alveolar air. Internal respiration and transport of gases The value of the composition of the gases of the alveolar air
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What does "alveolar air" mean?
Dictionary of medical terms
alveolar air
air that fills the alveoli of the lungs and is directly involved in gas exchange with the blood.
Alveolar air
a mixture of gases (mainly oxygen, carbon dioxide, nitrogen and water vapor) contained in the pulmonary alveoli. Volume A. in. (for a person 2.5≈3 l) and its composition fluctuate depending on the phases of the respiratory cycle, changing unevenly in different parts of the lungs. The supply of oxygen to the blood flowing through the pulmonary capillaries and the removal of carbon dioxide from it (see Gas exchange), as well as the regulation of respiration, depend on the composition of A. in. maintained in healthy animals and humans within certain narrow limits due to ventilation of the lungs (in humans normal A. v. contains 14≈15% oxygen and 5≈5.5% carbon dioxide). With a lack of oxygen in the inhaled air and some disease states, changes in the composition of A. century occur, which can lead to hypoxia. See breath.
atmospheric air, which a person inhales while outdoors (or in well-ventilated rooms), contains 20.94% oxygen, 0.03% carbon dioxide, 79.03% nitrogen. In enclosed spaces filled with people, the percentage of carbon dioxide in the air can be slightly higher.
Exhaled air contains an average of 16.3% oxygen, 4% carbon dioxide, 79.7% nitrogen (these figures are given in terms of dry air, that is, excluding water vapor, which is always saturated with exhaled air).
Composition of exhaled air very fickle; it depends on the intensity of the body's metabolism and on the volume of pulmonary ventilation. It is worth taking a few deep breathing movements or, on the contrary, holding your breath so that the composition of the exhaled air changes.
Nitrogen does not participate in gas exchange, however, the percentage of nitrogen in visible air is several tenths of a percent higher than in inhaled air. The fact is that the volume of exhaled air is somewhat less than the volume of inhaled air, and therefore the same amount of nitrogen, distributed in a smaller volume, gives a larger percentage. The smaller volume of exhaled air compared to the volume of inhaled air is due to the fact that slightly less carbon dioxide is released than oxygen is absorbed (part of the absorbed oxygen is used in the body to circulate compounds that are excreted from the body with urine and sweat).
Alveolar air differs from exhaled by a large percentage of non-acid and a smaller percentage of oxygen. On average, the composition of alveolar air is as follows: oxygen 14.2-14.0%, carbon dioxide 5.5-5.7%, nitrogen about 80%.
Definition composition of alveolar air important for understanding the mechanism of gas exchange in the lungs. Holden proposed a simple method for determining the composition of alveolar air. After a normal inhalation, the subject exhales as deeply as possible through a tube 1-1.2 m long and 25 mm in diameter. The first portions of exhaled air leaving through the tube contain the air of the harmful space; the last portions remaining in the tube contain alveolar air. For analysis, air is taken into the gas receiver from that part of the tube that is closest to the mouth.
The composition of the alveolar air varies somewhat depending on whether the air sample was taken for analysis at the height of inhalation or exhalation. If you make a quick, short and incomplete expiration at the end of a normal inspiration, then the air sample will reflect the composition of the alveolar air after filling the lungs with respiratory air, i.e. during inspiration. If you take a deep breath after a normal exhalation, then the sample will reflect the composition of the alveolar air during exhalation. It is clear that in the first case, the percentage of carbon dioxide will be somewhat less, and the percentage of oxygen will be somewhat greater than in the second. This can be seen from the results of Holden's experiments, who found that the percentage of carbon dioxide in the alveolar air at the end of inspiration is on average 5.54, and at the end of expiration - 5.72.
Thus, there is a relatively small difference in the content of carbon dioxide in the alveolar air during inhalation and exhalation: only 0.2-0.3%. This is largely due to the fact that during normal breathing, as mentioned above, only 1/7 of the volume of air in the pulmonary alveoli is renewed. The relative constancy of the composition of the alveolar air is of great physiological importance, as will be explained below.
1. The importance of the respiratory system. The concept of external and internal respiration.
The respiratory system is vital. Respiratory diseases are the 3rd leading cause of death and the most common cause of disability. Respiration is a cyclic process that ensures the delivery of oxygen to cells, is used to remove carbon dioxide, and deliver biological substances. In protozoa - through the outer integument, in insects - the tracheal type of breathing, in humans - the pulmonary type of breathing. Distinguish between external and internal respiration, carbon dioxide diffuses between the alveoli, gas is transported from the lungs and back to the cells. Internal respiration is the process of using oxygen inside cells in the oxidative process. In physiology, we study external respiration, in biochemistry - tissue, internal.
98% of gas exchange occurs in the alveoli of the lungs, 2% can pass through the skin.
Respiration is a physiological function that provides gas exchange (O 2 and CO 2) between environment and the body according to its metabolic needs.
Breathing proceeds in several stages: 1) external respiration - exchange of O 2 and CO 2 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 denoted as "pulmonary ventilation"; b) gas exchange between the alveolar air and the blood of the pulmonary capillaries; 2) transport O 2 and CO 2 blood; 3) exchange O 2 and CO 2 between blood and body cells; four) tissue respiration.
Respiration carries out the transfer of oxygen from atmospheric air to the cells of the body, and in the opposite direction removes CO 2, which is the most important product of cell metabolism.
Transport of O 2 and CO 2 in the human body and animals over considerable distances, for example, within the airways, lungs and in the circulatory system, is carried out convectively. The transfer of O 2 and CO 2 over short distances, for example, between alveolar air and blood, as well as between blood and body tissue cells, is carried out by diffusion. Each of the stages of the respiratory function, in accordance with the metabolic needs of the cells of the body, is regulated by nervous and humoral mechanisms.
2. Morpho-functional features of the bronchial tree. The concept of conductive and transitory zones. Dead space.
The respiratory system includes the upper and lower respiratory tract. The upper respiratory tract includes the nose, oral cavity, nasopharynx, larynx. Lower - trachea and bronchi. The lungs are connected to the airways - right (3 lobes) and left (2 lobes, only upper and lower). The lungs are located inside chest- musculoskeletal frame - ribs attached to the spine and sternum, there are muscles between the ribs, inside the chest is lined with a smooth sheet of parietal pleura, the lungs are covered with visceral pleura, between the lungs - space - with pleural fluid. The fluid reduces frictional forces and maintains a constant volume of the pleural cavity. The airways - there the air is moistened, warmed, cleaned, in the bronchi there are 23 consecutive divisions that reach the terminal bronchioles, and then the respiratory bronchioles begin, from which the alveolar passages depart, which pass into the alveolar sacs, ending in the alveolar sacs.
