Respiration is a physiological function that provides gas exchange (O2 and CO2) between the environment and the body in accordance with its metabolic needs.

Breathing proceeds in several stages: 1) external respiration - the exchange of O2 and CO2 between the external environment and the blood of the pulmonary capillaries. In turn, external respiration can be divided into two processes: a) gas exchange between the external environment and the alveoli of the lungs, which is referred to as "pulmonary ventilation"; b) gas exchange between the alveolar air and the blood of the pulmonary capillaries; 2) transport of O2 and CO2 by blood; 3) exchange of O2 and CO2 between blood and body cells; 4) tissue respiration.

Depending on which direction the dimensions change chest when breathing, there are chest, abdominal and mixed types of breathing. Chest breathing is more common in women. With it, the chest cavity expands mainly in the anteroposterior and lateral directions, then the ventilation of the lower parts of the lungs is often insufficient.

Abdominal breathing is more typical for men. The expansion of the chest cavity with it occurs mainly in the vertical direction, due to the diaphragm, ventilation of the tops of the lungs may be insufficient. With a mixed type of breathing, uniform expansion of the chest cavity in all directions ensures ventilation of all parts of the lungs.

Biomechanics of inhalation and exhalation.

Inhalation begins with the contraction of the respiratory (respiratory) muscles.

Muscles whose contraction leads to an increase in the volume of the chest cavity are called inspiratory, and muscles, the contraction of which leads to a decrease in the volume of the chest cavity, are called expiratory. The main inspiratory muscle is the diaphragm muscle. Contraction of the muscle of the diaphragm leads to the fact that its dome is flattened, the internal organs are pushed downward, which leads to an increase in the volume of the chest cavity in the vertical direction. The contraction of the external intercostal and interchondral muscles leads to an increase in the volume of the chest cavity in the sagittal and frontal directions.

With an increase in the volume of the chest, as a result of contraction of the inspiratory muscles, the parietal pleura will follow the chest. As a result of the appearance of adhesive forces between the layers of the pleura, the visceral layer will follow the parietal, and after them the lungs. This leads to an increase in negative pressure in the pleural cavity and to an increase in the volume of the lungs, which is accompanied by a decrease in pressure in them, it becomes lower than atmospheric and air begins to flow into the lungs - inhalation occurs.

Between the visceral and parietal layers of the pleura, there is a slit-like space called the pleural cavity. The pressure in the pleural cavity is always below atmospheric pressure, it is called negative pressure. The magnitude of the negative pressure in the pleural cavity is equal to: by the end of the maximum expiration - 1-2 mm Hg. Art., by the end of a calm exhalation - 2-3 mm Hg. Art., by the end of a calm breath -5-7 mm Hg. Art., by the end of maximum inspiration - 15-20 mm Hg. Art.

With deep breathing, a number of auxiliary respiratory muscles are involved in the act of inhalation, which include: the muscles of the neck, chest, back. The contraction of these muscles causes the ribs to move, which assists the inspiratory muscles.

With calm breathing, inhalation is carried out actively, and exhalation is passive. Forces providing a calm exhalation:

The strength of the chest;

Elastic traction of the lungs;

Abdominal pressure;

Elastic traction of rib cartilage twisted during inhalation.

The internal intercostal muscles, the posterior dentate muscle, and the abdominal muscles take part in active exhalation.

Forced inhalation.

Transport of substances in the digestive tract.

Oral cavity- a small amount of essential oils.

Stomach- water, alcohol, mineral salts, monosaccharides.

Duodenum- monomers, LCD.

Jejunum- up to 80% monomers.

In the upper section- monosaccharides, amino acids, fatty acids.

In the lower section- water, salt.

3. Biomechanics of inhalation and exhalation. Overcoming forces when inhaling. Primary lung volumes and capacities

Breathing is a set of processes that result in the consumption of O 2, the release of CO 2 and the conversion of the energy of chemicals into biologically useful forms.

Stages of the respiratory process.

1) Ventilation of the lungs.

2) Diffusion of gas in the lungs.

3) Transport of gases.

4) Exchange of gases in tissues.

5) Tissue respiration.

Biomechanics of active inhalation. Inspiration (inspiration) is an active process.

When inhaling, the chest increases in three directions:

1) in vertical- by reducing the diaphragm and lowering its tendon center. At the same time, the internal organs are pushed down;

2) in the sagittal direction - associated with the contraction of the external intercostal muscles and the retreat of the end of the sternum forward;

3) in the frontal- the ribs move up and out due to the contraction of the external intercostal and interchondral muscles.

1) Provided by increased contraction of the inspiratory muscles (external intercostal and diaphragm).

2) Contraction of accessory muscles:

a) extending the thoracic spine and fixing and abducting the shoulder girdle back - trapezoidal, rhomboid, lifting the scapula, small and large pectorals, anterior dentate;

b) lifting ribs.

Forced inspiration uses the reserve of the pulmonary system.

Inhalation is an active process, because when inhaling, forces are overcome:

1) elastic resistance of muscles and lung tissue (combination of stretching and elasticity).

2) inelastic resistance - overcoming the frictional force when moving the ribs, resistance internal organs diaphragm, the heaviness of the ribs, resistance to air movement in the bronchi of medium diameter. Depends on the tone of the bronchial muscles (10–20 mm Hg in adults, healthy people). It can increase up to 100mm with bronchospasm, hypoxia.

Inhalation process.

Inhalation increases the volume of the chest, the pressure in the pleural fissure from 6 mm Hg. Art. increases to - 9, and with a deep breath - up to 15 - 20 mm Hg. Art. This is negative pressure (i.e., below atmospheric pressure).

The lungs passively expand, the pressure in them becomes 2 - 3 mm below atmospheric pressure and air enters the lungs.

There was a breath.

Passive process. When the inhalation is over, the respiratory muscles are relaxed, the ribs fall under the influence of gravity, and the internal organs return the diaphragm to its place. The volume of the chest decreases, passive exhalation occurs. The pressure in the lungs is 3 - 4 mm higher than atmospheric.

Forced exhalation involves the internal intercostal muscles, the muscles flexing the spine and the abdominal muscles.

Role of a surfactant.

It is a phospholipid substance produced by granular pneumocytes. The stimulus for its development is deep breaths.

During inhalation, the surfactant is distributed over the surface of the alveoli with a 10 - 20 µm thick film. This film prevents the alveoli from collapsing during exhalation, since the surfactant increases the surface tension forces of the fluid layer lining the alveoli during inhalation.

When you exhale, it reduces them.

Pneumothorax- air entering the pleural fissure.

Open;

Closed;

Unilateral;

Bilateral.

Thoracic and abdominal breathing.

More effective than abdominal, since intra-abdominal pressure increases and the return of blood to the heart increases.

4. Research methods in humans of reflexes: tendon (knee, Achilles), Ashner, pupillary.

Ticket number 4

1. The principles of coordination of reflex activity: the relationship between excitation and inhibition, the principle of feedback, the principle of dominant.

Coordination is provided by selective excitation of some centers and inhibition of others. Coordination is the unification of the reflex activity of the central nervous system into a single whole, which ensures the implementation of all body functions. The following basic principles of coordination are distinguished:

The principle of irradiation of excitations. Neurons of different centers are interconnected by intercalary neurons, therefore, impulses arriving with strong and prolonged stimulation of receptors can cause excitation not only of neurons in the center of a given reflex, but also of other neurons. Irradiation of excitation ensures that a greater number of motor neurons are included in the response in case of strong and biologically significant stimuli.

The principle of a common final path. Impulses arriving in the central nervous system through different afferent fibers can converge (converge) to the same intercalary, or efferent, neurons. One and the same motoneuron can be excited by impulses coming from different receptors (visual, auditory, tactile), i.e. to participate in many reflex reactions (to be included in various reflex arcs).

Dominant principle. It was discovered by A.A. Ukhtomsky, who found that irritation of the afferent nerve (or cortical center), which usually leads to contraction of the muscles of the limbs when the intestines are overflowed, causes an act of defecation. In this situation, the reflex excitement of the center of defecation "suppresses, inhibits the motor centers, and the center of defecation begins to respond to extraneous signals for it.

A.A. Ukhtomsky believed that at every given moment of life a defining (dominant) focus of excitation arises, subordinating to itself the activity of all nervous system and the defining nature of the adaptive response. Excitations from different areas of the central nervous system converge to the dominant focus, and the ability of other centers to respond to signals arriving at them is inhibited. Thanks to this, conditions are created for the formation of a certain reaction of the organism to a stimulus that has the greatest biological significance, i.e. satisfying a vital need.

Under natural conditions of existence, dominant excitement can cover entire systems of reflexes, resulting in food, defensive, sexual and other forms of activity. The dominant center of excitement has a number of properties:

1) its neurons are characterized by high excitability, which contributes to the convergence of excitations to them from other centers;

2) his neurons are able to summarize incoming excitations;

3) excitement is characterized by persistence and inertia, i.e. the ability to persist even when the stimulus that caused the formation of the dominant has ceased to act.

4. The principle of feedback. The processes occurring in the central nervous system cannot be coordinated if there is no feedback, i.e. data on the results of the management of functions. Feedback allows you to correlate the severity of changes in the parameters of the system with its work. The connection between the output of the system and its input with a positive gain is called positive feedback, and with a negative gain, it is called negative feedback. Positive feedback is mainly characteristic of pathological situations.

Negative feedback ensures the stability of the system (its ability to return to its original state after the cessation of the influence of disturbing factors). Distinguish between fast (nervous) and slow (humoral) feedback. Feedback mechanisms ensure that all homeostasis constants are maintained.

5. The principle of reciprocity. It reflects the nature of the relationship between the centers responsible for the implementation of opposite functions (inhalation and exhalation, flexion and extension of the limbs), and consists in the fact that the neurons of one center, being excited, inhibit the neurons of the other, and vice versa.

6. The principle of subordination (subordination). The main trend in the evolution of the nervous system is manifested in the concentration of the functions of regulation and coordination in the higher parts of the central nervous system - the cephalization of the functions of the nervous system. In the central nervous system there are hierarchical relationships - the highest center of regulation is the cerebral cortex, the basal ganglia, the middle, medulla, and spinal cord obey its commands.

7. The principle of compensation of functions. The central nervous system has a tremendous compensatory capacity, i.e. can restore some functions even after the destruction of a significant part of the neurons that form the nerve center (see plasticity of nerve centers). When individual centers are damaged, their functions can pass to other brain structures, which is carried out with the obligatory participation of the cerebral cortex. In animals that, after the restoration of the lost functions, the bark was removed, their loss occurred again.

With a local failure of inhibitory mechanisms or with an excessive increase in excitation processes in a particular nerve center, a certain set of neurons begins to autonomously generate pathologically enhanced excitation - a generator of pathologically enhanced excitation is formed.

At high generator power, a whole system of non-ironic formations functioning in a single mode arises, which reflects qualitatively new stage in the development of the disease; rigid connections between the individual constituent elements of such a pathological system underlie its resistance to various therapeutic influences. Its essence lies in the fact that the structure of the central nervous system, which forms a functional premise, subordinates those parts of the central nervous system to which it is addressed and forms, together with them, a pathological system, determining the nature of its activity. Such a system is biologically negative. If, for one reason or another, the pathological system disappears, then the formation of the central nervous system, which played the main role, loses its determinant significance.

2. Digestion in the oral cavity and swallowing (its phases). Reflex regulation of these acts

Respiratory movements involve 4 anatomical and functional formations: airways, which are slightly extensible by their properties; elastic and extensible lung tissue; ribs; the diaphragm, as well as the inspiratory and expiratory muscles.

Airway- this is the space that provides the delivery of atmospheric air to the alveoli. It begins with the openings of the nose and mouth, includes the oral cavity, nasopharynx, larynx, trachea, bronchi and bronchioles up to the 16th generation inclusive (they do not have alveoli). These structures are not involved in gas exchange and constitute the anatomical dead space; its volume is about 150 ml. Bronchioles of the 17-19th generations form a transition zone, their gas mixture approaches the alveolar, and the bronchioles of the 20-23rd generations bear the main number of alveoli, in which gas exchange occurs - they form the respiratory zone. Although there is no gas exchange in the airways, they are necessary for normal breathing, since they are humidified, warmed, and cleaned from dust and microorganisms of the inhaled air. When irritated by dust particles and accumulated mucus of the receptors of the nasopharynx, larynx and trachea, a reflex act of coughing occurs, and when the receptors of the nasal cavity are irritated, sneezing occurs. Coughing and sneezing are protective functions.

The act of inhalation (inspiration) is an active process, since it is carried out thanks to the contractions of the respiratory muscles, which ensure the expansion of the chest cavity. Muscles, the contraction of which leads to an increase in the volume of the chest cavity, are called inspiratory, and the muscles, the contraction of which leads to a decrease in the volume of the difficult cavity, - expiratory. The main inspiratory muscle is the diaphragm muscle; when it contracts, its dome flattens with calm breathing by 1.5-2 cm, with deep breathing - up to 10 cm. At the same time, the internal organs are displaced downward, which leads to an increase in the volume of the chest in the vertical direction. In the implementation of a calm breath, in addition to the diaphragm, the external intercostal and interchondral muscles are also involved, the contraction of which leads to an increase in the volume of the chest in the sagittal and frontal directions. With forced inhalation, an auxiliary function is performed by muscles attached to the bones of the shoulder girdle, skull or spine and capable of lifting the ribs: sternocleidomastoid, trapezius, both pectoral muscles, muscle lifting the scapula, scalene, anterior dentate.

