when the brain is under quiet rest. Usually found in the occipital cortex, but also obtained in frontal and parietal regions. This rhythm is marked in occipitoparietal region. Any mental exertion, even with closed eyes, will disturb. The alpha waves disappear when eyes remain open. This alpha wave is disappeared with a replacement of fast, irregular and low voltage activity without any dominant frequency just after opening the eye. This phenomenon is known as α -block. This α-block is due to synchronisation of regular (synchronised) α-rhythm by any kind of sensory stimulation. This desynchronisation response is also called arousal or alerting response (fig 49). 84 Figure 49. Diagram shows the change of alpha rhythm after opening and closing eyes. Visual stimuli, mental concentration, etc., abolish alpha waves. During deep sleep, the alpha waves disappear entirely and with a specific mental activity the alpha waves are replaced by asynchronous high frequency low-voltage waves. The dream is accompanied by alpha waves. The alpha waves cannot occur without the connection of the reticular activating system. It is postulated that the reverberation between thalamus and cerebral cortex and also the recruiting response of the thalamus are responsible for the cause of the periodicity of the alpha waves. Rate—8-12 Hz or cycles per second, amplitude—highest average 50 microvolt. Beta waves. Usually found in the parietal and frontal regions of the scalp. Rate— about 18 -60 Hz, amitude—5-10 microvolts (less than alpha waves)—low voltage fast waves (fig 52). Types: Beta I waves have a frequency about twice that of alpha waves and disappear during reaction of mental activity, but such waves are replaced by asynchronous lowvoltage waves. Beta II waves appear during tension or during intense activation of the central nervous system. Figure 50. Normal electroencephalogram from different cortical areas in man showing alpha and beta waves during awake with closed eyes. 85 Theta waves. Usually found over the parietal and temporal regions. In children between the ages two and five year’s theta waves are prominent. Rate—4-8 Hz. Amplitude—100-150 microvolt. Delta waves. It is postulated that the delta waves occur due to separation of the cerebral cortex from the reticular activating system Rarely found in normal adults during waking periods, but usually found during deep sleep and in serious organic brain disease. In severe hypoxia and also in hypoglycemia 5-waves appear frequently. In infancy it appears both during deep sleep and waking. Rate— minimum 0,5-3,5 Hz or cycles per second, amplitude—variable 200~400 microvolt—high voltage slow-waves. Physiological basis of EEG Source of EEG. Originally it was of opinion that EEG waves are the summated action potential of cortical cells discharging in a volume conductor. But present concept is changed and it is due to current flow in the fluctuating dipoles formed on the dendrites of the cortical cells and cell bodies. Cortical dendrites are the forest of densely units placed in the superficial layers of the cerebral cortex. Dendrites are the sites of non propagated hyperpolarizing and hyperpolarizing local potential changes in the excitatory and inhibitory axo-dendritic synapses. Dendrites are not the processes for conduction and do not propagate action potentials. Action potentials are propagated through the axonic terminals. When the excitatory axodendritic synapses are activated, current flow into and out in between the cell body and axo-dendritic endings, causing a wave-like potential fluctuation in the volume conductor. (fig 51). Thus EEG is the potential fluctuation in volume conductor, but not the action potential and is conducted through the axon only. Thus the dipole formed in between the dendrites and the cell bodies fluctuates constantly due Figure 51. to the excitatory and inhibitory axo-dendritic synapses. Mechanism of desynchxonisation and synchronisation. Definite pattern с a-rhythm is due to synchronised activity of the many dendritic units. When the synchronised activities of the dendritic unit are disturbed by incoming different sensory impulses, the synchronized pattern of a-rhythm no longer persists and is replaced by desynchronised pattern of irregular low voltage activity. For the genesis of synchronised wave pattern, two factors are responsible, such as synchronising effects of two parallel nerve fibres, and the influences of impulses from 86 the thalamus and the brain stem. The characteristic feature of a wave indicates that the activities of many dendritic units are synchronised. Large bilateral lesions in the nonspecific projection nuclei of the thalamus abolish the EEG synchrony. Desynchronisation of EEG pattern with irregular low voltage acti v it y can be produced by stimulating the specific sensory input up to the level of the midbrain. High frequency stimulation of the reticular formation in the midbrain tegmentum and of the non-specific projection nuclei of the thalamus desynchronises the EEG pattern. II. Evoked cortical potentials Evoked activity in the cerebral cortex is elicited by stimulating directly the cortical surface (direct cortical response—DCR) or by stimulating the peripheral sense organ like retina—by photostimulation, ear—by auditory click or the peripheral sensory nerve endings or fibres. A characteristic response is seen in each case which is greatly influenced by the effect of narcotics, drugs, physiological conditions like sleep, etc. The waves consist of surface positive, followed by small negative and then by a larger more prolonged positive deflection (fig 52). Figure 52. Graphical representation showing response evoked in the contralateral sensory cortex by stimulation of the sciatic nerve. The first positive - negative waves sequence is the primary evoked response, the second one is the diffuse secondary response. Evoked and spontaneous electrical activities can be recorded directly from the cerebral cortex through either extracellular or intracellular recording with the help of microelectrodes (fig 53). 