Bronchial muscle. How do the human bronchi work?

Bronchitis is inflammation respiratory tract in the lungs. The main tubes through which air passes into the lungs are called bronchi, and the smaller tubes branching off from them are called bronchioles.

When these tubes become inflamed, it causes the airways to become narrowed, compressed, and blocked, leading to the symptoms of bronchitis. Bronchitis can be acute (lasting less than 6 weeks) or chronic (recurring many times over more than two years).

Acute bronchitis is a disease that begins suddenly and goes away on its own after a few weeks. Symptoms of acute bronchitis include a dry cough and coughing up mucus (phlegm). It is usually caused by a viral or bacterial infection in the upper respiratory tract. Although the symptoms can be bothersome, acute bronchitis in otherwise healthy people is rarely severe.

Chronical bronchitis

Chronic bronchitis is a recurrent disease in which there is a chronic inflammatory process, swelling and narrowing of the airways. It is defined as a cough producing sputum for at least a 3-month period of time, for two consecutive years. Chronic bronchitis is usually a consequence of damage to the lungs from chronic medical diseases or smoking.

Smokers and bronchitis

Smoking is one of the main irritants of the lungs; it causes damage at the cellular level. This is damage lung tissue, especially the cilia (cells in the lining of the lungs that help clear them of debris and mucus), causes the lungs to be more susceptible to acute bronchitis. Smokers end up causing so much damage to their lungs that they develop chronic bronchitis or COPD (chronic obstructive pulmonary disease).

What causes acute bronchitis?

Acute bronchitis is caused in 90% of cases viral infection upper respiratory tract. The other 10% of cases are caused by bacterial infections.

What causes chronic bronchitis?

Chronic bronchitis is caused by repeated inflammation of the lung tissue. People at high risk of developing chronic bronchitis are those who are susceptible to lung irritants due to professional activity(for example, miners, builders, mechanics, etc.) and smokers. High levels of air pollution can also contribute to the development of chronic bronchitis.

What are the symptoms of bronchitis?

Symptoms of bronchitis may include:

• Dyspnea
• Cough
• Coughing up phlegm
• Wheezing
• Temperature increase
• Fatigue

When should you see a doctor if you have bronchitis?

If you suspect you have bronchitis, you should consult a doctor if you experience the following symptoms:

• Dyspnea
• Chest pain
• High fever
• Coughing up blood
• Laryngeal edema
• Wheezing
• Symptoms that worsen in severity or last longer than 2 weeks

How to treat bronchitis at home?

If bronchitis symptoms are not severe, home remedies include:

• Use large quantity liquids
• To give up smoking
• Taking over-the-counter medicines such as aspirin, paracetamol, ibuprofen, naproxen, if advised by your doctor
• Enough rest

Bronchitis is usually diagnosed by a doctor after taking a medical history and performing a physical examination. Usually no need additional methods research.

In more severe cases bronchitis or chronic bronchitis may require chest x-rays. Blood tests or pulmonary function tests (spirography).

Treatment for bronchitis usually involves using home remedies such as drinking plenty of fluids, quitting smoking, resting, and taking over-the-counter fever medications.

Cough medications are rarely helpful and may be harmful in some young children.

Antibacterials are rarely prescribed because most cases of bronchitis are caused by viruses that do not respond to antibiotics.

If bronchitis symptoms are severe, the doctor may prescribe medications to the patient, including:

• Inhaled bronchodilators
• Corticosteroids
• Expectorants

Chronic bronchitis can be treated with:

• Inhaled bronchodilators
• Inhaled or oral corticosteroids
• Oxygen therapy
• Annual flu shots
• Vaccination against pneumococcus

Because chronic bronchitis makes the lungs more susceptible to bacterial infections, doctors may prescribe antibiotics to treat these secondary infections.

Treatment for COPD (chronic obstructive pulmonary disease) is similar to that for chronic bronchitis: inhaled bronchodilators, inhaled or oral corticosteroids, oxygen therapy, annual flu vaccination, pneumococcal vaccination.

The most important thing One thing people with COPD can do is quit smoking.

The most important thing a person can do to reduce their risk of developing bronchitis is not to smoke and avoid secondhand smoke.

