Human lungs, the basics of the respiratory system. Through brand new artificial airways, we blew air into the lungs

RESPIRATORY ORGANS
a group of organs that exchange gases between the body and the environment. Their function is to provide tissues with oxygen necessary for metabolic processes and excretion of carbon dioxide (carbon dioxide) from the body. Air first passes through the nose and mouth, then through the throat and larynx enters the trachea and bronchi, and then into the alveoli, where the actual breathing takes place - gas exchange between the lungs and blood. In the process of breathing, the lungs work like bellows: the chest alternately contracts and expands with the help of the intercostal muscles and the diaphragm. Functioning of the entire respiratory system coordinated and regulated by impulses coming from the brain through numerous peripheral nerves. Although all parts of the respiratory tract function as a single unit, they differ in both anatomical and clinical characteristics.
Nose and throat. The beginning of the airways (respiratory) are paired nasal cavities leading to the pharynx. They are formed by the bones and cartilages that make up the walls of the nose and are lined with mucous membranes. The inhaled air, passing through the nose, is cleaned of dust particles and warmed. Paranasal sinuses, i.e. cavities in the bones of the skull, also called paranasal sinuses nose, communicate with the nasal cavity through small openings. There are four pairs of paranasal sinuses: maxillary (maxillary), frontal, sphenoid and sinuses ethmoid bone. Throat - top part throat - is divided into the nasopharynx, located above the small tongue (soft palate), and the oropharynx - the area behind the tongue.
Larynx and trachea. After passing through the nasal passages, the inhaled air enters through the pharynx into the larynx, which contains the vocal cords, and then into the trachea - a non-collapsing tube, the walls of which consist of open cartilage rings. In the chest, the trachea divides into two main bronchi, through which air enters the lungs.

Collier Encyclopedia. - Open society. 2000 .

The main organs are the lungs. However, air, before it enters them, travels quite a long way: nose, nasopharynx, pharynx, larynx, trachea, bronchi. And this, as we will see below, is very important point to ensure normal breathing.

The nose performs, along with respiratory, olfactory, resonator functions, and such a very important for human life as a protective one. Dust particles and bacteria are mechanically retained at the entrance to the nose by hairs growing here.

The nasal passages are narrow and winding channels, which favors the warming of the passing air. To moisturize it, the mucous membrane normally releases about 0.5 liters of moisture per day. This mucus performs a dual task: it largely neutralizes the bacteria that have settled on the walls of the nose with dust particles, and it washes away into the nasopharynx, from where it is removed by expectoration and spitting.

Studies show that more than 50% of inhaled dust is trapped in the nose. If a person breathes through his mouth, then the polluted air passes into deeper Airways which can cause a number of diseases. From this it becomes obvious how important it is to constantly maintain nasal breathing.

In the nasal cavity, a network of olfactory moat is widely developed, thanks to which we are able to distinguish odors. With inflammation of the nasal mucosa, its edema, the charming function is sharply reduced or completely lost.

The pharynx and larynx also have protective function, reading the inhaled air from dust and microbes, warming and moistening it. When the walls of the nose, nasopharynx and larynx are irritated by any substances, sneezing and coughing occur.

Larynx plays important role in the formation of sound. Therefore, with inflammation of the mucous membrane of its walls, as well as the vocal cords, hoarseness occurs, and sometimes total loss vote.

Warmed and purified from dust and partially from microorganisms, the air enters the trachea and bronchi. The larynx, trachea and bronchi contain cartilage in their walls, which give them elasticity and prevent them from falling off. The two main bronchi extending from the trachea, like the branches of a tree, repeatedly divide into smaller and smaller ones, reaching the thinnest and thinnest branches - bronchioles, the diameter of which does not exceed fractions of a millimeter. They end in clusters of tiny bubbles, the so-called pulmonary alveoli, resembling a miniature grape brush. Their walls are very thin and braided with a dense network of capillary blood vessels. Inside the alveoli are lined superficially active substance, weakening the effect of surface tension and thereby preventing the collapse of the lungs on exhalation. The total thickness of the alveolus and capillary that separates blood from air usually does not exceed a thousandth of a millimeter, due to which oxygen easily penetrates from the alveolar air into the blood, and carbon dioxide from the blood into the air.