Airways larger than 1 mm - bronchi, less than 1 mm - bronchioles. In the bronchi, the basis is cartilaginous tissue, rings; in the bronchioles, the wall mainly consists of smooth muscle elements. The inner surface is covered with a mucous membrane with ciliated epithelium. In the bronchial tree, it is customary to distinguish 3 functional areas -
Conductive (conductive) - the first 16 divisions, only air flow occurs here, gas exchange does not occur, the volume of this zone is 150-155 cm3 and it belongs to dead space,
Subsequent 6 - transition zone - gas diffusion
Alveolar passages, sacs, respiratory bronchioles - this is the respiratory zone (only gas exchange without conducting air flow)
In connection with the successive division of the bronchial tree, there is an increase in the total area cross section. Cross-sectional area of the trachea - 2.5 cm2, at the level of the 16th division, total area 180 cm2. At the level of the 23rd division 11800 cm2. The number of pulmonary alveoli is 300-375 million. The diameter of the alveoli is from 150 to 300 microns and the total area of the pulmonary alveoli reaches 90 m2. External respiration is aimed at constant ventilation of the lungs and this is ensured by a periodic change in the acts of inhalation and exhalation. A person takes from 12 to 15 breaths and exhalations, and during each breath we absorb 500 ml of air. A kind of respiratory pump - the chest, intercostal muscles, diaphragm, Inhalation-inspiration, is an active act. We can inhale only with muscle contraction. Inspiratory muscles - diaphragm and external oblique intercostal muscles. The main respiratory muscle is the diaphragm. With the contraction of the muscular part, the dome of the diaphragm descends and the abdominal organs lowers. The vertical volume of the chest increases. With the help of the diaphragm, 75% of inspiration is carried out. With a calm breath, this is enough. When loaded, the intercostal muscles are connected. In the exhalation phase, the anterior oblique muscles are used. When loaded, the ribs are understood and take a horizontal position, the sternum moves forward, which increases the sagittal size of the chest, and a small turn of the rib also occurs (the lower edge of the rib is outward, which increases the frontal size of the chest) During inspiration, all three sizes of the chest change. Following is an increase in the volume of the lungs, while in the lungs there is a decrease in pressure, which is associated with the action of the gas law of Boel-Mariotte, which says that the product of the volume of gas, by the value of its pressure, is a constant value. The pressure inside the lungs becomes below atmospheric - "-1" - "-3" below atmospheric. Because of this, air can pass into the lungs. Inhalation, which is carried out by contracting the diaphragm - diaphragmatic, or abdominal (in children, adults) breathing, and due to the intercostal muscles - chest breathing (in women). The sternocleidomastoid muscles, scalene muscles, trapezius muscles can take part in an increased inhalation - these are additional muscles. The act of exit - the experiment can be passive and active. Passive is carried out as a result of relaxation of the inspiratory muscles, while the diaphragm begins to relax, the vertical size of the chest decreases, the relaxation of the intercostal muscles due to gravity lowers - the sagittal and frontal size of the chest decreases. The lungs begin to shrink. The expiratory muscles, which include the abdominal muscles, their contraction increases the pressure in the abdominal cavity and raises the diaphragm. Internal oblique intercostal muscles - from top to bottom and from front to back. With their contraction, they pull the ribs down, further contributing to a decrease in the volume of the chest. A decrease in volume helps to reduce the pressure below atmospheric inside the lungs by 3-5 cm. We can measure the force of exhalation with a manometer. Negative pressure in the interpleural space. Mechanisms of its formation. The lungs are covered with a visceral layer, and the chest with a parietal layer. The interpleural space is filled with fluid. The leaves are wet and slip. The pressure in this cavity is below atmospheric - called negative interpleural pressure. Through the airways, atmospheric air acts on the internal surfaces, which causes stretching of the lungs. Lungs - elastic formation. In the chest cavity, the lungs are in a stretched state. The elastic fibers will tend to compress the lungs. The alveoli (from the inside) are lined with a special substance - a surfactant - a complex of phospholipils, which is formed by specialized cells - type 2 alveolar pneumocytes. It causes a decrease in surface tension. If there is a surfactant, then the surface tension = 5 dynes per cm2, in its absence 20 dynes per cm2. Surfactant begins to be produced in the last months of pregnancy. It is difficult for premature babies to spread their lungs, respiratory failure occurs. Now artificial spraying of surfactant is used. The presence of surface tension tends to compress the lungs.
Exhalation = -2-5 mmHg pillar
Inspiration = -4-8 mmHg
Deep breath = -20 mmHg
3. The mechanism of inhalation and exhalation. Breath types. Changes in the type and frequency of breathing in children.
External respiration, i.e. the exchange of air between the alveoli of the lungs and the external environment is carried out as a result of rhythmic respiratory movements.
Inspiratory mechanism . The act of inhaling inspiration) is performed due to an increase in the volume of the chest, and, consequently, the chest cavity, in three directions - vertical, sagittal and frontal. This is due to the rise of the ribs and the lowering of the diaphragm. Raising the ribs occurs as a result of contraction of the external intercostal muscles, while the intercostal spaces expand.
In the first months after birth, respiratory movements are carried out mainly due to the contraction of the diaphragm. Newborn animals die after transection of the phrenic nerve. In different people, depending on age and gender, clothing and working conditions, breathing is carried out mainly either due to the intercostal muscles (rib, chest type of breathing), or due to the diaphragm (diaphragmatic, abdominal type of breathing.) The type of breathing is not strictly constant and can adapt to conditions this moment. When carrying weights, the chest is fixed by the muscles of the trunk and intercostal spaces motionlessly together with the spine, while breathing becomes diaphragmatic. During pregnancy, the rib type of breathing prevails, and the transverse size of the chest will change mainly.
Exhalation mechanism (expiration). When inhaling, the inspiratory muscles of a person overcome a number of forces: the heaviness of the raised ribs, the elastic resistance of the costal cartilages, the resistance of the walls of the abdomen and abdominal viscera, pushing the diaphragm upward. When the inhalation is over, under the influence of these forces, the ribs descend and the dome of the diaphragm rises. As a result, the volume of the chest decreases, therefore, expiration usually occurs passively, without the participation of muscles. With forced exhalation, these forces are joined by contraction of the internal intercostal muscles, abdominal muscles, and serratus posterior muscles.