In addition, to reduce the risk of developing bronchitis, you should:

• Exercise regularly
• Maintain a healthy and balanced diet
• Wash your hands often
• Reduce occupational exposure to lung irritants
• Avoid other people who may have symptoms infectious diseases upper respiratory tract

We try to provide the most relevant and useful information for you and your health.

What are the walls of the bronchi, what are they made of and what are they needed for? The material below will help you figure this out.

The lungs are an organ necessary for a person for breathing. They consist of lobes, each of which has a bronchus with 18-20 bronchioles emerging from it. The bronchiole ends in an acinus, which consists of alveolar fascicles, and they, in turn, end in alveoli.

Bronchi are organs involved in the act of breathing. The function of the bronchi is to deliver air into the lungs and remove it back, filtering it from dirt and small dust particles. In the bronchi, the air is heated to the desired temperature.

The structure of the bronchial tree is the same in every person and does not have any special differences. Its structure is as follows:

1. It begins with the trachea, the first bronchi are its continuation.
2. The lobar bronchi are located outside the lungs. Their sizes differ: the right one is shorter and wider, the left one is narrower and longer. This is due to the fact that the volume of the right lung is greater than that of the left.
3. Zonal bronchi (2nd order).
4. Intrapulmonary bronchi (bronchi of the 3rd-5th order). 11 in right lung and 10 in the left. Diameter - 2-5 mm.
5. Lobar (6-15th order, diameter - 1-2 mm).
6. Bronchioles, which end in alveolar fascicles.

Anatomy respiratory system The human lung is designed in such a way that the division of the bronchi is necessary for penetration into the most distant parts of the lung. This is the peculiarity of the structure of the bronchi.

Location of the bronchi

The chest contains numerous organs and systems. It is enclosed by a costomuscular structure whose function is to protect each vital organ. The lungs and bronchi are closely related to each other, and the size of the lungs is relatively chest very large, so they occupy its entire surface.

Where are the trachea and bronchi located?

They are located in the center of the respiratory system parallel to the anterior spine. The trachea lies under the anterior spine, and the bronchi are located under the costal mesh.

Bronchial walls

The bronchus consists of cartilaginous rings (this layer of the bronchial wall is otherwise called fibromuscular-cartilaginous), which decrease with each branch of the bronchi. At first they appear as rings, then semi-rings, and in the bronchioles they are completely absent. Cartilaginous rings prevent the bronchi from falling, and due to these rings the bronchial tree remains unchanged.

Organs also consist of a muscle layer. When contracting muscle tissue the organ changes its size. This happens due to low air temperature. The organs narrow and slow down the flow of air. This is necessary to keep warm. During active physical exercise the lumen increases to prevent shortness of breath.

Columnar epithelium

This is the next layer of the bronchial wall after the muscular layer. The anatomy of columnar epithelium is complex. It consists of several types of cells:

1. Ciliated cells. Cleanse the epithelium of foreign particles. Cells with their movements push dust particles out of the lungs. Thanks to this, the mucus begins to move.
2. Goblet cells. They secrete mucus, which protects the mucosal epithelium from damage. When dust particles hit the mucous membrane, mucus secretion increases. A person’s cough reflex is triggered, and the eyelashes begin to move forward. foreign bodies out. The secreted mucus moistens the air entering the lungs.
3. Basal cells. Restores the inner layer of the bronchi.
4. Serous cells. They secrete a secretion necessary for drainage and cleansing of the lungs ( drainage functions bronchi).
5. Clara cells. Located in bronchioles, they synthesize phospholipids.
6. Kulchitsky cells. They produce hormones (the productive function of the bronchi) and belong to the neuroendocrine system.
7. Outer layer. It is connective tissue that comes into contact with external environment, surrounding the organs.

The bronchi, the structure of which is described above, are penetrated by bronchial arteries that supply them with blood. The structure of the bronchi provides many lymph nodes, which receive lymph from lung tissue.

Therefore, the functions of the organs include not only delivering air, but also purifying it from all kinds of particles.

Research methods

The first method is a survey. In this way, the doctor finds out whether the patient has factors that could affect the respiratory system. For example, working with chemical materials, smoking, frequent contact with dust.