The process of gas exchange in the lungs is very fast due to the huge number of alveoli, equal to several hundred million, and the total area of ​​their expanded walls is almost 50 times the surface of the skin of the human body. Blood flows through the capillaries in the alveoli in about 2 seconds, but this is enough to establish oxygen and carbon dioxide balance.

The lungs (right and left) fill both halves of the chest. The right has three lobes, the left has two. Each of them has halves of a sheerly cut cone with a rounded top and a slightly depressed base that fits on the diaphragm - a wide flat muscle with a dense tendon dome-shaped raised middle that separates the chest cavity from the abdominal cavity.

Lungs covered thin shell- pleura, which also lines the walls chest cavity. Between the lung and parietal layers of the pleura, a slit-like hermetic closed space(pleural cavity). It contains a small amount of fluid secreted by the pleura, but no air. The pressure in the pleural cavity is less than atmospheric pressure and is called negative.

Every minute, 6-9 liters of air passes through the lungs at rest, and per day this will be at least 10,000 liters.

From defense mechanisms of the respiratory system, first of all, the ciliated epithelium lining the mucous membranes along the entire path of air movement, and goblet cells, should be noted. There are about five ciliated cells per one such cell. They are narrower than goblet-shaped, covered with cilia hairs, of which there are up to two hundred per cell and which are in constant motion, and selectively towards the large bronchi. Due to this, cilia play an extremely important role in cleansing the airways from foreign particles and substances.

Goblet cells secrete mucus on the surface of the ciliated epithelium, on which almost all the dust from the inhaled air is deposited, and with the help of cilia it moves towards the large bronchi, trachea, larynx, pharynx, and then is excreted when coughing.

Cough occurs as a result of irritation of certain zones located in places of the closest contact of the air flow with the bronchial mucosa, and occurs quickly, in hundredths of a second. But at this time, the human respiratory system is in a very tense state. First, a person takes a short breath. This is followed by closure of the glottis and a powerful short-term contraction of the intercostal muscles and diaphragm. At the moment of muscle contraction, intrathoracic pressure rises sharply, and as a result, the glottis opens and polluted air is pushed out from the bronchi and trachea.

Measuring the speed of the air flow during coughing shows that it reaches 50-120 m / s in the pharynx, that is, 100 km / h. In the trachea and main bronchi, the speed of air movement is somewhat reduced, but here it is 15–32 m/s, and in the small and smallest bronchi it drops to 1.2–6 m/s. Naturally, with such a “hurricane”, much of the foreign that got into the respiratory tract with air or was in it (sputum, accumulation of mucus and microorganisms, dust and other foreign particles) is rapidly thrown out.

Thus, our breathing system is equipped with a universal and trouble-free air filter and air conditioner, so that completely clean warm air always enters the lungs of a person.

But still main function lungs is to provide oxidative processes, resulting in the formation of energy that supports the vital activity of the body. And for the oxidation of proteins, fats and carbohydrates, it is constantly needed in enough oxygen. If you can live without food for more than a month, without water - about 10 days, then without oxygen, life fades away after a few minutes. It is on the lungs and respiratory muscles that the responsible role falls to ensure its delivery to the tissues of the body.

How are respiratory functions and gas exchange processes carried out?

The act of breathing consists of inhalation, exhalation and pause. It involves the diaphragm and external intercostal muscles. Regulates breathing is the so-called respiratory center, located in the medulla oblongata. From here, irritating impulses are transmitted along the phrenic nerve to the diaphragm and along the intercostal nerves to the intercostal muscles.

When inhaling, the intercostal muscles and the diaphragm contract. Its dome becomes flat and lowers, and the ribs rise. Thus, the volume of the chest increases. Since the pressure in the pleural cavity is negative, the lung expands well in the chest cavity and under the action of force atmospheric pressure filled with air. The degree of stretching of the lung tissue and the contraction of the respiratory muscles are controlled by mechanoreceptors located in the lungs and these muscles. Impulses from here go to respiratory center and signal the degree of filling of the lungs with air. Thus, a clear Feedback between the medulla oblongata and the respiratory organs.