Of great importance in the process of breathing is negative pleural pressure(pleural fissure). Each lung is covered with a serous membrane - pleura, consisting of visceral and parietal sheets.

In the pause between inhalation and exhalation, atmospheric pressure (Ratm.), Acting on the wall of the alveoli from the inside, is balanced by the sum of intrapleural pressure (P pl.) And the elastic traction of the lungs (P el.), Which occurs when the lung tissue is stretched: P atm = P pl + R el. With an increase in the volume of the chest as a result of contraction of the inspiratory muscles, the parietal leaf follows the chest. This leads to a decrease in pressure in the pleural fissure. As a result, atmospheric pressure stretches the lung tissue: P atm > R pl + R el. Therefore, the visceral leaf, and with it the lungs, follow the parietal leaf. Air begins to flow into the lungs, inhalation occurs. The lungs are stretched until atmospheric pressure is again balanced by the sum of pleural pressure and elastic traction.

The pressure in the pleural cavity is always negative(below atmospheric). The magnitude of the negative pressure in the pleural cavity is not the same in different phases of respiration: by the end of the maximum expiration, it is equal to 1–2 mm Hg. Art., by the end of a calm exhalation - 2-3 mm Hg. Art., towards the end of a calm breath - 5-7 mm Hg Art., by the end of maximum inspiration - 15-20 mm Hg. Art.

Negative pressure in the pleural cavity is due to the so-called elastic traction of the lungs- the force with which the lungs constantly strive to reduce their volume. Elastic traction is due to two reasons: the presence of a large number of elastic fibers in the wall of the alveoli; surface tension of the liquid film, which covers the inner surface of the walls of the alveoli. (Surfactant).

When inhaling, it protects the alveoli from overstretching, since the surfactant molecules are located far from each other, which is accompanied by an increase in the surface tension. When you exhale, it protects the alveoli from collapse, since the surfactant molecules are located close to each other, which is accompanied by a decrease in the surface tension.

In contrast to a calm inhalation, a calm exhalation is a passive process: it occurs without the participation of the expiratory muscles against the background of relaxation of the inspiratory muscles due to the energy that has accumulated during inhalation. To carry out a calm exhalation, the elastic properties of the lungs and the mass of tissues displaced during inhalation are usually sufficient.

A calm exhalation is provided by the following forces: the mass of the chest, returning to its original state under the influence of gravity; elastic traction of the lungs; pressure of the abdominal organs; elastic traction of the costal cartilage twisted during inhalation.

In this case, P atm< Р пл + Р эл., что приводит к уменьшению объема легких и изгнанию части воздуха в атмосферу.В форсированном выдохе принимают участие внутренние межреберные мышцы, задняя нижняя зубчатая мышца, мыш­цы живота.

Ticket number 4

The functional system - according to P.K. Anokhin - is a complex of selectively extracted body components, interactions and relationships of which are focused on obtaining a focused useful result.

Functional system:- is a unit of integrative activity of the whole organism;-differs from private mechanisms for the implementation of behavioral acts;- carries out the selective involvement of structures and processes in the implementation of a specific act of behavior or function of the body; - has a branched morphophysiological apparatus that maintains homeostasis and self-regulation.

There are functional systems of the first and second types.

There are two types of functional systems. 1. Functional systems of the first type ensure the constancy of certain constants of the internal environment due to the self-regulation system, the links of which do not go beyond the limits of the organism itself. An example is a functional system for maintaining the constancy of blood pressure, body temperature, etc. Such a system, using a variety of mechanisms, automatically compensates for the emerging shifts in the internal environment. 2. Functional systems of the second type use an external link of self-regulation. They provide an adaptive effect due to going outside the body through communication with the outside world, through changes in behavior. It is the functional systems of the second type that underlie various behavioral acts, various types of behavior.

2. Microcirculation) - transport of biological fluids at the tissue level. This concept includes capillary circulation (movement of blood through microvessels of the capillary type). Capillaries are the thinnest vessels with a diameter of 5-7 microns, a length of 0.5-1.1 mm. These vessels lie in the intercellular spaces, in close contact with the cells of organs and tissues of the body. The total length of all the capillaries of the human body is about 100,000 km, that is, a thread that could gird the earth three times along the equator. The physiological significance of capillaries lies in the fact that metabolism between blood and tissues is carried out through their walls. The walls of the capillaries are formed by only one layer of endothelial cells, outside of which there is a thin connective tissue basement membrane. The blood flow rate in the capillaries is small and amounts to 0.5-1 mm / s. Thus, each blood particle is in the capillary for about 1 s. The small thickness of the blood layer (7-8 microns) and its close contact with the cells of organs and tissues, as well as the continuous change of blood in the capillaries provide the possibility of metabolism between blood and tissue (intercellular) fluid. 1 mm2 more cross-section than in tissues in which the metabolism is less intense. So, in the heart there are 2 times more capillaries per 1 mm2 than in the skeletal muscle. In the gray matter of the brain, where there are many cellular elements, the capillary network is much denser than in white.

There are two types of functioning capillaries. Some of them form the shortest path between arterioles and venules (main capillaries). Others are lateral branches of the former: they depart from the arterial end of the main capillaries and flow into their venous end. These lateral branches form capillary networks. The volumetric and linear blood flow velocity in the main capillaries is greater than in the lateral branches. The main capillaries play an important role in the distribution of blood in the capillary networks and in other phenomena of microcirculation. Blood flows only in the "duty" capillaries. Some of the capillaries are cut off from the circulation. During the period of intensive activity of organs (for example, with muscle contraction or secretory activity of the glands), when the metabolism in them increases, the number of functioning capillaries increases significantly. Regulation of capillary blood circulation by the nervous system, the effect on it of physiologically active substances - hormones and metabolites - are carried out when exposed to them on the arteries and arterioles. The narrowing or widening of the arteries and arterioles changes both the number of functioning capillaries, the distribution of blood in the branching capillary network, and the composition of the blood flowing through the capillaries, that is, the ratio of erythrocytes and plasma. In this case, the total blood flow through the metarterioles and capillaries is determined by the contraction of smooth muscle cells of the arterioles, and the degree of contraction of the precapillary sphincters (smooth muscle cells located at the mouth of the capillary when it leaves the metaarteriole) determines how much of the blood will pass through the true capillaries.

In some parts of the body, for example, in the skin, lungs and kidneys, there are direct connections of arterioles and venules - arteriovenous anastomoses. This is the shortest path between arterioles and venules. Under normal conditions, the anastomoses are closed and blood flows through the capillary network. If the anastomoses open, then some of the blood can enter the veins, bypassing the capillaries. Arteriovenous anastomoses act as shunts that regulate capillary circulation. An example of this is the change in capillary blood circulation in the skin when the ambient temperature rises (above 35 ° C) or decreases (below 15 ° C). Anastomoses in the skin open and the blood flow from arterioles directly into the veins is established, which plays an important role in the processes of thermoregulation. The structural and functional unit of blood flow in small vessels is the vascular module - a complex of microvessels that is relatively isolated in hemodynamic respect, supplying blood to a certain cell population of the organ. In this case, the specificity of vascularization of tissues of various organs takes place, which is manifested in the peculiarities of branching of microvessels, density of capillarization of tissues, etc. The presence of modules allows you to regulate local blood flow in individual microsections of tissues. It unites the mechanisms of blood flow in small vessels and the exchange of fluid and gases and substances dissolved in it between blood vessels and tissue fluid, which is closely related to blood flow. The processes of exchange between blood and tissue fluid deserve special consideration. 8000-9000 liters of blood pass through the vascular system per day. About 20 liters of liquid is filtered through the wall of the capillaries and 18 liters are reabsorbed into the blood. About 2 liters of fluid flows through the lymphatic vessels. The laws governing the exchange of fluid between capillaries and tissue spaces were described by Sterling. The hydrostatic pressure of the blood in the capillaries (Prc) is the main force directed to the movement of fluid from the capillaries into the tissue.

3. The kidneys perform a number of homeostatic functions in the human body and higher animals. The functions of the kidneys include the following: 1) participation in the regulation of blood volume and extracellular fluid (volume regulation); 2) regulation of the concentration of osmotically active substances in the blood and other body fluids (osmoregulation); 3) regulation of the ionic composition of blood serum and the ionic balance of the body (ionic regulation); 4) participation in the regulation of the acid-base state (stabilization of blood pH) ", 5) participation in the regulation of blood pressure, erythropoiesis, blood coagulation, modulation of the action of hormones due to the formation and release of biologically active substances into the blood (endocrine function); 6) participation in metabolism of proteins, lipids and carbohydrates (metabolic function); 7) excretion from the body of end products of nitrogen metabolism and foreign substances, excess of organic substances (glucose, amino acids, etc.), taken with food or formed during metabolism (excretory function). Thus, the role of the kidney in the body is not limited only to the release of end products of metabolism and excess of inorganic and organic substances.The kidney is a homeostatic organ involved in maintaining the constancy of the basic physicochemical constants of fluids in the internal environment, in circulatory homeostasis, and stabilization of the metabolic parameters of various organic substances. the study of the work of the kidney follow t distinguish between two concepts - the functions of the kidney and the processes that provide them. The latter include ultrafiltration of fluid in the glomeruli, reabsorption and secretion of substances in the tubules, the synthesis of new compounds, including biologically active substances (Fig. 12.1). In the literature, when describing the activity of the kidney, the term "secretion" is used, which has a number of meanings. In some cases, this term means the transfer of a substance by nephron cells from the blood to the lumen of the tubule in an unchanged form, which causes the excretion of this substance by the kidney. In other cases, the term "secretion" means the synthesis and secretion of biologically active substances (for example, renin, prostaglandins) by cells in the kidney and their entry into the bloodstream. Finally, the process of synthesis in the cells of the tubules of substances that enter the lumen of the tubule and are excreted in the urine is also denoted by the term "secretion".

The structure of the nephron. Each kidney in humans contains about 1 million functional units - nephrons, in which urine is formed (Fig. 12.2). Each nephron begins with a renal, or malpighian, little body - a double-walled capsule of the glomerulus (capsule of Shumlyansky-Bowman), inside which there is a glomerulus of capillaries. The inner surface of the capsule is lined with epithelial cells; the resulting cavity between the visceral and parietal leaves of the capsule passes into the lumen of the proximal convoluted tubule. A feature of the cells of this tubule is the presence of a brush border - a large number of microvilli facing into the lumen of the tubule. The next section of the nephron is the thin descending part of the nephron loop (Henle's loop). Its wall is formed by low, flat epithelial cells. The descending part of the loop can go deep into the medulla, where the tubule bends 180 °, and turns towards the renal cortex, forming the ascending part of the nephron loop. It can include a thin and always has a thick ascending part, which rises to the level of the glomerulus of its own nephron, where the distal convoluted tubule begins. This part of the tubule necessarily touches the glomerulus between the efferent and efferent arterioles in the area of ​​the dense spot (see Fig. 12.2). The cells of the thick ascending part of Henle's loop and the distal convoluted tubule lack a brush border, they contain many mitochondria and the surface of the basal plasma membrane is enlarged due to folding. The terminal section of the nephron is a short connecting tubule that flows into the collecting tube 1. Starting in the renal cortex, the collecting tubes pass through the medulla and open into the cavity of the renal pelvis. The glomerular capsule diameter is about 0.2 mm, the total length of the tubules of one nephron reaches 35-50 mm. Based on the features of the structure and function of the renal tubules, the following segments of the nephron are distinguished: 1) the proximal, which includes the convoluted and straight parts of the proximal tubule; 2) the thin section of the nephron loop, including the descending and thin ascending parts of the loop; 3) the distal segment formed by the thick ascending section of the nephron loop, the distal convoluted tubule and the connecting section. The tubules of the nephron are connected to the collecting tubes: in the process of embryogenesis, they develop independently, but in the formed kidney the collecting tubes are functionally close to the distal segment of the nephron.

Several types of nephrons function in the kidney: superficial (superficial), intracortical and juxtamedullary (see Fig. 12.2). The difference between them lies in the localization in the kidney, the size of the glomeruli (juxtamedullary are larger than the superficial ones), the depth of the glomeruli and proximal tubules in the renal cortex (the glomeruli of juxtamedullary nephrons lie at the border of the cortical and medulla) and in the length of individual sections of the nephron, especially the nephron loops. Superofficial nephrons have short loops, juxtamedullary, on the contrary, long, descending into the inner medulla of the kidney. Strict zoning of the distribution of tubules within the kidney is characteristic. The zone of the nocturnal, in which the tubule is located, is of great functional importance, regardless of whether it is in the cortex or medulla. In the cortex are the renal glomeruli, proximal and distal tubules, and connecting sections. In the outer strip of the external medulla there are descending and thick ascending sections of the nephron loops, collecting tubes; in the internal medulla there are thin sections of the nephron loops and collecting tubes. The location of each of the parts of the nephron in the kidney is extremely important and determines the form of participation of certain nephrons in the activity of the kidney, in particular in the osmotic concentration of urine. Blood supply to the kidney. Under normal conditions, from 1/5 to 1/44 of the blood flowing from the heart to the aorta passes through both kidneys, the mass of which is only about 0.43% of the body weight of a healthy person. The blood flow through the cortex of the kidney reaches 4-5 ml / min per 1 g of tissue; this is the most high level organ blood flow. The peculiarity of renal blood flow is that under conditions of changes in systemic blood pressure in a wide range (from 90 to 190 mm Hg), it remains constant. This is due to a special system of self-regulation of blood circulation in the kidney.

