Respiratory system: lungs. Structure and functions of the human respiratory system

The respiratory organs include: nasal cavity, pharynx. larynx, trachea, bronchi and lungs. The nasal cavity is divided into two halves by the osteochondral septum. Its inner surface is formed by three winding passages. Through them, air entering through the nostrils passes into the nasopharynx. Numerous glands located in the mucous membrane secrete mucus, which moisturizes the inhaled air. The extensive blood supply to the mucous membrane warms the air. The moist surface of the mucous membrane retains dust particles and microbes in the inhaled air, which are neutralized by mucus and leukocytes.

The mucous membrane of the respiratory tract is lined with ciliated epithelium, whose cells have on the outer surface of the surface the thinnest outgrowths - cilia, capable of contracting. The contraction of the cilia occurs rhythmically and is directed towards the exit from the nasal cavity. At the same time, mucus and dust particles and microbes adhered to it are carried out of the nasal cavity. Thus, the air passing through the nasal cavity is warmed and cleared of dust and some microbes. This does not happen when air enters the body through the oral cavity. This is why you should breathe through your nose and not through your mouth. Air enters the larynx through the nasopharynx.

The larynx looks like a funnel, the walls of which are formed by several cartilages. The entrance to the larynx during food swallowing is closed by the epiglottis, the thyroid cartilage, which can be easily felt from the outside. The larynx serves to conduct air from the pharynx to the trachea.

The trachea, or windpipe, is a tube about 10 cm long and 15–18 mm in diameter, the walls of which consist of cartilaginous half-rings connected by ligaments. The posterior wall is membranous, contains smooth muscle fibers, and is adjacent to the esophagus. The trachea is divided into two main bronchi, which enter the right and left lungs and branch into them, forming the so-called bronchial tree

On the terminal bronchial branches there are the smallest pulmonary vesicles - alveoli, with a diameter of 0.15–0.25 mm and a depth of 0.06–0.3 mm, filled with air. The walls of the alveoli are lined with single-layer squamous epithelium, covered with a dense film of a substance that prevents their collapse. The alveoli are penetrated by a dense network of blood vessels - capillaries. Gas exchange occurs through their walls.

The lungs are covered with a membrane - the pulmonary pleura, which passes into the parietal pleura, lining the inner wall of the chest cavity. The narrow space between the pulmonary and parietal pleura forms a pleural fissure filled with pleural fluid. Its role is to facilitate the sliding of the pleura during breathing movements.

Sivakova Elena Vladimirovna

primary school teacher

MBOU Elninskaya secondary school No. 1 named after M.I. Glinka.

Essay

"Respiratory system"

Plan

Introduction

I. Evolution of the respiratory organs.

II. Respiratory system. Functions of breathing.

III. The structure of the respiratory organs.

1. Nose and nasal cavity.

2. Nasopharynx.

3. Larynx.

4. Windpipe (trachea) and bronchi.

5. Lungs.

6. Diaphragm.

7. Pleura, pleural cavity.

8. Mediastinum.

IV. Pulmonary circulation.

V. The principle of breathing.

1. Gas exchange in the lungs and tissues.

2. Mechanisms of inhalation and exhalation.

3. Regulation of breathing.

VI. Respiratory hygiene and prevention of respiratory diseases.

1. Infection through the air.

2. Flu.

3. Tuberculosis.

4. Bronchial asthma.

5. The effect of smoking on the respiratory system.

Conclusion.

Bibliography.

