What are lungs? Lungs Body organs originate in the lungs.
The lungs are paired respiratory organs. The characteristic structure of the lung tissue is formed in the second month intrauterine development fetus After the birth of a child, the respiratory system continues its development, finally forming around 22–25 years. After 40 years of age, lung tissue begins to gradually age.
This organ received its name in Russian due to its property of not sinking in water (due to the air content inside). The Greek word pneumon and the Latin word pulmunes are also translated as “lung.” Hence the inflammatory lesion of this organ is called “pneumonia”. A pulmonologist treats this and other diseases of the lung tissue.
Location
A person's lungs are in the chest cavity and occupy most of it. The chest cavity is bounded in front and behind by the ribs, and below is the diaphragm. It also contains the mediastinum, which contains the trachea, main body blood circulation - heart, large (main) vessels, esophagus and some other important structures human body. The chest cavity does not communicate with the external environment.
Each of these organs is completely covered on the outside with pleura - a smooth serous membrane with two layers. One of them fuses with the lung tissue, the second with the chest cavity and mediastinum. Between them is formed pleural cavity, filled Not a large number liquids. Due to negative pressure in the pleural cavity and the surface tension of the fluid in it, the lung tissue is kept in a straightened state. In addition, the pleura reduces its friction against the costal surface during the act of breathing.
External structure
Lung tissue resembles a finely porous sponge pink color. With age, as well as in pathological processes respiratory system, long-term smoking, the color of the pulmonary parenchyma changes and becomes darker.
Lung looks like an irregular cone, the top of which faces upward and is located in the neck area, protruding several centimeters above the collarbone. Below, at the border with the diaphragm, the pulmonary surface has a concave appearance. Its front and back surfaces are convex (and sometimes there are imprints of ribs on it). The inner lateral (medial) surface borders the mediastinum and also has a concave appearance.
On the medial surface of each lung there are so-called gates, through which it penetrates into the lung tissue. main bronchus and vessels - an artery and two veins.
The sizes of both lungs are not the same: the right one is about 10% larger than the left one. This is due to the location of the heart in the chest cavity: to the left of the midline of the body. This “neighborhood” also determines their characteristic shape: the right one is shorter and wider, and the left one is long and narrow. The shape of this organ also depends on the person’s physique. Thus, in thin people, both lungs are narrower and longer than in obese people, which is due to the structure chest.
There is no human lung tissue pain receptors, and the occurrence of pain in some diseases (for example, pneumonia) is usually associated with involvement in pathological process pleura.
WHAT ARE THE LUNGS MADE OF?
The human lungs are anatomically divided into three main components: bronchi, bronchioles and acini.
Bronchi and bronchioles
The bronchi are hollow tubular branches of the trachea and connect it directly to the lung tissue. Main function The bronchi are the air passage.
At approximately the level of the fifth thoracic vertebra, the trachea divides into two main bronchi: right and left, which then go to the corresponding lungs. In the anatomy of the lungs important has a system of bronchial branches, the appearance of which resembles a tree crown, which is why it is called “bronchial tree”.
When the main bronchus enters the pulmonary tissue, it is first divided into lobar and then into smaller segmental ones (corresponding to each pulmonary segment). Subsequent dichotomous (paired) division of the segmental bronchi ultimately leads to the formation of terminal and respiratory bronchioles - the smallest branches of the bronchial tree.
Each bronchus consists of three membranes:
- external (connective tissue);
- fibromuscular (contains cartilage tissue);
- internal mucosa, which is covered with ciliated epithelium.
As the diameter of the bronchi decreases (in the process of branching) cartilage tissue and mucous membrane gradually disappear. The smallest bronchi (bronchioles) no longer contain cartilage in their structure, and the mucous membrane is also absent. Instead, a thin layer of cubic epithelium appears.
Acini
The division of the terminal bronchioles leads to the formation of several respiratory orders. From each respiratory bronchiole, alveolar ducts branch in all directions, which blindly end in alveolar sacs (alveoli). The membrane of the alveoli is densely covered with a capillary network. This is where gas exchange occurs between inhaled oxygen and exhaled carbon dioxide.