The short renal arteries branch off from the abdominal aorta, branch out into smaller and smaller vessels in the kidney, and one afferent (afferent) arteriole enters the glomerulus. Here it breaks up into capillary loops, which, merging, form an efferent (efferent) arteriole, along which blood flows from the glomerulus. The diameter of the efferent arteriole is narrower than that of the afferent. Soon after leaving the glomerulus, the efferent arteriole again disintegrates into capillaries, forming a dense network around the proximal and distal convoluted tubules. Thus, most of the blood in the kidney passes twice through the capillaries - first in the glomerulus, then at the tubules. The difference in the blood supply to the juxtamedullary nephron is that the efferent arteriole does not disintegrate into the peri-tubular capillary network, but forms straight vessels descending into the medulla of the kidney. These vessels provide blood supply to the renal medulla; blood from the peri-tubular capillaries and direct vessels flows into the venous system and through the renal vein enters the inferior vena cava of the Juxtaglomerular apparatus (Fig. 12.3). Morphologically, it forms a kind of triangle, two sides of which are represented by afferent and efferent arterioles approaching the glomerulus, and the base by cells of the dense spot (mucula densa) of the distal tubule. The inner surface of the afferent arteriole is lined with endothelium, and the muscle layer near the glomerulus is replaced by large epithelial cells containing secretory granules. The cells of the dense spot are in close contact with the juxtaglomerular substance, consisting of a mesh network with small cells and passing into the glomerulus, where the mesangial tissue is located. The juxtaglomerular apparatus is involved in the secretion of renin and a number of other biologically active substances.

Ticket number 5 1. Reflex(from lat. reflexus reflected) stereotypical reaction a living organism for a certain effect, which takes place with the participation of the nervous system. Reflexes exist in multicellular living organisms with a nervous system. Classification:

By type of education: conditional and unconditional.

By types of receptors: exteroceptive (skin, visual, auditory, olfactory), interoceptive (from receptors of internal organs) and proprioceptive (from receptors of muscles, tendons, joints)

By effectors: somatic, or motor, (reflexes skeletal muscle), for example, flexor, extensor, locomotor, statokinetic, etc.; vegetative internal organs - digestive, cardiovascular, excretory, secretory, etc.

By biological significance: defensive, or protective, digestive, sexual, indicative.

According to the degree of complexity of the neural organization of reflex arcs, monosynaptic arcs are distinguished, the arcs of which consist of afferent and efferent neurons (for example, the knee), and polysynaptic, the arches of which also contain 1 or more intermediate neurons and have 2 or more synaptic switches (for example, flexor).

By the nature of the influences on the activity of the effector: excitatory - causing and intensifying (facilitating) its activity, inhibitory - weakening and suppressing it (for example, a reflex increase in the heart rate of the sympathetic nerve and its reduction or cardiac arrest - by a wandering one).

According to the anatomical location of the central part of the reflex arcs, spinal reflexes and reflexes of the brain are distinguished. In the implementation of spinal reflexes, neurons located in the spinal cord are involved. An example of the simplest spinal reflex is pulling the hand away from a sharp pin. Reflexes of the brain are carried out with the participation of neurons in the brain. Among them are bulbar, carried out with the participation of neurons of the medulla oblongata; mesencephalic - with the participation of midbrain neurons; cortical - with the participation of neurons in the cerebral cortex.

Reflex arc (nerve arc) - the path traversed by nerve impulses during the implementation of the reflex.

The reflex arc consists of: a receptor - a nerve link that perceives irritation; afferent link - centripetal nerve fiber - processes of receptor neurons that transmit impulses from sensitive nerve endings to the central nervous system; the central link is the nerve center (an optional element, for example, for the axon reflex); efferent link - carry out transmission from the nerve center to the effector. effector - an executive organ whose activity changes as a result of a reflex.

Distinguish: - monosynaptic, two-neuronal reflex arcs; polysynaptic reflex arcs (include three or more neurons).

Reflector ring- a set of structures of the nervous system involved in the implementation of the reflex and the transmission of information about the nature and strength of the reflex action in the central nervous system. The reflex ring includes: a reflex arc; reverse afferentation from the effector organ to the central nervous system.

Meaning reverse afferentation consists in the fact that in any physiological process or in a behavioral act of an animal, which is aimed at obtaining some kind of adaptive effect, inverse afferentation informs about the results of the perfect action, making it possible for the body to assess the degree of success of the action performed by it, i.e. through the link of reverse afferentation, a constant assessment of the actually obtained result is carried out with the one that was "programmed" in the acceptor of the result of the action.

2) The heart cycle consists of systole and diastole. Systole- a contraction that lasts 0.1–0.16 s in the atrium and 0.3–0.36 s in the ventricle. Atrial systole is weaker than ventricular systole. Diastole- relaxation, at the atria it takes 0.7–0.76 s, at the ventricles - 0.47–0.56 s. The duration of the cardiac cycle is 0.8–0.86 s and depends on the frequency of contractions. The time during which the atria and ventricles are at rest is called the general pause in the activity of the heart. It lasts approximately 0.4 seconds. During this time, the heart rests, and its chambers are partially filled with blood. Systole and diastole are complex phases and consist of several periods. In systole, two periods are distinguished - tension and expulsion of blood, including:

1) the phase of asynchronous contraction - 0.05 s;

2) the phase of isometric contraction - 0.03 s;

3) the phase of rapid expulsion of blood - 0.12 s;

4) the phase of slow expulsion of blood - 0.13 s.

Diastole lasts about 0.47 s and consists of three periods:

1) protodiastolic - 0.04 s;

2) isometric - 0.08 s;

3) the period of filling, in which the phase of rapid expulsion of blood is distinguished - 0.08 s, the phase of slow expulsion of blood - 0.17 s, the presystole time - filling the ventricles with blood - 0.1 s.

In general, we can say that the main parameters characterizing systemic hemodynamics are: systemic blood pressure, total peripheral vascular resistance, cardiac output, heart function, venous return of blood to the heart, central venous pressure, and circulating blood volume.

3) Inorganic substances of blood plasma:

Cations: Na +, K +, Ca2 +, Mg2 +, Fe3 +, Cu2 +; - anions Cl-, PO43-, HCO3-, I-. Value: ensuring the osmotic pressure of the blood (60% - NaCl). Normally, the osmotic blood pressure is 7.7-8.1 atm .; providing blood pH equal to 7.36-7.4; ensuring a certain level of sensitivity of cells involved in the formation of membrane potential.

Osmotic pressure is the excess hydrostatic pressure on a solution separated from a pure solvent by a semipermeable membrane, at which the diffusion of the solvent through the membrane stops. This pressure tends to equalize the concentrations of both solutions due to the counter-diffusion of solute and solvent molecules. A solution that has a higher osmotic pressure compared to another solution is called hypertonic, and a solution that has a lower osmotic pressure is called hypotonic. Osm value blood pressure - 7.6 - 8.1 atm. It is created mainly by salts in a dissociated state. Osmotic pressure is essential in maintaining the concentration of various substances dissolved in body fluids and determines the distribution of water between blood, cells and tissues.

Isotonic solution is a solution, the osmotic pressure of which is equal to the osmotic pressure of the blood (for example, 0.85% NaCl solution). Erythrocytes placed in such a solution do not change, since the osmotic pressure in them and in the solution is the same. This solution is called physiological. Hypotonic solution is a solution, the osmotic pressure of which is lower than the osmotic pressure of blood (for example, 0.3% NaCl solution). Erythrocytes placed in such a solution swell and burst (hemolyzed) as a result of the passage of water into the cell, since the osmotic pressure in the erythrocyte is higher than in the solution. Hypertonic solution is a solution, the osmotic pressure of which is higher than the osmotic pressure of blood (for example, 2% NaCl solution). Erythrocytes placed in such a solution shrink as a result of the release of water from the cell, since the osmotic pressure in the erythrocytes is lower than in the solution.

A functional system that ensures the constancy of the osmotic pressure of the blood.

1) The spinal cord (medulla spinalis) is a part of the central nervous system located in the spinal canal.

The spinal cord performs reflex and conduction functions. The first is provided by its nerve centers, the second by pathways.

It has a segmental structure. Moreover, the division into segments is functional. Each segment forms anterior and posterior roots. The hind ones are sensitive, i.e. afferent, anterior motor, efferent. The roots of each segment innervate 3 body metameres, but as a result of overlapping, each metamere is innervated by three segments. Therefore, when the anterior roots of one segment are affected, the motor activity of the corresponding metamer is only weakened.

Morphologically the bodies of neurons spinal cord form its gray matter. Functionally, all of its neurons are divided into motoneurons, intercalary, neurons of the sympathetic and parasympathetic divisions of the autonomic nervous system.

Motoneurons, depending on their functional value, are divided into alpha and gamma motor neurons. The fibers of the afferent pathways go to a-motoneurons, which start from intrafusal, i.e. receptor muscle cells. The bodies of a-motor neurons are located in the anterior horns of the spinal cord, and their axons innervate skeletal muscles. Gamma motoneurons regulate muscle spindle tension i.e. intrafusal fibers. Thus, they are involved in the regulation of skeletal muscle contractions. Therefore, when the anterior roots are cut, muscle tone disappears.

Interneurons provide communication between the centers of the spinal cord and the overlying parts of the central nervous system.

The neurons of the sympathetic part of the autonomic nervous system are located in the lateral horns of the thoracic segments, and the parasympathetic in the sacral part.

The conductive function is to ensure the connection of peripheral receptors, centers of the spinal cord with the overlying parts of the central nervous system, as well as its nerve centers with each other. It is carried out by conducting pathways. All pathways of the spinal cord are divided into own or propriospinal, ascending and descending. Propriospinal pathways connect the nerve centers of different segments of the spinal cord. Their function is to coordinate muscle tone, movements of various metamers of the trunk. TO ascending paths several paths belong. Gaulle and Burdach beams conduct nerve impulses from the proprioceptors of muscles and tendons to the corresponding nuclei of the medulla oblongata, and then the thalamus and somatosensory areas of the cortex. Thanks to these paths, the body posture is assessed and corrected. Govers and Fleksig bundles transmit excitation from proprioceptors, mechanoreceptors of the skin to the cerebellum. Due to this, perception and unconscious coordination of the posture is ensured. Spinothalamic tracts conduct signals from pain, temperature, tactile receptors of the skin to the thalamus, and then the somatosensory zones of the cortex. They ensure the perception of the corresponding signals and the formation of sensitivity. Descending paths also formed by several tracts. Corticospinal pathways go from pyramidal and extrapyramidal neurons of the cortex to a-motoneurons of the spinal cord. Due to them, the regulation of voluntary movements is carried out. Rubrospinal the path conducts signals from the red nucleus of the midbrain to the a-motor neurons of the flexor muscles. Vestibulospinal path transmits signals from the vestibular nuclei of the medulla oblongata, primarily the Deiters nucleus, to the a-motor neurons of the extensor muscles. Due to these two paths, the tone of the corresponding muscles is regulated with changes in body position.

Reflex function

All reflexes of the spinal cord are divided into somatic, i.e. motor and vegetative.

Somatic reflexes are divided into tendon or myotatic and cutaneous. Tendon reflexes occur with mechanical irritation of muscles and tendons. Their slight stretching leads to the excitation of tendon receptors and a-motoneurons of the spinal cord. As a result, muscle contraction occurs, primarily the extensors. Tendon reflexes include knee, Achilles, elbow, wrist, etc., arising from mechanical irritation of the corresponding tendons. For example, the knee is the simplest monosynaptic, since there is only one synapse in its central part. Skin reflexes are caused by irritation of skin receptors, but are manifested by motor reactions. They are plantar and abdominal (explanation). The spinal nerve centers are under the control of the overlying ones. Therefore, after the section between the medulla oblongata and the spinal cord, spinal shock occurs and the tone of all muscles will significantly decrease.

Vegetative reflexes spinal cord are divided into sympathetic and parasympathetic. Both are manifested by the reaction of internal organs to irritation of the receptors of the skin, internal organs, muscles. The vegetative neurons of the spinal cord form the lower centers for the regulation of vascular tone, cardiac activity, bronchial lumen, sweating, urination, defecation, erection, ejaculation, etc.

2) The respiratory center is located in the medial part of the reticular formation of the medulla oblongata. Its upper border is below the nucleus of the facial nerve, and the lower one is above the penis.

This center consists of inspiratory and expiratory neurons... In the first, nerve impulses begin to be generated shortly before inhalation and continue throughout the entire inhalation. Expiratory neurons located somewhat lower. They are excited towards the end of the inhalation and are in an excited state during the entire exhalation. The inspiratory center has 2 groups of neurons. These are respiratory a - and b-neurons. The former are excited by inhalation. At the same time, impulses from expiratory neurons arrive at b-respiratory neurons. They are activated simultaneously with a-respiratory neurons and ensure their inhibition at the end of inspiration. Thanks to these connections of the neurons of the respiratory center, they are in reciprocal relationships (i.e., when the inspiratory neurons are excited, the expiratory ones are inhibited and vice versa). In addition, the neurons of the bulbar respiratory center are characterized by the phenomenon of automation. This is their ability to generate rhythmic discharges of biopotentials even in the absence of nerve impulses from peripheral receptors.

