What is the name of the respiratory system? Sections of the respiratory system, structural features

We inhale air from the atmosphere; The body exchanges oxygen and carbon dioxide, after which the air is exhaled. This process is repeated many thousands of times per day; it is vital to every single cell, tissue, organ and organ system.

The respiratory system can be divided into two main sections: the upper and lower respiratory tract.

• Upper respiratory tract:

1. Sinuses
2. Pharynx
3. Larynx

• Lower respiratory tract:

1. Trachea
2. Bronchi
3. Lungs

• The ribcage protects the lower respiratory tract:

1. 12 pairs of ribs forming a cage-like structure
2. 12 thoracic vertebrae to which the ribs are attached
3. The sternum, to which the ribs are attached at the front

Structure of the upper respiratory tract

Nose

The nose is the main channel through which air enters and exits the body.

The nose consists of:

• The nasal bone that forms the bridge of the nose.
• The nasal concha, from which the lateral wings of the nose are formed.
• The tip of the nose is formed by flexible septal cartilage.

The nostrils are two separate openings leading into the nasal cavity, separated by a thin cartilaginous wall - the septum. The nasal cavity is lined with ciliated mucous membrane, consisting of cells that have cilia that work like a filter. The cuboid cells produce mucus, which traps all foreign particles that enter the nose.

Sinuses

Sinuses are air-filled cavities in the frontal, ethmoid, sphenoid bones And lower jaw opening into the nasal cavity. The sinuses are lined with mucous membrane, just like the nasal cavity. Mucus retention in the sinuses can cause headaches.

Pharynx

The nasal cavity passes to the pharynx ( rear end throat), also covered with mucous membrane. The pharynx is formed by muscle and fibrous tissue, and it can be divided into three sections:

1. The nasopharynx, or nasal section of the pharynx, provides air flow when we breathe through our nose. It is connected to both ears by channels - the Eustachian (auditory) tubes - containing mucus. Through the eustachian tubes, throat infections can easily spread to the ears. The adenoids are located in this section of the larynx. They are composed of lymphatic tissue and perform immune function, filtering out harmful air particles.
2. The oropharynx, or oral part of the pharynx, is the passageway for air inhaled by the mouth and food. It contains tonsils, which, like adenoids, have a protective function.
3. The laryngopharynx serves as a passage for food before it enters the esophagus, which is the first part digestive tract and leads to the stomach.

Larynx

The pharynx passes into the larynx (upper throat), through which air flows further. Here he continues to cleanse himself. The larynx contains cartilage that forms the vocal folds. The cartilage also forms the lid-like epiglottis, which hangs over the entrance to the larynx. The epiglottis prevents food from entering the airways when swallowing.

Structure of the lower respiratory tract

Trachea

The trachea begins after the larynx and extends down to chest. Here, air filtration by the mucous membrane continues. The trachea is formed in front by C-shaped hyaline cartilages, connected behind in circles by visceral muscles and connective tissue. These semi-solid structures prevent the trachea from constricting and blocking the air flow. The trachea descends into the chest approximately 12 cm and there diverges into two sections - the right and left bronchi.

Bronchi

The bronchi are pathways similar in structure to the trachea. Through them, air enters the right and left lungs. The left bronchus is narrower and shorter than the right and divides into two parts at the entrance to the two lobes of the left lung. The right bronchus is divided into three parts, since right lung three beats. The mucous membrane of the bronchi continues to purify the air passing through them.

Lungs

The lungs are soft, spongy oval structures located in the chest on either side of the heart. The lungs are connected to the bronchi, which diverge before entering the lobes of the lungs.

In the lobes of the lungs, the bronchi branch further, forming small tubes - bronchioles. The bronchioles have lost their cartilaginous structure and are made up of only smooth tissue, making them soft. The bronchioles end in alveoli, small air sacs that are supplied with blood through a network of small capillaries. In the blood of the alveoli vital important process exchange of oxygen and carbon dioxide.

On the outside, the lungs are covered with a protective membrane, the pleura, which has two layers:

• Smooth inner layer, attached to the lungs.
• Wall outer layer connected to fins and diaphragm.

The smooth and parietal layers of the pleura are separated by the pleural cavity, which contains a liquid lubricant that allows movement between the two layers and breathing.

Functions of the respiratory system

Respiration is the process of exchanging oxygen and carbon dioxide. Oxygen is inhaled, transported blood cells, to nutrients from digestive system could have been oxidized, i.e. broken down, adenosine triphosphate was produced in the muscles and a certain amount of energy was released. All cells in the body need a constant supply of oxygen to keep them alive. Carbon dioxide is formed during the absorption of oxygen. This substance must be removed from the cells in the blood, which transports it to the lungs and it is exhaled. We can live without food for several weeks, without water for several days, and without oxygen for only a few minutes!

The breathing process involves five actions: inhalation and exhalation, external respiration, transport, internal respiration and cellular respiration.

Breath

Air enters the body through the nose or mouth.

Breathing through the nose is more effective because:

• The air is filtered by cilia, clearing foreign particles. They are thrown back when we sneeze or blow our nose, or enter the hypopharynx and are swallowed.
• As the air passes through the nose, it is heated.
• The air is humidified with water from mucus.
• Sensory nerves sense the smell and report it to the brain.

Breathing can be defined as the movement of air into and out of the lungs as a result of inhalation and exhalation.

Inhale:

• The diaphragm contracts, pushing the abdominal cavity downward.
• The intercostal muscles contract.
• The ribs rise and expand.
• The chest cavity increases.
• The pressure in the lungs decreases.
• Air pressure increases.
• Air fills the lungs.
• The lungs expand as they fill with air.