When the inhalation is over and the respiratory muscles relax, the chest returns to its original position: the ribs fall, the dome of the diaphragm protrudes upward. The volume of the chest decreases, which entails a decrease in the volume of the lungs. As a result, the air that entered during inhalation is pushed out.

After exhalation, there is a pause, then the respiratory act is repeated.

The respiratory center automatically regulates the rhythm and depth of breathing. But a person can intervene in this automated process, consciously changing it and even stopping it for a while (holding the breath). In the same time increased concentration carbon dioxide is stronger than usual, irritates the respiratory center, which leads to increased breathing.

Its frequency in an adult is 16-20 times per minute, that is, about 600,000,000 breaths during a lifetime. At rest, in sleep, in the supine position, the respiratory rate decreases to 14-16 per minute. With physical activity, fast walking, running, on the contrary, it increases. The total volume of air that can be exhaled as much as possible after the deepest breath (vital capacity) is one of the indicators of a person's physical development. Normally, for men, it is 3.5-4 liters, and for women - 2.5-3 liters. Lessons physical education, breathing exercises increase the vital capacity of the lungs, which means they improve the supply of oxygen to the body. At the same time, the vital capacity of the lungs reaches 4.5-5 liters.

Each person must develop right rhythm breathing. Breathing exercises help with this. For example, take a deep breath first. The abdomen bulges forward as much as possible, the sides of the chest expand, the shoulders turn slightly, then after 5 seconds exhale - abdominal wall pulled inward. Gradually, the gap between inhalation and exhalation increases to 10 seconds or more. Such exercises are recommended to be carried out 2-3 times a day. Do breathing exercises you can sit, lie down or while walking (inhale - hold - exhale - hold; each element in four steps).

Now consider the process of gas exchange that occurs in the lungs during the respiratory act. Atmospheric air, saturated with oxygen, enters through the respiratory tract into the smallest branches of the bronchi. Oxygen molecules that have penetrated from the alveoli into the blood immediately bind to hemoglobin, which is in the red blood cells- erythrocytes, resulting in the formation of a new compound - oxyhemoglobin. In this form, oxygen is delivered to the tissues, where it is easily released to participate in tissue respiration. As soon as oxyhemoglobin is freed from oxygen, it immediately enters into contact with carbon dioxide. A new compound is formed, called carbohemoglobin. Since this compound is fragile, it quickly breaks down in the capillaries of the lungs, and the released carbon dioxide enters the alveolar air and then is removed into the atmosphere. Up to 600 ml of oxygen is delivered to tissues per minute, which enters into biochemical metabolic reactions.

Respiratory system. The respiratory system includes the lungs and the airways that carry air to and from the lungs.

The respiratory system includes the lungs and the airways that carry air to and from the lungs. The respiratory tract is represented by the nasal cavity, pharynx, larynx, trachea and bronchi. Air enters first into the nasal (oral) cavity, then into the nasopharynx, larynx and further into the trachea. The trachea is divided into two main bronchi - right and left, which, in turn, are divided into lobar and enter into lung tissue. In the lungs, each of the bronchi divides into smaller and smaller lobes, forming the bronchial tree. The final smallest branches of the bronchi (bronchioles) pass into closed alveolar passages, in the walls of which there are a large number of spherical formations - pulmonary vesicles (alveoli). Each alveolus is surrounded by a dense network blood capillaries. The structure of the pulmonary alveoli is quite complex and corresponds to their function - gas exchange (Fig. 2.3).

The breathing mechanism has a reflex (automatic) character. At rest, the exchange of air in the lungs occurs as a result of rhythmic respiratory movements of the chest. When you inhale, the volume of the lungs increases (the chest expands), the pressure in the lungs becomes lower than atmospheric pressure, and air enters the respiratory tract. At rest, the expansion of the chest is carried out by the diaphragm (a special respiratory muscle) and external intercostal muscles, and with intense physical work other skeletal muscles are included. During exhalation, the volume of the chest cavity decreases, the air in the lungs is compressed, the pressure in them becomes higher than atmospheric pressure, and the air from the lungs is pushed out. Exhale in calm state carried out passively due to the heaviness of the chest and relaxation of the diaphragm. Forced exhalation occurs due to contractions of the internal intercostal muscles, and, in part, due to the muscles of the shoulder girdle and abdominals.