The diameter of the alveoli is very small and ranges from 150 microns in a newborn child to 280–300 microns in an adult.
The inner surface of each alveoli is covered with a special substance - surfactant. It prevents its collapse, as well as the penetration of fluid into the structures of the respiratory system. In addition, surfactant has bactericidal properties and is involved in some immune defense reactions.
The structure, which includes the respiratory bronchiole and the alveolar ducts and sacs emanating from it, is called the primary lobule of the lung. It has been established that approximately 14–16 respiratory tracts arise from one terminal bronchiole. Consequently, this number of primary lung lobules forms the main structural unit of the lung tissue parenchyma - the acinus.
This anatomical and functional structure received its name because of its characteristic appearance, reminiscent of a bunch of grapes (Latin Acinus - “bunch”). There are approximately 30 thousand acini in the human body.
The total area of the respiratory surface of the lung tissue due to the alveoli ranges from 30 square meters. meters when exhaling and up to about 100 square meters. meters when inhaling.
LOLES AND SEGMENTS OF THE LUNG
Acini form lobules, from which are formed segments, and from segments – shares, making up the whole lung.
IN right lung There are three lobes, the left one has two (due to its smaller size). In both lungs, the upper and lower lobes are distinguished, and the middle lobe is also distinguished on the right. The lobes are separated from each other by grooves (fissures).
Shares divided into segments, which do not have visible demarcation in the form of connective tissue layers. Usually there are ten segments in the right lung, eight in the left. Each segment contains a segmental bronchus and a corresponding branch of the pulmonary artery. The appearance of the pulmonary segment is similar to an irregularly shaped pyramid, the apex of which faces the pulmonary hilum and the base faces the pleural layer.
The upper lobe of each lung has an anterior segment. The right lung also has an apical and posterior segment, and the left lung has an apical-posterior segment and two lingular segments (superior and inferior).
In the lower lobe of each lung, there are superior, anterior, lateral and posterobasal segments. In addition, the mediobasal segment is determined in the left lung.
IN middle share right lung There are two segments: medial and lateral.
Separation by segment of the human lung is necessary to determine clear localization pathological changes lung tissue, which is especially important for medical practitioners, for example, in the process of treating and monitoring the course of pneumonia.
FUNCTIONAL PURPOSE
The main function of the lungs is gas exchange, in which gas is removed from the blood. carbon dioxide with its simultaneous saturation with oxygen, necessary for the normal metabolism of almost all organs and tissues of the human body.
Oxygenated when inhaled air enters the alveoli through the bronchial tree.“Waste” blood from the pulmonary circulation, containing a large amount of carbon dioxide, also enters there. After gas exchange, carbon dioxide is again expelled through the bronchial tree during exhalation. And oxygenated blood enters big circle blood circulation and is sent further to the organs and systems of the human body.
The act of breathing in humans is involuntary, reflexive. A special structure of the brain is responsible for this - the medulla oblongata ( respiratory center). The degree of saturation of the blood with carbon dioxide regulates the rate and depth of breathing, which becomes deeper and more frequent as the concentration of this gas increases.
There is no muscle tissue in the lungs. Therefore, their participation in the act of breathing is exclusively passive: expansion and contraction during movements of the chest.
Participates in breathing muscle tissue diaphragm and chest. Accordingly, there are two types of breathing: abdominal and thoracic.
On inhalation, the volume of the thoracic cavity increases, in it negative pressure is created(below atmospheric), which allows air to flow freely into the lungs. This is accomplished by contraction of the diaphragm and the muscular frame of the chest ( intercostal muscles), which leads to raising and divergence of the ribs.
On exhalation, on the contrary, the pressure becomes higher than atmospheric pressure, and the removal of air saturated with carbon dioxide is carried out almost passively. In this case, the volume of the chest cavity decreases due to relaxation of the respiratory muscles and lowering of the ribs.
For some pathological conditions The act of breathing also includes the so-called auxiliary respiratory muscles: neck, abdominal, etc.