Introduction

Breathing is the basis of life and health itself, the most important function and need of the body, a task that never gets boring! Human life without breathing is impossible - people breathe in order to live. During the process of breathing, air entering the lungs introduces atmospheric oxygen into the blood. Carbon dioxide is exhaled - one of the end products of cell activity.
The more perfect the breathing, the greater the physiological and energy reserves of the body and the stronger the health, the longer the life without disease and the better its quality. The priority of breathing for life itself is clearly and clearly visible from a long-known fact - if you stop breathing for just a few minutes, life will immediately end.
History has given us a classic example of such an act. The ancient Greek philosopher Diogenes of Sinope, as the story goes, “accepted death by biting his lips with his teeth and holding his breath.” He committed this act at the age of eighty. At that time, such a long life was quite rare.
Man is a single whole. The breathing process is inextricably linked with blood circulation, metabolism and energy, acid-base balance in the body, water-salt metabolism. The relationship between breathing and functions such as sleep, memory, emotional tone, performance and physiological reserves of the body, its adaptive (sometimes called adaptive) abilities has been established. Thus,breath – one of the most important functions of regulating the life of the human body.

Pleura, pleural cavity.

Pleura is a thin, smooth, serous membrane rich in elastic fibers that covers the lungs. There are two types of pleura: wall or parietal lining the walls of the chest cavity, andvisceral or pulmonary covering the outer surface of the lungs.A hermetically sealed seal is formed around each lung.pleural cavity , which contains a small amount of pleural fluid. This fluid, in turn, helps facilitate the breathing movements of the lungs. Normally, the pleural cavity is filled with 20-25 ml of pleural fluid. The volume of fluid that passes through the pleural cavity during the day is approximately 27% of the total volume of blood plasma. The sealed pleural cavity is moistened and there is no air in it, and the pressure in it is negative. Thanks to this, the lungs are always pressed tightly against the wall of the chest cavity, and their volume always changes along with the volume of the chest cavity.

Mediastinum. The mediastinum includes the organs that separate the left and right pleural cavities. The mediastinum is bounded by the thoracic vertebrae in the back and by the sternum in the front. The mediastinum is conventionally divided into anterior and posterior. The organs of the anterior mediastinum include mainly the heart with the pericardial sac and the initial sections of large vessels. The organs of the posterior mediastinum include the esophagus, descending branch of the aorta, thoracic lymphatic duct, as well as veins, nerves and lymph nodes.

IV .Pulmonary circulation

With each heartbeat, deoxygenated blood is pumped from the right ventricle of the heart to the lungs through the pulmonary artery. After numerous arterial branches, the blood flows through the capillaries of the alveoli (air bubbles) of the lung, where it is enriched with oxygen. As a result, the blood enters one of the four pulmonary veins. These veins go to the left atrium, from where blood is pumped through the heart into the systemic circulatory system.

The pulmonary circulation provides blood flow between the heart and lungs. In the lungs, the blood receives oxygen and releases carbon dioxide.

Pulmonary circulation . The lungs are supplied with blood from both circulations. But gas exchange occurs only in the capillaries of the pulmonary circulation, while the vessels of the systemic circulation provide nutrition to the lung tissue. In the area of ​​the capillary bed, vessels of different circles can anastomose with each other, providing the necessary redistribution of blood between the circulatory circles.

The resistance to blood flow in the vessels of the lungs and the pressure in them is less than in the vessels of the systemic circulation; the diameter of the pulmonary vessels is larger and their length is shorter. During inhalation, the blood flow into the vessels of the lungs increases and, due to their distensibility, they are able to accommodate up to 20-25% of the blood. Therefore, the lungs, under certain conditions, can act as a blood depot. The walls of the capillaries of the lungs are thin, which creates favorable conditions for gas exchange, but with pathology this can lead to their rupture and pulmonary hemorrhage. The blood reserve in the lungs is of great importance in cases where urgent mobilization of an additional amount of blood is necessary to maintain the required cardiac output, for example, at the beginning of intense physical work, when other mechanisms of blood circulation regulation have not yet turned on.

V. How breathing works

Breathing is the most important function of the body; it ensures the maintenance of an optimal level of redox processes in cells, cellular (endogenous) respiration. During the process of breathing, ventilation of the lungs and gas exchange between the cells of the body and the atmosphere occur, atmospheric oxygen is delivered to the cells, and it is used by the cells for metabolic reactions (oxidation of molecules). In this case, during the oxidation process, carbon dioxide is formed, which is partially used by our cells, and partially released into the blood and then removed through the lungs.