Exhalation:

• The diaphragm relaxes and returns to its dome shape.
• The intercostal muscles relax.
• The ribs return to their original position.
• The chest cavity returns to its normal shape.
• The pressure in the lungs increases.
• Air pressure decreases.
• Air may escape from the lungs.
• The elastic traction of the lung helps displace air.
• Contraction of the abdominal muscles increases exhalation, lifting the abdominal organs.

After exhalation, there is a short pause before a new inhalation, when the pressure in the lungs is the same as the air pressure outside the body. This state is called equilibrium.

Breathing is controlled nervous system and occurs without conscious effort. The breathing rate changes depending on the state of the body. For example, if we need to run to catch the bus, it increases, providing the muscles with enough oxygen to complete this task. After we board the bus, our breathing rate decreases because our muscles' need for oxygen decreases.

External breathing

The exchange of oxygen from the air and carbon dioxide occurs in the blood in the alveoli of the lungs. This exchange of gases is possible due to the difference in pressure and concentration in the alveoli and capillaries.

• The air entering the alveoli has greater pressure than the blood in the surrounding capillaries. Because of this, oxygen can easily pass into the blood, increasing blood pressure. When the pressure equalizes, this process, called diffusion, stops.
• Carbon dioxide in the blood, brought from the cells, has a higher pressure than the air in the alveoli, in which its concentration is lower. As a result, carbon dioxide contained in the blood can easily penetrate from the capillaries into the alveoli, raising the pressure in them.

Transportation

Transportation of oxygen and carbon dioxide is carried out through the pulmonary circulation:

• After gas exchange in the alveoli, the blood carries oxygen to the heart through the veins of the pulmonary circulation, from where it is distributed throughout the body and consumed by cells that release carbon dioxide.
• After this, the blood carries carbon dioxide to the heart, from where it enters the lungs through the arteries of the pulmonary circulation and is removed from the body with exhaled air.

Internal breathing

Transportation ensures the supply of oxygen-enriched blood to the cells in which gas exchange occurs by diffusion:

• The oxygen pressure in the brought blood is higher than in the cells, so oxygen easily penetrates them.
• The pressure in the blood coming from the cells is less, which allows carbon dioxide to enter it.

Oxygen is replaced by carbon dioxide, and the whole cycle begins again.

Cellular respiration

Cellular respiration is the absorption of oxygen by cells and the production of carbon dioxide. Cells use oxygen to produce energy. During this process, carbon dioxide is released.

It is important to understand that the breathing process is decisive for each individual cell, and the frequency and depth of breathing must correspond to the needs of the body. Although breathing is controlled by the autonomic nervous system, certain factors such as stress and poor posture can affect the respiratory system, reducing breathing efficiency. This, in turn, affects the functioning of cells, tissues, organs and systems of the body.

During the procedures, the therapist must monitor both his own breathing and the breathing of the patient. The therapist's breathing quickens with increasing physical activity, and the client's breathing calms down as they relax.

Possible violations

Possible violations respiratory system from A to Z:

• ADENOIDS enlarged - can block the entrance to auditory tube and/or passage of air from the nose to the throat.
• ASTHMA - difficulty breathing due to narrow passageways for air. May be caused by external factors - acquired bronchial asthma, or internal - hereditary bronchial asthma.
• BRONCHITIS - inflammation of the lining of the bronchi.
• HYPERVENTILATION - rapid, deep breathing, usually associated with stress.
• INFECTIOUS MONONUCLEOSIS is a viral infection that is most susceptible to the age group from 15 to 22 years. Symptoms include persistent sore throat and/or tonsillitis.
• croup is a childhood viral infection. Symptoms are fever and severe dry cough.
• LARINGITIS - inflammation of the larynx, causing hoarseness and/or loss of voice. There are two types: acute, which develops quickly and passes quickly, and chronic, which recurs periodically.
• NASAL POLYP is a harmless growth of mucous membrane in the nasal cavity that contains fluid and obstructs the passage of air.
• ARI is a contagious viral infection, the symptoms of which are a sore throat and runny nose. Usually lasts 2-7 days, full recovery may take up to 3 weeks.
• PLEURITIS - inflammation of the pleura surrounding the lungs, usually occurring as a complication of other diseases.
• PNEUMONIA - inflammation of the lungs as a result of a bacterial or viral infection, manifested as chest pain, dry cough, fever, etc. Bacterial pneumonia takes longer to treat.
• PNEUMOTHORAX - collapsed lung (possibly as a result of a ruptured lung).
• HAYLINOSIS is a disease caused by allergic reaction on pollen. Affects the nose, eyes, sinuses: pollen irritates these areas, causing a runny nose, eye inflammation and excess mucus production. The respiratory tract may also be affected, then breathing becomes difficult, with whistling.
• LUNG CANCER is a life-threatening malignant tumor of the lungs.
• Cleft Palate - deformation of the palate. Often occurs simultaneously with cleft lip.
• RINITIS - inflammation of the mucous membrane of the nasal cavity, which causes a runny nose. The nose may be stuffy.
• SINUSITIS - inflammation of the mucous membrane of the sinuses, causing blockage. Can be very painful and cause inflammation.
• STRESS is a condition that causes the autonomous system to increase the release of adrenaline. This causes rapid breathing.
• TONSILLITIS - inflammation of the tonsils, painful in the throat. Occurs more often in children.
• TUBERCULOSIS - infection, causing the formation of nodular thickenings in tissues, most often in the lungs. Vaccination is possible. PHARYNGITIS - inflammation of the pharynx, manifested as a sore throat. May be acute or chronic. Acute pharyngitis very common, goes away in about a week. Chronic pharyngitis lasts longer, typical for smokers. EMPHYSEMA - inflammation of the alveoli of the lungs, causing a slowdown in the flow of blood through the lungs. Usually accompanies bronchitis and/or occurs in old age. The respiratory system plays a vital role in the body.