The amount of air that a person inhales and exhales at one time (tidal volume) is about half a liter. An average of 16–18 respiratory movements are performed per minute. More than one day passes through the lung tissue 13 thousand liters of air!
The average lung capacity is approximately 3–6 liters. In humans it is excessive: during inhalation we use only about one-eighth of this capacity.
In addition to gas exchange, the human lungs have other functions:
- Participation in maintaining acid-base balance.
- Removal of toxins, essential oils, alcohol vapors, etc.
- Maintaining the body's water balance. Normally, about half a liter of water per day evaporates through the lungs. At extreme situations daily water excretion can reach 8–10 liters.
- The ability to retain and dissolve cell conglomerates, fatty microemboli and fibrin clots.
- Participation in blood clotting processes (coagulation).
- Phagocytic activity – participation in the functioning of the immune system.
Consequently, the structure and functions of the human lungs are closely interconnected, which allows for the smooth functioning of the entire human body.
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The human lungs are located in the chest paired organ, responsible for supplying oxygen to the entire body.
Brief description of the structure of the lungs
A person has two lungs. The right lung, compared to the left, has a larger volume, greater width and is slightly shorter. This is explained by the location of the diaphragm and heart. The heart is located in the middle of the chest and is more shifted to the left bottom. The right side of the diaphragm, in turn, rises upward.
Both lungs have the appearance of an irregular cone. The left lung consists of two lobes, the right - of three. The basis, or skeleton, of the lungs is the bronchi. They look like wood. At the ends of each branch there are alveoli, in which the accumulation of air and all gas exchange actually occur.
Lung functions
The main function of the lungs is to accumulate oxygen and supply it to the entire body, as well as to remove carbon dioxide from the body. Gas exchange occurs due to the movements of the diaphragm, chest and lungs themselves. The motor activity of the lungs is expressed in their expansion when air enters through the nasal passages and in their contraction to their original size.
In addition to the main function, the lungs also perform additional functions. They maintain the necessary acid-base balance due to the fact that they take part in regulating the required amount (concentration) of ions in the body. The lungs also remove other gases (aromatic substances), ethers and other volatile substances.
Maintaining the body's water balance also occurs with the participation of the lungs. From their surface, from half a liter of water to ten (in special extreme cases) evaporates per day. Average healthy levels are 0.3 - 0.8 liters per day.
Breathing of the lungs and the whole body
Just like the rest of the body, the lungs need to breathe, that is, they also need oxygen. Their ventilation occurs as a result of the difference in pressure between inhalation and exhalation. When exhaling pulmonary pressure exceeds atmospheric pressure, and upon inhalation it decreases noticeably.
How does the body breathe? There are two types of breathing: abdominal and thoracic.
Abdominal breathing is carried out through the diaphragm. Inhalation occurs, as was written above, due to a decrease in pressure in the lungs. When the diaphragm muscles contract, the amount of available space in the chest increases. The lungs expand and inhalation occurs. Exhalation occurs as a result of relaxation of the diaphragm muscles and its return to its original size.
Inhale at thoracic breathing, or rib breathing, is carried out by contracting and relaxing the external intercostal muscles, one end of which is attached to the rib, and the other to the vertebra. When exhaling, as a rule, no muscles are used. Exhalation during costal breathing is passive. However, in case of any serious violations The respiratory system in the breathing process involves the internal intercostal muscles, which carry out exhalation.
The control center for breathing and the respiratory system is located in medulla oblongata. Regulation of breathing, as such, occurs through certain receptors that are located in the blood vessels, in the bronchi, and in the area of the carotid arteries.
Treatment of diseases of the bronchopulmonary system
Pneumonia is one of the most severe lung diseases. Like other diseases, it is easier to prevent. For the purpose of prevention, especially with an existing predisposition, it is good to use peptide preparations for the lungs and bronchi. For example, peptide bioregulator for the respiratory system, to normalize the bronchial mucosa and regulate lung functions, in a solution for the bronchi and lungs. Also great help complex application various drugs for the respiratory system. Included traditional treatment they speed up recovery and enhance the effect of medications.