Specialized organs (nose, lungs, diaphragm, heart) and cells (erythrocytes - red blood cells containing hemoglobin, a special protein for oxygen transport, nerve cells that respond to carbon dioxide and oxygen - chemoreceptors of blood vessels and nerves) are involved in ensuring the breathing process brain cells that form the respiratory center)

Conventionally, the respiration process can be divided into three main stages: external respiration, transport of gases (oxygen and carbon dioxide) by the blood (between the lungs and cells) and tissue respiration (oxidation of various substances in the cells).

External breathing - gas exchange between the body and the surrounding atmospheric air.

Transport of gases by blood . The main carrier of oxygen is hemoglobin, a protein found inside red blood cells. Hemoglobin also transports up to 20% of carbon dioxide.

Tissue or "internal" respiration . This process can be divided into two: the exchange of gases between blood and tissues, the consumption of oxygen by cells and the release of carbon dioxide (intracellular, endogenous respiration).

The respiratory function can be characterized taking into account the parameters with which breathing is directly related - the content of oxygen and carbon dioxide, indicators of pulmonary ventilation (frequency and rhythm of breathing, minute volume of breathing). It is obvious that the state of health is determined by the state of the respiratory function, and the reserve capabilities of the body, the reserve of health, depend on the reserve capabilities of the respiratory system.

Gas exchange in the lungs and tissues

The exchange of gases in the lungs occurs thanks todiffusion.

The blood that flows to the lungs from the heart (venous) contains little oxygen and a lot of carbon dioxide; the air in the alveoli, on the contrary, contains a lot of oxygen and less carbon dioxide. As a result, two-way diffusion occurs through the walls of the alveoli and capillaries - oxygen passes into the blood, and carbon dioxide enters the alveoli from the blood. In the blood, oxygen enters red blood cells and combines with hemoglobin. The oxygenated blood becomes arterial and flows through the pulmonary veins into the left atrium.

In humans, the exchange of gases is completed in a few seconds while the blood passes through the alveoli of the lungs. This is possible due to the huge surface of the lungs, which communicates with the external environment. The total surface of the alveoli is over 90 m 3 .

The exchange of gases in tissues occurs in capillaries. Through their thin walls, oxygen flows from the blood into the tissue fluid and then into the cells, and carbon dioxide passes from the tissues into the blood. The concentration of oxygen in the blood is greater than in the cells, so it diffuses easily into them.

The concentration of carbon dioxide in the tissues where it accumulates is higher than in the blood. Therefore, it passes into the blood, where it binds to chemical compounds in the plasma and partly with hemoglobin, is transported by the blood to the lungs and released into the atmosphere.

Mechanisms of inhalation and exhalation

Carbon dioxide constantly flows from the blood into the alveolar air, and oxygen is absorbed by the blood and consumed; ventilation of the alveolar air is necessary to maintain the gas composition of the alveoli. It is achieved through breathing movements: alternating inhalation and exhalation. The lungs themselves cannot pump or expel air from their alveoli. They only passively follow changes in the volume of the chest cavity. Due to the difference in pressure, the lungs are always pressed against the walls of the chest and precisely follow the change in its configuration. When inhaling and exhaling, the pulmonary pleura slides along the parietal pleura, repeating its shape.

Inhale consists in the fact that the diaphragm moves down, pushing the abdominal organs, and the intercostal muscles lift the chest up, forward and to the sides. The volume of the chest cavity increases, and the lungs follow this increase, as the gases contained in the lungs press them against the parietal pleura. As a result, the pressure inside the pulmonary alveoli drops, and outside air enters the alveoli.

Exhalation begins with the intercostal muscles relaxing. Under the influence of gravity, the chest wall goes down, and the diaphragm rises up, since the stretched abdominal wall puts pressure on the internal organs of the abdominal cavity, and they put pressure on the diaphragm. The volume of the chest cavity decreases, the lungs are compressed, the air pressure in the alveoli becomes higher than atmospheric pressure, and some of it comes out. All this happens with calm breathing. When you inhale and exhale deeply, additional muscles are activated.