Pathological forms of the chest are divided into several types:

1. Paralytic chest. Occurs in patients with frequent illnesses lungs and pleura. The shape of the chest becomes asymmetrical, the costal spaces increase.
2. Emphysematous chest. Occurs in the presence of pulmonary emphysema. The chest becomes barrel-shaped. Coughing with emphysema increases it top part stronger than the rest.
3. Rachitic type. Appears in people who suffered from rickets in childhood. At the same time, the chest protrudes forward, like the keel of a bird. This occurs due to protrusion of the sternum. This pathology is called “chicken breast”.
4. Funnel-shaped type (shoemaker's chest). This pathology is characterized by the fact that the sternum and xiphoid process are pressed into the chest. Most often this defect is congenital.
5. Scaphoid type. A visible defect consisting of a recessed position of the sternum relative to the rest of the chest. Occurs in people with syringomyelia.
6. Kyphoscoliotic type (round back syndrome). Appears due to inflammation of the bone part of the spine. May cause problems with the heart and lungs.

The doctor palpates the chest for the presence of uncharacteristic subcutaneous formations, strengthening or weakening voice tremors.

Auscultation (listening) of the lungs is carried out special device- endoscope. The doctor listens to the movement of air in the lungs, trying to understand if there are any suspicious noises or wheezing - whistling or making noise. The presence of certain wheezing and noises that are not characteristic of healthy person, can be a symptom of various diseases.

The most serious and precise method The study is a chest x-ray. It allows you to view the entire bronchial tree and pathological processes in the lungs. In the image you can see the expansion or narrowing of the lumen of the organs, thickening of the walls, the presence of fluid or tumor in the lungs.

The structure of the bronchial tree is the trachea and the bronchial trunks extending from it. The totality of these branches constitutes the structure of the tree. The structure is identical in all people and has no striking differences. Bronchi are tubular branches of the main trachea that have the ability to conduct air and connect it with the respiratory parenchyma of the lung.

The structure of the main bronchi

The first branch of the trachea is the two main bronchi, which extend from it almost at a right angle, and each of them is directed towards the left or right lung, respectively. The bronchial system is asymmetrical and has slight differences in the structure of different sides. For example, the main left bronchus is slightly narrower in diameter than the right one and has a greater extent.

The structure of the walls of the main air-conducting trunks is the same as that of the main trachea, and they consist of a number of cartilaginous rings that are connected to each other by a system of ligaments. The only one distinctive feature is that in the bronchi all rings are always closed and have no mobility. In quantitative terms, the difference between the versatile trunks is determined by the fact that the right one has a length of 6-8 rings, and the left - up to 12. Inside, all bronchi are covered

Bronchial tree

The main bronchi begin to branch at their termination. Branching occurs into 16-18 smaller tubular leads. Such a system, thanks to its appearance, and was called the "bronchial tree". The anatomy and structure of the new branches differ little from the previous sections. They have smaller dimensions and a smaller diameter of air passages. This branching is called lobar. It is followed by segmental bronchi, with branching into the lower, middle and upper lobar bronchi. And then they are divided into systems of apical, posterior, and anterior segmental tracts.

Thus, the bronchial tree branches more and more, reaching the 15th order of division. The smallest bronchi are lobular. Their diameter is only 1 mm. These bronchi are also divided into terminal bronchioles, ending in respiratory bronchi. At their ends there are alveoli and alveolar ducts. bronchioles are a collection of alveolar ducts and alveoli that fit tightly together and form the lung parenchyma.

In general, the wall of the bronchi consists of three membranes. These are: mucosa, muscular-cartilaginous, adventitial. In turn, the mucosa is densely lined and has a multirow structure, covered with cilia, secretes secretions, has its own neuroendocrine cells capable of forming and secreting biogenic amines, as well as cells involved in the processes of mucosal regeneration.

Physiological functions

The main and most important is the conduction of air masses into the respiratory parenchyma of the lung and in the opposite direction. The bronchial tree is also a security system for the parts of the respiratory system and protects them from dust, various microorganisms, and harmful gases. Regulation of the volume and speed of air flow passing through the bronchial system is carried out by changing the difference between the pressure of the air itself in the alveoli and in the surrounding air. This effect is achieved through the work of the respiratory muscles.