Thanks to the automation of the respiratory center, a spontaneous change in the phases of breathing occurs. The automation of neurons is explained by the rhythmic fluctuations of metabolic processes in them, as well as the effect of carbon dioxide on them. The efferent pathways from the bulbar respiratory center go to the motor neurons of the respiratory intercostal and diaphragmatic muscles. The motor neurons of the diaphragmatic muscles are located in the anterior horns of 3-4 cervical segments of the spinal cord, and intercostal in the anterior horns of the thoracic segments. As a result, the transection at the level of 1-2 cervical segments leads to the cessation of contractions of the respiratory muscles. In the front part of the pons, there are also groups of neurons involved in the regulation of respiration. These neurons have ascending and descending connections with the neurons of the bulbar center. Impulses from his inspiratory neurons go to them, and from them to expiratory ones. This ensures a smooth transition from inhalation to exhalation, as well as coordination of the duration of the breathing phases.

Apnea center respiratory depression is located at the bottom of the bridge and provides a sufficient duration of inspiration. Although it is still unclear whether this center plays a role in the regulation of respiration in humans, it has been shown to be involved in increasing the duration of inspiration.

Pneumotaxic center located in the parabrachial nucleus at the top of the pons, provides cessation of inspiration (i.e., restricts inspiration). A more pronounced activity of this center causes a shortening of the inhalation (up to 0.5 s) and an increase in breathing up to 30-40 breaths per minute, and weak activity - a long inhalation (up to 5 seconds or more) and a decrease in the respiratory rate to several breaths per minute. The pneumotaxic center is involved in the regulation of inspiratory volume.

3) Blood group - a description of the individual antigenic characteristics of erythrocytes, determined using methods for identifying specific groups of carbohydrates and proteins included in the membranes of erythrocytes.

Blood groups of the ABO system are indicated by Roman numerals and a duplicate antigen name:

I (0) - erythrocytes do not contain agglutinogens, but the plasma contains agglutinins a and b.

II (A) - agglutinogens A and agglutinins b.

III (B) - agglutinogens B and agglutinins a.

IV (AB) - in erythrocytes agglutinogens A and B, there are no agglutinins in plasma.

Rhesus blood is an antigen (protein) that is found on the surface of red blood cells (erythrocytes). In contrast to the ABO antigenic system, where there are corresponding agglutinins to agglutinogens A and B, there are no agglutinins to the Rh antigen in the blood. They are produced when Rh positive blood (containing Rh factor) is poured into a recipient with Rh negative blood. At the first transfusion of Rh incompatible blood, there will be no transfusion reaction. However, as a result of sensitization of the recipient's body, after 3-4 weeks, Rh agglutinins will appear in his blood. They persist for a very long time. Therefore, with repeated transfusion of Rh-positive blood to this recipient, agglutination and hemolysis of erythrocytes of donor blood will occur.

Another difference between these two antigenic systems is that Rh agglutinins are significantly smaller than a and b. Therefore, they can penetrate the placental barrier. In the last weeks of pregnancy, during childbirth and even during abortion, fetal red blood cells can enter the mother's bloodstream. If the fetus has Rh-positive blood, and the mother is Rh-negative, then the Rh antigens that enter her body with the erythrocytes of the fetus will cause the formation of Rh agglutinins. The titer of Rh agglutinins grows slowly, so there are no special complications during the first pregnancy. If, during repeated pregnancy, the fetus again inherits Rh-positive blood, then the mother's Rh-agglutinins entering the placenta will cause agglutination and hemolysis of the fetal erythrocytes. In mild cases, anemia occurs, hemolytic jaundice of newborns. In severe fetal erythroblastosis and stillbirth. This phenomenon is called Rh-conflict.

Currently, about 400 antigenic blood systems are known. In addition to the ABO and Rh systems, the systems MNSs, P, Kell, Kidda and others are known. Considering all antigens, the number of their combinations is about 300 million. But since their antigenic properties are poorly expressed, their role for blood transfusion is insignificant.

Blood transfusion (blood transfusion)- a therapeutic method, which consists in the introduction into the bloodstream of the patient (recipient) of whole blood or its components, harvested from the donor or from the recipient himself (autohemotransfusion), as well as blood poured into the body cavity during injuries and operations (reinfusion).

Indications for prescribing a transfusion of any transfusion medium, as well as its dosage and the choice of a transfusion method, are determined by the attending physician based on clinical and laboratory data. The doctor is obliged, regardless of the previously conducted studies and available records, to personally conduct the following control studies:

1) determine the group affiliation of the recipient's blood according to the AB0 system and check the result with the data of the medical history;

2) determine the group belonging of the donor's erythrocytes and compare the result with the data on the container or bottle label;

3) conduct tests for compatibility in relation to blood groups of the donor and recipient according to the AB0 system and the Rh factor;

4) conduct a biological test.

Ticket number 7

1 Types of IRR - a set of congenital (genotype) and acquired (phenotype) properties of the nervous system, which determine the nature of the interaction of the body with the environment and are reflected in all functions of the body.

Various combinations of the three main properties of the nervous system - the strength of the processes of excitation and inhibition, their balance and mobility - allowed I.P. Pavlova, distinguish four sharply outlined types, differing in adaptive abilities and resistance to neurotic agents.

T.VND strong unbalanced- is characterized by a strong irritable process and a lagging inhibitory process, therefore, a representative of this type in difficult situations is easily susceptible to violations of VND. Able to train and greatly improve insufficient inhibition. According to the doctrine of temperaments, this is the choleric type.

T. VND balanced inert- with strong processes of excitement and inhibition and with their poor mobility, always having difficulty switching from one type of activity to another. According to the doctrine of temperaments, this is a phlegmatic type.

T.VND strong balanced movable- has equally strong processes of excitation and inhibition with their good mobility, which provides high adaptive capabilities and stability in difficult life situations. According to the doctrine of temperaments, this is a sanguine type.

T.VND weak- characterized by the weakness of both nervous processes - excitement and inhibition, poorly adapts to environmental conditions, prone to neurotic disorders. According to the classification of temperaments, it is a melancholic type.

Temperament - a stable combination of individual personality traits associated with dynamic, rather than meaningful aspects of activity. Temperament is the basis for character development; in general, from a physiological point of view, temperament is a type of human higher nervous activity.

Hippocratic temperament:

The predominance of yellow bile makes a person impulsive, "hot" - choleric.

The predominance of lymph makes a person calm and slow - phlegmatic.

The predominance of blood makes a person mobile and cheerful - sanguine.

The predominance of black bile makes a person sad and fearful - melancholic.

Constitution- This is a set of functional and morphological characteristics of the body, formed on the basis of hereditary and acquired properties, which determine the originality of the body's response to external and internal stimuli.

Kretschmer's human typology:

Asthenic - differs in weak growth "in thickness" with greater growth "in length"; thin, thin, with poor juices and blood skin, narrow shoulders, long and flat chest. He has a fragile constitution, tall stature, an elongated face, and a long thin nose. The lower limbs are long and thin. Asthenic women resemble male asthenics, but they are not only thin, but also short. Their premature aging is striking.

A picnic - of medium or small stature, with a rich fatty tissue, a loose body, a round head on short neck, with a shallow wide face. Shows a tendency towards obesity.

Athletic - has good muscles, strong build, high or medium height, wide shoulder girdle and narrow hips, prominent facial bones.

Sheldon's somatotyping system:

Pure endomorph characterized by spherical shapes, as far as it is generally possible for a person. Such an individual has a round head big belly, weak, limp arms and legs, with a lot of fat on the shoulders and hips, but thin wrists and ankles. A similar person with a lot subcutaneous fat could be called simply fat if all the profile sizes of his body (including the chest and pelvis) did not prevail over the transverse ones. This constitution is largely accompanied by excessive fat deposition.

Pure mesomorph is a classic Hercules with a predominance of bones and muscles. He has a massive cubic head, broad shoulders and ribcage, muscular arms and legs. The amount of subcutaneous fat is minimal, the profile dimensions are small.

A pure ectomorph is a lanky person. He has a thin, elongated face, a chin pulled back, a high forehead, a narrow chest and abdomen, a narrow heart, thin and Long hands and legs. The subcutaneous fat layer is almost absent, the muscles are undeveloped. Obesity is not at all threatened by an explicit ectomorph.

2) The oral cavity is the initial part of the digestive tract, where the analysis of the taste properties of substances is carried out and their separation into food and rejected, protection of the digestive tract from the ingress of low-quality food substances and exogenous microflora, grinding, wetting food with saliva, initial hydrolysis of carbohydrates and the formation of a food lump. In addition, irritation of mechano-, chemo-, thermoreceptors occurs, causing reflex excitement of the activity of the salivary glands, stomach glands, pancreas, liver, duodenal glands.

Saliva- a clear, colorless liquid, a liquid biological environment of the body secreted into the oral cavity by three pairs of large salivary glands (submandibular, parotid, sublingual) and many small salivary glands of the oral cavity.

Saliva has a pH of 5.6 to 7.6. It consists of 98.5% water, contains salts of various acids, trace elements and cations of some alkali metals, mucin (forms and glues a food lump), lysozyme (bactericidal agent), enzymes amylase and maltase, which break down carbohydrates to oligo- and monosaccharides, and also other enzymes, some vitamins. Also, the composition of the secretion of the salivary glands varies depending on the nature of the stimulus.

On average, 1-2.5 liters of saliva are secreted per day. Salivation is controlled by the autonomic nervous system. The salivation centers are located in the medulla oblongata. Stimulation of the parasympathetic endings produces a large amount of saliva with a low protein content. Conversely, sympathetic stimulation results in the secretion of a small amount of viscous saliva. Without stimulation, saliva secretion occurs at a rate of about 0.5 ml / min.

Saliva production decreases with stress, fright, or dehydration, and virtually stops during sleep and anesthesia. Increased salivation occurs under the action of olfactory and gustatory stimuli, as well as due to mechanical irritation by large food particles and during chewing.

Chewing serves for mechanical processing of food, i.e. her biting off crushing, grinding. When chewing, food is moistened with saliva, and a food lump is formed from it. Chewing is due to the complex coordination of muscle contractions that move the teeth, tongue, cheeks, and the floor of the mouth.

Chewing is a complex reflex act. Those. it is carried out unconditionally - and by conditioned reflex mechanisms. Absolutely reflex is that the food irritates the mechanoreceptors of the periodontal teeth and oral mucosa. From them, impulses along the afferent fibers of the trigeminal, glossopharyngeal and superior laryngeal nerves enter the chewing center of the medulla oblongata. Through the efferent fibers of the trigeminal, facial and hypoglossal nerves, impulses go to chewing muscles by carrying out unconscious concerted contractions. Conditioned reflex influences make it possible to arbitrarily regulate the chewing act.

Swallowing- a complex reflex act that begins voluntarily. The formed food lump moves to the back of the tongue, the tongue is pressed against the hard palate and moves to the root of the tongue. Here it irritates the mechanoreceptors of the tongue root and palatine arches. From them, along the afferent nerves, impulses go to the center of swallowing of the medulla oblongata. From it, along the efferent fibers of the hypoglossal, trigeminal, glossopharyngeal and vagus nerves, they go to the muscles of the oral cavity, pharynx, larynx, esophagus. The soft palate rises reflexively and closes the entrance to the nasopharynx. At the same time, the larynx rises and the epiglottis descends, closing the entrance to the larynx. A lump of food is pushed into the dilated pharynx. This ends oropharyngeal phase swallowing. Then the esophagus is pulled up and its upper sphincter relaxes.

Begins esophageal phase... The food lump moves along the esophagus due to its peristalsis. The circular muscles of the esophagus contract above the food bolus and relax below it. The contraction-relaxation wave spreads to the stomach. This process is called primary peristalsis. When the food lump approaches the stomach, the lower esophageal or cardiac sphincter relaxes, allowing the lump to enter the stomach. Outside of swallowing, it is closed and serves to prevent gastric contents from being thrown into the esophagus. If the food lump gets stuck in the esophagus, then from its location, secondary peristalsis begins, which is identical in mechanisms to the primary one. Solid food moves along the esophagus for 8-9 seconds. The liquid flows down passively, without peristalsis, in 1-2 seconds.

3) The pituitary gland - a cerebral appendage in the form of a rounded formation, located in the Turkish saddle, produces hormones that affect growth, metabolism and reproductive function. Is the central organ of the endocrine system; interacts closely with the hypothalamus.

Hormones of the anterior pituitary gland

Adrenocorticotropic hormone (ACTH)- (adrenocorticotropin, corticotropin) - has a stimulating effect on the function of the adrenal cortex.

Growth hormone (STH)(growth hormone, somatotropin) - participates in the regulation of all types of metabolism in the human body, but the main action is to stimulate skeletal growth and increase body size

Thyroid stimulating hormone (TSH)(thyrotropin) - the biological role is to maintain the normal structure and functional activity of the thyroid gland.