Neurohumoral regulation of respiration

Breathing regulation

Nervous regulation of breathing . The respiratory center is located in the medulla oblongata. It consists of inhalation and exhalation centers that regulate the functioning of the respiratory muscles. The collapse of the pulmonary alveoli, which occurs during exhalation, reflexively causes inhalation, and the expansion of the alveoli reflexively causes exhalation. When you hold your breath, the inhalation and exhalation muscles contract simultaneously, keeping the chest and diaphragm in the same position. The work of the respiratory centers is also influenced by other centers, including those located in the cerebral cortex. Thanks to their influence, breathing changes when speaking and singing. It is also possible to consciously change your breathing rhythm during exercise.

Humoral regulation of respiration . During muscle work, oxidation processes intensify. Consequently, more carbon dioxide is released into the blood. When blood with excess carbon dioxide reaches the respiratory center and begins to irritate it, the activity of the center increases. The person begins to breathe deeply. As a result, excess carbon dioxide is removed, and the lack of oxygen is replenished. If the concentration of carbon dioxide in the blood decreases, the work of the respiratory center is inhibited and involuntary holding of breath occurs. Thanks to nervous and humoral regulation, in any conditions the concentration of carbon dioxide and oxygen in the blood is maintained at a certain level.

VI .Respiratory hygiene and prevention of respiratory diseases

The need for respiratory hygiene is very well and accurately expressed

V.V. Mayakovsky:

You can't lock a person in a box,
Ventilate your home cleaner and more often .

To maintain health, it is necessary to maintain normal air composition in residential, educational, public and work areas and constantly ventilate them.

Green plants grown indoors remove excess carbon dioxide from the air and enrich it with oxygen. In industries that pollute the air with dust, industrial filters and specialized ventilation are used, and people work in respirators - masks with an air filter.

Among the diseases that affect the respiratory system are infectious, allergic, and inflammatory. TOinfectious include influenza, tuberculosis, diphtheria, pneumonia, etc.; Toallergic - bronchial asthma, toinflammatory - tracheitis, bronchitis, pleurisy, which can occur under unfavorable conditions: hypothermia, exposure to dry air, smoke, various chemicals or, as a result, after infectious diseases.

1. Infection through the air .

There are always bacteria in the air along with dust. They settle on dust particles and remain suspended for a long time. Where there is a lot of dust in the air, there are a lot of microbes. From one bacterium at a temperature of +30(C), two bacteria are formed every 30 minutes; at +20(C), their division slows down by half.
Microbes stop multiplying at +3 +4 (C. There are almost no microbes in the frosty winter air. The sun's rays have a detrimental effect on microbes.

Microorganisms and dust are retained by the mucous membrane of the upper respiratory tract and are removed from them along with mucus. Most microorganisms are thus neutralized. Some microorganisms that penetrate the respiratory system can cause various diseases: influenza, tuberculosis, sore throat, diphtheria, etc.

2. Flu.

Flu is caused by viruses. They are microscopically small and do not have a cellular structure. Influenza viruses are contained in mucus released from the noses of sick people, in their sputum and saliva. When sick people sneeze and cough, millions of invisible droplets containing infection enter the air. If they penetrate the respiratory organs of a healthy person, he can become infected with the flu. Thus, influenza is a droplet infection. This is the most common disease of all existing ones.
The influenza epidemic, which began in 1918, killed about 2 million people in a year and a half. The influenza virus changes its shape under the influence of drugs and exhibits extreme resistance.

The flu spreads very quickly, so people with the flu should not be allowed to work or attend classes. It is dangerous due to its complications.
When communicating with people with the flu, you need to cover your mouth and nose with a bandage made from a piece of gauze folded in four. Cover your mouth and nose with a tissue when coughing or sneezing. This will protect you from infecting others.