Particular attention is paid to the nature of the respiratory movements, which in a healthy person are performed due to the contraction of the respiratory muscles: intercostal, diaphragmatic and partly the muscles of the abdominal wall. There are chest, abdominal (Fig. 25) and mixed types of breathing.
With the chest (costal) type of breathing, which is more common in women, respiratory movements are carried out by contraction of the intercostal muscles. In this case, the chest expands and rises slightly during inhalation, narrows and slightly lowers during exhalation.
In the abdominal (diaphragmatic) type of breathing, which is more common in men, respiratory movements are carried out mainly by the diaphragm. During inhalation, the diaphragm contracts and descends, which increases the negative pressure in the chest cavity, and the lungs fill with air. Intra-abdominal pressure rises and the abdominal wall protrudes. During exhalation, the diaphragm relaxes, rises, and the abdominal wall returns to its original position.
With a mixed type, the intercostal muscles and the diaphragm participate in the act of breathing.
Thoracic type of breathing in men may be due to inflammation of the diaphragm or peritoneum (peritonitis), increased intra-abdominal pressure (ascites, flatulence).
The abdominal type of breathing in women is observed with dry pleurisy, intercostal neuralgia, fracture of the ribs, which makes their movements painful.
4. Negative pressure in the interpleural space, its origin and significance for respiration. Pneumothorax. The role of the surfactant.
Negative pressure in the interpleural space. Mechanisms of its formation. The lungs are covered with a visceral layer, and the chest with a parietal layer. The interpleural space is filled with fluid. The leaves are wet and slip. The pressure in this cavity is below atmospheric - called negative interpleural pressure. Through the airways, atmospheric air acts on the internal surfaces, which causes stretching of the lungs. Lungs - elastic formation. In the chest cavity, the lungs are in a stretched state. The elastic fibers will tend to compress the lungs. The alveoli (from the inside) are lined with a special substance - a surfactant - a complex of phospholipils, which is formed by specialized cells - type 2 alveolar pneumocytes. It causes a decrease in surface tension. If there is a surfactant, then the surface tension = 5 dynes per cm2, in its absence 20 dynes per cm2. Surfactant begins to be produced in the last months of pregnancy. It is difficult for premature babies to spread their lungs, respiratory failure occurs. Now artificial spraying of surfactant is used. The presence of surface tension tends to compress the lungs.
Pressure in the pleural cavity = Atmospheric pressure - elastic pressure.
Exhalation = -2-5 mmHg pillar
Inspiration = -4-8 mmHg
Deep breath = -20 mmHg
Uneven growth - the chest grows faster than the lungs. The pleural cavity sucks in gases. Maintaining negative pressure is of great importance for breathing (it provides stretching of the lungs and maintains their respiratory surface, volume change during inhalation / exhalation) and hematopoiesis. Inside the veins, the pressure decreases, this contributes to the return of blood to the heart - venous return. When damaged chest area- pneumothorax - the lung collapses, the lung is poorly ventilated. Pneumothorax can be open and closed (lung tissue damage - air from the airways enters the pleural cavity), valvular pneumothorax - air is sucked through the membrane, and on the way back the membrane closes and air accumulates inside. Pneumothorax reduces the flow of blood to the heart. Pneumothorax requires urgent intervention and closing the hole in any way
Lung compliance (compliance, C) serves as an indicator elastic properties systems external respiration. The value of lung compliance is measured as a pressure-volume relationship and calculated by the formula: C = V/ Δ P, where FROM - distensibility of the lungs.
The normal value of the distensibility of the lungs of an adult is about 200 ml * cm of water. -one . In children, the index of lung distensibility is much less than in an adult.
The decrease in lung compliance is caused by the following factors: increased pressure in the vessels of the lungs or overflow of the vessels of the lungs with blood; prolonged lack of ventilation of the lungs or their departments; untrained respiratory function; decrease in the elastic properties of lung tissue with age.
surface tension liquid is called the force acting in the transverse direction on the boundary of the liquid. The value of surface tension is determined by the ratio of this force to the length of the liquid boundary, the unit of measurement in the SI system is n/m. The surface of the alveoli is covered with a thin layer of water. The molecules of the surface layer of water are attracted to each other with great force. The force of surface tension of a thin layer of water on the surface of the alveoli is always directed to the compression and collapse of the alveoli. Therefore, the surface tension of the fluid in the alveoli is another very important factor influencing lung compliance. Moreover, the surface tension of the alveoli is very significant and can cause their complete collapse, which would exclude any possibility of lung ventilation. The collapse of the alveoli is prevented by an anti-atelectatic factor, or surfactant. In the lungs, alveolar secretory cells, which are part of the air-blood barrier, contain osmiophilic lamellar bodies, which are released into the alveoli and are converted into a surfactant. Synthesis and replacement of surfactant occurs quite quickly, so a violation of the blood flow in the lungs can reduce its reserves and increase the surface tension of the fluid in the alveoli, which leads to their atelectasis, or collapse. Insufficient function of the surfactant leads to respiratory disorders, often causing death.
In the lungs, the surfactant performs the following functions: reduces the surface tension of the alveoli; increases the extensibility of the lungs; ensures the stability of the pulmonary alveoli, preventing their collapse and the appearance of atelectasis; prevents transudation (exit) of fluid to the surface of the alveoli from the plasma of the capillaries of the lung.
5. Vital capacity of the lungs (VC). Volumes, its components. Residual volume of air. The concept of functional residual capacity. total lung capacity. Minute respiratory volume (MOD). Features of VC and MOD in children.
In various positions of the chest, the lungs contain
different amounts of air. There are four main chest positions:
1) maximum inhalation position, 2) calm inhalation position, 3) maximum exhalation position, 4) quiet exhalation position.
The state after a quiet exhalation is called calm breathing level. It is the starting point for determining all lung volumes and capacities.
The volume of air in the lungs after maximum inhalation is total lung capacity (TLC)). It consists of lung capacity (ZEL, the amount of air that can be exhaled at maximum expiration after maximum inspiration), and residual volume (OO, the amount of air that remains in the lungs after maximum expiration).