Knowledge

You should make sure you are breathing correctly, otherwise it can cause a number of problems.

These include: muscle cramps, headaches, depression, anxiety, chest pain, fatigue, etc. To avoid these problems, you need to know how to breathe correctly.

The following types of breathing exist:

• Lateral costal breathing is normal breathing, in which the lungs receive enough oxygen for daily needs. This type of breathing is associated with the aerobic energy system, with air filling two upper lobes lungs.
• Apical - shallow and rapid breathing, which is used to get the maximum amount of oxygen to the muscles. Such cases include sports, childbirth, stress, fear, etc. This type of respiration is associated with the anaerobic energy system and leads to oxygen debt and muscle fatigue, if energy requirements exceed oxygen consumption. Air enters only the upper lobes of the lungs.
• Diaphragmatic - deep breathing associated with relaxation, which replenishes any oxygen debt resulting from apical breathing. With it, the lungs can be completely filled with air.

Correct breathing can be learned. Practices such as yoga and tai chi place a lot of emphasis on breathing techniques.

Whenever possible, breathing techniques should accompany procedures and therapy, as they are beneficial for both therapist and patient, clearing the mind and energizing the body.

• Begin the procedure with a deep breathing exercise to relieve the patient's stress and tension and prepare him for therapy.
• End of the procedure breathing exercise will allow the patient to see the connection between breathing and stress levels.

Breathing is underestimated and taken for granted. However, special care must be taken to ensure that the respiratory system can perform its functions freely and effectively and does not experience stress and discomfort, which cannot be avoided.

a set of processes that ensure the supply of oxygen to the body and its use in biological oxidation organic matter and removal from the body of carbon dioxide formed during the metabolic process. As a result of biological oxidation in cells, energy is released for the life of the body.

Respiratory system -

The nasal cavity, pharynx, larynx, trachea, bronchi and lungs provide air circulation and gas exchange.

Execute function gas exchange, delivery of oxygen to the body and removal of carbon dioxide from it.

The airways include the nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles and lungs. In the upper respiratory tract, the air is warmed, cleared of various particles and moistened. Gas exchange occurs in the alveoli of the lungs. In the nasal cavity, which is lined with mucous membrane and covered with ciliated epithelium, mucus is secreted. It humidifies the inhaled air and envelops solid particles. The mucous membrane warms the air, because it is abundantly supplied with blood vessels. Air enters the nasopharynx through the nasal passages and then into the larynx.

Larynx

performs two functions - respiratory and voice formation. The complexity of its structure is associated with the formation of the voice. In the larynx are vocal cords, consisting of elastic fibers of connective tissue. Sound occurs as a result of vibration vocal cords. The larynx takes part only in the formation of sound. Articulate speech involves the lips, tongue, soft palate, and paranasal sinuses. The larynx changes with age. Its growth and function are associated with the development of the gonads. The size of the larynx in boys increases during puberty. The voice changes (mutates). From the larynx air enters trachea.

Trachea –

tube, 10-11 cm long, consisting of 16–20 cartilaginous rings, not closed at the back. The rings are connected by ligaments. The posterior wall of the trachea is formed by dense fibrous connective tissue. Food bolus, passing through the esophagus adjacent to the posterior wall of the trachea, does not experience resistance from it.

The trachea is divided into two elastic main bronchi. The main bronchi branch into smaller bronchi - bronchioles. The bronchi and brochioles are lined with ciliated epithelium. Bronchioles lead to the lungs.

Lungs –

paired organs located in chest cavity. The lungs consist of pulmonary vesicles - alveoli. The wall of the alveoli is formed by a single-layer epithelium and is intertwined with a network of capillaries into which atmospheric air enters. Between the outer layer of the lung and the chest there is pleural cavity, filled with a small amount of fluid that reduces friction when the lungs move. It is formed by two layers of pleura, one of which covers the lung, and the other lines the inside of the chest. Pressure in pleural cavity less than atmospheric and is about 751 mm Hg. Art. When inhaling The chest cavity expands, the diaphragm descends, and the lungs stretch. When exhaling the volume of the chest cavity decreases, the diaphragm relaxes and rises. The external intercostal muscles, diaphragm muscles, and internal intercostal muscles are involved in respiratory movements. With increased breathing, all the muscles of the chest, the levator ribs and sternum, and the muscles of the abdominal wall are involved.

Breathing movements controlled by the respiratory center of the medulla oblongata. The center has inspiratory sections And exhalation. From the center of inspiration, impulses travel to the respiratory muscles. Inhalation occurs. From the respiratory muscles, impulses enter the respiratory center via the vagus nerve and inhibit the inhalation center. Exhalation occurs. The activity of the respiratory center is influenced by the level blood pressure, temperature, pain and other irritants. Humoral regulation occurs when the concentration of carbon dioxide in the blood changes. Its increase stimulates the respiratory center and causes faster and deeper breathing. The ability to voluntarily hold your breath for some time is explained by the controlling influence of the cerebral cortex on the breathing process.

Gas exchange in the lungs and tissues occurs by diffusion of gases from one medium to another. The oxygen pressure in atmospheric air is higher than in alveolar air, and it diffuses into the alveoli. From the alveoli, for the same reasons, oxygen penetrates into the venous blood, saturating it, and from the blood into the tissues.

The pressure of carbon dioxide in tissues is higher than in the blood, and in the alveolar air is higher than in atmospheric air. Therefore, it diffuses from tissues into the blood, then into the alveoli and into the atmosphere.