87 Figure 53. Diagram showing discharge of Betz cells of the motor cortex stimulated by electrode at the cortical surface. A – recording extracellularly and B-recording intracellularly. III. Registration of electrical processes occurring in the separate nerve cells. The study of the separate cells activity of various organs and tissues is of great interest as it allows getting information of mechanisms and special features of agitation and inhibition of these cells, the character of responses to different irritations, principles of information coding in the CNS etc. There are 2 methods of cells activity registration – intracellular and extracellular. Extracellular method is methodically easier than intracellular as it presupposes the use of comparatively thick (up to 50 – 100 mcm) glass and metal electrodes. The activity of several neighboring cells is registered by such electrodes. In case of intracellular activity registration microelectrodes filled with electrolyte solution with the tip diameter of 0,5 – 1,0 mcm are usually used. Method of surgical extirpations. Method of surgical extirpations includes removal of different cerebral structures, their mechanical destruction or coagulation by direct current anode. Functional cerebral structures switching-off is achieved by their cooling or anodic polarization. The disadvantage of this method is hemorrhage to the destruction zone and irritation by the forming cicatricial tissue. Stereotaxic method of irritative electrodes introduction to the certain cerebral points through the trepanation skull foramina is widely used. Stereotaxic technique. For the electrodes introduction to the brain the animal’s head is fixed in the stereotaxic apparatus by holders under anaesthetic. Holders are introduced into acoustic passages and fixed with the lower edges of orbits or upper jaws. 88 For electrodes orientation in the brain stereotaxic atlases are used for certain kinds of animals. The atlases represent serial sections of the brain in the frontal, horizontal and sagittal planes (fig 54). Figure 54. Stereotaxic technique. Counting is performed in zero planes. Frontal zero plane is in the external acoustic passages. Sagittal zero plane is located along the sagittal suture. The immersing electrode is fixed in the electrode clamp so as the electrode tip to be located in the frontal zero plane. Then the clamp is moved forward and aside. At this point of the skull the hole is perforated, and the electrode is immersed into the brain at the certain depth. The additional control of electrodes tips localization is performed by roentgenoscopy. There are stereotaxises with the special atlases for a human being use in clinics. Nowadays computer tomography is used for stereotaxic neurosurgery operations. It allows using images of serial sections of brain for exact determination of coordinates of any point in deep formations of brain. The stereotaxic neurosurgery together with methods of temporary and continuous neuromodulations besides the reversible and dosed influence at Parkinson's illness is also applied in treatment of serious stump and neurogenic pains, essential tremor, difficult hyperkinesia, the spastic syndromes arising at a cerebral palsy, injuries of spinal cord. The stereotaxic neurosurgery is used in treatment of muscular dystonia, critical ischemia of extremities, the expressed spastic stricture of distal segments of coronary arteries (H-syndrome), at serious posttraumatic erectile dysfunction and defecation. It is used for restoration of spontaneous respiration, in prophylaxis and treatment of decubitus at high injuries of spinal cord. Exercise 1. Determination of individual profile of functional asymmetry 89 Procedure. Students test themselves or work in pairs “observer - probationer”. The right part of the table 15 should be closed. Table 15 I. Tests for motor asymmetry determination. 1. Interlacing of In right-handed persons the finger of the right hand is placed on fingers top, in left-handed ones– the finger of the left hand. 2.Crossing of In right-handed persons the right hand is placed on top, in lefthands handed - the left one. “Napoleon’s position” 3. Test of In right-handed persons the right hand performs percussion applauding movements, in left-handed – the left hand does. 4.Test of winding The leading hand performs winding, the passive one fixes clock clock up position. 5.Simultaneous The quality of the drawing performed by the leading hand is drawing (without higher. The quality of lines and completeness of picture are visual control) of estimated. the same figures (a circle, a square, a flower, a star) by the right and left hands 6. Test of hit The leading hand performs the test more exactly (declination is exactness (eyes less than 10 cm). are closed). The paper target of 20x20 cm is placed on the table at a hand distance. The tested person makes 10 points with right and left hands aiming at the target center. 90 7. Dinamometry The force of each hand is measured three times. The average value is calculated. 8. To cross legs 4 times. 9. To compare the size of thumb’s nail bed of the right and left hands. 10. To measure the step length by the ruler, having previously marked 2 steps of each leg on the floor. 