On inhalation, the diameter of the lumen of the bronchi changes towards expansion, which is achieved by regulating the tone of smooth muscles, and on exhalation it decreases significantly. Emerging disturbances in the regulation of smooth muscle tone are both causes and consequences of many diseases associated with the respiratory system, such as asthma and bronchitis.

Dust particles entering the air, as well as microorganisms, are eliminated by the movement of mucous secretions thanks to the system of cilia in the direction of the trachea to the upper respiratory organs. Mucus containing foreign impurities is removed by coughing.

Hierarchy

The branching of the bronchial system does not occur chaotically, but follows a strictly established order. Hierarchy of the bronchi:

• The main ones.
• Zonal - second order.
• Segmental and subsegmental are the 3rd, 4th, 5th orders.
• Small - 6-15 orders.
• Terminal.

This hierarchy fully corresponds to the division of lung tissue. Thus, lobar bronchi correspond to the lobes of the lung, and segmental bronchi correspond to segments, etc.

Blood supply

Blood supply to the bronchi is carried out through the arterial bronchial lobes of the thoracic aorta, as well as through the esophageal arteries. Deoxygenated blood drained by the azygos and semi-gypsy veins.

Where are the human bronchi located?

The chest contains numerous organs and vessels. Formed by the costomuscular structure. It is designed to protect the most vital important systems located inside it. Answering the question: “Where are the bronchi?”, it is necessary to consider the location of the lungs, the blood vessels connecting to them, lymphatic vessels and nerve endings.

The dimensions of the human lungs are such that they occupy the entire anterior surface of the chest. located in the center of this system, are located under the anterior spine, located in the central part between the ribs. All bronchial leads are located under the costal mesh of the anterior sternum. The bronchial tree (its location diagram) associatively corresponds to the structure of the chest. Thus, the length of the trachea corresponds to the location of the central spinal column chest. And its branches are located under the ribs, which can also be visually identified as the branching of the central column.

Bronchial examination

Methods for studying the respiratory system include:

• Questioning the patient.
• Auscultation.
• X-ray examination.
• and bronchi.

Research methods, their purpose

When interviewing a patient, it is established possible factors that can affect the respiratory system, such as smoking, harmful conditions work. During the examination, the doctor pays attention to the color of the patient’s skin, the frequency of breaths, their intensity, the presence of cough, shortness of breath, unusual normal breathing sounds. Palpation of the chest is also carried out, which can clarify its shape, volume, the presence of subcutaneous emphysema, the nature of vocal tremor and frequency of sounds. Deviation from the norm of any of these indicators indicates the presence of a disease that is reflected in such changes.

Performed using an endoscope and performed to detect changes breath sounds, the presence of wheezing, whistling and other sounds uncharacteristic of normal breathing. Using this method, by ear, the doctor can determine the nature of the disease, the presence of swelling of the mucous membranes, and sputum.

One of critical roles X-ray plays a role in the study of diseases of the bronchial tree. Survey X-ray the human chest allows one to distinguish the character pathological processes occurring in the respiratory system. The structure of the bronchial tree is clearly visible and can be analyzed to identify pathological changes. The picture shows changes occurring in the structure of the lungs, their expansions, lumens of the bronchi, thickening of the walls, and the presence of tumor formations.

MRI of the lungs and bronchi is performed in anteroposterior and transverse projections. This makes it possible to examine and study the condition of the trachea and bronchi in their layer-by-layer image, as well as in cross-section.

Treatment methods

TO modern methods Treatments include both surgical and non-surgical treatment of diseases. This:

1. Therapeutic bronchoscopy. It is aimed at removing bronchial contents and is performed in the treatment room, under the influence of local or general anesthesia. First of all, the trachea and bronchi are examined to establish the nature and area of ​​damage from the effects of inflammatory changes. Then rinsing is carried out with indifferent or antiseptic solutions, drugs are administered.
2. Sanitation of the bronchial tree. This method is the most effective known and includes a number of procedures aimed at clearing the bronchial tract of excess mucus, eliminating inflammatory processes. For this, the following can be used: chest massage, use of expectorants, installation of special drainage up to several times a day, inhalation.