Oxygen is transported to tissues as part of oxyhemoglobin. A small portion of carbon dioxide is transported from tissues to the lungs by carbohemoglobin. Most of it forms carbon dioxide with water, which in turn forms potassium and sodium bicarbonates. In their composition, carbon dioxide is transferred to the lungs.

Thematic assignments

A1. Gas exchange between blood and atmospheric air

happens in

1) alveoli of the lungs

2) bronchioles

4) pleural cavity

A2. Breathing is a process:

1) obtaining energy from organic compounds with the participation of oxygen

2) energy absorption during the synthesis of organic compounds

3) the formation of oxygen during chemical reactions

4) simultaneous synthesis and decomposition of organic compounds.

A3. The respiratory organ is not:

1) larynx

3) oral cavity

A4. One of the functions of the nasal cavity is:

1) retention of microorganisms

2) enrichment of blood with oxygen

3) air cooling

4) air dehumidification

A5. The larynx protects from food getting into it:

1) arytenoid cartilage

3) epiglottis

4) thyroid cartilage

A6. The respiratory surface of the lungs increases

2) bronchioles

3) eyelashes

4) alveoli

A7. Oxygen enters the alveoli and from them into the blood by

1) diffusion from an area with lower gas concentration to an area with higher concentration

2) diffusion from an area with a higher gas concentration to an area with a lower concentration

3) diffusion from body tissues

4) under the influence of nervous regulation

A8. A wound that breaks the tightness of the pleural cavity will lead to

1) inhibition of the respiratory center

2) restriction of lung movement

3) excess oxygen in the blood

4) excessive lung mobility

A9. The cause of tissue gas exchange is

1) the difference in the amount of hemoglobin in the blood and tissues

2) the difference in concentrations of oxygen and carbon dioxide in the blood and tissues

3) different rates of transition of oxygen and carbon dioxide molecules from one environment to another

4) difference in air pressure in the lungs and pleural cavity

IN 1. Select the processes occurring during gas exchange in the lungs

1) diffusion of oxygen from blood into tissues

2) formation of carboxyhemoglobin

3) formation of oxyhemoglobin

4) diffusion of carbon dioxide from cells into the blood

5) diffusion of atmospheric oxygen into the blood

6) diffusion of carbon dioxide into the atmosphere

AT 2. Establish the correct sequence of passage of atmospheric air through the respiratory tract

A) larynx

B) bronchi

D) bronchioles

B) nasopharynx

D) lungs

Breathing called a set of physiological and physical chemical processes, ensuring the body’s consumption of oxygen, the formation and elimination of carbon dioxide, and the production of energy used for life through the aerobic oxidation of organic substances.

Breathing is carried out respiratory system, represented by the respiratory tract, lungs, respiratory muscles, nerve structures that control functions, as well as blood and cardiovascular system transporting oxygen and carbon dioxide.

Airways divided into upper (nasal cavities, nasopharynx, oropharynx) and lower (larynx, trachea, extra- and intrapulmonary bronchi).

To maintain the vital functions of an adult, the respiratory system must deliver about 250-280 ml of oxygen per minute to the body under conditions of relative rest and remove approximately the same amount of carbon dioxide from the body.

Through the respiratory system, the body is constantly in contact with atmospheric air - the external environment, which may contain microorganisms, viruses, and harmful substances chemical nature. They are all capable by airborne droplets enter the lungs, penetrate the airborne barrier into the human body and cause the development of many diseases. Some of them are fast-spreading - epidemic (influenza, acute respiratory viral infections, tuberculosis, etc.).

Rice. Airway diagram

Air pollution poses a major threat to human health chemicals technogenic origin (harmful industries, vehicles).

Knowledge about these pathways of impact on human health contributes to the adoption of legislative, anti-epidemic and other measures to protect against the effects of harmful factors atmosphere and preventing its pollution. This is possible subject to medical workers extensive explanatory work among the population, including the development of a number of simple rules of behavior. Among them are the prevention of environmental pollution, compliance with basic rules of behavior during infections, which must be vaccinated from early childhood.

A number of respiratory physiology problems are associated with specific types human activity: space and high-altitude flights, staying in the mountains, scuba diving, using pressure chambers, staying in an atmosphere containing toxic substances and an excessive amount of dust particles.

Functions of the respiratory tract

One of the most important functions of the respiratory tract is to ensure that air from the atmosphere enters the alveoli and is removed from the lungs. The air in the respiratory tract is conditioned, being purified, warmed and humidified.

Air purification. The air is especially actively cleared of dust particles in the upper respiratory tract. Up to 90% of the dust particles contained in the inhaled air settle on their mucous membrane. The smaller the particle, the more likely all penetration into the lower respiratory tract. Thus, particles with a diameter of 3-10 microns can reach bronchioles, and particles with a diameter of 1-3 microns can reach alveoli. Removal of settled dust particles is carried out due to the flow of mucus in the respiratory tract. The mucus covering the epithelium is formed from the secretion of goblet cells and mucus-producing glands of the respiratory tract, as well as fluid filtered from the interstitium and blood capillaries of the walls of the bronchi and lungs.