Rice. 2.3. human oxygen transport pathway

The amount of air passing through the lungs during a quiet inhalation (exhalation) is the tidal volume (400-500 ml). The volume of air that can be inhaled (exhaled) after a normal inhalation (exhalation) is called the inspiratory (expiratory) reserve volume. Tidal volume (TO), inspiratory and expiratory reserve volumes constitute the vital capacity of the lungs (VC). VC depends on sex, age, body size and fitness. VC averages 2.5–4.0 liters in women, and 3.5–5.0 liters in men. Under the influence of training, VC increases, in well-trained athletes it reaches 8 liters.

The amount of air that a person inhales and exhales in one minute is called respiratory minute volume (MV). At rest, the MOD is 6-8 liters, with strenuous physical activity it can increase 20-25 times and reach 120-150 liters per minute. MOD is one of the main indicators of the external respiration apparatus.

In the process of gas exchange between the body and atmospheric air great importance has ventilation of the lungs, providing renewal of alveolar gas. The intensity of ventilation depends on the depth and frequency of breathing. The measure of lung ventilation is minute volume, defined as the product of tidal volume times the number of breaths (RR) per minute. For example, with a BH of 14 times / min, the MOD will be 7 liters: 500 ml (DO) x 14 times / min (BH) \u003d 7000 ml (MOD).

From a physiological point of view, the main indicator of the effectiveness of external respiration is not the MOD, but the part of it that reaches the alveoli - alveolar ventilation. The fact is that not all the inhaled air reaches the alveoli, where gas exchange occurs. Part of the inhaled air (150 ml) remains in the "dead" space (oral cavity, nose, pharynx, larynx, trachea and bronchi). Thus, with a MOD of 7 liters, alveolar ventilation (effective exchange) is about 5 liters (7000 - 150x14 times / min = 4900 ml).

The respiratory system is a set of organs and anatomical structures that ensure the movement of air from the atmosphere to the lungs and vice versa (breathing cycles inhalation - exhalation), as well as gas exchange between the air entering the lungs and blood.

Respiratory organs are the upper and lower respiratory tract and lungs, consisting of bronchioles and alveolar sacs, as well as arteries, capillaries and veins pulmonary circle circulation.

The respiratory system also includes the chest and respiratory muscles (the activity of which provides stretching of the lungs with the formation of inhalation and exhalation phases and a change in pressure in the pleural cavity), and in addition, the respiratory center located in the brain, peripheral nerves and receptors involved in the regulation of breathing .

The main function of the respiratory organs is to ensure gas exchange between air and blood by diffusion of oxygen and carbon dioxide through the walls of the pulmonary alveoli into the blood capillaries.

Diffusion- a process in which gas from an area of ​​more than high concentration tends to an area where its concentration is low.

A characteristic feature of the structure of the respiratory tract is the presence of a cartilaginous base in their walls, as a result of which they do not collapse.

In addition, the respiratory organs are involved in sound production, odor detection, the production of certain hormone-like substances, lipid and water-salt exchange in maintaining the body's immunity. In the airways, purification, moistening, warming of the inhaled air, as well as the perception of thermal and mechanical stimuli take place.

Airways

The airways of the respiratory system start from the external nose and nasal cavity. The nasal cavity is divided by an osteochondral septum into two parts: right and left. Inner surface cavity, lined with mucous membrane, equipped with cilia and permeated with blood vessels, covered with mucus, which traps (and partially renders harmless) microbes and dust. Thus, in the nasal cavity, the air is cleaned, neutralized, warmed and moistened. That is why it is necessary to breathe through the nose.

Throughout life nasal cavity holds up to 5 kg of dust

passed pharyngeal part airways, air enters next body larynx, which looks like a funnel and is formed by several cartilages: the thyroid cartilage protects the larynx from the front, the cartilaginous epiglottis closes the entrance to the larynx when food is swallowed. If you try to speak while swallowing food, it can get into the airways and cause suffocation.