Providing the body with oxygen, and therefore ensuring the body’s ability to live, is achieved through the coordinated work of the respiratory system and blood supply. The relationship of these systems, as well as the speed of processes, determine the body’s ability to control and carry out various processes occurring in it. In case of change or violation physiological processes breath turns out bad influence on the state of the organism as a whole.

Initially, the trachea is divided into two main bronchi (left and right), leading to both lungs. Then each main bronchus is divided into lobar bronchi: the right one into 3 lobar bronchi, and the left into two lobar bronchi. The main and lobar bronchi are bronchi of the first order, and are extrapulmonary in location. Then there are zonal (4 in each lung) and segmental (10 in each lung) bronchi. These are interlobar bronchi. The main, lobar, zonal and segmental bronchi have a diameter of 5–15 mm and are called large-caliber bronchi. Subsegmental bronchi are interlobular and belong to the bronchi of medium caliber (d 2 - 5 mm). Finally, the small bronchi include bronchioles and terminal bronchioles (d 1–2 mm), which are intralobular in location.

Main bronchi (2) extrapulmonary

Lobes (2 and 3) of the first order are large

Zonal (4) II order interlobar bronchi

Segmental (10) III order 5 – 15

Subsegmental IV and V order interlobular middle

Small intralobular bronchioles

Terminal bronchioles bronchi

The segmental structure of the lungs allows the clinician to easily establish the exact localization of the pathological process, especially radiographically and during surgical operations on the lungs.

There are 3 segments (1, 2, 3) in the upper lobe of the right lung, 2 (4, 5) in the middle lobe, and 5 segments (6, 7, 8, 9, 10) in the lower lobe.

In the upper lobe of the left lung there are 3 segments (1, 2, 3), in the lower lobe - 5 (6, 7, 8, 9, 10), in the uvula of the lung - 2 (4, 5).

Structure of the bronchial wall

The mucous membrane of the large-caliber bronchi is lined with ciliated epithelium, the thickness of which gradually decreases and in the terminal bronchioles the epithelium is single-row ciliated, but cubic. Among the ciliated cells there are goblet, endocrine, basal, as well as secretory cells (Clara cells), bordered, non-ciliated cells. Clara cells contain numerous secretory granules in the cytoplasm and are characterized by high metabolic activity. They produce enzymes that break down the surfactant that coats the respiratory tract. In addition, Clara cells secrete some surfactant components (phospholipids). The function of nonciliated cells has not been established.

The border cells have numerous microvilli on their surface. These cells are believed to function as chemoreceptors. An imbalance of hormone-like compounds of the local endocrine system significantly disrupts morphofunctional changes and can be the cause of asthma of immunogenic origin.

As the caliber of the bronchi decreases, the number of goblet cells decreases. As part of the epithelium covering lymphoid tissue, there are special M-cells with a folded apical surface. Here they are attributed an antigen-presenting function.

The lamina propria of the mucous membrane is characterized by a large content of longitudinally located elastic fibers, which ensure stretching of the bronchi during inhalation and return them to their original position during exhalation. The muscle layer is represented by obliquely circular bundles of smooth muscle cells. As the caliber of the bronchus decreases, the thickness of the muscle layer increases. Contraction of the muscle layer causes the formation of longitudinal folds. Prolonged contraction of muscle bundles during bronchial asthma leads to difficulty breathing.

The submucosa contains numerous glands arranged in groups. Their secretion moisturizes the mucous membrane and promotes the adhesion and envelopment of dust and other particles. In addition, mucus has bacteriostatic and bactericidal properties. As the caliber of the bronchus decreases, the number of glands decreases, and in small-caliber bronchi they are completely absent. The fibrocartilaginous membrane is represented by large plates of hyaline cartilage. As the caliber of the bronchi decreases, the cartilage plates become thinner. In the bronchi of medium caliber cartilage tissue in the form of small islands. In these bronchi, replacement of hyaline cartilage with elastic cartilage is noted. In the small bronchi there is no cartilaginous membrane. Because of this, the small bronchi have a star-shaped lumen.