Luteinizing hormone (LH)(lutropin) is a gonadotropic hormone that stimulates the development of the sex glands in men and women, and in women also ovulation.

Prolactin(lactogenic hormone, luteotropic hormone, luteotropin, mammotropin) - has a broad biological activity: it stimulates the growth and development of mammary glands, the growth and function of the sebaceous glands and the growth of internal organs. Prolactin stimulates reproductive processes, the manifestation of the maternal instinct, and in men - the growth of the prostate gland.

Follicle-stimulating hormone (FSH)- stimulates the growth and development of follicles in the ovaries and spermatogenesis in the seminal vesicles.

Hormones of the posterior lobe of the pituitary gland:

Oxytocin- a hormone that stimulates the separation of milk in women during feeding and contraction of the muscles of the uterus;

Vasopressin (ADH)- the hormone, which has an antidiuretic and vasopressor effect, increases the reabsorption of water by the kidney, thus increasing the concentration of urine and reducing its volume.

1) Excitability Is the ability of living tissue to respond to stimulation with an active specific reaction - excitation, i.e. generation of a nerve impulse, contraction, secretion. Those. excitability characterizes specialized tissues - nervous, muscular, glandular, which are called excitable.

Excitation Is a complex of processes of response of an excitable tissue to the action of an irritant, manifested by a change in the membrane potential, metabolism, etc. Excitable tissues are conductive. This is the tissue's ability to conduct excitation. The nerves and skeletal muscles have the highest conductivity.

Stimulus Is a factor of the external or internal environment acting on living tissue.

Chronaximetry- a method for studying the excitability of tissues depending on the time of action of the stimulus (determination of chronaxia and rheobase).

Physiological lability (mobility)- this is a greater or lesser frequency of reactions with which a tissue can respond to rhythmic stimulation. The faster its excitability is restored after the next irritation, the higher its lability. The definition of lability was proposed by N.E. Vvedensky. The greatest lability in the nerves, the least in the heart muscle.

Irritation threshold Is the minimum strength of the stimulus at which arousal occurs.

Pessimum- inhibition of the activity of nervous and muscle tissues caused by excessive frequency of stimulation of the nerve trunk, edges cannot be reproduced in the form of biopotentials of the nerve itself and synchronous contractions of the muscle it innervates. It corresponds to such a frequency, with a cut, each subsequent irritation falls on the muscle in the phase of its abs. refractoriness (non-excitability). Pessimum is accompanied by a weakening of muscle contraction as a result of the transformation of the frequency of stimulation.

Optimum- the maximum level of activity of the nervous and muscle tissues, which can be stably reproduced both in the nerve itself and in the form of synchronous contractions of the muscle it innervates. The optimum is due to a certain frequency of stimulation of the nerve trunk, with a cut each subsequent stimulation enters the muscle in the phase of its increased excitability, contributing to a long-term continuous contraction - tetanus.

2) Nervous regulation of cardiac activity is carried out by the sympathetic and parasympathetic divisions of the autonomic nervous system. The nuclei of the vagus nerve that innervates the heart are located in the medulla oblongata. The vagus nerves end at the intramural ganglia. Postganglionic fibers of the right vagus go to the sinoatrial node, and the left to the atrioventricular. In addition, they innervate the myocardium of the corresponding atria. There are no parasympathetic endings in the ventricular myocardium. Due to this innervation, the right vagus affects mainly the heart rate, and the left one affects the rate of conduction of excitation in the atrioventricular node.

The bodies of sympathetic neurons innervating the heart are located in the lateral horns of the 5 upper thoracic segments of the spinal cord. The axons of these neurons go to the stellate ganglion. Postganglionic fibers depart from it, numerous branches of which innervate both the atria and ventricles. The heart has a developed intracardiac nervous system, including afferent, efferent, intercalary neurons and nerve plexuses. It is considered a division of the metasympathetic nervous system.

The vagus nerves have the following effects on the heart:

1. Negative chronotropic effect. This is a decrease in heart rate. It is associated with the fact that the right vagus inhibits the generation of impulses in the sinoatrial node. Under the influence of the vagus, their generation may temporarily stop.

2. Negative inotropic effect. Decreased heart rate. It is caused by a decrease in the amplitude and duration of APs generated by pacemaker cells.

3. Negative dromotropic effect. Decrease in the rate of conduction of excitation through the conducting system of the heart. Associated with the effect of the left vagus on the atrioventricular node. With a sufficiently strong arousal, a temporary atrioventricular block may occur.

4. Negative batmotropic effect. This is a decrease in the excitability of the heart muscle. Under the influence of the vagus, the refractory phase is lengthened.

These effects of the vaguses on the heart are due to the fact that their endings release acetylcholine. It binds to the M-cholinergic receptors of cardiomyocytes and causes hyperpolarization of their membrane. Therefore, the excitability, conductivity, automaticity of cardiomyocytes decrease, and as a result, the strength of contractions.

If the vagus nerves are irritated for a long time, the initially stopped heart begins to contract again. This phenomenon is called the escape of the heart from the influence of the vagus. It is a consequence of the parallel amplification of the influence of the sympathetic nerves. The centers of the vagus nerves are in a state of tone. Therefore, impulses from them constantly go to the heart.

Sympathetic nerves have the opposite effect on cardiac activity. They have positive chronotropic, inotropic, batmotropic and dromotropic effects. The mediator of sympathetic nerves, norepinephrine, interacts with the β1-adrenergic receptors of the cardiomyocyte membrane. Its depolarization occurs, and as a result, the slow diastolic depolarization in the P-cells of the sinoatrial node accelerates, the amplitude and duration of the generated AP increases, and the excitability of the cells of the conducting system increases. As a result, excitability, automation, conductivity and strength of contractions of the heart muscle increase. The tone of the sympathetic centers for the regulation of cardiac activity is much less pronounced than the parasympathetic ones.

3) The transport of oxygen from the lungs to the tissues is carried out by the blood mainly in the form of a chemical compound with hemoglobin - oxyhemoglobin and, to a lesser extent, in a dissolved state.

Hemoglobin (Hb) is a hemoprotein found in red blood cells. The hemoglobin molecule is formed by four subunits, each of which includes a heme connected to an iron atom and a protein part of globin. Heme is synthesized in the mitochondria of erythroblasts, and globin in their ribosomes. In an adult, hemoglobin contains two a - and two b-polypeptide chains. It is called A-hemoglobin (adult-adult). IN mature age it makes up the bulk of hemoglobin.

Heme contains an atom of 2-valent iron, which easily combines with oxygen and gives it away easily. In this case, the valence of iron does not change. One gram of hemoglobin is capable of binding 1.34 ml of oxygen. The combination of hemoglobin with oxygen that forms in the capillaries of the lungs is called oxyhemoglobin (HbO2). Hemoglobin, which has given up oxygen in the capillaries of tissues, is called deoxyhemoglobin or reduced (Hb).

From 10 to 30% of carbon dioxide entering the blood from tissues is combined with the amide group of hemoglobin. The readily dissociating compound carbhemoglobin (HbCO2) is formed. In this form, some of the carbon dioxide is transported to the lungs.

In some cases, hemoglobin forms pathological compounds. Carbon monoxide poisoning produces carboxyhemoglobin (HbCO). The affinity of hemoglobin with carbon monoxide is much higher than with oxygen, and the rate of dissociation of carboxyhemoglobin is 200 times less than that of oxyhemoglobin. Therefore, the presence of even 1% carbon monoxide in the air leads to a progressive increase in the amount of carboxyhemoglobin and dangerous carbon monoxide poisoning. The blood loses its ability to carry oxygen. When poisoning with strong oxidants, such as nitrites, potassium permanganate, red blood salt, methemoglobin (MetHb) is formed. In this compound of hemoglobin, iron becomes trivalent. Therefore, methemoglobin is a very weakly dissociating compound. It does not release oxygen to tissues.

Oxyhemoglobin dissociation curve:

At its initial point, when PaO2, hemoglobin does not contain oxygen and SaO2 is also zero. As PaO2 increases, hemoglobin begins to quickly become saturated with oxygen, turning into oxyhemoglobin: a slight increase in oxygen tension is sufficient for a significant increase in the HbO2 content. At 40 mm Hg. Art. the content of HbO2 already reaches 75%. Then the slope of the curve becomes more and more gentle. In this part of the curve, hemoglobin is already less willing to add oxygen to itself, and to saturate the remaining 25% of Hb, it is necessary to raise PaO2 from 40 to 150 mm Hg. Art. However, under natural conditions, the hemoglobin of the arterial Blood is never completely saturated with oxygen, because the UTR when breathing in atmospheric air PaO2 does not exceed 100 mm Hg. Art.

Blood oxygen capacity- the amount of oxygen that can be associated with blood when it is fully saturated; expressed in percent by volume (vol%); depends on the concentration of hemoglobin in the blood. Determination of the oxygen capacity of the blood is important for characterizing the respiratory function of the blood. The oxygen capacity of human blood is about 18-20 vol%.

1) Sleep is a long-term functional state characterized by a significant decrease in neuropsychic and motor activity, which is necessary to restore the ability of the brain for analytic-synthetic activity.

Types of sleep:

1.Physiological daily sleep.

2.Seasonal sleep in animals (ground squirrel 9 months)

3. Hypnotic sleep.

4. Narcotic sleep.

5. Pathological sleep.

The duration of daily sleep in newborns is about 20 hours, in one-year-old children 13-15 hours, in adults 6-9 hours. (Napoleon's views on sleep, bad habit, life expectancy of short-sleeping, medium-sleeping, long-sleeping people).

During physiological sleep, 2 forms of sleep periodically replace each other: REM sleep or paradoxical sleep, NREM sleep. REM sleep occurs 4-5 times per night and lasts 1/4 of the total sleep time. During REM sleep, the brain is in a long state: this is evidenced by the aa-rhythm of the EEG, rapid movements of the eyeballs, twitching of the eyelids, limbs, pulse and breathing become more frequent, etc. If a person is awakened during REM sleep, he will talk about dreams. During slow sleep, these phenomena are absent, and a delta rhythm is recorded on the EEG, which is indicative of inhibitory processes in the brain. For a long time it was believed that during slow wave sleep there are no dreams; now it has been established that dreams during this period of sleep are less vivid, prolonged and real. The occurrence of nightmares is also associated with slow sleep patterns. Moreover, it was found that somnabulism or sleepwalking occurs precisely during slow wave sleep.

Sleep meaning:

1.Cleaning Ts.N.S. from metabolites accumulated during wakefulness.

2. Removal of unnecessary information accumulated during the day and preparation for receiving new information.

3. Transfer of information from short-term memory to long-term memory. It occurs during slow wave sleep. Therefore, memorizing the material before going to bed contributes to memorization and better reproduction of the memorized. Memorization of logically unrelated material is especially improved.

4. Emotional restructuring. During REM sleep, there is a decrease in the excitability of foci of motivational arousal, which arose as a result of an unmet need. During sleep, unmet needs are reflected in dreams (Z. Freud. On the dream). Patients with depressive conditions have unusually vivid dreams. Thus, in a dream, psychological stabilization occurs and the personality is to a certain extent protected from unresolved conflicts. It was found that people who do not sleep much, in whom the duration of REM sleep is relatively longer, are better adapted to life and calmly experience psychological problems. Long sleepers are burdened with psychological and social conflicts.

2) Three types of digestive juices are poured into the duodenum: pancreatic (pancreatic juice), bile, intestinal juice. They all have a pronounced alkaline reaction. Pancreatic and intestinal juice contains three types of enzymes that break down proteins, fats and carbohydrates. Proteolytic enzymes: trypsin, chymotrypsin, elastase, carboxypeptidase. The role of proteolytic enzymes is the degradation of native proteins and products of their primary processing in the stomach (albumosis and peptones) to low molecular weight polypeptides and amino acids. Amylolytic enzymes: alpha-amylase. Their role is to further break down carbohydrates into glucose and maltose. Lipolytic enzymes: lipase, phospholipase A. Lipase is secreted in an active state, its activity increases under the action of bile acids

Pancreas: Its external secretory activity consists in the release of pancreatic juice into the duodenum, containing enzymes involved in digestion processes.

The regulation of the formation and secretion of pancreatic juice is carried out by the humoral and nervous pathways with the participation of secretin (a hormone formed by the action of acidic gastric contents in the mucous membrane of the small intestine) and secretory fibers of the vagus and sympathetic nerves. Physiological stimulants of the pancreatic department - hydrochloric acid and some other acids, bile, food. Composition of pancreatic juice. During the day, the pancreas secretes 1500-2000 ml juice. Pancreatic juice, obtained in its pure form, is a colorless transparent liquid of an alkaline reaction (pH = 7.8-8.4) due to the presence of sodium bicarbonate in it. Pancreatic juice contains a significant amount of solid substances (1.3%), which determines its high specific gravity (1.015). From organic substances it consists mainly of proteins, from inorganic - bicarbonates, chlorides and other salts. Pancreatic juice also contains mucous substances secreted by the glands of the excretory duct. The composition of the juice varies depending on whether its separation is caused by irritation of the vagus nerve or by the action of secretin. But the main constituent part of pancreatic juice are enzymes that are of great importance in the digestion processes. These enzymes are as follows: trypsin, lipase, amylase, maltase, pvertase, lactase, nuclease, as well as a small amount of erepsin and renin.