When swallowing, the cartilage moves up, then returns to its original place. With this movement, the epiglottis closes the entrance to the larynx, saliva or food goes into the esophagus. What else is in the throat? Vocal cords. When a person is silent, the vocal cords diverge; when he speaks loudly, the vocal cords are closed; if he is forced to whisper, the vocal cords are ajar.

1. Trachea;
2. Aorta;
3. Main left bronchus;
4. Main right bronchus;
5. Alveolar ducts.

The length of the human trachea is about 10 cm, the diameter is about 2.5 cm

From the larynx, air enters the lungs through the trachea and bronchi. The trachea is formed by numerous cartilaginous semirings located one above the other and connected by muscle and connective tissue. The open ends of the half rings are adjacent to the esophagus. In the chest, the trachea divides into two main bronchi, from which the secondary bronchi branch off, continuing to branch further to the bronchioles (thin tubes about 1 mm in diameter). The branching of the bronchi is a rather complex network called the bronchial tree.

Bronchioles are divided into even thinner tubes - alveolar ducts, which end in small thin-walled (wall thickness - one cell) sacs - alveoli, collected in clusters like grapes.

Mouth breathing causes deformation of the chest, hearing impairment, disruption of the normal position of the nasal septum and the shape of the lower jaw

The lungs are the main organ of the respiratory system.

The most important functions of the lungs are gas exchange, the supply of oxygen to hemoglobin, the removal of carbon dioxide, or carbon dioxide, which is the end product of metabolism. However, lung functions are not limited to this alone.

The lungs are involved in maintaining a constant concentration of ions in the body, they can also remove other substances from it, except for toxins ( essential oils, aromatics, "alcohol plume", acetone, etc.). When breathing, water evaporates from the surface of the lungs, which leads to cooling of the blood and the whole body. In addition, the lungs create air currents vibrating the vocal cords of the larynx.

Conditionally, the lung can be divided into 3 sections:

1. air-bearing (bronchial tree), through which air, as through a system of channels, reaches the alveoli;
2. alveolar system in which gas exchange occurs;
3. circulatory system of the lung.

The volume of inhaled air in an adult is about 0 4-0.5 liters, and the vital capacity of the lungs, that is, the maximum volume, is about 7-8 times more - usually 3-4 liters (in women it is less than in men), although athletes can exceed 6 liters

1. Trachea;
2. Bronchi;
3. apex of the lung;
4. Upper lobe;
5. Horizontal slot;
6. Average share;
7. Oblique slit;
8. lower lobe;
9. Heart cutout.

The lungs (right and left) lie in the chest cavity on either side of the heart. The surface of the lungs is covered with a thin, moist, shiny membrane of the pleura (from the Greek pleura - rib, side), consisting of two sheets: the inner (pulmonary) covers lung surface, and the outer (parietal) - lines the inner surface of the chest. Between the sheets, which are almost in contact with each other, a hermetically closed slit-like space, called the pleural cavity, is preserved.

In some diseases (pneumonia, tuberculosis), the parietal pleura can grow together with the pulmonary leaf, forming so-called adhesions. In inflammatory diseases accompanied by excessive accumulation of fluid or air in the pleural space, it expands sharply, turns into a cavity

The pinwheel of the lung protrudes 2-3 cm above the clavicle, going into the lower region of the neck. The surface adjacent to the ribs is convex and has the greatest extent. The inner surface is concave, adjacent to the heart and other organs, convex and has the greatest length. The inner surface is concave, adjacent to the heart and other organs located between the pleural sacs. On it are the gates of the lung, a place through which the main bronchus and pulmonary artery enter the lung and two pulmonary veins exit.

Each lung is divided by pleural grooves into two lobes (upper and lower), right into three (upper, middle and lower).