Thus, as the caliber of the airways decreases, there is a thinning of the epithelium, a decrease in the number of goblet cells, and an increase in the number of endocrine cells and cells in the epithelial layer; the number of elastic fibers in the layer proper, a decrease and complete disappearance of the number of mucous glands in the submucosa, thinning and complete disappearance of the fibrocartilaginous membrane. The air in the airways is warmed, purified, and moistened.

Gas exchange between blood and air occurs in respiratory department lungs, the structural unit of which is acini. The acini begins with a respiratory bronchiole of the 1st order, in the wall of which single alveoli are located.

Then, as a result of dichotomous branching, respiratory bronchioles of the 2nd and 3rd order are formed, which in turn are divided into alveolar ducts containing numerous alveoli and ending in alveolar sacs. In each pulmonary lobe, which has a triangular shape, with a diameter of 10-15 mm. and 20-25 mm high, contains 12-18 acini. At the mouth of each alveoli there are small bundles of smooth muscle cells. Between the alveoli there are communications in the form of openings - alveolar pores. Between the alveoli lie thin layers of connective tissue containing a large number of elastic fibers and numerous blood vessels. Alveoli have the appearance of vesicles, the inner surface of which is covered with a single-layer alveolar epithelium, consisting of several types of cells.

Alveolocytes of the 1st order(small alveolar cells) (8.3%) have an irregular elongated shape and a thinned plate-shaped anucleated part. Their free surface, facing the alveolar cavity, contains numerous microvilli, which significantly increases the area of ​​contact between air and the alveolar epithelium.

Their cytoplasm contains mitochondria and pinocytotic vesicles. These cells are located on the basement membrane, which merges with the basement membrane of the capillary endothelium, due to which the barrier between blood and air is extremely small (0.5 microns). This is an aerohematic barrier. In some areas, thin layers of connective tissue appear between the basement membranes. Another numerous type (14.1%) are alveolocytes type 2(large alveolar cells), located between type 1 alveolocytes and having a large rounded shape. There are also numerous microvilli on the surface. The cytoplasm of these cells contains numerous mitochondria, a lamellar complex, osmiophilic bodies (granules with big amount phospholipids) and a well-developed endoplasmic reticulum, as well as acid and alkaline phosphatase, nonspecific esterase, redox enzymes. It is suggested that these cells may be the source of the formation of type 1 alveolocytes. However, the main function of these cells is the secretion of lipoprotein substances of the merocrine type, collectively called surfactant. In addition, the surfactant contains proteins, carbohydrates, water, and electrolytes. However, its main components are phospholipids and lipoproteins. Surfactant covers the alveolar lining in the form of a surface-active film. Surfactant has a very great importance. This way it lowers surface tension, which prevents the alveoli from sticking together when exhaling, and when inhaling it protects against overstretching. In addition, the surfactant prevents the sweating of tissue fluid and thereby prevents the development pulmonary edema. Surfactant is involved in immune reactions: immunoglobilins are found in it. Surfactant performs protective function, activating the bactericidal activity of pulmonary macrophages. Surfactant is involved in the absorption of oxygen and its transport through the airborne barrier.

The synthesis and secretion of surfactant begins at the 24th week of intrauterine development of the human fetus and by the birth of the child, the alveoli are covered with a sufficient amount and full-fledged surfactant, which is very important. When a newborn baby takes his first deep breath, the alveoli straighten, filling with air, and thanks to the surfactant, they no longer collapse. In premature babies, as a rule, there is still an insufficient amount of surfactant, and the alveoli can collapse again, which causes breathing problems. Shortness of breath and cyanosis appear, and the child dies in the first two days.

It is important to note that even in a healthy full-term baby, some of the alveoli remain in a collapsed state and straighten out a little later. This explains the predisposition of infants to pneumonia. The degree of maturity of the fetal lungs is characterized by the content of amniotic fluid surfactant that gets there from the lungs of the fetus.

However, the bulk of the alveoli of newborn children at birth is filled with air, expands, and such a lung does not sink when lowered into water. This is used in judicial practice to decide whether a child was born alive or dead.