11. Test of declination. The tested person makes 8 steps forward with closed eyes. The leading hand exceeds the other hand by 2 kg. The difference of less than 2 kg is an index of hands’ equality. The leading leg is on top. The nail bed of the leading hand is bigger. The equality indicates “latent left-hander”. The step of the leading leg is longer. The declination to the left indicates prevalence of the right leg and vice versa. Coefficient of motor asymmetry is calculated in percentage by a formula: Cr = [(Dr - Dl)/( Dr + Dl + Do)] x100% Cr- coefficient asymmetry of the right hand, Dr - number domination cases of right hand, Dl - number domination cases of left hand, Do - absent domination of any hand Coefficient asymmetry (Cr) may be positive in 100% and less in right-hander and 91 negative in left-hander. If the coefficient asymmetry more than +15 – it seemed to be domination of right hand. If coefficient asymmetry less than -15 - it seemed to be domination of left hand. If the figures situated between -15 and +15 - it is motor symmetry. Conclusions: 1. What are the leading hand and leg of the tested person? 2. What are the leading hand and leg of the group majority? 3. In what field of medicine and sport should the functional motor asymmetry be considered? II. Tests for sensor asymmetry determination. Table 16 1) Visual asymmetry. 1.Ask the tested person to wink. The leading eye usually stays open. 2. The tested person shows how he looks He uses the leading eye. into the microscope 3. The tested person holds in his hand a When the leading eye is closed pen and compares it with vertical line in representation of the pen harsh displaces, the distance of 3-5 m (the window or the when the not leader eye is closed the door), then he closes his right and then displacement is little. left eyes. 2) Acoustic asymmetry. 1.The tested person shows how he He holds on the telephone to the leading usually uses the telephone ear. 2. The tested person listening the watch The distance from leading ear is longer. by each ear wary far from the ear Conclusions: 1. What are the leading eye and ear of the tested person? 2. In what field of medicine and sport should the functional sensor system be considered? Lesson 2. Conditioned Reflexes. Conditioned Inhibitory Reflexes. Methods of Making Reflexes and Methods of Formation of Conditioned Inhibitory Reflexes. 92 Questions for studying. 1. The conditioned reflexes by Pavlov. The biologic role of the conditioned reflexes. 2. The classification of the conditioned reflexes. 3. The inhibition of the conditioned reflexes. 4. The mechanism of formation of the temporal connection between the nervous centers. 5. Sleep. Slow wave sleep. 6. Paradoxical sleep. 7. Basic theories of sleep: role of the reticular activating system, neuronal centers, transmitters and mechanisms that can cause sleep. Reflex concept. Reflex classification. A reflex is the response to a stimulus from the central nervous system. Reflexes can be: congenital (unconditioned) and acquired (conditioned). Congenital reflexes (for example, sucking) are inherent in the species as a whole, are inherited and do not require special development. They are nutritious, sexual, protective, and adaptive. Conditioned reflexes are developed throughout life. They are individual and not inherited. Conditioned reflexes can be food, sexual, protective. Also they can be: - natural (developed on the basis of natural reinforcement) and artificial (developed on the basis of artificial reinforcement) - reflexes I, II and higher orders. The first order reflex is developed on the basis of unconditional reflex. The second order reflex develops on the basis of the first order reflex, etc. Higher-order reflexes are more difficult to develop. 2. Rules for the development of conditioned reflexes. Rules for the development of conditioned reflexes. To develop a conditioned reflex, two stimuli are needed: 1) a conditioned or indifferent stimulus (for example, light, bell, etc.). 2) unconditioned stimulus (food, electric current, etc.) - The conditioned stimulus should be biologically less significant than the unconditioned stimulus. - The conditioned stimulus should not be very strong - The animal must be healthy, awake and free from other dominants (be hungry, have a sexual dominant, etc.) (fig. 55). 93 Figure 55. Making conditioned reflex. Scheme and mechanisms of formation of temporary connections during the development of conditioned reflexes. A hungry dog has a dominant focus of excitation in the cerebral cortex and if we give meat to s dog, a salivary reflex arises. If we turn on a light bulb before eating, a focus of excitation also arises in the cerebral cortex. With the repeated combination of conditioned and unconditioned stimuli, (the light and a food), a new conditioned reflex of salivation to light arises. In this case, conditioned reflex connections between the cortical centers of the conditioned stimulus and the cortical centers of the unconditioned stimulus are closed. A temporary connection is formed (fig.56). Figure 56. Mechanisms of formation of temporary connections in the cerebral cortex during making condition reflex. 94 Inhibition in HNA. Inhibition in HNA is process as a result of conditioned reflexes are weakened up to a total disappearance. It’s distinguished external (unconditioned) and internal (conditioned) inhibition. 1. Unconditioned inhibition always accompanies excitement process, doesn`t demand special elaboration and special conditions for realization. There are three types of unconditioned inhibition. - The dying – away inhibition. It arises at action of a new irritant which causes an oriented reflex. This reflex inhibition is a conditioned reflex on the mechanism of negative induction - The constant inhibition arises on the disturbing influences (pain, for example). - Ultra boundary or guarding inhibition. It arises at action of super strong conditioned irritants and protects cortical cells from an overstrain. 