The human lungs perform many functions. The main functions performed by the lungs include gas exchange, removal of carbon dioxide, and supply of hemoglobin with oxygen. The initiation of gas exchange in the lungs occurs through a process called diffusion. This means that the thin walls, as well as the capillaries, allow oxygen contained in the inhaled air to pass through. In this case, carbon dioxide, as the final product of metabolism, on the contrary, comes from the blood into the air.
The result of the difference in the concentrations of these gases in the air, as well as in the blood, is a consequence of the diffusion that occurs. The penetration of oxygen into red blood cells causes the saturation of hemoglobin with it. In this case, the blood turns into arterial blood and goes straight to the corresponding tissues, nourishing them. In turn, the tissues release carbon dioxide, which through diffusion passes into the blood and is delivered to the lungs.
This process continues until oxygen balance between the blood and the air contained in the alveoli is achieved. Considering the short residence time of blood in the capillaries of the alveoli, it seems quite difficult to provide body tissues with oxygen dissolved in the blood, the amount of which cannot exceed 0.003 cubic centimeters in the same volume of blood plasma.
Nature has implemented a mechanism for saturating the blood with oxygen through pulmonary diffusion by introducing into the process a substance that easily reacts with oxygen. This property of hemoglobin allows it to retain oxygen in sufficiently large quantities, as well as easily part with it if necessary. It is these properties of hemoglobin that allow it to come into contact with oxygen in the lungs and carry it with it in an amount that is equivalent to a fifth of the volume of blood, after which it is transferred to the tissues of the body.
Performing the main function of getting rid of carbon dioxide, the lungs use the services of red blood cells located in the lungs, which replace the HCO3 anions with an anion such as Cl. The membrane has a special channel that serves to carry out similar process. Gas exchange can be blocked by interaction with a specific inhibitor that binds to the protein that is the basis for the formation of this channel.
In addition to its primary, respiratory functions, the lungs also perform various secondary functions such as metabolic and pharmacological. The metabolic, or filtration function, is represented by the activity of the lungs in retaining and destroying cell conglomerates, as well as fatty microemboli and fibrin clots that come with the blood. Enzyme systems play a major role in the production of such activities.
Synthesizable mast cells an alveolar element called chymotrypsin, as well as various other proteases, is actively involved in these processes along with proteases and lipolytic enzymes synthesized by alveolar macrophages. This function of the lungs does not allow higher fatty acids, as well as emulsified fats that enter directly into the venous bloodstream through the thoracic lymphatic channel and move further than the pulmonary capillaries. The destruction of these elements occurs during hydrolysis, which is activated in the lungs. In this case, some of the captured proteins, as well as various lipids, are used to ensure the synthesis of surfactant.
Carrying out their pharmacological function, the lungs synthesize substances that are valuable to the body from the point of view of biological activity. Since the lungs are the organ that leads in histamine content, they play important role in the process of regulation of microcirculation caused by a stressful state. Side effect such a process are bronchospasms and vasoconstriction caused by allergic reactions. This increases the degree of permeability of the alveolocapillary membranes. Lung tissue also synthesizes and destroys serotonin.
A huge number of lung cells produce nitric oxide, which plays a major role in preventing loss of pulmonary vessels to vasodilation, or relaxation smooth muscle vessel walls, with chronic hypoxia. As a rule, this problem is observed under conditions of exposure to endothelium-dependent substances. Among other things, the lungs are a source of blood clotting cofactors. These include thromboplastin and other elements containing an activator capable of converting plasminogen into plasmin. Also, mast cells of the alveoli synthesize heparin, which has an antithrombotic effect.
But the positive effects of heparin do not end there, since it has powerful antihistamine effect and is able to activate lipoprotein lipase. Heparin can also remove the effect of hyaluronidase. The lungs synthesize both substances that can resist the formation of platelet clots and substances that can have the opposite effect. This is the most important organ human body, which ensures the fulfillment of many vital important functions body.
The lungs (pulmones) are a paired organ that occupies almost the entire chest cavity and is the main organ of the respiratory system. Their size and shape are not constant and can change depending on the phase of breathing.