3. Tuberculosis.

The causative agent of tuberculosis, the tuberculosis bacillus, most often affects the lungs. It can be in the inhaled air, in droplets of sputum, on dishes, clothes, towels and other items used by the patient.
Tuberculosis is not only a droplet infection, but also a dust infection. Previously, it was associated with poor nutrition and poor living conditions. Now a powerful surge in tuberculosis is associated with a general decrease in immunity. After all, there has always been a lot of tuberculosis bacillus, or Koch bacillus, outside, both before and now. It is very tenacious - it forms spores and can be stored in dust for decades. And then it enters the lungs by air, without causing illness, however. Hence, almost everyone today has a “dubious” reaction
Mantoux. And for the development of the disease itself, you need either direct contact with the patient, or a weakened immune system when the stick begins to “act”.
In large cities there are now many homeless people and those released from prison - and this is a real breeding ground for tuberculosis. In addition, new strains of tuberculosis have appeared that are not sensitive to known drugs, and the clinical picture has blurred.

4. Bronchial asthma.

Bronchial asthma has become a real disaster recently. Asthma today is a very common disease, serious, incurable and socially significant. Asthma is a protective reaction of the body taken to the point of absurdity. When harmful gas enters the bronchi, a reflex spasm occurs, blocking the toxic substance from entering the lungs. Currently, a protective reaction in asthma has begun to occur to many substances, and the bronchi have begun to “slam shut” from the most harmless odors. Asthma is a typically allergic disease.

5. Effect of smoking on the respiratory system .

Tobacco smoke, in addition to nicotine, contains about 200 substances that are extremely harmful to the body, including carbon monoxide, hydrocyanic acid, benzopyrene, soot, etc. The smoke of one cigarette contains about 6 mmg. nicotine, 1.6 mmg. ammonia, 0.03 mmg. hydrocyanic acid, etc. When smoking, these substances penetrate the oral cavity, upper respiratory tract, settle on their mucous membranes and the film of pulmonary vesicles, are swallowed with saliva and enter the stomach. Nicotine is harmful not only to the smoker. A non-smoker who spends a long time in a smoky room can become seriously ill. Tobacco smoke and smoking are extremely harmful at a young age.
There is direct evidence of a decline in mental abilities in adolescents due to smoking. Tobacco smoke causes irritation of the mucous membranes of the mouth, nasal cavity, respiratory tract and eyes. Almost all smokers develop inflammation of the respiratory tract, which is associated with a painful cough. Constant inflammation reduces the protective properties of the mucous membranes, because... phagocytes cannot cleanse the lungs of pathogenic microbes and harmful substances that come with tobacco smoke. Therefore, smokers often suffer from colds and infectious diseases. Particles of smoke and tar settle on the walls of the bronchi and pulmonary vesicles. The protective properties of the film are reduced. A smoker's lungs lose their elasticity and become inextensible, which reduces their vital capacity and ventilation. As a result, the oxygen supply to the body is reduced. Performance and general well-being deteriorate sharply. Smokers are much more likely to have pneumonia and 25 times more often - lung cancer.
The saddest thing is that the person who smoked30 years, and then quit, even after10 I have not been immune from cancer for years. Irreversible changes have already occurred in his lungs. You need to quit smoking immediately and forever, then this conditioned reflex quickly fades away. It is important to be convinced of the dangers of smoking and to have willpower.

You can prevent respiratory diseases yourself by adhering to certain hygiene requirements.

During an epidemic of infectious diseases, get vaccinated in a timely manner (anti-influenza, anti-diphtheria, anti-tuberculosis, etc.)

During this period, you should not visit crowded places (concert halls, theaters, etc.)

Adhere to the rules of personal hygiene.

Undergo medical examination, that is, a medical examination.

Increase the body's resistance to infectious diseases through hardening and vitamin nutrition.