2. Conditioned (internal) inhibition. - Extinctive inhibition. –it appears in the absence of unconditional reinforcement. - Differentiate inhibition. It provides distinction of similar signals, one of which ceases to be supported. - Conditioned inhibition. It arises at action of the additional irritant preceding a conditioned irritant. - The late inhibition (a reflex for delay). It allows including reflex reaction with a delay after action of conditioned irritant. Exercise 1. Making defensive conditioned reflex on human. Purpose. To observe making defensive conditioned reflex on students. The response to a stimulus that previously elicited little or no response, acquired by repeatedly pairing the stimulus with another stimulus that normally does produce the response is called a conditioned reflex. After the conditioned stimulus and unconditioned stimulus had been paired a sufficient number of times, the conditioned stimulus produced the response originally evoked only by the unconditioned stimulus. Moreover the conditioned stimulus had to precede the unconditioned stimulus. Equipment. Electrostimulator with electrodes, Ringer’s solution, lamp, watch. Procedure. 1. The probationer put his fingers on electrodes. 2. Select the current’s force is sufficient to produce distinct defensive reflex. The 95 conditioned stimulus must precede the unconditioned stimulus. The conditioned stimulus must be lasted 2-3 sec. 3. In 2-3 sec the unconditioned stimulus must be added to the conditioned stimulus. 4. Both of stimuli must be followed after each other in a minute interval. 5. After 5 – 6 combinations of conditioned and unconditioned stimulus isolated using of conditioned stimulus only elicit reflex withdrawal of the limb. This is conditioned reflex. Conclusions. After repeated using combination of conditioned and unconditioned stimulus we have made the conditioned reflex at the probationer. Lesson 3. Speciality of Human’s Mental Activity. Types of Highest Nervous Activity. Analytical-synthesis Functions of Cerebral Cortex. Questions for studying. 1. The types of temperament. Methods of studying of types of temperament. 2. Dynamic stereotype. 3. Language. Speech. Development of speech. Aphasia, classification of aphasias (word-blindness, word-deafness, pure motor aphasia, agraphia, cortical aphasia). 4. Emotion. Different types of behavioral changes of emotion. Neural control of emotion (hypothalamus, thalamus, cerebral cortex and limbic system). 5. Memory. Learning and Memory. Stages of memory (short-term memory, recent memory, and long-term memory). Physiological basis of memory. 6. Reading. Writing. 7. Attention. Physiological mechanisms of attention. Dynamic stereotype. Dynamic stereotype is a complex of conditioned and unconditioned reflexes recorded in memory. It is formed at frequent repetition in certain sequence of irritants. At the same time the end of one reflex starts the following reflex. The dynamic stereotype plays an important role in training. Memory. Types and mechanisms of memory. Memory is the ability of neurons to record, store and reproduce information. Types of memory: short-term (seconds-hours), intermediate (hours-days) and long-term (daysyears) memory. Memory mechanisms. The basis of sensory memory is the trace potentials of a nerve impulse. The synaptic basis of short-term (working) memory, possibly, is the long-term circulation of impulses in the nerve circuits. The mechanisms of intermediate memory (consolidation) are 96 associated with the activation of gene transcription and protein synthesis ("memory proteins"). Long-term memory is associated with the mechanisms of activation of the genome encoding proteins that improve synaptic transfer. Types of Highest Nervous Activity. The general classification of the types of higher nervous activity in humans and animals was founded by I.P. Pavlov on the characteristics of arousal and inhibition. They are assessed by strength (strong and weak), balance (balanced and unbalanced) and mobility (agile and inert). The ratio of types of temperaments according to the classification of Hippocrates and I.P. Pavlov (fig. 57): - Melancholic. Weak nervous processes. Weak type according to I. Pavlov - Choleric. Nervous processes are strong, mobile, unbalanced. The impetuous type according to I. Pavlov - Phlegmatic. Nervous processes are strong, balanced, but not very mobile. Inert type according to I. Pavlov. - Sanguine person. Nervous processes are strong, mobile, balanced. Strong type according to I.P. Pavlov. Figure 57. Four types of temperament Exercise 1. Determination of the types of high nervous activity by psychological test. Procedure. 97 1. Students test themselves or work in pairs “observer - probationer” with the list of the characteristics of different temperaments (tab.17). It is necessary to put the sign “+” in the corresponding column if this characteristic of temperament corresponds to probationers. If this quality is absent in probationer’s character, it is necessary to put the sign “-” in the corresponding column. Characteristics Choleric Phlegmatic Sanguine of (Ch) (Phl) (S) temperament 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Sum of Ach Aphl As characteristics 2. Calculate sum of «+» in each column (Ach, Aphl, As, Am: A= Ach + Aphl+ As + Am. 3. Calculate percentage for each temperament, where A is 100%. For example: Ach = 5, Aphl = 10, As = 15, Am = 5 A= Ac + Aph + As + Am = 5+10+15+5=35 If “35” is 100%, Ach = 14%, Aphl = 28%, As = 42% , Am = 14%. 