The thickness of the mucus layer is 5-7 microns. Its movement is created by the beating (3-14 movements per second) of the cilia of the ciliated epithelium, which covers all the respiratory tract with the exception of the epiglottis and true vocal cords. The efficiency of the cilia is achieved only when they beat synchronously. This wave-like movement will create a flow of mucus in the direction from the bronchi to the larynx. From the nasal cavities, mucus moves towards the nasal openings, and from the nasopharynx towards the pharynx. U healthy person per day, about 100 ml of mucus is formed in the lower respiratory tract (part of it is absorbed by epithelial cells) and 100-500 ml in the upper respiratory tract. With synchronous beating of the cilia, the speed of mucus movement in the trachea can reach 20 mm/min, and in small bronchi and bronchioles it is 0.5-1.0 mm/min. Particles weighing up to 12 mg can be transported with the mucus layer. The mechanism for expelling mucus from the respiratory tract is sometimes called mucociliary escalator(from lat. mucus- slime, ciliare- eyelash).

The volume of mucus expelled (clearance) depends on the rate of mucus formation, viscosity and efficiency of the cilia. The beating of the cilia of the ciliated epithelium occurs only with sufficient formation of ATP in it and depends on the temperature and pH of the environment, humidity and ionization of the inhaled air. Many factors can limit mucus clearance.

So. at congenital disease— cystic fibrosis, caused by a mutation of the gene that controls the synthesis and structure of the protein involved in the transport of mineral ions through the cell membranes of the secretory epithelium, increases the viscosity of mucus and makes it difficult for it to be evacuated from the respiratory tract by cilia. Fibroblasts from the lungs of patients with cystic fibrosis produce ciliary factor, which disrupts the functioning of epithelial cilia. This leads to impaired ventilation of the lungs, damage and infection of the bronchi. Similar changes in secretion may occur in gastrointestinal tract, pancreas. Children with cystic fibrosis need constant intensive care medical care. Disruption of the beating processes of cilia, damage to the epithelium of the respiratory tract and lungs, followed by the development of a number of other unfavorable changes in the bronchopulmonary system, is observed under the influence of smoking.

Warming the air. This process occurs due to the contact of inhaled air with the warm surface of the respiratory tract. The effectiveness of warming is such that even when a person inhales frosty atmospheric air, it heats up when entering the alveoli to a temperature of about 37 ° C. The air removed from the lungs gives up to 30% of its heat to the mucous membranes of the upper respiratory tract.

Air humidification. Passing through the respiratory tract and alveoli, the air is 100% saturated with water vapor. As a result, the water vapor pressure in the alveolar air is about 47 mmHg. Art.

Due to the mixing of atmospheric and exhaled air, which has different contents of oxygen and carbon dioxide, “ buffer space» between the atmosphere and the gas exchange surface of the lungs. It helps maintain the relative constancy of the composition of alveolar air, which differs from atmospheric air more low content oxygen and higher levels of carbon dioxide.

The airways are reflexogenic zones of numerous reflexes that play a role in the self-regulation of breathing: the Hering-Breuer reflex, the protective reflexes of sneezing, coughing, the “diver” reflex, and also affecting the work of many internal organs(heart, blood vessels, intestines). The mechanisms of a number of these reflexes will be discussed below.

The respiratory tract is involved in generating sounds and giving them a certain color. Sound is produced when air passes through the glottis, causing the vocal cords to vibrate. For vibration to occur, there must be an air pressure gradient between the outside and internal sides vocal cords. IN natural conditions such a gradient is created during exhalation, when the vocal cords close when speaking or singing, and the subglottic air pressure, due to the action of factors that ensure exhalation, becomes greater than atmospheric pressure. Under the influence of this pressure, the vocal cords shift for a moment, a gap is formed between them, through which about 2 ml of air breaks through, then the cords close again and the process repeats again, i.e. vibration of the vocal cords occurs, generating sound waves. These waves create the tonal basis for the formation of singing and speech sounds.

The use of breathing to form speech and sing is called respectively speech And singing breath. The presence and normal position of teeth are a necessary condition correct and clear pronunciation of speech sounds. Otherwise, vagueness, lisp, and sometimes the inability to pronounce individual sounds appear. Speech and singing breathing constitute a separate subject of study.

About 500 ml of water evaporates through the respiratory tract and lungs per day, and thus they participate in the regulation of water-salt balance and body temperature. The evaporation of 1 g of water consumes 0.58 kcal of heat and this is one of the ways the respiratory system participates in heat transfer mechanisms. Under resting conditions, up to 25% of water and about 15% of the produced heat are removed from the body per day due to evaporation through the respiratory tract.

The protective function of the respiratory tract is realized through a combination of air conditioning mechanisms, protective reflex reactions and the presence of an epithelial lining covered with mucus. Mucus and ciliated epithelium with secretory, neuroendocrine, receptor, and lymphoid cells included in its layer create the morphofunctional basis of the airway barrier of the respiratory tract. This barrier, due to the presence of lysozyme, interferon, some immunoglobulins and leukocyte antibodies in the mucus, is part of the local immune system of the respiratory system.

The length of the trachea is 9-11 cm, the internal diameter is 15-22 mm. The trachea branches into two main bronchi. The right one is wider (12-22 mm) and shorter than the left one, and extends from the trachea at a large angle (from 15 to 40°). The bronchi branch, as a rule, dichotomously and their diameter gradually decreases, and the total lumen increases. As a result of the 16th branching of the bronchi, terminal bronchioles are formed whose diameter is 0.5-0.6 mm. This is followed by the structures that form the morphofunctional gas exchange unit of the lung - acini. The capacity of the airways to the level of the acini is 140-260 ml.

The walls of small bronchi and bronchioles contain smooth myocytes, which are located in them circularly. The lumen of this part of the airways and the speed of air flow depend on the degree of tonic contraction of myocytes. Regulation of the speed of air flow through the respiratory tract is carried out mainly in their lower sections, where the lumen of the airways can change actively. Myocyte tone is under the control of neurotransmitters of the autonomic nervous system, leukotrienes, prostaglandins, cytokines and other signaling molecules.