Conclusion

From all of the above and having understood the role of the respiratory system in our lives, we can conclude about its importance in our existence.
Breath is life. Now this is completely indisputable. Meanwhile, just three centuries ago, scientists were convinced that a person breathes only in order to remove “excess” heat from the body through the lungs. Deciding to refute this absurdity, the outstanding English naturalist Robert Hooke invited his colleagues at the Royal Scientific Society to conduct an experiment: use an airtight bag for breathing for some time. Not surprisingly, the experiment stopped in less than a minute: the pundits began to choke. However, even after this, some of them stubbornly continued to insist on their own. Hook then just threw up his hands. Well, we can even explain such unnatural stubbornness by the work of the lungs: when breathing, too little oxygen enters the brain, which is why even a born thinker becomes stupid right before our eyes.
Health is established in childhood, any deviation in the development of the body, any disease subsequently affects the health of an adult.

We must cultivate the habit of analyzing our condition even when we feel good, learn to exercise our health, and understand its dependence on the state of the environment.

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Respiratory system.

Functions of the respiratory system:

1. Provides body tissues with oxygen and removes carbon dioxide from them;

3. participates in the sense of smell;

4. participates in the production of hormones;

5. participates in metabolism;

6. participates in immunological protection.

In the airways, the air is warmed or cooled, purified, moistened, and olfactory, temperature and mechanical stimuli are also perceived. The respiratory system begins with the nasal cavity.

The entrance openings to the nasal cavity are the nostrils. The anterior lower wall separates the nasal cavity from the oral cavity, and consists of the soft and hard palate. The posterior wall of the nose is the nasopharyngeal opening (choanae) which passes into the nasopharynx. The nasal plate consists of the anterior ethmoid bone and vomer. From the nasal septum, on different sides there are curved bone plates - the nasal turbinates. The nasolacrimal duct opens into the lower nasal passage.

The mucous membrane is lined with ciliated epithelium and contains a significant number of glands that secrete mucus. There are also many vessels that warm cold air and nerves that perform the olfactory function, which is why it is considered the organ of smell. Through the choanae, air enters the pharynx and then into the larynx.

Larynx (larynx)– located in the front of the neck at the level of the IV-VII cervical vertebrae; on the surface of the neck it forms a small (in women) and strongly protruding (in men) elevation - the protrusion of the larynx (Adam's apple, prominent lyngeria). In front, the larynx is suspended at the hyoid bone, below it connects to the trachea. The muscles of the neck lie in front of the larynx, and the neurovascular bundles lie on the side. Consists of cartilage. They are divided into:

1. unpaired (cricoid, thyroid, epiglottis);

2. paired (arytenoid, corniculate, wedge-shaped).

Laryngeal cartilages.

Main cartilage- This is the cricoid cartilage, which connects below with ligaments to the first cartilaginous ring.

The basis of the larynx is hyaline cricoid cartilage, which connects to the first tracheal cartilage using a ligament. It has an arc and a quadrangular plate; the arch of cartilage is directed forward, the plate is directed backward. On the arch of the cricoid cartilage there is hyaline unpaired, the largest cartilage of the larynx - thyroid . Arytenoid cartilage paired, hyaline, similar to a quadrangular pyramid. Horn-shaped And sphenoid cartilage are located in the thickness of the arytenoid ligament.

The cartilages of the larynx are connected to each other by joints and ligaments. Muscles of the larynx. All muscles of the larynx are divided into three groups: dilators, which narrow the glottis and change the tension of the vocal cords. 1. Muscle that expands the glottis - posterior cricoarytenoid(paired muscle);

The larynx has membranes:

1.mucous membrane – covered with ciliated epithelium, except for the vocal cords.

2. fibrocartilaginous - - consists of hyaline and elastic cartilage.

3. connective tissue (adventitia).

In children, the size of the larynx is smaller than in adults; vocal cords are shorter, voice timbre is higher. The size of the larynx may change during puberty, leading to changes in voice.