VC (lung capacity) includes consists of three lung volumes: -
- tidal volume (TO) is the volume of air exchanged in each respiratory cycle;
- reserve volume of inspiration (ROI) - the volume of air that can be inhaled at maximum inspiration after a quiet breath;
- reserve expiration volume (ROE) - the volume that can be exhaled at maximum exhalation after a quiet exhalation.
During quiet breathing, the lungs remain ROE and OO. Their sum is called functional residual capacity (FRC). Sum BEFORE and ROI called inspiratory capacity (IU).
After complete collapse of the lungs with bilateral pneumothorax, the lungs remain so-called. collapsing air that doesn't let you drown human lung who has taken at least one breath after birth.
It is believed that in the nome, OO in relation to VC is 30% in a healthy adult, DO - 15-20%, ROI and ROHE - 40-45% each.
Since lung volumes depend on age, height, sex and weight, in order to judge whether the lung volumes of a given person correspond to normal values, they should be compared with the so-called due values. There are many various methods calculation proper vital capacity of the lungs (JEL), various formulas, tables and nomograms. You will study them in class.
Normally, VC should not differ from VC by 15%.
Each of the lung volumes and capacities has a certain physiological significance. The most widely used in various studies is VC. A decrease in VC occurs with stenosis of the respiratory tract, with a decrease in the respiratory surface of the lungs, with an increase in the blood filling of the lungs (stagnation, edema). In addition, VC decreases in all conditions that prevent the maximum expansion of the lung and chest (exudate in the pleural cavity, pneumothorax, pneumonia, emphysema, ascites, pregnancy, obesity, cartilage ossification, muscle weakness, chest trauma, etc.).
TO - (tidal volume, depth of breathing) is associated with maintaining a certain level of partial pressure of oxygen and carbon dioxide in the alveolar air and ensures the normal tension of gases in the blood. With calm breathing, TO ranges from 300 to 500 ml. The value of DO is related to the respiratory rate - usually deep breathing happens rare, superficial - frequent. During muscular work, DO can increase several times, becoming close to VC.
ROI - (inspiratory reserve volume) determines the ability to increase the amount of ventilated air, the need for which occurs with an increase in the body's need for oxygen.
ROE - (expiratory reserve volume) naturally changes depending on the position of the body: lying down it is smaller. The ratio of ROI to ROHE is defined as the level of respiration. It is believed that if it is below 1, then the efficiency of lung ventilation is greater.
An increase in VC can be regarded positively only if the TLC (total lung capacity) does not change or increases, but less than VC. In this case, the increase in VC is due to a decrease in RO. If the VC, regardless of its value and the percentage of VC, is below 70% of the CL, then the function of external respiration cannot be considered normal.
Importance of the airways . Only the air filling the alveoli is directly involved in gas exchange. The volume of the airways, which is 120-150 ml, is called the volume of harmful space - ORP. A change in the lumen of the bronchi can significantly change the value of ORP.
Atmospheric air, passing through the airways, is cleaned of dust, warmed and moistened. When large particles of dust enter the trachea and bronchi, a cough reflex occurs, and when they enter the nose, sneezing occurs. Coughing and sneezing are protective respiratory reflexes that clear the airways of foreign particles and mucus that make breathing difficult.
6. Gas composition of inhaled, exhaled and alveolar air. The relative constancy of the gas composition of the alveolar air, its causes.
At rest, an average of 250 ml of O 2 is consumed in the body per minute and about 230 ml of CO 2 is released.
Of the total O 2 inhaled air (21% of the total volume), only 1/3 enters the blood through the air-blood barrier in the lungs. The normal partial pressure of gases in the alveolar air is maintained if the pulmonary ventilation is equal to 25 times the amount of O 2 consumed. Another prerequisite for maintaining a normal concentration of gases in the alveolar air is the optimal ratio of alveolar ventilation to cardiac output (Q): VA / Q, which usually corresponds to 0.8-1.0. For gas exchange in the lungs, this ratio is optimal. The different areas of the lung do not provide an ideal model for maintaining an optimal VA/Q ratio because the alveoli are unevenly ventilated with air and perfused with blood.
To maintain a certain composition of alveolar air, the value of alveolar ventilation and its relation to the level of metabolism, i.e., the amount of O 2 consumed and CO 2 released, are important. In any transitional state (for example, the beginning of work, etc.), time is needed for the formation of the optimal composition of the alveolar air. Of primary importance are the optimal ratios of alveolar ventilation to blood flow.
The composition of the alveolar air is measured in the mouth in the second half of the expiratory phase using high-speed analyzers. In physiological practice, a mass spectrometer is used, which allows you to determine the amount of any respiratory gas; infrared CO 2 analyzer and O 2 analyzer. Analyzers continuously record the concentration of gases in the exhaled air.
7. Gas exchange in the lungs. The role of partial pressure in gas exchange between air, blood and tissues. Features of the diffusion of O2 and CO2 in the lungs. Diffusion capacity of the lungs.
O 2 transport is carried out in a physically dissolved and chemically bound form. Physical processes, i.e., the dissolution of gas, cannot provide the body's needs for O 2. It is estimated that physically dissolved O 2 can maintain normal O 2 consumption in the body (250 ml * min -1) if the minute volume of blood circulation is approximately 83 l * min -1 at rest. The most optimal is the mechanism of O 2 transport in a chemically bound form.
According to Fick's law, O 2 gas exchange between alveolar air and blood occurs due to the presence of an O 2 concentration gradient between these media. In the alveoli of the lungs, the partial pressure of O 2 is 13.3 kPa, or 100 mm Hg, and in the venous blood flowing to the lungs, the partial pressure of O 2 is approximately 5.3 kPa, or 40 mm Hg. The pressure of gases in water or in the tissues of the body is denoted by the term "gas tension" and is denoted by the symbols Po 2, Pco 2. The O 2 gradient on the alveolar-capillary membrane, equal to an average of 60 mm Hg, is one of the most important, but not the only, according to Fick's law, factors in the initial stage of diffusion of this gas from the alveoli into the blood.
O 2 transport begins in the capillaries of the lungs after its chemical binding to hemoglobin.
Hemoglobin (Hb) is able to selectively bind O 2 and form oxyhemoglobin (HbO 2) in the zone high concentration O 2 in the lungs and release molecular O 2 in the area of low O 2 content in tissues. At the same time, the properties of hemoglobin do not change and it can perform its function for a long time.