Receptors of the respiratory tract and lungs

An important role in the regulation of breathing is played by receptors, which are especially abundantly supplied in the upper respiratory tract and lungs. In the mucous membrane of the upper nasal passages, between the epithelial and supporting cells there are olfactory receptors. They are sensitive nerve cells having movable cilia that provide the reception of odorous substances. Thanks to these receptors and the olfactory system, the body is able to perceive the odors of substances contained in environment, the presence of nutrients, harmful agents. Exposure to certain odorous substances causes a reflex change in the patency of the respiratory tract and, in particular, in people with obstructive bronchitis may cause an asthma attack.

The remaining receptors of the respiratory tract and lungs are divided into three groups:

• sprains;
• irritant;
• juxtaalveolar.

Stretch receptors located in the muscular layer of the respiratory tract. An adequate stimulus for them is stretching. muscle fibers, caused by changes in intrapleural pressure and pressure in the lumen of the respiratory tract. The most important function of these receptors is to control the degree of stretching of the lungs. Thanks to them functional system breathing regulation controls the intensity of ventilation of the lungs.

There is also a number of experimental data on the presence of collapse receptors in the lungs, which are activated when there is a strong decrease in lung volume.

Irritant receptors have the properties of mechano- and chemoreceptors. They are located in the mucous membrane of the respiratory tract and are activated by the action of an intense stream of air during inhalation or exhalation, the action of large dust particles, the accumulation of purulent discharge, mucus, and the entry of food particles into the respiratory tract. These receptors are also sensitive to the action of irritating gases (ammonia, sulfur vapor) and other chemicals.

Juxtaalveolar receptors located in the intestinal space of the pulmonary alveoli near the walls of the blood capillaries. An adequate stimulus for them is an increase in blood filling of the lungs and an increase in volume intercellular fluid(they are activated, in particular, during pulmonary edema). Irritation of these receptors reflexively causes frequent shallow breathing.

Reflex reactions from respiratory tract receptors

When stretch receptors and irritant receptors are activated, numerous reflex reactions occur that provide self-regulation of breathing, protective reflexes and reflexes that affect the functions of internal organs. This division of these reflexes is very arbitrary, since the same stimulus, depending on its strength, can either provide regulation of the change in phases of the quiet breathing cycle, or cause defensive reaction. The afferent and efferent pathways of these reflexes pass in the trunks of the olfactory, trigeminal, facial, glossopharyngeal, vagus and sympathetic nerves, and the closure of most reflex arcs is carried out in the structures of the respiratory center of the medulla oblongata with the connection of the nuclei of the above nerves.

Self-regulation reflexes of breathing ensure regulation of the depth and frequency of breathing, as well as the lumen of the airways. Among them are the Hering-Breuer reflexes. Hering-Breuer inspiratory inhibitory reflex manifests itself in the fact that when the lungs are stretched during a deep breath or when air is blown in by artificial respiration devices, inhalation is reflexively inhibited and exhalation is stimulated. With strong stretching of the lungs, this reflex acquires a protective role, protecting the lungs from overstretching. The second of this series of reflexes is expiratory facilitation reflex - manifests itself in conditions when air enters the respiratory tract under pressure during exhalation (for example, with artificial respiration). In response to such an effect, exhalation is reflexively prolonged and the appearance of inhalation is inhibited. Lung collapse reflex occurs with the deepest possible exhalation or with chest injuries accompanied by pneumothorax. It is manifested by frequent shallow breathing, which prevents further collapse of the lungs. Also distinguished Head's paradoxical reflex manifested by the fact that with intensive blowing of air into the lungs for a short time (0.1-0.2 s), inhalation can be activated, which is then replaced by exhalation.

Among the reflexes that regulate the lumen of the respiratory tract and the force of contraction of the respiratory muscles, there is reflex to decrease pressure in the upper respiratory tract, which is manifested by contraction of the muscles that expand these airways and prevent them from closing. In response to a decrease in pressure in the nasal passages and pharynx, the muscles of the wings of the nose, the genioglossus and other muscles reflexively contract, displacing the tongue ventrally anteriorly. This reflex promotes inhalation by reducing resistance and increasing the upper airway's patency for air.

A decrease in air pressure in the lumen of the pharynx also reflexively causes a decrease in the force of contraction of the diaphragm. This pharyngeal-phrenic reflex prevents further decrease in pressure in the pharynx, sticking of its walls and the development of apnea.

Glottis closure reflex occurs in response to irritation of the mechanoreceptors of the pharynx, larynx and root of the tongue. This closes the vocal and supraglottic cords and prevents food, liquids and irritating gases from entering the inhalation tract. In patients who are in unconscious or under anesthesia, the reflex closure of the glottis is impaired and vomit, as well as pharyngeal contents, can enter the trachea and cause aspiration pneumonia.

Rhinobronchial reflexes arise from irritation of the irritant receptors of the nasal passages and nasopharynx and are manifested by a narrowing of the lumen of the lower respiratory tract. In people prone to spasms of smooth muscle fibers of the trachea and bronchi, irritation of the irritant receptors of the nose and even certain odors can provoke the development of an attack of bronchial asthma.