98 Table 17 Melancholic (M) Am Conclusion: The probationer’s temperament is sanguine (42%). Characteristics of temperament (types of high nervous activity). Choleric: 1. Fussy, busting 2. Hot-tempered, irascibility 3. Sharpness, harshness in relationships 4. Resoluteness, initiativity 5. Stubbornness 6. Resourcefulness in dispute (argument) 7. Habit to work spurt 8. Tendency to risk 9. Not unforgiving 10. Fast and emotion speech 11. Intolerable to defects 12. Tendency to rood jokes 13. Expressiveness of facial expressions 14. Striving for new 15. Sharpness in moving 16. Persistency in achievement of goal 17. Tendency to sharp changing of mood Phlegmatic: 1. Possibility to be quiet in any circumstances 2. Succession and thoroughness in affairs 3. Care and reasonableness 4. Possibility to wait 5. Silent 6. Quiet speech 7. Ability to finish the beginning affairs 8. Tendency not to waist force for nothing 9. Ability to have system in the work 10. Low impressionable to approval or reprimand 11. Not aggressive 12. Constancy of interests 13. Impossibility to begin and finish work fast 14. Equal attitude to everybody 15. Tidy in everything 16. Difficult adaptation to the new circumstances 99 17. Self-discipline person Sanguine: 1. Energy and efficiency 2. Tendency to overestimate myself 3. Ability to grasp the mining fast 4. Instability of interests 5. Easy attitude to failure 6. High adaptability to different circumstances 7. Enthusiasm in any new affair 8. Tendency to lose interest fast to some affairs 9. Unwillingness to do the same, everyday work 10. Sociable, lightness in relations with new people 11. High endurance, high ability to work 12. Loud, fast, emotional speech with 13. Ability to stay self-control in difficult circumstances 14. Ability to save always good mood 15. Ability to wake up and fall asleep fast 16. Not self-disciplined person 17. Tendency to superficiality opinion Melancholic: 1. Tendency to get lost in new circumstances 2. Difficulties in relations with new people 3. Unbelief in self force 4. Easy attitude to loneliness 5. Tendency to retire into oneself 6. Fast fatigue 7. Silent speech 8. Tendency to adapt to character of interlocutor 9. Impressionability for tires 10. High impressionable to approval or reprimand 11. To make big demands of himself 12. Tendency to suspiciousness 13. Vulnerable, high sensitivity 14. Secretiveness, not sociability 15. Not activeness and timidity 16. Tendency to submit to one’s will 17. Striving for gaining sympathy Observations, results and conclusion. 100 THEME 6. SENSORY SYSTEM. Lesson 1. The Special Senses. The Physiology of Visual System. Questions for studying. 1. Types of sensory receptors. 2. Transduction of sensory stimuli into nerve impulses. 3. Receptor potentials and generator potentials. 4. Adaptation of receptors. 5. The optic system of the eye. 6. Physical principles of optics. 7. Anatomy and function of the structural elements of the retina. 8. Photochemistry of vision, color vision. 9. Neural organization of the retina. 10. Function of different types of cells. 11. The visual pathway from the eyes to the visual cortex. 12. Function of the primary visual cortex. 13. Visual acuity and the fields of vision. 14. Accommodation. 101 Definition of the analyzer according to I.P. Pavlov. Functions of the analyzer. The analyzer is a part of the nervous system that includes peripheral receptors, pathways and sensory centers. The analyzer consists of three parts: receptor, conductive and cortical (by Pavlov I.P.). Functions of the analyzer: 1) Detection. 2) Distinction. The law of Weber and Fekhner works. “Intensity of feeling is directly proportional to a logarithm of incentive power”. 3) Coding. 4) Transfer and transformation. Thus there is a restriction of surplus information and allocation of essential signs of a signal. 5) Pattern of recognition. It is a final and the most difficult operation of the analyzer. Thus there is a classification of an image, its reference to a class of objects which the organism met earlier. The visual system. The structure of the eye is shown in the figure 58. Figure 58. The structure of the eye. The tissue of the sclera is continuous with the transparent cornea. Light passes through the cornea to enter the anterior chamber of the eye. Light then passes through the central round aperture called the pupil, which is surrounded by a pigmented muscle, known as 102 the iris. After passing through the pupil, light enters the lens. Light from the lens that passes through the vitreous body enters the neural layer, which contains photoreceptors, at the back of the eye. This neural layer is called the retina. Light that passes through the retina is absorbed by a darkly pigmented choroid layer underneath. Receptor apparatus. There are two types of photoreceptor neurons in retina: rods and cones. Both receptor cell types contain pigment molecules that undergo dissociation in response to light, and it is this photochemical reaction that eventually results in the production of action potentials in the optic nerve. Rods provide black-and-white vision under conditions of low light intensities, whereas cones provide sharp color vision when light intensities are greater. Fig. 59. Receptor apparatus The photoreceptors - rods and cones - are activated when light produces a chemical change in molecules of pigment contained within the membranous discs of the outer segments of the receptor cells. Rods contain a purple pigment known as rhodopsin or visual purpule. When light falls on the retina, the rhodopsin passes rapidly through several stages. A rod or cone contains many Na+ channels in the plasma membrane of its outer segment, and in the dark, many of these channels are open. As a consequence, Na+ 103 continuously diffuses into the outer segment and across the narrow stalk to the inner segment. This small flow of Na+ that occurs in the absence of light stimulation is called the dark current, and it causes the membrane of a photoreceptor to be somewhat depolarized in the dark. The Na+ channels in the outer segment rapidly close in response to light, reducing the dark current and causing the photoreceptor to hyperpolarize (fig. 60). Fig. 60. Photochemical process in retina Conductive part of the visual analyzer. Axon of ganglion cells form an optic nerve (fig. 61). Optic nerves of both eyes partially cross in the field of the skull basis. Further there is a visual tract. The fibers of the visual tract go to the lateral geniculate bodies, the upper tubercles of the quadruple, the thalamus, the suprachiasmatic nucleus of the hypothalamus and the nucleus of the oculomotor nerve. From the upper tubercles quadruple fibers of the optic tract fall into the pulvinar. Information comes from the thalamus are sent to the occipital lobe of the brain. 