Trachea– this is a tube 10-15 cm long, has 2 parts: cervical and thoracic. The esophagus passes behind, the thyroid gland, thymus, aortic arch and its branches pass in front. At the level of the lower edge of the VI cervical vertebra, and ends at the level of the upper edge of the V thoracic vertebra. It is divided into 2 bronchi, which extend into the right and left lungs. This place is called a bifurcation.

Right – length 3 cm, consists of 6-8 cartilages. Shorter and wider, extends from the trachea at an obtuse angle.

Left – length 4-5cm, consists of 9-12 cartilages. Long and narrow, goes under the aortic arch.

The trachea and bronchi consist of 16-20 hyaline cartilaginous half-rings. The semirings are connected to each other by ring ligaments. From the inside, the trachea and bronchi are lined with mucous membrane, then submucous membrane, and behind it cartilage tissue. The mucous membrane has no folds, is lined with multirow plasmatic ciliated epithelium and also has a large number of goblet cells.

Lungs- these are the main organs of the respiratory apparatus, occupying almost the entire chest cavity. They change shape and size depending on the breathing phase. It has the shape of a truncated cone. The apex of the lung faces above the clavicular fossa. At the bottom, the lungs have a concave base. They are adjacent to the diaphragm.

There are three surfaces in the lung: convex, costal adjacent to the inner surface of the wall of the chest cavity; diaphragmatic– adjacent to the diaphragm; medial (mediastinal), directed towards the mediastinum.

Each lung is divided into lobes by grooves: the right one into 3 (upper, middle, lower), the left into 2 (upper and lower).

Each lung consists of branched bronchi, which form the bronchial tree and the pulmonary vesicle system. A bronchus with a diameter of 1 mm is called lobular. Each alveolar duct ends in two alveolar sacs. The walls of the alveolar sacs consist of the pulmonary alveoli. The diameter of the alveolar duct and alveolar sac is 0.2 - 0.6 mm, the alveoli - 0.25-0.30 mm.

The respiratory bronchioles, as well as the alveolar ducts, alveolar sacs and alveoli of the lung form alveolar tree (pulmonary acinus), which is the structural and functional unit of the lung. The number of pulmonary acini in one lung is 15,000; the number of alveoli is on average 300-350 million, and the area of ​​the respiratory surface of all alveoli is about 80 m2.

Pleura- a thin, smooth serous membrane that envelops each lung.

Distinguish visceral pleura, which tightly fuses with the lung tissue and extends into the cracks between the lobes of the lung, and parietal, which lines the inside of the chest cavity wall.

The parietal pleura consists of the costal, mediastinal and diaphragmatic pleura.

A slit-like closed space is formed between the parietal and visceral pleura - pleural cavity. It contains a small amount of serous fluid.

Mediastinum (mediastinum) – is a complex of organs located between the right and left pleural cavities. The mediastinum is limited in front by the sternum, in the back by the thoracic spine, and on the sides by the right and left mediastinal pleura. At the top, the mediastinum continues to the superior thoracic aperture, and at the bottom to the diaphragm. There are two sections of the mediastinum: superior and inferior.

Breathing is one of the most basic properties of any living organism. Its enormous importance cannot be overestimated. A person only thinks about how important normal breathing is when it suddenly becomes difficult, for example, when a cold appears. If a person can still live for some time without food and water, then without breathing - only a matter of seconds. In one day, an adult takes more than 20,000 inhalations and the same number of exhalations.

The structure of the human respiratory system - what it is, we will analyze in this article.

How a person breathes

This system is one of the most important in the human body. This is a whole set of processes that occur in a certain relationship and are aimed at ensuring that the body receives oxygen from the environment and releases carbon dioxide. What is breathing and how do the respiratory organs work?

The human respiratory organs are conventionally divided into airways and lungs.

The main role of the former is the unhindered delivery of air to the lungs. The human respiratory tract begins with the nose, but the process itself can also occur through the mouth if the nose is stuffy. However, nasal breathing is preferable, because when passing through the nasal cavity, the air is purified, but if it enters through the mouth, it is not.