3) Thermoregulation is a combination of physiological processes of heat generation and heat transfer, ensuring the maintenance of normal body temperature. Thermoregulation is based on the balance of these processes. The regulation of body temperature by changing the intensity of metabolism is called chemical thermoregulation. Heat generation is enhanced by the intensification of metabolic processes, this is called non-trembling thermogenesis. It is provided by brown fat. Its cells contain many mitochondria and a special peptide that causes uncoupling of the processes of oxidation and phosphorylation and stimulates the breakdown of lipids with the release of heat. In addition, thermogenesis enhances involuntary muscle activity in the form of tremors, voluntary motor activity. Heat generation is most intense in working muscles. With hard physical work, it increases by 500%.

Heat transfer serves to release excess heat generated and is called physical thermoregulation. By means of heat radiation 60% of heat is released, convection (15%), thermal conductivity (3%), evaporation of water from the surface of the body and from the lungs (20%).

The balance of the processes of heat generation and heat transfer is provided by nervous and humoral mechanisms. When the body temperature deviates from the normal value, the thermoreceptors of the skin, blood vessels, internal organs, and upper respiratory tract are excited. These receptors are specialized ends of the dendrites of sensory neurons, as well as thin fibers of type C. There are more cold receptors in the skin than heat receptors and they are located more superficially. Nerve impulses from these neurons along the spinothalamic tracts enter the thalamus, hypothalamus and cerebral cortex. A feeling of cold or warmth is formed. In the posterior hypothalamus and the preoptic region of the anterior, the center of thermoregulation is located. The neurons of the posterior hypothalamus mainly provide chemical thermoregulation, and the anterior one - physical. There are three types of neurons in the center. The first is thermosensitive neurons. They are located in the preoptic region and respond to changes in the temperature of the blood passing through the brain. Fewer of the same neurons are found in the spinal cord and medulla oblongata. The second group is interneurons. They receive information from peripheral temperature receptors and thermoreceptor neurons. This group of neurons serves to maintain the setpoint, i.e. a certain body temperature. One part of these neurons receives information from cold, the other from peripheral heat receptors and thermoreceptor neurons. The third type of neurons is efferent. They are located in the posterior hypothalamus and regulate the mechanisms of heat production.

The center of thermoregulation carries out its effects on the executive mechanisms through the sympathetic and somatic nervous systems, endocrine glands. With an increase in body temperature, peripheral heat receptors and thermoreceptor neurons are excited. Impulses from them go to interneurons, and then to the effector ones. The effector neurons are the sympathetic centers of the hypothalamus. As a result of their excitation, sympathetic nerves are activated, which dilate the vessels of the skin and stimulate sweating. When cold receptors are excited, the opposite picture is observed. The frequency of nerve impulses going to the skin vessels and sweat glands decreases, the vessels narrow, sweating is inhibited. At the same time, the vessels of the internal organs expand. If this does not lead to the restoration of temperature homeostasis, other mechanisms are activated. First, the sympathetic nervous system enhances the processes of catabolism, and therefore heat production. Norepinephrine released from the endings of the sympathetic nerves stimulates lipolysis. Brown fat plays a special role in this. This phenomenon is called non-shaking thermogenesis. Secondly, nerve impulses begin to go from the neurons of the posterior hypothalamus to the motor centers of the midbrain and medulla oblongata. They are excited and activate the a-motoneurons of the spinal cord. Involuntary muscle activity occurs in the form of cold shivers. The third way is to increase voluntary motor activity. Corresponding behavioral change that is provided by the cortex is essential. Of the humoral factors, adrenaline, norepinephrine and thyroid hormones are of the greatest importance. The first two hormones cause a short-term increase in heat production due to increased lipolysis and glycolysis. With adaptation to prolonged cooling, the synthesis of thyroxine and triiodothyronine is enhanced. They significantly increase energy metabolism and heat production by increasing the amount of enzymes in mitochondria.

1) Nerve- a complex formation, consisting of a nerve fiber (myelinated or non-myelinated), loose fibrous connective tissue that forms the sheath of the nerve.

The mechanism for conducting excitation along nerve fibers depends on their type. There are two types of nerve fibers: myelinated and nonmyelinated.

Metabolic processes in myelin-free fibers do not provide quick compensation for energy expenditure. The propagation of excitement will go with a gradual attenuation - with a decrement. Decremental behavior of arousal is characteristic of a low-organized nervous system. Excitation propagates due to small circular currents that occur inside the fiber or into the surrounding fluid. A potential difference arises between the excited and unexcited areas, which contributes to the appearance of circular currents. The current will spread from "+" charge to "-". At the exit point of the circular current, the permeability of the plasma membrane for Na ions increases, as a result of which membrane depolarization occurs. A potential difference arises again between the newly excited area and the neighboring unexcited one, which leads to the appearance of circular currents. Excitation gradually covers the adjacent areas of the axial cylinder and so it spreads to the end of the axon.

In myelin fibers, due to the perfection of metabolism, excitation passes without dying out, without decrement. Due to the large radius of the nerve fiber due to the myelin sheath, electric current can enter and exit the fiber only in the interception area. When irritation is applied, depolarization occurs in the area of ​​interception A, the adjacent intercept B is polarized at this time. A potential difference arises between interceptions, and circular currents appear. Due to circular currents, other interceptions are excited, while the excitement spreads in a saltatory manner, abruptly from one interception to another. The saltatory way of propagation of excitation is economical, and the speed of propagation of excitation is much higher (70-120 m / s) than along non-myelinated nerve fibers (0.5-2 m / s).

There are three laws of the conduction of irritation along the nerve fiber.

The law of anatomical and physiological integrity.

Conducting impulses along the nerve fiber is possible only if its integrity is not violated. If the physiological properties of the nerve fiber are violated by cooling, the use of various drugs, squeezing, as well as cuts and damage to the anatomical integrity, it will be impossible to conduct a nerve impulse through it.

The law of isolated conduction of excitation.

There are a number of features of the propagation of excitation in peripheral, pulp and non-pulp nerve fibers.

In peripheral nerve fibers, excitation is transmitted only along the nerve fiber, but is not transmitted to neighboring ones, which are in the same nerve trunk.

In the pulp nerve fibers, the myelin sheath acts as an insulator. Due to myelin, the resistivity increases and the electrical capacity of the shell decreases.

In the non-fleshy nerve fibers, excitation is transmitted in isolation. This is because the resistance of the fluid that fills the intercellular gaps is much lower than the resistance of the nerve fiber membrane. Therefore, the current that occurs between the depolarized area and the unpolarized one passes through the intercellular gaps and does not enter the adjacent nerve fibers.

The law of bilateral conduction of excitation.

The nerve fiber conducts nerve impulses in two directions - centripetal and centrifugal.

In a living organism, excitation is carried out in only one direction. Bilateral conduction of the nerve fiber is limited in the body by the place of origin of the impulse and the valve property of synapses, which consists in the possibility of conducting excitation in only one direction.

2) TRANSMISSION OF EXCITATION IN THE MYOCARDIUM.

The appearance of electrical potentials in the heart muscle is associated with the movement of ions across the cell membrane. The main role in this is played by sodium and potassium catoins. It is known that there is more potassium inside the cell than in the pericellular fluid; the concentration of intracellular sodium, on the contrary, is less than that of pericellular. At rest, the outer surface of the myocardial cell has a positive charge as a result of the predominance of sodium cations; the inner surface of the cell membrane has a negative charge due to the predominance of anions inside the cell. Under these conditions, the cell is polarized. Under the influence of an external electrical impulse, the cell membrane becomes permeable to sodium cations, which are directed into the cell, and transfers its positive infection there. The outer surface of this area of ​​the cell acquires a negative charge due to the preponderance of anaons there. This process is called DEPOLARIZATION and is related to the action potential. Soon, the entire surface of the cell will again acquire a negative charge, and the inner one - positive. So what happens REVERSE POLARIZATION... Repolarization of the membrane causes gradual closure of potassium channels and reactivation of sodium channels. As a result, the excitability of the myocardial cell is restored - this is the period of the so-called relative refractoriness. In the cells of the working myocardium (atria, ventricles), the membrane potential is maintained at a more or less constant level.

The above processes occur during systole. If the entire surface again acquires a positive charge, and the inner one - negative, then this corresponds to diastole. During diastole, gradual reverse movements of potassium and sodium ions occur, which have little effect on the charge of the cell, since sodium ions leave the cell, and potassium ions enter it simultaneously. These processes balance each other.

The above processes refer to the excitation of a single muscle fiber of the myocardium. Having arisen during depolarization, the impulse causes excitation of neighboring areas of the myocardium, which gradually covers the entire myocardium, and develops in a chain reaction type. Excitation of the heart begins in the slug node. Then, from the sinus node, the excitation process spreads to the atria. From the atria, it goes to the node. Having turned around this connection, the excitement goes to the trunk of the His bundle.

The speed of propagation of excitation is different in different parts of the conducting system, so in the atria and along the Giss's bundle, excitation propagates at a speed of 1 m / s, along the Purkinje fibers - 3 m / s, and in the atrioventricular node at a speed of 0.05 m / s. The rapid spread of excitation in the atria and ventricles causes a one-time coverage of the excitation of the entire myocardium. At the same time, its simultaneous reduction contributes to an increase in ejection force and work efficiency. At the same time, the delay in excitation in the atrioventricular node ensures a consistent contraction of the atria and ventricles, which is also a very important point in hemodynamics.

ELECTROCARDIOGRAPHY (ECG) is a test that allows you to obtain valuable information about the state of the heart. The essence of this method consists in registering electrical potentials arising during the work of the heart and in their graphic display on a display or paper.

APPLICATION

Determination of the frequency and regularity of heart contractions (for example, extrasystoles (extraordinary contractions), or the loss of individual contractions - arrhythmias).

Shows acute or chronic myocardial damage (myocardial infarction, myocardial ischemia).

It can be used to detect metabolic disorders of potassium, calcium, magnesium and other electrolytes.

Identification of intracardiac conduction disorders (various blockages).

The P wave reflects the period of atrial excitation; the Q wave reflects the period of excitation of the interventricular septum; the R wave is the highest in the ECG, it corresponds to the period of tension of the ventricular bases; S wave - full coverage of the ventricular myocardium by excitation; the T wave reflects the complete restoration of the membrane potential of myocardial cells, i.e. rest potential.

An ECG is a record of the total electrical potential that appears when many myocardial cells are excited, and the research method is called electrocardiography.

3) The sex glands (testes in men, ovaries in women) are glands with mixed function, the intrasecretory function is manifested in the formation and secretion of sex hormones, which directly enter the blood.

Male sex hormones - androgens are formed in the interstitial cells of the testes. There are two types of androgens - testosterone and androsterone.

Androgens stimulate the growth and development of the reproductive apparatus, male sex characteristics, and the appearance of sexual reflexes.

They control the process of maturation of spermatozoa, contribute to the preservation of their motor activity, the manifestation of sexual instinct and sexual behavioral reactions, increase the formation of protein, especially in muscles, and reduce the content of fat in the body. With an insufficient amount of androgen in the body, inhibition processes in the cerebral cortex are disrupted.

Female sex hormones estrogens are formed in the ovarian follicles. The synthesis of estrogens is carried out by the follicle membrane, progesterone - by the corpus luteum of the ovary, which develops at the site of the burst follicle.

Estrogens stimulate the growth of the uterus, vagina, tubes, cause proliferation of the endometrium, promote the development of secondary female sexual characteristics, the manifestation of sexual reflexes, increase the contractility of the uterus, increase its sensitivity to oxytocin, stimulate the growth and development of mammary glands.

Progesterone ensures the normal course of pregnancy, promotes the proliferation of the endometrial mucosa, implantation of a fertilized egg into the endometrium, inhibits the contractility of the uterus, reduces its sensitivity to oxytocin, inhibits the maturation and ovulation of the follicle by inhibiting the formation of pituitary lutropin.

The formation of sex hormones is influenced by the gonadotropic hormones of the pituitary gland and prolactin. In men, gonadotropic hormone promotes the maturation of sperm, in women - the growth and development of the follicle. Lutropin determines the production of female and male sex hormones, ovulation and the formation of the corpus luteum. Prolactin stimulates the production of progesterone.

Melatonin inhibits the activity of the gonads.

The nervous system takes part in the regulation of the activity of the gonads due to the formation of gonadotropic hormones in the pituitary gland. The central nervous system regulates the course of intercourse. With a change in the functional state of the central nervous system, a violation of the sexual cycle and even its termination can occur.

The menstrual cycle includes four periods.

1. Pre-ovulation (from the fifth to the fourteenth day). Changes are caused by the action of follitropin, an increased formation of estrogens occurs in the ovaries, they stimulate the growth of the uterus, the proliferation of the mucous membrane and its glands, the maturation of the follicle is accelerated, its surface breaks, and an egg comes out of it - ovulation occurs.

2. Ovulation (from the fifteenth to the twenty-eighth day). It begins with the release of the egg into the tube, the contraction of the smooth muscles of the tube promotes its advance to the uterus, fertilization can occur here. A fertilized egg, entering the uterus, attaches to its mucous membrane and pregnancy occurs. If fertilization has not occurred, the post-ovulation period begins. At the site of the follicle, a corpus luteum develops, it produces progesterone.