104 Fig. 61. Conduction and central parts of the visual analyzer The visual acuity. The visual acuity is the eye’s ability to differentiate two luminous points separately in space. It is the sharpness to which the details and contours of objects are perceived. If a series of black lines on a white paper is moved gradually far and far away from the observer then a point will come when the observer fails to distinguish the objects on such uniformly grey sheet of paper. Thus the resolving power of the eye is the angle subtended at the eye by the spacing between the lines at the point where they are just resolvable. The visual acuity must not be confused with the visual threshold. The visual threshold is the minimal amount of light that elicits light sensation. The visual acuity is usually defined in terms of minimum separable or resolution threshold, the shortest distance, at which two lines will be perceived separately. The visual acuity depends upon the sensitivity of retina to light, illumination of the surface, and ability to recognize the distance of parallel rays. Visual acuity helps in determining shape form, outline and minute details of the surroundings. It is expressed as the reciprocal of the angle subtended at the nodal point of the eye—visual angle. The visual angle is generally one minute (60 seconds) when the retinal images are separated by 4-5 µ. Visual acuity is found to be: maximum at the fovea centralis where there is a large number of cones; and there is minimum at the peripheral part of the retina where the number of cones is very few. The visual acuity increases with monochromatic light. Errors of refraction reduce the visual acuity. Exercise 1. Determination of visual acuity with Rot’s apparatus and Sivcev’s table. 105 Principle. In determining the visual acuity (acuteness of vision), figures such as a broken circle Landolt’s “О” , Sivcev’s table with different letters, and Snellen's prong “E”, printed black on a white ground and in graded sizes are applied (fig. 62). Landolt’s “C” is almost universally used in scientific studies and is distinguishable from a circle by a white gap; and the power to recognize the position of the gap, depends upon the angle it subtends at the eye. The Landolt’s “C” can be rotated into eight separate positions. The subject is seated at a distance of 5 meters and a letter is placed with the gap of the “О” or the prong of the “E” turned to the right or left; he is asked to say in which position the letter is directed. The width of the lines composing the letters and the gap in the “С” or the spaces between the prongs of the “E”, subtend angles of different degrees, depending on the size of the letter, when placed at a distance of 5 meters. The width of the whole figure is five times thicker than its parts. By finding the smallest letter whose position can be recognized the subject's visual acuity in terms of the visual angle is ascertained. The maximum acuity measured with a Landolt “C” subtending 05 minute of arc, is about 2·1. In testing the visual acuity for fitting of glasses, Snellen's test and Sivcev’s table is most commonly applied. Figure 62. a –Snelen’s table; b- Landolt’s broken circle “О”; c- Sivcev table Snellen's test type or Sivcev’s table (Russian variant). Clinically Snellen's test is applied to measure the ability of the subject in discriminating different letters which are constructed so that their details, subtend a known angle at a given distance from the eye. This test type is devised upon the basis that two points or lines separated by a space having a visual angle of 1 minute can be resolved by the average normal eye. This test 106 comprises 10 or 12 rows of block letters printed in black upon a white background. The rows of these letters are arranged in descending order of size from above down. The width of the lines forming the letters of the first row subtends an angle of 1 minute at 50 meters from the eye, whereas that of the letters in the two to nine rows, have a visual angle of 1 minute at 36, 24, 18, 12, 9, 6, 5, and 4 meters respectively. The top letter is constructed in such a fashion that its details subtend 1 minute at 50 meters. The subject stands at a distance of 5 meters and reads these letters with one eye closed. The acuteness of vision is expressed, by a fraction of which the numerator is 5 (distance of 5 meters from the letters) and the denominator is the distance at which the smallest letters can be read by the eye. V = d / D, where V- visus, visual acuity; d - is the distance at which the letters are seen by the tested person; D- is the distance at which the letters are seen by the person with normal vision. Snellen's test types of rectangular grid are also widely used. Each line of letters of a different size is marked, with the distance in meters at which the small squares subtend 1 minute of arc. A normal individual at a distance of 5 meters distinguish the letters of the 5 meter line and his visual acuity will be 5/5 = 1. Subjects, having defective vision, distinguish letters standing 50 meters from a well-lit chart then his acuity will be 5/50 =0,1. There is a number near each row, which means the distance at which the letters are seen by the person with normal vision (in meters). At right side is shown the vision acuity, which is calculated by the formula. Equipment. Rot’s apparatus, shield (fig.63). Rot’s apparatus is a box with mirror sidewalls for reflection of light of a lamp and the lamp lighting the Sivcev’s table with different letters of different size on the back wall of the box. 107 Figure 63. Rot’s apparatus with Sivcev’s table. Procedure: 1. Patient seats on the chair in the distance from the Rot’s apparatus (5 meters). 