Each lung has the shape of a truncated cone, the rounded apex (apex pulmonis) (Fig. 202, 203, 204) of which is directed to the supraclavicular fossa and through the upper opening of the chest protrudes into the neck to the level of the neck of the 1st rib, and a slightly concave base (basis pulmonis ) (Fig. 202) facing the dome of the diaphragm. The outer convex surface of the lungs is adjacent to the ribs, with inside they include the main bronchi, pulmonary artery, pulmonary veins and nerves that form the root of the lungs (radix pulmonis). The right lung is wider and shorter. In the lower anterior edge of the left lung there is a depression to which the heart is adjacent. It is called the cardiac notch of the left lung (incisura cardiaca pulmonis sinistri) (Fig. 202, 204). In addition, it contains a lot lymph nodes. On the concave surface of the lungs there is a depression called the hilus pulmonum. At this point, the pulmonary and bronchial arteries, bronchi and nerves enter the lungs and the pulmonary and bronchial veins exit, as well as lymphatic vessels.
The lungs consist of lung lobes (lobi pulmones). Deep grooves, each of which is called an oblique fissure (fissura obliqua) (Fig. 202, 203, 204), the right lung is divided into three lobes. Among them there are upper lobe(lobus superior) (Fig. 202, 203, 204), the middle lobe (lobus medius) (Fig. 202, 203) and the lower lobe (lobus inferior) (Fig. 202, 204), and the left - into two: upper and bottom. The upper interlobar groove of the right lung is called the horizontal fissure (fissura horizontalis) (Fig. 202). The lungs are divided into the costal surface (facies costalis) (Fig. 202, 203, 204), the diaphragmatic surface (facies diaphragmatica) (Fig. 202, 203, 204) and the medial surface (facies medialis), in which the vertebral part (pars vertebralis) is distinguished ) (Fig. 203), mediastinal, or mediastinal, part (pars mediastinalis) (Fig. 203, 204) and cardiac indentation (impressio cardica) (Fig. 203, 204).
| Rice. 202. Lungs: 1 - larynx; |
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 | Rice. 203. Right lung: 1 - apex of the lung; |
 | Rice. 204. Left lung: 1 — lung root; |
 | Rice. 205. Lobule of lung: 1 - bronchiole; |
  | Rice. 206. Bronchopulmonary segments A - front; B - behind; B - right; G - left; D - from the inside and to the right; |
 | Rice. 207. Boundaries of the lungs A - front view: |
 | Rice. 207. Boundaries of the lungs B - rear view: |
 |
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| Rice. 208. Boundaries of the right lung (side view): 1 - upper lobe; | Rice. 209. Borders of the left lung (side view): 1 - upper lobe; |
The peculiar skeletal basis of the organ is made up of the main bronchi, which are woven into the lungs, forming the bronchial tree (arbor bronchialis), with the right bronchus forming three branches, and the left - two. The branches, in turn, are divided into bronchi of the 3rd–5th order, the so-called subsegmental, or middle, bronchi, and those into small bronchi, the cartilaginous rings in the walls of which decrease and turn into small plaques.
The smallest of them (1–2 mm in diameter) are called bronchioli (Fig. 205), they do not contain glands and cartilage at all, branch into 12–18 border, or terminal, bronchioles (bronchioli terminales), and those - to the respiratory, or respiratory, bronchioles (bronchioli respiratorii) (Fig. 205). The branches of the bronchi supply air to the lobes of the lungs, into which they are intertwined, thereby carrying out gas exchange between tissues and blood. Respiratory bronchioles supply air to small areas of the lung, which are called acini (acini) and represent the main structural and functional unit of the respiratory department. Within the acinus, the respiratory bronchioles branch, expand and form alveolar ducts (ductuli alveolares) (Fig. 205), each of which ends in two alveolar sacs. On the walls of the alveolar ducts and sacs there are vesicles, or alveoli, of the lungs (alveoli pulmonis) (Fig. 205). In an adult, their number reaches 400 million. One acini contains approximately 15–20 alveoli. The walls of the alveoli are lined with single-layer squamous epithelium, under which in the connective tissue septa there are blood capillaries, which are air-blood barrier(between blood and air), but do not interfere with gas exchange and the release of vapors.