The tissue of the lung is formed by bronchioles and many tiny pulmonary vesicles of the alveoli, which look like hemispherical protrusions of the bronchioles. The thinnest walls of the alveoli are a biologically permeable membrane (consisting of a single layer of epithelial cells surrounded by a dense network of blood capillaries), through which gas exchange occurs between the blood in the capillaries and the air filling the alveoli. From the inside, the alveoli are covered with a liquid surfactant, which weakens the forces of surface tension and prevents the alveoli from completely collapsing during exit.

Compared with the volume of the lungs of a newborn, by the age of 12, lung volume increases 10 times, by the end of puberty - 20 times

The total thickness of the walls of the alveoli and the capillary is only a few micrometers. Due to this, oxygen easily penetrates from the alveolar air into the blood, and carbon dioxide from the blood into the alveoli.

Respiratory process

Respiration is a complex process of gas exchange between the external environment and the body. Inhaled air differs significantly in its composition from exhaled air: oxygen, a necessary element for metabolism, enters the body from the external environment, and carbon dioxide is released outside.

Stages of the respiratory process

• filling the lungs with atmospheric air (pulmonary ventilation)
• the transfer of oxygen from the pulmonary alveoli into the blood flowing through the capillaries of the lungs, and the release from the blood into the alveoli, and then into the atmosphere of carbon dioxide
• delivery of oxygen from the blood to the tissues and carbon dioxide from the tissues to the lungs
• oxygen consumption by cells

The processes of air entering the lungs and gas exchange in the lungs are called pulmonary (external) respiration. The blood brings oxygen to the cells and tissues, and carbon dioxide from the tissues to the lungs. Constantly circulating between the lungs and tissues, blood thus provides a continuous process of supplying cells and tissues with oxygen and removing carbon dioxide. In the tissues, oxygen from the blood goes to the cells, and carbon dioxide is transferred from the tissues into the blood. This process of tissue respiration occurs with the participation of special respiratory enzymes.

The biological significance of respiration

• providing the body with oxygen
• removal of carbon dioxide
• oxidation of organic compounds with the release of energy, necessary for a person for life
• removal of metabolic end products (water vapor, ammonia, hydrogen sulfide, etc.)

Mechanism of inhalation and exhalation. Inhalation and exhalation occur due to the movements of the chest (thoracic breathing) and the diaphragm (abdominal type of breathing). The ribs of a relaxed chest go down, thereby reducing its internal volume. Air is forced out of the lungs, much like air being forced out of an air pillow or mattress. By contracting, the respiratory intercostal muscles raise the ribs. The chest expands. Situated between the chest and abdominal cavity the diaphragm contracts, its tubercles smooth out, and the volume of the chest increases. Both pleural sheets (pulmonary and costal pleura), between which there is no air, transmit this movement to the lungs. A vacuum develops in the lung tissue like that, which appears when the accordion is stretched. Air enters the lungs.

The respiratory rate in an adult is normally 14-20 breaths per 1 minute, but with significant physical exertion it can reach up to 80 breaths per 1 minute

When the respiratory muscles relax, the ribs return to their original position and the diaphragm loses tension. The lungs contract, releasing exhaled air. In this case, only a partial exchange occurs, because it is impossible to exhale all the air from the lungs.

With calm breathing, a person inhales and exhales about 500 cm 3 of air. This amount of air is the respiratory volume of the lungs. If you take an additional deep breath, then about 1500 cm 3 more air will enter the lungs, called the inspiratory reserve volume. After a calm exhalation, a person can exhale about 1500 cm 3 more air - the expiratory reserve volume. The amount of air (3500 cm 3), consisting of the tidal volume (500 cm 3), inspiratory reserve volume (1500 cm 3), expiratory reserve volume (1500 cm 3), is called the vital capacity of the lungs.

Of the 500 cm 3 of inhaled air, only 360 cm 3 pass into the alveoli and give oxygen to the blood. The remaining 140 cm 3 remain in the airways and do not participate in gas exchange. Therefore, the airways are called "dead space".

After a person exhales 500 cm 3 tidal volume), and then takes another deep breath (1500 cm 3), approximately 1200 cm 3 of residual air volume remains in his lungs, which is almost impossible to remove. Therefore, lung tissue does not sink in water.

Within 1 minute a person inhales and exhales 5-8 liters of air. This is the minute volume of breathing, which, with intensive physical activity can reach 80-120 l in 1 min.