2. First close by shield the right, and then close the left eye. 3. Say the pointed letters on the table. 4. Define the visual acuity each other. 5. Calculate the visual acuity by formula and make conclusion. For example, my visual acuity or visus equals = 1.0. Observations, results and conclusion. Exercise 2. Determination of visual fields (or range of vision). Definition. On looking strait ahead, with the eyeball fixed, that part of the external world which can be seen with each eye is called the visual field of that eye. Extent. Laterally, it extends up to 1040 i.e., behind the horizontal plane on the nasal side about 650. In front there is a cone-shaped area in which the two fields overlap and enjoy binocular vision. The visual field for blue, red and green are progressively smaller (fig.64). 108 Figure 64. Visual fields of left eye for white, blue, red and green colors. The map of the visual field (Perimetry) is determined by using Forster’s perimeter (fig.65). It consists of a metal piece shaped like an arc of a circle, the centre of which is always marked by a fixed pointer attached to the base of the instrument. The subject’s head is supported in the chinrest and the eye to be examined is placed very close to the metal point indicating the center of arc. The other eye is covered. An index mark, white in color with the diameter of about 2 mm, is made to slide along the arc to find the limits of visual field in that meridian. The index mark can be blue, red, or green to find out the corresponding color field. The arc can be rotated around a horizontal axis through a full circle, and at each new situation the test is repeated to find out the field in that meridian. These results when plotted give the visual field. During special diseases, also lesions of optic pathway, visual fields are various: the local part of visual field or half of it can disappear (scotoma, hemianopsia). 109 Figure 65. Determination of visual fields with Forster’s perimeter. Equipment. Forester’s perimeter, shield. Procedure: 1. Patient closes by a shield one eye, fixes the view on white point, and he doesn’t move his eye. 2. Observer takes a special wand with white index mark and start moving it from peripheral side of arc to its center. 3. Patient has to say when he can see the wand by peripheral vision and to define the color of mark. 4. Observer notes a value on a-degree scale of arc and draws the results in the special blank, paper with concentric circle lines and meridian lines over them (fig. 43). It is the normal visual field for right or left eye on the blank (trait lines). 5. Connect the obtained points and compare the area between the normal and taken results. Observations, results and conclusion. 110 Lesson 2. The Sense of Hearing. The questions for studying: 1. Structure of the ear, Its parts. 2. Structures and functions of the external ear and middle ear. 3. The internal ear. A structure of cochlea. 4. The organ of Corti – structure and function. 5. Conduction of sound from the tympanic membrane to the cochlea. 6. Excitation of the hair cells. Hair cell Receptor Potential and excitation of auditory nerve fibers. 7. Auditory Pathways 8. Function of the Cerebral cortex in hearing. 9. Deafness. Types of Deafness. Deafness The primary acoustic centre is in the temporal lobe of the cerebrum. Removal of both temporal lobe is followed by complete deafness and of one temporal lobe is followed by impairment of hearing. This holds that some fibres from each ear cross at some point in their afferent pathways and terminate in the opposite cortex. Deafness may be of two types: (1) conductive deafness, and (2) nerve deafness. 1. In conductive deafness there is interference with the passage of sound waves through the external ear and middle ear. (1) External ear obstructions— the conductive deafness occurs due to entrance of foreign bodies, or due to hard or dry wax in the external ear. The damage or perforation of tympanic membrane may be the cause of failure of conduction. (2) Middle ear disease — any condition which prevents the normal functioning of the ossicles. This condition is frequently observed in nasal catarrh, otosclerosis, etc. 2. The nerve deafness is due to loss of function of organ of Corti and also due to interference of transmission of impulses by the auditory nerve. The temporary nerve deafness occurs after exposure to a very loud sound. The main causes are: 1) Due to bacterial or viral infection as in Meningitis in children. 2) Due to acoustic trauma as in boiler-makers. 3) Due to toxic action of the drugs - some antibiotics (streptomycin, kanamycin), quinine, measles, etc. 4) Due to pressure of a tumour at the junction of cerebellum and pons. The nerve deafness is also found in Meniere's syndrome which occurs in adult and is accompanied by vertigo. This is due to increased hydrostatic pressure in the endolymph. There may be also hereditary nerve deafness. 