Hemoglobin carries O2 from the lungs to the tissues. This function depends on two properties of hemoglobin: 1) the ability to change from a reduced form, which is called deoxyhemoglobin, to an oxidized one (Hb + O 2 à HbO 2) at a high rate (half-time of 0.01 s or less) at normal Horn in alveolar air; 2) the ability to donate O 2 in tissues (HbO 2 à Hb + O 2) depending on the metabolic needs of body cells.
The dependence of the degree of oxygenation of hemoglobin on the partial pressure of oxygen in the alveolar air is graphically represented as oxyhemoglobin dissociation curve, or saturation curve (Fig. 8.7). The plateau of the dissociation curve is characteristic of saturated O 2 (saturated) arterial blood, and the steep descending part of the curve is characteristic of venous, or desaturated, blood in the tissues.
The affinity of oxygen for hemoglobin is influenced by various metabolic factors, which is expressed as a shift in the dissociation curve to the left or right. The affinity of hemoglobin for oxygen is regulated by the most important factors of tissue metabolism: Po 2 pH, temperature and intracellular concentration of 2,3-diphosphoglycerate. The pH value and the content of CO 2 in any part of the body naturally change the affinity of hemoglobin to O 2: a decrease in blood pH causes a shift in the dissociation curve, respectively, to the right (the affinity of hemoglobin to O 2 decreases), and an increase in blood pH causes a shift in the dissociation curve to the left (the affinity of hemoglobin to O 2 increases). O 2) (see Fig. 8.7, A). For example, the pH in erythrocytes is 0.2 units lower than in blood plasma. In tissues, due to the increased content of CO 2, the pH is also less than in blood plasma. The effect of pH on the oxyhemoglobin dissociation curve is called "Bohr effect".
An increase in temperature reduces the affinity of hemoglobin for O 2 . In working muscles, an increase in temperature contributes to the release of O 2. A decrease in tissue temperature or the content of 2,3-diphosphoglycerate causes a shift to the left of the oxy-hemoglobin dissociation curve (see Fig. 8.7, B).
Metabolic factors are the main regulators of O 2 binding to hemoglobin in the capillaries of the lungs, when the level of O 2, pH and CO 2 in the blood increases the affinity of hemoglobin to O 2 along the pulmonary capillaries. Under the conditions of body tissues, these same metabolic factors reduce the affinity of hemoglobin to O 2 and contribute to the transition of oxyhemoglobin to its reduced form - deoxyhemoglobin. As a result, O 2 flows from the blood of tissue capillaries into the tissues of the body along the concentration gradient.
Carbon monoxide (II) - CO, is able to combine with the iron atom of hemoglobin, changing its properties and reaction with O 2. The very high affinity of CO for Hb (200 times higher than that of O 2 ) blocks one or more iron atoms in the heme molecule, changing the affinity of Hb for O 2 .
9. Transport of oxygen by blood. Oxyhemoglobin dissociation curve, its analysis. Factors affecting the dissociation of oxyhemoglobin in tissues. Carbon dioxide voltage value (Bohr effect). oxygen capacity of the blood.
10. Transport of carbon dioxide by blood. Processes occurring in the capillaries of tissues and lungs. The value of carbonic anhydrase. Factors that increase the ability of the blood to bind carbon dioxide (the Haldane effect).
(answers combined for convenience)
Under oxygen capacity of the blood understand the amount of oxygen that is bound by blood until hemoglobin is completely saturated. When the content of hemoglobin in the blood is 8.7 mmol * l -1, the oxygen capacity of the blood is 0.19 ml O 2 in 1 ml of blood (temperature 0 o C and barometric pressure 760 mm Hg, or 101.3 kPa). The value of the oxygen capacity of the blood determines the amount of hemoglobin, 1 g of which binds 1.36-1.34 ml of O 2 . Human blood contains about 700-800 g of hemoglobin and can thus bind almost 1 liter of O 2 . There is very little O 2 physically dissolved in 1 ml of blood plasma (about 0.003 ml), which cannot provide oxygen demand for tissues. The solubility of O 2 in blood plasma is 0.225 ml * l -1 * kPa -1.
O 2 exchange between the blood of capillaries and tissue cells is also carried out by diffusion. The concentration gradient O 2 between arterial blood (100 mm Hg, or 13.3 kPa) and tissues (about 40 mm Hg, or 5.3 kPa) is on average 60 mm Hg. (8.0 kPa). The change in the gradient may be due to both the O 2 content in the arterial blood and the O 2 utilization factor, which averages 30–40% for the organism. Oxygen utilization factor called the amount of O 2 given up during the passage of blood through tissue capillaries, referred to the oxygen capacity of the blood.
On the other hand, it is known that at a voltage of O 2 in the arterial blood of capillaries equal to 100 mm Hg. (13.3 kPa), on the membranes of cells located between the capillaries, this value does not exceed 20 mm Hg. (2.7 kPa), and in mitochondria it is on average 0.5 mm Hg. (0.06 kPa).
8.5.4. Gas exchange and CO 2 transport
The intake of CO 2 in the lungs from the blood to the alveoli is provided from the following sources: 1) from CO 2 dissolved in blood plasma (5-10%); 2) from bicarbonates (80-90%); 3) from carbamic compounds of erythrocytes (5-15%), which are able to dissociate.
For CO 2, the solubility coefficient in the membranes of the air-blood barrier is greater than for O 2, and averages 0.231 mmol * l -1 kPa -1; therefore, CO 2 diffuses faster than O 2. This provision is true only for the diffusion of molecular CO 2 . Most of CO 2 is transported in the body in a bound state in the form of bicarbonates and carbamic compounds, which increases the CO 2 exchange time spent on the dissociation of these compounds.
In venous blood flowing to the capillaries of the lungs, the voltage of CO 2 is on average 46 mm Hg. (6.1 kPa), and in the alveolar air, the partial pressure of CO 2 is on average 40 mm Hg. (5.3 kPa), which ensures the diffusion of CO 2 from the blood plasma into the alveoli of the lungs along the concentration gradient.
The capillary endothelium is permeable only to molecular CO 2 as a polar molecule (O - C - O). Molecular CO 2, physically dissolved in the blood plasma, diffuses from the blood into the alveoli. In addition, CO 2 diffuses into the alveoli of the lungs, which is released from the carbamic compounds of erythrocytes due to the oxidation reaction of hemoglobin in the capillaries of the lung, as well as from plasma bicarbonates as a result of their rapid dissociation with the help of the carbonic anhydrase enzyme contained in erythrocytes.