3. Post-ovulation period. An unfertilized egg dies when it reaches the uterus. Progesterone reduces the formation of follitropin and decreases the production of estrogen. The changes that have arisen in the woman's genitals disappear. In parallel, the formation of lutropin decreases, which leads to atrophy of the corpus luteum. Due to a decrease in estrogen, the uterus contracts, the mucous membrane is rejected. In the future, its regeneration takes place.

4. The rest period and post-ovulation period last from the first to the fifth day of the sexual cycle.

Spermatogenesis. Spermatogenesis consists of three stages and occurs in the seminiferous tubules of the male sex glands - the testes (testes). The first stage is numerous mitosis of sperm-forming cells; the second is meiosis; the third is spermiogenesis. First, spermatogonia are formed, located on the outer wall of the spermatic cord. They then sequentially transform into first-order spermatocytes. The latter, by meiotic division, give two identical cells - second-order spermatocytes. During the second division, second-order spermatocytes produce four immature germ cells - gametes. They are called spermatids. The resulting four spermatids are gradually transformed into active moving sperm.

1) Inhibition of conditioned reflexes. This process is based on two mechanisms: unconditional (external) and conditional (internal) inhibition... And outrageous braking. Unconditioned inhibition occurs instantly due to the termination of conditioned reflex activity. Allocate external and transcendental inhibition.

To activate external inhibition, the action of a new strong stimulus is necessary, capable of creating a dominant focus of excitation in the cerebral cortex. As a result, the work of all nerve centers is inhibited, and the temporary neural connection ceases to function. This type of inhibition causes a quick switch to a more important biological signal.

Extreme inhibition plays a protective role and protects neurons from overexcitation, as it prevents the formation of a connection under the action of a superstrong stimulus.

For the occurrence of conditioned inhibition, special conditions are required (for example, the absence of signal reinforcement). There are four types of braking:

1) fading (eliminates unnecessary reflexes due to the lack of their reinforcement);

2) trim (leads to the sorting of close stimuli);

3) delayed (occurs when the duration of the action between two signals increases, leads to getting rid of unnecessary reflexes, forms the basis for assessing the balance and balance of excitation and inhibition processes in the central nervous system);

4) a conditioned brake (manifests itself only under the action of an additional stimulus of moderate strength, which causes a new focus of excitation and inhibits the rest, is the basis for the processes of training and education).

Inhibition frees the body from unnecessary reflex connections and further complicates a person's relationship with the environment. Outrageous braking. This type of inhibition differs from external and internal in terms of the mechanism of occurrence and physiological significance. It occurs with an excessive increase in the strength or duration of the action of the conditioned stimulus, due to the fact that the strength of the stimulus exceeds the efficiency of the cortical cells. This inhibition has a protective value, since it prevents the depletion of nerve cells. In its mechanism, it resembles the phenomenon of "pessimum", which was described by N.E. Vvedensky. Transcendental inhibition can be caused by the action of not only a very strong stimulus, but also by the action of a small in strength, but prolonged and monotonous stimulus. This irritation, constantly acting on the same cortical elements, leads to their depletion, and, consequently, is accompanied by the emergence of protective inhibition. Extreme inhibition develops more easily with a decrease in working capacity, for example, after a severe infectious disease, stress, more often it develops in the elderly.

2) Glomerular filtration... (~ 155-170 liters per day of primary urine). The initial stage of urine formation is filtration: in the renal corpuscle from the capillary glomerulus, the liquid part of the blood is filtered into the capsule cavity. Glomerular filtration is a passive process. Under resting conditions in an adult, about 1/4 of the blood ejected into the aorta by the left ventricle of the heart enters the renal arteries. In other words, about 1300 ml of blood per minute passes through both kidneys in an adult man, somewhat less in women. The total filtration surface of the kidney glomeruli is approximately 1.5 m 2. In the glomeruli from the blood capillaries into the lumen of the capsule of the renal glomerulus, ultrafiltration of blood plasma occurs, as a result of which primary urine is formed, in which there is practically no protein. Normally, proteins as colloidal substances do not pass through the capillary wall into the cavity of the renal glomerulus capsule. Glomerular filtration is equal to 100–125 ml per 1 min. The daily amount of ultrafiltrate is 3 times the total amount of fluid contained in the body. Naturally, the primary urine, while moving along the renal tubules, gives up most of its constituent parts, especially water, back into the blood. Only 1% of the fluid filtered by the glomeruli is converted into urine.

The tubules reabsorb 99% of water, sodium, chlorine, hydrocarbonate, amino acids, 93% potassium, 45% urea, etc. As a result of reabsorption, secondary, or final, urine is formed from the primary urine, which then enters the renal cups, the pelvis and enters the bladder through the ureters.

The functional significance of individual renal tubules in the process of urination is not the same. The cells of the proximal segment of the nephron reabsorb glucose, amino acids, vitamins, electrolytes in the filtrate; 6/7 of the primary urine fluid is also reabsorbed in the proximal tubules. Primary urine water is partially (partially) reabsorbed in the distal tubules. In the same tubules, additional sodium reabsorption occurs, potassium, ammonium, hydrogen ions, etc. can be secreted into the lumen of the nephron.

Regulation of GFR carried out at the expense nervous and humoral mechanisms... Regardless of the nature, regulatory factors affect GFR by changing: 1) glomerular arteriole tone and, accordingly, the volumetric blood flow (plasma flow) through them and the magnitude of the filtration pressure; 2) tonus of mesangial cells and filtration surface; 3) podocyte activity and their "suction" function.

In order to determine the function of the renal glomeruli, in practice, methods for determining the glomerular filtration rate (GFR) by the clearance of various exogenous and endogenous substances are most often used. To calculate the amount of fluid filtered in the glomeruli, a physiologically inert substance is used that freely penetrates the glomerular membrane with a protein-free part of the plasma. Accordingly, its concentration in the glomerular fluid will be equal to its concentration in the blood plasma. If this substance is not reabsorbed and not secreted by the renal tubules, then it will be excreted in the urine in the same amount in which it passed through the glomerular filter. Since most of the water in the filtrate is reabsorbed, the substance used to determine the volume of the filtrate will be concentrated as many times as the volume of water in the renal tubules decreases. The clearance of any substance is calculated by the formula:

(1)C = (U × V) / P, where C is the clearance of the substance (ml / min), U is the concentration of the test substance in the urine (mmol / l), P is the concentration of the same substance in the blood (mmol / l), V is the minute diuresis (ml / min).

To determine GFR, inulin, sodium paraaminogippurate, unlabeled iohexol, (51) creatinine-ethylenediaminetetraacetic acid ((51) Cr-EDTA) are used. Assessment of glomerular filtration rate by inulin clearance is recognized as the "gold standard" for determining renal function.

External respiration is an exchange of gases between the body and the external environment. It is carried out using two processes - pulmonary respiration and respiration through the skin.

Pulmonary respiration consists in the exchange of gases between the alveolar air and the environment and between the alveolar air and capillaries. During gas exchange with the external environment, air is supplied containing 21% oxygen and 0.03-0.04% carbon dioxide, and the exhaled air contains 16% oxygen and 4% carbon dioxide. Oxygen enters the alveolar air from the atmospheric air, and carbon dioxide is released in the opposite direction.

When exchanging with the capillaries of the pulmonary circulation in the alveolar air, the oxygen pressure is 102 mm Hg. Art., and carbon dioxide - 40 mm Hg. Art., the tension in the venous blood oxygen - 40 mm Hg. Art., and carbon dioxide - 50 mm Hg. Art. As a result of external respiration, arterial blood flows from the lungs, rich in oxygen and poor in carbon dioxide.

External respiration is carried out as a result of the rhythmic movements of a difficult cell. The breathing cycle consists of the phases of inhalation and exhalation, between which there is no pause. At rest in an adult, the frequency of respiratory movements is 16-20 per minute.

Inhale is an active process. With a calm breath, the external intercostal and interchondral muscles contract. They raise the ribs, while the sternum is pushed forward. This leads to an increase in the sagittal and frontal dimensions of the chest cavity. At the same time, the muscles of the diaphragm contract. its dome descends and the abdominal organs move down, to the sides, and forward. Due to this, the chest cavity also increases in the vertical direction.

After the end of inhalation, the respiratory muscles relax - it begins exhalation. Calm exhalation is a passive process. During it, the chest returns to its original state under the influence of its own weight, the stretched ligamentous apparatus and pressure on the diaphragm of the abdominal organs. At physical activity, pathological conditions accompanied by shortness of breath (pulmonary tuberculosis, bronchial asthma etc.) forced breathing occurs. Accessory muscles are involved in the act of inhalation and exhalation. With forced inhalation, the sternocleidomastoid, scalene, pectoral and trapezius muscles are additionally reduced. They contribute to additional lifting of the ribs. With forced exhalation, the internal intercostal muscles contract, which increase the lowering of the ribs. Those. forced exhalation is an active process.

Pressure in the pleural cavity and its origin and role in the mechanism of external respiration. Changes in pressure in the pleural cavity in different phases of the respiratory cycle.

The pressure in the pleural cavity is always below atmospheric - negative pressure.

The magnitude of the negative pressure in the pleural cavity:

By the end of maximum expiration - 1-2 mm Hg. Art.,

By the end of a calm exhalation - 2-3 mm Hg. Art.,

· By the end of a calm breath - 5-7 mm Hg. Art.,

By the end of maximum inspiration - 15-20 mm Hg. Art.

The growth rate of the chest is higher than that of the lung tissue. This leads to an increase in the volume of the pleural cavity, and since it is sealed, the pressure becomes negative.

Elastic traction of the lungs- the force with which the tissue tends to fall off.

The elastic traction of the lungs is due to :

1) the surface tension of the liquid film covering the inner surface of the alveoli;

2) the elasticity of the tissue of the walls of the alveoli due to the presence of elastic fibers in them;

3) the tone of the bronchial muscles.

5. VC and its constituent components. Methods for their determination. Residual air.

The functioning of the external respiration apparatus can be judged by the volume of air entering the lungs during one respiratory cycle. The volume of air that enters the lungs at maximum inspiration forms the total lung capacity. It is approximately 4.5-6 liters and consists of the vital capacity of the lungs and the residual volume.

Lung vital capacity- the amount of air that a person is able to exhale after a deep breath. She is one of the indicators physical development organism and is considered pathological if it is 70-80% of the proper volume. During life, this value can change. It depends on a number of reasons: age, height, body position in space, food intake, physical activity, the presence or absence of pregnancy.

The vital capacity of the lungs consists of respiratory and reserve volumes. Respiratory volume is the amount of air that a person inhales and exhales into calm state... Its value is 0.3-0.7 liters. It maintains the partial pressure of oxygen and carbon dioxide in the alveolar air at a certain level. Inspiratory reserve volume - the amount of air that a person can additionally inhale after a calm breath. As a rule, it is 1.5-2.0 liters. It characterizes the ability of the lung tissue for additional stretching. Expiratory reserve volume is the amount of air that can be exhaled following a normal exhalation.

Residual volume- constant volume of air in the lungs even after maximum expiration. It is about 1.0-1.5 liters.

An important characteristic of the respiratory cycle is the respiratory rate per minute. Normally, it is 16-20 movements per minute. The duration of the respiratory cycle is calculated by dividing 60 s by the value of the respiratory rate.

The time of entry and expiration can be determined by the spirogram.

Pulmonary volumes:

1. Tidal volume (DO) = 500 ml

2. Reserve volume of inspiration (RO inspiration) = 1500-2500 ml

3. Reserve volume of expiration (RO expiration) = 1000 ml

4. Residual volume (RO) = 1000 -1500 ml

Lung containers:

Total lung capacity (OEL) = (1 + 2 + 3 + 4) = 4-6 liters

Lung vital capacity (VC) = (1 + 2 + 3) = 3.5-5 liters

Functional residual lung capacity (FRC) = (3 + 4) = 2-3 liters

- inhalation capacity (EB) = (1 + 2) = 2-3 liters

Minute volume of ventilation of the lungs and its changes under various loads, methods for its determination. "Harmful space" and effective pulmonary ventilation. Why rare and deep breathing is more effective.

Minute volume- the amount of air exchanged with the environment during calm breathing. It is determined by the product of the tidal volume and the respiratory rate and is 6-8 liters.

Its value, on average, is 500 ml, the respiration rate per minute is 12-16 and, therefore, the minute respiration volume, on average, is 6-8 liters.

However, not all the air entering the respiratory system takes part in gas exchange. Part of the air fills the airways (larynx, trachea, bronchi, bronchioles) and does not reach the alveoli, because when you exhale, it leaves the body first.

This air was named - air of harmful space. Its volume, on average, is 140-150 ml. Therefore, the concept of effective pulmonary ventilation is introduced. This is the amount of air in one minute that takes part in gas exchange. Effective pulmonary ventilation at the same respiratory minute volume can be different. So, the larger the tidal volume, the lower the relative volume of air in the harmful space. Therefore, rare and deep breathing is more effective for supplying the body with oxygen, since ventilation of the alveoli increases.

Respiration biomechanics. Inspiratory biomechanics.

Parameter name	Meaning
Topic of the article:	Respiration biomechanics. Inspiratory biomechanics.
Rubric (thematic category)	The medicine

Rice. 10.1. Effect of contraction of the diaphragmatic muscle on the volume of the chest cavity... Contraction of the diaphragmatic muscle during inhalation (dashed line) causes the diaphragm to move downward, displacement of the abdominal organs downward and forward. As a result, the volume of the chest cavity increases.