The lungs are also divided into bronchopulmonary segments(segmenta bronchopulmonalia): right - at 11, and left - at 10 (Fig. 206). These are the plots pulmonary lobe, which are ventilated by only one bronchus of the 3rd order and supplied with blood by one artery. Veins are usually common to two adjacent segments. The segments are separated from each other by connective tissue septa and have the shape of irregular cones or pyramids. The apex of the segments faces the hilum, and the base faces the outer surface of the lungs.
Outside, each lung is surrounded by pleura (Fig. 205), or pleural sac, which is a thin, shiny, smooth, moist serous membrane (tunica serosa). There is a parietal, or parietal, pleura (pleura parietalis), lining inner surface the walls of the chest, and the pulmonary (pleura pulmonalis), tightly fused with the lung tissue, which is also called visceral. Between these pleurae a gap is formed, called the pleural cavity (cavum pleurae) and filled with pleural fluid (liquor pleurae), which facilitates the respiratory movements of the lungs.
A space is formed between the pleural sacs, which is limited in front by the sternum and costal cartilages, and in the back by spinal column, and from below - the tendon part of the diaphragm. This space is called the mediastinum and is conventionally divided into anterior and posterior mediastinum. In the anterior are located the heart with the pericardial sac, large vessels hearts, phrenic vessels and nerves, as well as thymus. The trachea lies in the back, thoracic part aorta, esophagus, thoracic lymphatic duct, azygos and semi-gypsy veins, sympathetic nerve trunks and vagus nerves.
One of the most vital human organs is the lungs, which carry out the breathing process and ensure the exchange of oxygen and carbon dioxide in the body. In addition, they are involved in several other important processes in the body’s functioning and have a unique structure. In order to have a clear understanding of the work of this organ, you need to have a good knowledge of the anatomy of the lungs and their location. This paired organ consists of the left and right lungs.
Noticeably different from others internal organs, lung tissue has its own characteristic structure buildings. The name of this organ is due to its ability to remain on the surface of the water, due to the high volume of air in it. Latin name"pulmones" and the Greek "pneumon" also mean "lung". This is where the words “” (which heals) come from pulmonary diseases) and “pneumonia” (pulmonary inflammatory process).
The lungs are located in the chest cavity, occupying its main part (90%). The location and structure of the lungs makes it possible to unite all the important (main) vessels.
Occupying almost the entire chest cavity, the lungs are located below with their base on the dome of the diaphragm. The right lower pulmonary section is separated by the diaphragm from the liver, the left – from the stomach, spleen, and part of the intestine. The median region is closely adjacent to the heart on both sides. The upper base is 4–5 cm above the collarbone.
The lungs are covered on the outside with a serous protective membrane - the pleura. On one side it passes into the pulmonary tissue, and on the other into the mediastinum and chest cavity. The resulting pleural cavity is filled with fluid. Due to this and due to the effect of negative pressure inside the cavity, the lung tissue is in a straightened state. The pleura located on the surface also protects the lungs from friction against the ribs during breathing.
The lungs are shaped like a cone, divided vertically into two parts. In this case, a convex surface and two concave ones are clearly visible. The convex pulmonary area (costal) is so close to the ribs that sometimes even the lung tissue has traces of them on the surface. One concave surface is located in the middle part of the body, and the second borders the diaphragm. In turn, each of them is also divided into interlobar sections.
By appearance healthy lung tissue looks like a pink, finely porous sponge. Under the influence of unfavorable factors, its color changes - it becomes darker when age-related changes, pathologies, bad habits(smoking).
According to the anatomical structure, the lungs have different sizes, the right one is about 10% larger than the left one and they also differ in shape. The left one is smaller due to its “neighborhood” with the heart, which is closer to it, as if slightly displacing this area, called the cardiac notch. In this place, part of the pericardium remains unclosed, and there is a protrusion below, called the “pulmonary uvula”. The right lung is slightly higher than the left, due to the fact that the liver underneath it pushes it up a little.