In trained, physically developed people, the vital capacity of the lungs can be significantly greater and reach 7000-7500 cm 3. Women have less vital capacity than men

Gas exchange in the lungs and transport of gases in the blood

The blood that comes from the heart to the capillaries surrounding the pulmonary alveoli contains a lot of carbon dioxide. And in the pulmonary alveoli there is little of it, therefore, due to diffusion, it leaves the bloodstream and passes into the alveoli. This is also facilitated by the walls of the alveoli and capillaries, which are moist from the inside, consisting of only one layer of cells.

Oxygen enters the blood also through diffusion. There is little free oxygen in the blood, because hemoglobin in erythrocytes continuously binds it, turning into oxyhemoglobin. The arterial blood leaves the alveoli and travels through the pulmonary vein to the heart.

In order for gas exchange to take place continuously, it is necessary that the composition of gases in the pulmonary alveoli be constant, which is supported by pulmonary respiration: excess carbon dioxide is removed to the outside, and the oxygen absorbed by the blood is replaced by oxygen from a fresh portion of the outside air.

tissue respiration occurs in the capillaries of the systemic circulation, where the blood gives off oxygen and receives carbon dioxide. There is little oxygen in the tissues, and therefore oxyhemoglobin is decomposed into hemoglobin and oxygen, which passes into the tissue fluid and is used there by cells for the biological oxidation of organic substances. The energy released in this case is intended for the vital processes of cells and tissues.

A lot of carbon dioxide accumulates in the tissues. It enters the tissue fluid, and from it into the blood. Here, carbon dioxide is partially captured by hemoglobin, and partially dissolved or chemically bound by blood plasma salts. Deoxygenated blood takes him to right atrium, from there it enters the right ventricle, which pushes out through the pulmonary artery venous circle closes. In the lungs, the blood becomes arterial again and, returning to the left atrium, enters the left ventricle, and from it into big circle circulation.

The more oxygen is consumed in the tissues, the more oxygen is required from the air to compensate for the costs. That is why during physical work, both cardiac activity and pulmonary respiration are simultaneously enhanced.

Thanks to amazing property hemoglobin to combine with oxygen and carbon dioxide, the blood is able to absorb these gases in a significant amount

In 100 ml arterial blood contains up to 20 ml of oxygen and 52 ml of carbon dioxide

Action carbon monoxide on the body. The hemoglobin of erythrocytes is able to combine with other gases. So, with carbon monoxide (CO) - carbon monoxide, formed during incomplete combustion of fuel, hemoglobin combines 150 - 300 times faster and stronger than with oxygen. Therefore, even with a small amount of carbon monoxide in the air, hemoglobin does not combine with oxygen, but with carbon monoxide. In this case, the supply of oxygen to the body stops, and the person begins to suffocate.

If there is carbon monoxide in the room, a person suffocates, because oxygen does not enter the tissues of the body

Oxygen starvation - hypoxia- can also occur with a decrease in the hemoglobin content in the blood (with significant blood loss), with a lack of oxygen in the air (high in the mountains).

When a foreign body enters the respiratory tract, with swelling of the vocal cords due to the disease, respiratory arrest may occur. Asphyxiation develops - asphyxia. When breathing stops, artificial respiration is performed using special devices, and in their absence, according to the mouth-to-mouth, mouth-to-nose method or special techniques.

Breathing regulation. Rhythmic, automatic alternation of inhalations and exhalations is regulated from the respiratory center located in the medulla oblongata. From this center, impulses: come to the motor neurons of the vagus and intercostal nerves that innervate the diaphragm and other respiratory muscles. The work of the respiratory center is coordinated by the higher parts of the brain. Therefore, a person can a short time hold or intensify breathing, as happens, for example, when talking.

The depth and frequency of breathing is affected by the content of CO 2 and O 2 in the blood. These substances irritate chemoreceptors in the walls of large blood vessels, nerve impulses from them enter the respiratory center. With an increase in the content of CO 2 in the blood, breathing deepens, with a decrease in 0 2, breathing becomes more frequent.