Molecular CO 2 passes through the air-blood barrier and then enters the alveoli.
Normally, after 1 s, the concentrations of CO 2 on the alveolar-capillary membrane are equalized, therefore, in half the time of capillary blood flow, a complete exchange of CO 2 through the air-blood barrier occurs. In reality, equilibrium comes somewhat more slowly. This is due to the fact that the transfer of CO 2 , as well as O 2 , is limited by the perfusion rate of the lung capillaries.
During the gas exchange of CO 2 between tissues and blood, the content of HCO3 - in the erythrocyte increases and they begin to diffuse into the blood. To maintain electrical neutrality, additional C1 ions from the plasma will begin to enter the erythrocytes - The largest amount of bicarbonates in the blood plasma is formed with the participation of erythrocyte carbonic anhydrase.
The carbamic complex of CO 2 with hemoglobin is formed as a result of the reaction of CO 2 with the NH 2 radical of globin. This reaction proceeds without the participation of any enzyme, i.e., it does not need catalysis. The reaction of CO 2 with Hb leads, firstly, to the release of H + ; secondly, during the formation of carbamic complexes, the affinity of Hb for O 2 decreases. The effect is similar to that of low pH. As is known, low pH in tissues potentiates the release of O 2 from oxyhemoglobin at high concentrations of CO 2 (Bohr effect). On the other hand, the binding of O 2 by hemoglobin reduces the affinity of its amino groups for CO 2 (Holden effect).
Each reaction is now well studied. For example, the half-cycle of the exchange of C1 - and HCO 3 - is 0.11-0.16 s at 37 o C . Under in vitro conditions, the formation of molecular CO 2 from bicarbonates is extremely slow and the diffusion of this gas takes about 5 minutes, while in the capillaries of the lung, equilibrium occurs after 1 s. This is determined by the function of the enzyme carbonic anhydrase. In the function of carbonic anhydrase, the following types of reactions are distinguished:
CO 2 + H 2 Oß > H 2 CO 3ß > H + + HCO 3 -
The process of removal of CO 2 from the blood into the alveoli of the lung is less limited than the oxygenation of the blood. This is due to the fact that molecular CO 2 more easily penetrates through biological membranes than O 2 . For this reason, it easily penetrates from tissues into the blood. In addition, carbonic anhydrase promotes the formation of hydrogen carbonate. Poisons that limit the transport of O 2 (such as CO, methemoglobin-forming substances - nitrites, methylene blue, ferrocyanides, etc.) do not affect the transport of CO 2. Carbonic anhydrase blockers, such as diacarb, which are often used in clinical practice or for the prevention of mountain or altitude sickness, never completely disrupt the formation of molecular CO 2. Finally, tissues have a large buffer capacity, but are not protected from O 2 deficiency. For this reason, a violation of O 2 transport occurs in the body much more often and faster than a violation of CO 2 gas exchange. However, in some diseases, high CO 2 levels and acidosis can be the cause of death.
Measurement of voltage O 2 and CO 2 in arterial or mixed venous blood is carried out by polarographic methods using a very small amount of blood. The amount of gases in the blood is measured after their complete extraction from the blood sample taken for analysis.
Such studies are performed using manometric devices such as the Van Slyke apparatus, or a hemoalkarimeter (0.5–2.0 ml of blood is needed) or on a Holander micromanometer (about 50 µl of blood is needed).
11. Respiratory center, its location, main types of respiratory trunk neurons.
According to modern concepts respiratory center- this is a set of neurons that provide a change in the processes of inhalation and exhalation and adaptation of the system to the needs of the body. There are several levels of regulation:
1) spinal;
2) bulbar;
3) suprapontal;
4) cortical.
spinal level It is represented by motoneurons of the anterior horns of the spinal cord, the axons of which innervate the respiratory muscles. This component has no independent significance, as it obeys impulses from the overlying departments.
The neurons of the reticular formation of the medulla oblongata and the pons form bulbar level. The following types of nerve cells are distinguished in the medulla oblongata:
1) early inspiratory (excited 0.1-0.2 s before the start of active inspiration);
2) full inspiratory (activated gradually and send impulses throughout the inspiratory phase);
3) late inspiratory (they begin to transmit excitation as the action of the early ones fades);
4) post-inspiratory (excited after inhibition of inspiratory);
5) expiratory (provide the beginning of active exhalation);
6) preinspiratory (begin to generate a nerve impulse before inhalation).
The axons of these nerve cells can be directed to the motor neurons of the spinal cord (bulbar fibers) or be part of the dorsal and ventral nuclei (protobulbar fibers).
The neurons of the medulla oblongata, which are part of the respiratory center, have two features:
1) have a reciprocal relationship;
2) can spontaneously generate nerve impulses.
The pneumotoxic center is formed by the nerve cells of the bridge. They are able to regulate the activity of underlying neurons and lead to a change in the processes of inhalation and exhalation. If the integrity of the central nervous system in the region of the brainstem is violated, the respiratory rate decreases and the duration of the inspiratory phase increases.
Suprapontial level It is represented by the structures of the cerebellum and midbrain, which provide the regulation of motor activity and autonomic function.
Cortical component consists of neurons of the cerebral cortex, affecting the frequency and depth of breathing. Basically, they have a positive effect, especially on the motor and orbital zones. In addition, the participation of the cerebral cortex indicates the possibility of spontaneously changing the frequency and depth of breathing.
Thus, various structures of the cerebral cortex take on the regulation of the respiratory process, but the bulbar region plays a leading role.
12. Humoral regulation of respiration. Carbon dioxide is a specific causative agent
respiratory center. Influence of reduced oxygen tension on the respiratory center. The value of central and peripheral receptors in the regulation of respiration.
For the first time, humoral regulation mechanisms were described in the experiment of G. Frederick in 1860, and then studied by individual scientists, including I. P. Pavlov and I. M. Sechenov.
G. Frederick conducted an experiment in cross-circulation, in which he connected the carotid arteries and jugular veins of two dogs. As a result, the head of dog #1 received blood from the torso of animal #2, and vice versa. When the trachea was clamped in dog No. 1, carbon dioxide accumulated, which entered the body of animal No. 2 and caused an increase in the frequency and depth of breathing - hyperpnea. Such blood entered the dog's head under No. 1 and caused a decrease in the activity of the respiratory center up to hypopnea and apopnea. Experience proves that the gas composition of the blood directly affects the intensity of breathing.