An increase in the volume of the chest cavity during inspiration occurs as a result of contraction of the inspiratory muscles: the diaphragm and the external intercostal muscles. The main respiratory muscle is the diaphragm, which is located in the lower third of the chest cavity and separates the chest and abdominal cavities. With the contraction of the diaphragmatic muscle, the diaphragm moves down and shifts the abdominal organs down and anteriorly, increasing the volume of the chest cavity mainly vertically (Fig.10.1).

An increase in the volume of the chest cavity during inspiration contributes to the contraction of the external intercostal muscles, which lift the chest upward, increasing the volume of the chest cavity. This effect of contraction of the external intercostal muscles is due to the peculiarities of the attachment of muscle fibers to the ribs - the fibers go from top to bottom and from back to front (Fig.10.2). With a similar direction of the muscle fibers of the external intercostal muscles, their contraction rotates each rib around an axis passing through the points of articulation of the rib head with the body and the transverse process of the vertebra. As a result of this movement, each underlying costal arch rises up more than the superior one descends. The simultaneous upward movement of all costal arches leads to the fact that the sternum rises up and anteriorly, and the volume of the chest increases in the sagittal and frontal planes. Contraction of the external intercostal muscles not only increases the volume of the chest cavity, but also prevents the chest from dropping down. For example, in children with undeveloped intercostal muscles, the rib cage decreases in size during contraction of the diaphragm (paradoxical movement).

Rice. 10.2. The direction of the fibers of the external intercostal muscles and the increase in the volume of the chest cavity during inhalation... a - contraction of the external intercostal muscles during inhalation raises the lower rib more than lowers the upper one. As a result, the costal arches rise upward and increase (b) the volume of the chest cavity in the sagittal and frontal planes.

Breathing deeply into inspiratory biomechanism, as a rule, auxiliary respiratory muscles are involved - sternocleidomastoid and anterior scalene muscles, and their reduction further increases the volume of the chest. In particular, the scalene muscles lift the upper two ribs, and the sternocleidomastoid muscles raise the sternum. Inhalation is an active process and requires energy expenditure during contraction of the inspiratory muscles, which is spent on overcoming elastic resistance against rigid chest tissues, elastic resistance of easily stretchable lung tissue, aerodynamic resistance of the airways to air flow, as well as increasing intra-abdominal pressure and the resulting displacement organs of the abdominal cavity from top to bottom.

Exhale at rest in humans, it is carried out passively under the action of the elastic traction of the lungs, which returns the volume of the lungs to its original value. Nevertheless, with deep breathing, as well as with coughing and sneezing, exhalation should be active, and a decrease in the volume of the chest cavity occurs due to the contraction of the internal intercostal muscles and abdominal muscles. Muscle fibers the internal intercostal muscles run relative to the points of their attachment to the ribs from the bottom up and from the back to the front. When they contract, the ribs rotate around an axis passing through the points of their articulation with the vertebra, and each superior costal arch descends more than the lower one rises up. As a result, all costal arches, together with the sternum, go down, reducing the volume of the chest cavity in the sagittal and frontal planes.

With deep breathing of a person, the contraction of the abdominal muscles in expiratory phase increases the pressure in the abdominal cavity, which contributes to the upward displacement of the dome of the diaphragm and decreases the volume of the chest cavity in the vertical direction.

Contraction of the respiratory muscles of the chest and diaphragm during inhalation causes increased lung volume, and when they relax during exhalation, the lungs collapse to their original volume. The volume of the lungs, both during inhalation and exhalation, changes passively, since, due to their high elasticity and extensibility, the lungs follow the changes in the volume of the chest cavity caused by the contraction of the respiratory muscles. This position is illustrated by the following model of passive increase in lung volume(fig.10.3). In this model, the lungs are considered as an elastic balloon placed inside a container made of rigid walls and a flexible diaphragm. The space between the bladder and the container walls is sealed. This model allows the pressure inside the vessel to be varied as the flexible diaphragm moves downward. With an increase in the volume of the container, caused by the downward movement of the flexible diaphragm, the pressure inside the container, that is, outside the cylinder, becomes lower than atmospheric in accordance with the ideal gas law. The balloon inflates because the pressure inside it (atmospheric) becomes higher than the pressure in the container around the balloon.

Rice. 10.3. Diagram of a model showing passive lung inflation when the diaphragm is lowered... When the diaphragm is pushed down, the air pressure inside the container becomes below atmospheric pressure, which causes the bladder to inflate. P - atmospheric pressure.

Attached to human lungs that completely fill chest cavity volume, their surface and the inner surface of the chest cavity are covered with a pleural membrane. The pleural membrane of the surface of the lungs (visceral pleura) is not physically in contact with the pleural membrane covering the chest wall (parietal pleura), since there is pleural space(synonym - intrapleural space), filled with a thin layer of fluid - pleural fluid. This fluid moistens the surface of the lobes of the lungs and facilitates their sliding relative to each other during inflation of the lungs, and also facilitates friction between the parietal and visceral pleura. The liquid is incompressible and its volume does not increase with decreasing pressure in pleural cavity... For this reason, highly elastic lungs exactly follow the change in the volume of the chest cavity during inhalation. The bronchi, blood vessels, nerves and lymphatic vessels form the root of the lung, with which the lungs are fixed in the mediastinal region. The mechanical properties of these tissues determine the main degree of effort, ĸᴏᴛᴏᴩᴏᴇ must develop the respiratory muscles during contraction in order to cause increased lung volume... Under normal conditions, the elastic traction of the lungs creates an insignificant amount of negative pressure in a thin layer of fluid in the intrapleural space relative to atmospheric pressure. Negative intrapleural pressure varies in accordance with the phases of the respiratory cycle from -5 (exhalation) to -10 cm aq. Art. (inhale) below atmospheric pressure (fig. 10.4). Negative intrapleural pressure can cause a decrease (collapse) in the volume of the chest cavity, which the chest tissues counteract with their extremely rigid structure. The diaphragm, in comparison with the chest, is more elastic, and its dome rises upward under the influence of the pressure gradient that exists between the pleural and abdominal cavities.

In a state where the lungs do not expand or collapse (pause, respectively, after inhalation or exhalation), there is no air flow in the airways and the pressure in the alveoli is equal to atmospheric. In this case, the gradient between atmospheric and intrapleural pressure will precisely balance the pressure developed by the elastic traction of the lungs (see Fig. 10.4). Under these conditions, the value of intrapleural pressure is equal to the difference between the pressure in the airways and the pressure developed by the elastic traction of the lungs. For this reason, the more the lungs are stretched, the stronger the elastic traction of the lungs will be and the more negative relative to atmospheric is the value of intrapleural pressure. This happens during inspiration, when the diaphragm goes down and the elastic traction of the lungs counteracts the inflation of the lungs, and the value of intrapleural pressure becomes more negative. When inhaled, this negative pressure promotes the movement of air through the airway towards the alveoli, overcoming airway resistance. As a result, air flows from the external environment into the alveoli.

Rice. 10.4. Alveolar pressure and intrapleural pressure during inspiration and expiration of the respiratory cycle... In the absence of air flow in the airways, the pressure in them is equal to atmospheric (A), and the elastic traction of the lungs creates pressure in the alveoli E. Under these conditions, the value of intra-pleural pressure is equal to the difference A - E. When inhaling, contraction of the diaphragm increases the value of negative pressure in the pleural cavities up to -10 cm aq. Art., ĸᴏᴛᴏᴩᴏᴇ helps to overcome the resistance to air flow in the respiratory tract, and air moves from the external environment to the alveoli. The value of intrapleural pressure is due to the difference between the pressures A - R - E. When you exhale, the diaphragm relaxes and intrapleural pressure becomes less negative relative to atmospheric pressure (-5 cm H2O). The alveoli, due to their elasticity, reduce their diameter, the pressure E rises in them. The pressure gradient between the alveoli and the external environment contributes to the removal of air from the alveoli through the respiratory tract into the external environment. The value of intrapleural pressure is due to the sum of A + R minus the pressure inside the alveoli, i.e. A + R - E. A is atmospheric pressure, E is the pressure in the alveoli arising from the elastic traction of the lungs, R is the pressure that ensures overcoming the resistance to air flow in the airways, P - intrapleural pressure.

When you exhale, the diaphragm relaxes and the value of intrapleural pressure becomes less negative. Under these conditions, the alveoli, due to the high elasticity of their walls, begin to decrease in size and push air out of the lungs through the respiratory tract. The resistance of the airways to the flow of air maintains positive pressure in the alveoli and prevents them from collapsing rapidly. Τᴀᴋᴎᴍ ᴏϬᴩᴀᴈᴏᴍ, in a calm state during exhalation, the air flow in the airways is due only to the elastic traction of the lungs.

Pneumothorax... If air enters the intrapleural space, for example through a wound opening, collapse occurs in the lungs, the chest increases slightly in volume, and the diaphragm goes down as soon as the intrapleural pressure becomes equal to atmospheric pressure. This condition is usually called pneumothorax, in which the lungs lose the ability to follow the change. chest cavity volume during breathing. Moreover, during inhalation, air enters the chest cavity through the wound opening and exits during exhalation without changing the volume of the lungs during respiratory movements, which makes it impossible for gas exchange between the external environment and the body.

External respiration process due to a change in the volume of air in the lungs during the phases of inhalation and exhalation of the respiratory cycle. With calm breathing, the ratio of the duration of inhalation to exhalation in the respiratory cycle is on average 1: 1.3. External respiration of a person is characterized by the frequency and depth of respiratory movements. Breathing rate a person is measured by the number of respiratory cycles within 1 min and its value at rest in an adult varies from 12 to 20 per 1 min. This indicator of external respiration increases with physical work, an increase in ambient temperature, and also changes with age. For example, in newborns, the respiratory rate is 60-70 per minute, and in people aged 25-30 years - on average 16 per minute. The depth of breathing is determined by the volume of inhaled and exhaled air during one breathing cycle. The product of the frequency of respiratory movements by their depth characterizes the main value of external respiration - ventilation of the lungs... The quantitative measure of lung ventilation is the minute volume of respiration - this is the volume of air that a person inhales and exhales in 1 minute. The value of the minute volume of respiration of a person at rest varies within 6-8 liters. During physical work in a person, the minute volume of respiration can increase by 7-10 times.

Rice. 10.5. Volumes and capacities of air in the lungs and a curve (spirogram) of changes in the volume of air in the lungs with calm breathing, deep inhalation and exhalation. FOE - functional residual capacity.

Pulmonary air volumes... IN physiology of respiration adopted a unified nomenclature of human lung volumes, which fill the lungs with calm and deep breathing in the phase of inhalation and exhalation of the respiratory cycle (Fig. 10.5). The lung volume, which is inhaled or exhaled by a person with calm breathing, is usually called tidal volume... Its value with calm breathing is on average 500 ml. The maximum amount of air, ĸᴏᴛᴏᴩᴏᴇ a person can inhale in excess of the tidal volume, is usually called inspiratory reserve volume(on average 3000 ml). The maximum amount of air, ĸᴏᴛᴏᴩᴏᴇ a person can exhale after a calm exhalation, is usually called the reserve expiratory volume (on average, 1100 ml). Finally, the amount of air, ĸᴏᴛᴏᴩᴏᴇ remains in the lungs after maximum expiration, is usually called the residual volume, its value is approximately 1200 ml.

The sum of the values ​​of two pulmonary volumes or more is usually called lung capacity. Air volume in the human lungs it is characterized by the inspiratory capacity of the lungs, the vital capacity of the lungs and the functional residual capacity of the lungs. The inspiratory capacity of the lungs (3500 ml) is the sum of the tidal volume and the inspiratory reserve volume. Lung vital capacity(4600 ml) includes tidal volume and inspiratory and expiratory reserve volumes. Functional residual lung capacity(1600 ml) is the sum of expiratory reserve and residual lung volume. Sum lung capacity and residual volume it is customary to call the total lung capacity, the value of which in humans is on average 5700 ml.

When inhaling, the lungs of a person due to the contraction of the diaphragm and the external intercostal muscles, they begin to increase their volume from the level, and its value with calm breathing is tidal volume, and with deep breathing - reaches various values reserve volume inhalation. When you exhale, the volume of the lungs returns to the initial level of functional residual capacity passively, due to the elastic traction of the lungs. If air begins to enter the volume of exhaled air functional residual capacity, which takes place with deep breathing, as well as when coughing or sneezing, then exhalation is carried out due to the contraction of the muscles of the abdominal wall. In this case, the value of intrapleural pressure, as a rule, becomes higher than atmospheric pressure, which determines the highest air flow rate in the respiratory tract.

When inhaling, an increase in the volume of the chest cavity is prevented elastic traction of the lungs, movement of the rigid chest, abdominal organs and, finally, the resistance of the airways to the movement of air in the direction of the alveoli. The first factor, namely the elastic traction of the lungs, is the most likely to inhibit the increase in lung volume during inspiration.

Respiration biomechanics. Inspiratory biomechanics. - concept and types. Classification and features of the category "Biomechanics of respiration. Biomechanics of inspiration." 2017, 2018.