On the medial side of each of them there is a “gate”. Through them important metabolic processes: enters the lungs pulmonary artery, bronchi, nerve plexuses, and go out pulmonary veins, lymphatic vessels. Together all this makes up the root of the lung. On the right, the pulmonary root is located behind the atrium and the superior vena cava, below the azygos vein, on the left - under the aortic arch.
Components of the lungs
The structure of the lungs is a complex structure, which consists of:
- bronchi;
- bronchioles;
- acini.
An important part of the respiratory system is the bronchi. These are tubular branches of the trachea that connect it to the lungs. Their main task– air passage. In shape they resemble the crown of a tree, due to the many branches and are called the “bronchial tree”. The bifurcation of the trachea into the left and right bronchi occurs in the area of the fifth thoracic vertebra. Then they enter the lung tissue and branch into lobar, then into segmental, and finally into the smallest channels - bronchioles.
Each pulmonary bronchus with the largest diameter has three membranes: 
- external;
- fibrinous-muscular, having cartilaginous tissue;
- located inside them mucus layer with ciliated epithelium.
As the diameters of the branches of the bronchi decrease, their cartilage tissue and mucous membrane gradually decrease. They are no longer present in the bronchioles, but cuboidal epithelium (a thin layer) is formed.
The framework of the lungs is the bronchial system, which has a branched structure. Many lobules measuring 15x25 mm make up each lung. The apices of the lobules include bronchioles (branches of the bronchi), at the ends of which there are acini - special formations covered with a large number of alveoli.
Acini got their name because of their appearance, reminiscent of a bunch of grapes. Translated from Latin, Acinus means “bunch”. This is the main structural unit of lung tissue, which includes bronchioles, alveolar ducts, and primary pulmonary lobes in the form of small sacs.
The most important pulmonary elements are the alveoli, which ensure normal exchange of oxygen and carbon dioxide in the body. They are small thin-walled bubbles, tightly enveloped in a network of capillaries. Through the alveolar ducts blood vessels continuously supplied with oxygen and cleared of carbon dioxide. The tissue of each lung has 300 million alveoli. Oxygen is supplied to them by arterial capillaries, and carbon dioxide is taken in by venous vessels.
The alveoli themselves are microscopic in size - 0.3 mm. But, thanks to their huge number, the average respiratory surface area when exhaling is 35 square meters, and when inhaling it can reach up to 100 square meters. Of course, the indicators depend on the person’s constitution - height, weight, fitness. Athletes have the highest marks.
From small structures Acini form lobules, then larger ones, of which the largest pulmonary area is formed - the lobe. The structure of the left and right lungs is different.
The right lung consists of three lobes:
- the upper of the three segments;
- the middle of the two segments;
- lower lobe of five segments.
The left lung consists of two lobes:
- top of five segments;
- the lower of the five segments.
Division into lobes occurs through grooves. One of them (oblique) begins at each lung below 6–7 cm from their apices and extends to the diaphragm, separating the upper lobe from the lower. In the right lung, in the region of the IV rib, there is a horizontal groove separating the wedge-shaped pulmonary area - the middle lobe.
The bronchopulmonary segments do not have clearly defined divisions. The pulmonary segment is a separate area into which blood flows from one artery and ventilation is provided by one bronchus (third order). Lung tissue divided into segments different shapes, which differ not only in the right and left lungs, but are also located individually in each person.
Basic functions
In addition to the main respiratory function– ensuring gas exchange in the body, the lungs perform several more important missions:
- They normalize the pH composition in the blood, taking part in water, lipid, salt metabolism, and regulating the chlorine balance.
- They protect the body from respiratory infections because they produce antimicrobial substances, immunoglobulins.
- Provide thermoregulation.
- Helps maintain normal water balance in the body.
- Participate in the creation of vocal sounds.
- They serve as a kind of blood storage (contain approximately 9% of the total volume).
- Protect the heart from mechanical influences.
- Promote the removal of toxins, essential and other compounds.
- Participate in coagulation (blood clotting).