The excitatory effect on the neurons of the respiratory center is exerted by:
1) decrease in oxygen concentration (hypoxemia);
2) an increase in the content of carbon dioxide (hypercapnia);
3) an increase in the level of hydrogen protons (acidosis).
Braking effect occurs as a result of:
1) increase in oxygen concentration (hyperoxemia);
2) lowering the content of carbon dioxide (hypocapnia);
3) decrease in the level of hydrogen protons (alkalosis).
Currently, scientists have identified five ways in which blood gas composition influences the activity of the respiratory center:
1) local;
2) humoral;
3) through peripheral chemoreceptors;
4) through central chemoreceptors;
5) through chemosensitive neurons of the cerebral cortex.
local action occurs as a result of the accumulation in the blood of metabolic products, mainly hydrogen protons. This leads to the activation of the work of neurons.
Humoral influence appears with an increase in work skeletal muscle and internal organs. As a result, carbon dioxide and hydrogen protons are released, which flow through the bloodstream to the neurons of the respiratory center and increase their activity.
Peripheral chemoreceptors- these are nerve endings from the reflexogenic zones of the cardiovascular system (carotid sinuses, aortic arch, etc.). They react to a lack of oxygen. In response, impulses are sent to the central nervous system, leading to an increase in the activity of nerve cells (Bainbridge reflex).
The reticular formation is composed of central chemoreceptors, which are highly sensitive to the accumulation of carbon dioxide and hydrogen protons. Excitation extends to all areas of the reticular formation, including the neurons of the respiratory center.
Nerve cells of the cerebral cortex also respond to changes in the gas composition of the blood.
Thus, the humoral link plays an important role in the regulation of the neurons of the respiratory center.
13. Reflex regulation of breathing. Hering-Breuer reflex. Mechanism of the first breath of the newborn.
Nervous regulation is carried out mainly by reflex pathways. There are two groups of influences - episodic and permanent.
There are three types of permanent:
1) from peripheral chemoreceptors of the cardiovascular system (Heimans reflex);
2) from the proprioreceptors of the respiratory muscles;
3) from nerve endings of lung tissue stretching.
During breathing, the muscles contract and relax. Impulses from proprioreceptors enter the CNS simultaneously to the motor centers and neurons of the respiratory center. Muscle work is regulated. If any obstruction of breathing occurs, the inspiratory muscles begin to contract even more. As a result, a relationship is established between the work of skeletal muscles and the body's need for oxygen.
Reflex influences from lung stretch receptors were first discovered in 1868 by E. Hering and I. Breuer. They found that nerve endings located in smooth muscle cells provide three types of reflexes:
1) inspiratory-braking;
2) expiratory-relieving;
3) Head's paradoxical effect.
During normal breathing, inspiratory-braking effects occur. During inhalation, the lungs expand, and impulses from receptors along the fibers of the vagus nerves enter the respiratory center. Here, inhibition of inspiratory neurons occurs, which leads to the cessation of active inhalation and the onset of passive exhalation. The significance of this process is to ensure the beginning of exhalation. When the vagus nerves are overloaded, the change of inhalation and exhalation is preserved.
The expiratory-relief reflex can only be detected during the experiment. If you stretch the lung tissue at the time of exhalation, then the onset of the next breath is delayed.
The paradoxical Head effect can be realized in the course of the experiment. With maximum stretching of the lungs at the time of inspiration, an additional breath or sigh is observed.
Episodic reflex influences include:
1) impulses from irritary receptors of the lungs;
2) influence from juxtaalveolar receptors;
3) influence from the mucous membrane of the respiratory tract;
4) influences from skin receptors.
Irritary receptors located in the endothelial and subendothelial layers of the respiratory tract. They simultaneously perform the functions of mechanoreceptors and chemoreceptors. Mechanoreceptors have a high threshold of irritation and are excited with a significant collapse of the lungs. Such falls normally occur 2-3 times per hour. With a decrease in the volume of lung tissue, receptors send impulses to the neurons of the respiratory center, which leads to an additional breath. Chemoreceptors respond to the appearance of dust particles in the mucus. When irritary receptors are activated, there is a feeling of sore throat and cough.
Juxtaalveolar receptors are in the interstitium. They react to the appearance of chemicals - serotonin, histamine, nicotine, as well as to changes in fluid. This leads to a special type of shortness of breath with edema (pneumonia).
With severe irritation of the mucous membrane of the respiratory tract respiratory arrest occurs, and with moderate, protective reflexes appear. For example, when the receptors of the nasal cavity are irritated, sneezing occurs, when the nerve endings of the lower respiratory tract are activated, coughing occurs.
The respiratory rate is influenced by impulses from temperature receptors. For example, when immersed in cold water there is a delay in breathing.
Upon activation of noceceptors first there is a stoppage of breathing, and then there is a gradual increase.
During irritation of the nerve endings embedded in the tissues of the internal organs, there is a decrease in respiratory movements.
As pressure increases, there is sharp decline frequency and depth of breathing, which leads to a decrease in the suction capacity of the chest and the restoration of blood pressure, and vice versa.
Thus, the reflex influences exerted on the respiratory center maintain the frequency and depth of breathing at a constant level.
14. Influence muscle activity to breath.
During physical activity, the consumption of O 2 and the production of CO 2 increase on average 15-20 times. At the same time, ventilation is increased and the tissues of the body receive the required amount of O 2, and CO 2 is excreted from the body.
Each person has individual indicators of external respiration. Normally, the respiratory rate varies from 16 to 25 per minute, and the tidal volume is from 2.5 to 0.5 liters. With muscle load different power pulmonary ventilation, as a rule, is proportional to the intensity of the work performed and the consumption of O 2 by body tissues. In an untrained person with maximum muscular work, the minute breathing volume does not exceed 80 l * min -1, and a trained person can have 120-150 l * min -1 and more. A short-term arbitrary increase in ventilation can be 150-200 l * min -1.
At the beginning of muscular work, ventilation increases rapidly, however, during the initial period of work, there are no significant changes in the pH and gas composition of arterial and mixed venous blood. Consequently, peripheral and central chemoreceptors, as the most important sensitive structures of the respiratory center, sensitive to hypoxia and to a decrease in the pH of the extracellular fluid of the brain, do not participate in the occurrence of hyperpnea at the beginning of physical work.