Surfactant is constantly renewed due to the presence of an antisurfactant system: (Clara cells secrete phospholipids; basal and secretory cells of bronchioles, alveolar macrophages).

In addition to these cellular elements, the alveolar lining includes another type of cell - alveolar macrophages. These are large, round cells that grow both inside the alveolar wall and as part of the surfactant. Their thin processes spread on the surface of the alveolocytes. There are 48 macrophages per two adjacent alveoli. The source of macrophage development is monocytes. The cytoplasm contains many lysosomes and inclusions. Alveolar macrophages are characterized by 3 features: active movement, high phagocytic activity and high level metabolic processes. Overall, alveolar macrophages represent the most important cellular defense mechanism in the lung. Pulmonary macrophages are involved in phagocytosis and removal of organic and mineral dust. They perform a protective function and phagocytose various microorganisms. Macrophages have a bactericidal effect due to the secretion of lysozyme. They participate in immune reactions by primary processing of various antigens.

Chemotaxis stimulates the migration of alveolar macrophages to the area of ​​inflammation. Chemotactic factors include microorganisms that penetrate the alveoli and bronchi, the products of their metabolism, as well as the body’s own dying cells.

Alveolar macrophages synthesize more than 50 components: hydrolytic and proteolytic enzymes, complement components and their inactivators, arachidontic acid oxidation products, reactive oxygen species, monokines, fibronectins. Alveolar macrophages express more than 30 receptors. The most important receptors in functional terms include Fc receptors, which determine selective recognition, binding and recognition antigens, microorganisms, receptors for complement component C3, necessary for effective phagocytosis.

Contractile protein filaments (active and myosin) are found in the cytoplasm of pulmonary macrophages. Alveolar macrophages are very sensitive to tobacco smoke. Thus, in smokers they are characterized by an increase in oxygen absorption, a decrease in their ability to migrate, adhere, and phagocytosis, as well as inhibition of bactericidal activity. The cytoplasm of alveolar macrophages of smokers contains numerous electron-dense kaolinite crystals formed from tobacco smoke condensate.

Viruses have a negative effect on pulmonary macrophages. Thus, the toxic products of the influenza virus inhibit their activity and lead them (90%) to death. This explains the predisposition to bacterial infection when infected with a virus. The functional activity of macrophages is significantly reduced by hypoxia, cooling, under the influence of drugs and corticosteroids (even in a therapeutic dose), as well as by excessive air pollution. The total number of alveoli in an adult is 300 million with a total area of ​​80 sq.m.

Thus, alveolar macrophages perform 3 main functions: 1) clearance, aimed at protecting the alveolar surface from contamination. 2) modulation of the immune system, i.e. participation in immune reactions due to phagocytosis of antigenic material and its presentation to lymphocytes, as well as by enhancing (due to interleukins) or suppressing (due to prostaglandins) the proliferation, differentiation and functional activity of lymphocytes. 3) modulation of the surrounding tissue, i.e. influence on surrounding tissue: cytotoxic damage to tumor cells, effect on the production of elastin and fibroblast collagen, and therefore on the elasticity of lung tissue; produces a growth factor that stimulates fibroblast proliferation; stimulates the proliferation of type 2 alveocytes. Under the influence of elastase produced by macrophages, emphysema develops.

The alveoli are located quite closely relative to each other, due to which the capillaries intertwining them, with one surface bordering on one alveoli, and the other on the neighboring one. This creates optimal conditions for gas exchange.

Thus, aerogematic barer includes the following components: surfactant, lamellar part of type 1 alveocytes, basement membrane, which can merge with the basement membrane of the endothelium, and cytoplasm of endothelial cells.

Blood supply in the lung carried out through two vascular systems. On the one hand, the lungs receive blood from great circle blood circulation through the bronchial arteries, which extend directly from the aorta and form arterial plexuses in the wall of the bronchi, and feed them.

On the other hand, venous blood enters the lungs for gas exchange from the pulmonary arteries, i.e. from the pulmonary circulation. The branches of the pulmonary artery intertwine the alveoli, forming a narrow capillary network through which red blood cells pass in one row, which creates optimal conditions for gas exchange.