To the classics protective reflexes The respiratory system also includes the cough, sneeze and diver reflexes. Cough reflex caused by irritation of the irritant receptors of the pharynx and underlying respiratory tract, especially the tracheal bifurcation area. When it is implemented, a short inhalation occurs first, then the vocal cords close, the expiratory muscles contract, and the subglottic air pressure increases. Then the vocal cords instantly relax and the air stream passes through the airways, glottis and open mouth into the atmosphere at high linear speed. At the same time, excess mucus, purulent contents, some inflammatory products, or accidentally ingested food and other particles are expelled from the respiratory tract. A productive, “wet” cough helps cleanse the bronchi and performs a drainage function. To more effectively cleanse the respiratory tract, doctors prescribe special medications that stimulate the production of liquid secretions. Sneeze reflex occurs when the receptors in the nasal passages are irritated and develops similarly to the left cough reflex, except that the expulsion of air occurs through the nasal passages. At the same time, tear formation increases, tear fluid nasolacrimal duct enters the nasal cavity and moisturizes its walls. All this helps cleanse the nasopharynx and nasal passages. Diver reflex caused by fluid entering the nasal passages and manifests itself as a short-term stoppage breathing movements, preventing the passage of fluid into the underlying respiratory tract.

When working with patients, resuscitation doctors, maxillofacial surgeons, otolaryngologists, dentists and other specialists need to take into account the features of the described reflex reactions that occur in response to receptor irritation oral cavity, pharynx and upper respiratory tract.

Respiration is the process of exchange of gases such as oxygen and carbon between the internal environment of a person and the outside world. Human breathing is a complexly regulated act of joint work between nerves and muscles. Their coordinated work ensures inhalation - the entry of oxygen into the body, and exhalation - the release of carbon dioxide into the environment.

The respiratory apparatus has a complex structure and includes: organs of the human respiratory system, muscles responsible for the acts of inhalation and exhalation, nerves regulating the entire process of air exchange, as well as blood vessels.

Vessels are of particular importance for breathing. Blood through the veins enters the lung tissue, where gases are exchanged: oxygen enters and carbon dioxide leaves. The return of oxygenated blood is carried out through the arteries, which transport it to the organs. Without the process of tissue oxygenation, breathing would have no meaning.

Respiratory function is assessed by pulmonologists. The important indicators are:

1. Width of the bronchial lumen.
2. Breath volume.
3. Reserve volumes of inhalation and exhalation.

A change in at least one of these indicators leads to a deterioration in health and is an important signal for additional diagnostics and treatment.

In addition, there are secondary functions that breathing performs. This:

1. Local regulation of the breathing process, which ensures the adaptation of blood vessels to ventilation.
2. Synthesis of various biologically active substances, constricting and dilating blood vessels as needed.
3. Filtration, which is responsible for the resorption and disintegration of foreign particles, and even blood clots in small vessels.
4. Deposition of cells of the lymphatic and hematopoietic systems.

Stages of the breathing process

Thanks to nature, which came up with such a unique structure and function of the respiratory organs, it is possible to carry out such a process as air exchange. Physiologically, it has several stages, which, in turn, are regulated by the central nervous system, and only because of this they work like a clock.

So, as a result of many years of research, scientists have identified the following stages that collectively organize breathing. This:

1. External respiration is the delivery of air from the external environment to the alveoli. All organs of the human respiratory system take an active part in this.
2. Delivery of oxygen to organs and tissues by diffusion, as a result of this physical process tissue oxygenation occurs.
3. Respiration of cells and tissues. In other words, the oxidation of organic substances in cells with the release of energy and carbon dioxide. It is easy to understand that without oxygen, oxidation is impossible.

The importance of breathing for humans

Knowing the structure and functions of the human respiratory system, it is difficult to overestimate the importance of such a process as breathing.

In addition, thanks to it, gases are exchanged between the internal and external environment of the human body. The respiratory system is involved:

1. In thermoregulation, that is, it cools the body when elevated temperature air.
2. In the function of releasing random foreign substances such as dust, microorganisms and mineral salts, or ions.
3. In creating speech sounds, which is extremely important for social sphere person.
4. In the sense of smell.

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

The respiratory system also includes the chest and respiratory muscles(the activity of which ensures stretching of the lungs with the formation of the inhalation and exhalation phases and changes 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 as a result of which gas tends from an area of ​​higher concentration 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, smell detection, the production of certain hormone-like substances, lipid and water-salt metabolism, and maintaining the body's immunity. In the airways, the inhaled air is cleansed, moistened, warmed, as well as the perception of temperature and mechanical stimuli.

Airways

The airways of the respiratory system begin with the external nose and nasal cavity. The nasal cavity is divided by the osteochondral septum into two parts: right and left. The inner surface of the cavity, lined with mucous membrane, equipped with cilia and penetrated by blood vessels, is covered with mucus, which retains (and partially neutralizes) microbes and dust. Thus, the air in the nasal cavity is purified, neutralized, warmed and moistened. This is why you need to breathe through your nose.

Over the course of a lifetime, the nasal cavity retains up to 5 kg of dust

Having passed pharyngeal part airways, air enters next body larynx, having the shape of a funnel and formed by several cartilages: the thyroid cartilage protects the larynx in front, the cartilaginous epiglottis closes the entrance to the larynx when swallowing food. If you try to speak while swallowing food, it can get into your airways and cause suffocation.

When swallowing, the cartilage moves upward and 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 there in the larynx? 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 slightly open.

1. Trachea;
2. Aorta;
3. Main left bronchus;
4. Right main 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 half-rings located one above the other and connected by muscle and connective tissue. The open ends of the semirings are adjacent to the esophagus. In the chest, the trachea divides into two main bronchi, from which secondary bronchi branch, which continue to branch further to the bronchioles (thin tubes with a diameter of about 1 mm). The branching of the bronchi is a rather complex network called the bronchial tree.

The bronchioles are divided into even thinner tubes - alveolar ducts, which end in small thin-walled (the thickness of the walls is 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, supplying oxygen to hemoglobin, and removing carbon dioxide, or carbon dioxide, which is the end product of metabolism. However, the functions of the lungs are not limited to this alone.