The level of ventilation in the first seconds of muscle activity is regulated by signals that come to the respiratory center from the hypothalamus, cerebellum, limbic system and motor cortex. At the same time, the activity of the neurons of the respiratory center is enhanced by irritation of the proprioceptors of the working muscles. Quite quickly, the initial sharp increase in lung ventilation is replaced by its smooth rise to a fairly stable state, or the so-called plateau. During the “plateau” period, or stabilization of lung ventilation, there is a decrease in Rao 2 and an increase in Raco 2 of the blood, the transport of gases through the air-blood barrier increases, peripheral and central chemoreceptors begin to be excited. During this period, humoral influences join the neurogenic stimuli of the respiratory center, causing an additional increase in ventilation during the work performed. During heavy physical work, the level of ventilation will also be affected by an increase in body temperature, the concentration of catecholamines, arterial hypoxia, and individually limiting factors in the biomechanics of respiration.
The state of "plateau" occurs on average 30 seconds after the start of work or a change in the intensity of work already in progress. In accordance with the energy optimization of the respiratory cycle, an increase in ventilation during exercise occurs due to a different ratio of the frequency and depth of breathing. With very high pulmonary ventilation, the absorption of O 2 by the respiratory muscles greatly increases. This circumstance limits the ability to perform extreme physical activity. The end of work causes a rapid decrease in lung ventilation to a certain value, after which there is a slow recovery of breathing to normal.
15. Breathing at high and low barometric pressure.
During underwater work, the diver breathes at a pressure higher than atmospheric pressure by 1 atm. for every 10 m dive. If a person inhales the air of the usual composition, then nitrogen dissolves in adipose tissue. Diffusion of nitrogen from tissues is slow, so the rise of the diver to the surface must be carried out very slowly. Otherwise, intravascular formation of nitrogen bubbles is possible (the blood "boils") with severe damage to the central nervous system, organs of vision, hearing, and severe pain in the joints. There is a so-called caisson disease. For treatment, the victim must be re-placed in an environment with high pressure. Gradual decompression can last several hours or days.
The likelihood of decompression sickness can be significantly reduced by breathing special gas mixtures, such as an oxygen-helium mixture. This is due to the fact that the solubility of helium is less than that of nitrogen, and it diffuses faster from tissues, since its molecular weight is 7 times less than that of nitrogen. In addition, this mixture has a lower density, so the work expended on external respiration is reduced.
With an increase in altitude above sea level, the barometric pressure and the partial pressure of O 2 fall, however, the saturation of the alveolar air with water vapor at body temperature does not change. At an altitude of 20,000 m, the content of O 2 in the inhaled air drops to zero. If the inhabitants of the plains climb the mountains, hypoxia increases their lung ventilation by stimulating arterial chemoreceptors. Changes in breathing during high-altitude hypoxia are different for different people. The reactions of external respiration arising in all cases are determined by a number of factors: 1) the speed with which hypoxia develops; 2) the degree of consumption of O 2 (rest or exercise stress); 3) the duration of hypoxic exposure.
The initial hypoxic stimulation of respiration, which occurs when ascending to a height, leads to leaching of CO 2 from the blood and the development of respiratory alkalosis. This in turn causes an increase in the pH of the extracellular fluid of the brain. Central chemoreceptors respond to such a shift in pH in the cerebrospinal fluid by a sharp decrease in their activity, which inhibits the neurons of the respiratory center to such an extent that it becomes insensitive to stimuli emanating from peripheral chemoreceptors. Quite quickly, hyperpnea is replaced by involuntary hypoventilation, despite persistent hypoxemia. Such a decrease in the function of the respiratory center increases the degree of hypoxic state of the body, which is extremely dangerous, especially for the neurons of the cerebral cortex.
During acclimatization to high altitude conditions, adaptation of physiological mechanisms to hypoxia occurs. The main factors of long-term adaptation include: an increase in the content of CO 2 and a decrease in the content of O 2 in the blood against the background of a decrease in the sensitivity of peripheral chemoreceptors to hypoxia, as well as an increase in the concentration of hemoglobin.
Accent placement: ALVEOLAR AIR
ALVEOLAR AIR (alveolar gas) - the air in the pulmonary alveoli. It makes up 94-95% of the air available in respiratory tract and lungs, the remaining 5-6% of the air is in the so-called. dead, or harmful space(cm.).
Composition and partial tension of gases A. v. depending on the state of pulmonary ventilation in a healthy adult are presented in the table.
Partial pressure of oxygen and carbon dioxide in A. century. is of great importance, since it determines the diffusion exchange of gases. From the alveoli, oxygen diffuses into the blood, and from the blood, carbon dioxide diffuses into the alveoli. Decreased oxygen content in A. c. reflex causes spasm of pulmonary arterioles and hypertension of the pulmonary circulation. The composition of A. century, and above all the oxygen content, in different parts of the lungs is somewhat different, especially in pulmonary pathology. A.'s volume in, increases with emphysema, decreases with atelectasis and pulmonary edema.
The volume of all air contained in the alveoli and respiratory tract can be measured by dilution of indicator gas (helium, nitrogen, radioactive xenon, etc.).
The average partial tension of carbon dioxide in A. c. (P A CO 2) is always close to the arterial blood carbon dioxide tension (P A CO 2) except in cases of severe pulmonary pathology. Oxygen tension in A. century. (P A O 2) can be calculated using the alveolar air equation:
R A O 2 \u003d R I O 2 - R A CO 2 ⋅ 1.2
where P I O 2 is the oxygen tension in the inhaled air (usually 150 mm rt. Art.); R A CO 2 - CO 2 voltage in A. c. (it is measured in the final portions of exhaled air with a capnograph or equated to R A CO 2, usually measured using the Astrup device in portions of blood drawn from an artery or from a finger); 1.2 is the correction factor for the usual value of the respiratory coefficient equal to 0.8. Determination of the voltage of gases A. c. important for assessing gas exchange in the lungs.
Bibliographer.: Comro D. G. and others. Lungs, clinical physiology and functional tests, trans. from English, M., 1961; Navratil M., Kadlec K. and Daum S. Pathophysiology of respiration, trans. from Czech., M., 1967.
M. I. ANOKHIN
Sources:
- Big medical encyclopedia. Volume 1 / Editor-in-Chief Academician B. V. Petrovsky; publishing house "Soviet Encyclopedia"; Moscow, 1974.- 576 p.