111 1. Auditory analyzer. Structure. Functions. Auditory analyzer is a sensory system that perceives vibrations of the external and internal environment (frequency from 20 hertz to 20 kilohertz) and forms sound sensations. Auditory analyzer includes the auricle, external acoustic canal, middle ear and inner ear (fig.66). Figure 66. Auditory analyzer. In the inner ear, the bony canal of the cochlea divides two membranes into three canals: high, lower, and middle. Endolymph fills the middle canal. The organ of Corti is in the middle channel. This organ includes the cochlear hair receptor cells and the tectorial membrane. The electric phenomena in a snail: - Receptor potential. It is connected with bending of stereocillia at action of a sound. - Cochlear microphone potential arises at action of a sound and is generated by external hair cells. The emergence of excitation in the receptor of the auditory analyzer. Stereocilia are bent by sound. The greater the displacement of the basilar membrane and the bending of the stereocilia, the greater the amount of transmitter released by the hair cell, and therefore the greater the generator potential produced in the sensory neuron. A greater bending will result in a higher frequency of action potentials, which will be perceived as a louder sound (fig.67). 112 Figure 67. Organ of Corti. Conductive section of the auditory analyzer. Sensory neurons in the vestibulocochlear nerve (VIII) synapse with neurons in the medulla oblongata that project to the inferior colliculus of the midbrain. Neurons in this area, in turn, project to the thalamus, which sends axons to the auditory cortex of the temporal lobe. Cortical section of the auditory analyzer. The primary auditory cortex is the 41st field of the Heschl gyrus and the 42nd field of the superior temporal cortex. Provides a sense of tones, noises, sounds. The secondary auditory cortex is the 22nd field of the superior temporal cortex. This provides an understanding of the sequence of tones. Exercise 1. Determination of auditory acuity. Determination of auditory acuity is finding out of patient’s ability to distinguish silent whisper speech. The person with normal hearing perceives speech by whisper at a distance of 4-5 meters. Equipment. Tape-measure. Procedure: 1. Patient sits back to observer at a distance of 5-6 meters. One of patient’s ears is closed; another is opened and directed to the observer. 113 2. Observer names in a low voice different numbers. 3. Patient should repeat heard words. If he does not hear a word then the observer approaches gradually to the patient until he starts repeating the pronounced words correctly. Observations, results and conclusion. Test for deafness. Principle. Rinne’s test. The base of a vibrating tuning fork is placed over the mastoid process of the subject. When the sound fades away (bone-conduction ceases) the prongs of the fork are brought towards the external auditory canal. If there is no abnormality in the tympanic membrane and ear ossicles, the air-conducted sound is heard for a longer period by the subject and the test is said to be positive. If the sound is heard longer by bone-conduction the test is said to be negative, and indicates conductive deafness (fig.68 c). In case of internal ear disease affecting the nervous conduction the test is said to be positive and indicates perceptive deafness (fig.68 b). Weber’s test. The base of a vibrating tuning fork is placed over the midline of the vertex of the subject (fig.68 a). The sound is heard equally in both ears. In unilateral middle ear disease affecting the conductive system, the sound is better heard in the diseased ear and Weber's test is said to be positive. In case of unilateral internal ear disease affecting the nervous conduction the sound is better heard in the normal ear. Rinne's and Weber's tests help to differentiate middle ear or conductive deafness from internal ear or perceptive deafness. Figure 68. a. The Weber test furnishes only a comparison of two ears. If a subject has nerve deafness which is worse in one ear than the other, the tone will be heard best in the better ear. The tone will be heard in the poorer ear if the subject has asymmetric conductive deafness. b. Tone heard longer by air conduction - Rinne positive. c. Tone heard longer by bone conduction - Rinne negative. Exercise 2. Determination of bone conductivity of sound. 114 The Weber’s test is test of bone conductivity. The research of bone conductivity of a sound allows differentiate defeats of middle and internal ears. Equipment. Set of tuning forks, hammer. Procedure. 1. Take a tuning fork С128 and strike it with a hammer. 2. Put the base of a sounding tuning fork over the midline of the vertex of the patient (put it to parietal bone in the middle of the patient’s head). In norm the patient hears a sound of a tuning fork equally with both ears. 3. The patient closes one ear with a wadded ball (simulating defeat of a middle ear): the sound in opened ear will be stronger. At defeat of an internal ear the sensation of a sound increases in a healthy ear. Observations, results and conclusion. Exercise 3. Determination of bone and air conductivity of sound. Principle. Air conductivity of a sound is provided with distribution of a sound wave through a hearing aid of an external and middle ear. Bone conductivity of a sound is a transfer of sound waves through bones of a skull to an internal ear. For comparison of air- and bone- conductivity of a sound carry out Rinne’s test. Equipment. Set of tuning forks, hammer. Procedure: The basis of a vibrating tuning fork put to a shoot of a temporal bone. Mark time of sounding of a tuning fork. At disappearance of a sound a tuning fork bring to an external ear (distance of a tuning fork from external auditory canal equally 0.5 - 1 sm). The patient again hears a sound. Define time during which the sound is audible. Compare time of air- and bone- conductivity. In norm time of air conductivity in 2 times is longer, than time of bone conductivity. Observations, results and conclusion. 115