The lungs are involved in maintaining a constant concentration of ions in the body; they can remove other substances from it, except toxins (essential oils, aromatic substances, “alcohol plume”, acetone, etc.). When you breathe, water evaporates from the surface of the lungs, which cools the blood and the entire body. In addition, the lungs create air currents that vibrate the vocal cords of the larynx.

Conventionally, the lung can be divided into 3 sections:

1. pneumatic (bronchial tree), through which air, like a system of canals, reaches the alveoli;
2. the 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 approximately 7-8 times greater - usually 3-4 liters (in women less than in men), although in athletes it can exceed 6 liters

1. Trachea;
2. Bronchi;
3. Apex of the lung;
4. Upper lobe;
5. Horizontal slot;
6. Average share;
7. Oblique slot;
8. Lower lobe;
9. Heart tenderloin.

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, the pleura (from the Greek pleura - rib, side), consisting of two layers: the inner (pulmonary) covers the surface of the lung, and the outer (parietal) covers the inner surface of the chest. Between the sheets, which are almost in contact with each other, there is a hermetically closed slit-like space called the pleural cavity.

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

The spindle of the lung protrudes 2-3 cm above the collarbone, extending 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 extent. The inner surface is concave, adjacent to the heart and other organs located between the pleural sacs. On it there is the gate 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 into lobes by pleural grooves: the left into two (upper and lower), the right into three (upper, middle and lower).

Lung tissue is formed by bronchioles and many tiny pulmonary vesicles of the alveoli, which look like hemispherical protrusions of the bronchioles. The thinnest walls 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. The inside of the alveoli is coated with a liquid surfactant (surfactant), which weakens the forces of surface tension and prevents the complete collapse of the alveoli during exit.

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

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

Respiratory process

Breathing represents difficult process gas exchange between the external environment and the body. The inhaled air differs significantly in composition from the exhaled air: oxygen enters the body from the external environment, necessary element for metabolism, and carbon dioxide is released outside.

Stages of the respiratory process

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

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

Biological meanings 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 movements of the chest ( chest breathing) and diaphragm (abdominal breathing). The ribs of the relaxed chest fall down, thereby reducing its internal volume. Air is forced out of the lungs, similar to air being forced out of an air pillow or mattress under pressure. By contracting, the respiratory intercostal muscles raise the ribs. The chest expands. Located between the chest and abdominal cavity the diaphragm contracts, its tubercles are smoothed out, and the volume of the chest increases. Both pleural layers (pulmonary and costal pleura), between which there is no air, transmit this movement to the lungs. A vacuum occurs in the lung tissue, similar to that which appears when an accordion is stretched. Air enters the lungs.

The respiratory rate of an adult is normally 14-20 breaths per 1 minute, but with significant physical activity 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 compress, releasing exhaled air. In this case, only a partial exchange occurs, because it is impossible to exhale all the air from the lungs.

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

Out of 500 cm 3 of inhaled air, only 360 cm 3 passes into the alveoli and releases oxygen into the blood. The remaining 140 cm 3 remains in the airways and does not participate in gas exchange. Therefore, the airways are called “dead space”.

After a person exhales a tidal volume of 500 cm3) and then exhales deeply (1500 cm3), there is still approximately 1200 cm3 of residual air volume left in his lungs, which is almost impossible to remove. That's why 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 during intense physical activity can reach 80-120 liters per minute.

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

Gas exchange in the lungs and transport of gases by blood

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

Oxygen also enters the blood due to diffusion. There is little free oxygen in the blood, because it is continuously bound by hemoglobin found in red blood cells, turning into oxyhemoglobin. Blood that has become arterial leaves the alveoli and pulmonary vein goes 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 maintained pulmonary breathing: excess carbon dioxide is removed outside, and the oxygen absorbed by the blood is replaced with 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 breaks down 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 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 salts of the blood plasma. Deoxygenated blood takes him to right atrium, from there it enters the right ventricle, which pulmonary artery pushes out the venous circle and closes. In the lungs, the blood again becomes arterial and, returning to the left atrium, enters the left ventricle, and from it into big circle blood circulation

The more oxygen is consumed in the tissues, the more oxygen is required from the air to compensate for the costs. That's why when physical work At the same time, both cardiac activity and pulmonary respiration increase.

Thanks to amazing property hemoglobin combines with oxygen and carbon dioxide; the blood is able to absorb these gases in significant quantities

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

Action carbon monoxide on the body. Hemoglobin in red blood cells can combine with other gases. Thus, hemoglobin combines with carbon monoxide (CO), carbon monoxide formed during incomplete combustion of fuel, 150 - 300 times faster and stronger than with oxygen. Therefore, even with a small content of carbon monoxide in the air, hemoglobin combines not with oxygen, but with carbon monoxide. At the same time, 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 body tissues

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

When hit foreign body into the respiratory tract, with swelling of the vocal cords due to the disease, respiratory arrest may occur. Choking develops - asphyxia. If breathing stops, do artificial respiration using special devices, and in their absence - using the “mouth to mouth”, “mouth to nose” method or special techniques.

Breathing regulation. The rhythmic, automatic alternation of inhalations and exhalations is regulated from the respiratory center located in the medulla oblongata. From this center, impulses: travel to the motor neurons of the vagus and intercostal nerves, which 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 hold or intensify their breathing for a short time, as happens, for example, when talking.

The depth and frequency of breathing are affected by the content of CO 2 and O 2 in the blood. These substances irritate the chemoreceptors in the walls of large blood vessels, nerve impulses from them enter the respiratory center. With an increase in CO2 content in the blood, breathing deepens; with a decrease in CO2, breathing becomes more frequent.