There are three main processes in breathing:

• external breathing;
• transfer of gases through the bloodstream;
• internal (cellular) respiration;

When you inhale through your nose or mouth, air first enters the throat. Together with the larynx and paranasal sinuses, these anatomical cavities belong to the upper respiratory tract.

The lower respiratory tract is the trachea, the bronchi connected to it, and the lungs.

All together they form a single functional system.

It is easier to visualize its structure using a diagram or table.

During respiration, sugar molecules are broken down and carbon dioxide is released.

The process of breathing in the body

Gas exchange occurs due to their different concentrations in the alveoli and capillaries. This process is called diffusion. In the lungs, oxygen flows from the alveoli into the vessels, and carbon dioxide flows back. Both alveoli and capillaries consist of a single layer of epithelium, which allows gases to easily penetrate them.

The transport of gas to the organs occurs as follows: first, oxygen enters the lungs through the airways. When air enters the blood vessels, it forms unstable compounds with hemoglobin in red blood cells, and together with it moves to various organs. Oxygen is easily detached and then enters the cells. In the same way, carbon dioxide combines with hemoglobin and is transported in the opposite direction.

When oxygen reaches cells, it penetrates first into the intercellular space and then directly into the cell.

The main purpose of breathing is the generation of energy in cells.

The parietal pleura, pericardium and peritoneum are attached to the tendons of the diaphragm, which means that during breathing there is a temporary displacement of the organs of the chest and abdominal cavity.

When you inhale, the volume of the lungs increases and when you exhale, it decreases accordingly. At rest, a person uses only 5 percent of the total lung capacity.

Functions of the respiratory system

Its main purpose is to supply the body with oxygen and remove waste products. But the functions of the respiratory system may be different.

During respiration, oxygen is constantly absorbed by the cells and at the same time they give off carbon dioxide. However, it should be noted that the organs of the respiratory system are also involved in other important functions of the body, in particular, they are directly involved in the formation of speech sounds, as well as the sense of smell. In addition, the respiratory organs are actively involved in the process of thermoregulation. The temperature of the air that a person inhales directly affects his body temperature. Exhaled gases reduce body temperature.

Excretory processes also partially involve the organs of the respiratory system. A certain amount of water vapor is also released.

The structure of the respiratory organs and the respiratory organs also provide the body’s defenses, because when air passes through the upper respiratory tract, it is partially cleansed.

On average, a person consumes about 300 ml of oxygen in one minute and emits 200 g of carbon dioxide. However, if physical activity increases, oxygen consumption increases significantly. In one hour, a person is able to release from 5 to 8 liters of carbon dioxide into the external environment. Also, during the breathing process, dust, ammonia and urea are removed from the body.

The respiratory organs are directly involved in the formation of the sounds of human speech.

Respiratory organs: description

All respiratory organs are interconnected.

Nose

This organ is not only an active participant in the breathing process. It is also an organ of smell. This is where the respiratory process begins.

The nasal cavity is divided into sections. Their classification is as follows:

• lower section;
• average;
• upper;
• general.

The nose is divided into bony and cartilaginous sections. The nasal septum separates the right and left halves.

The inside of the cavity is covered with ciliated epithelium. Its main purpose is to clean and warm the incoming air. The viscous mucus found here has bactericidal properties. Its quantity increases sharply with the appearance of various pathologies.

The nasal cavity contains a large number of small venous vessels. When they are damaged, nosebleeds occur.

Larynx

The larynx is an extremely important component of the respiratory system, located between the pharynx and trachea. It is a cartilaginous formation. Laryngeal cartilages are:

1. Paired (arytenoid, corniculate, wedge-shaped, granular).
2. Unpaired (thyroid, cricoid and epiglottis).

In men, the junction of the plates of the thyroid cartilage protrudes greatly. They form the so-called “Adam's apple”.

The joints of the organ ensure its mobility. The larynx has many different ligaments. There is also a whole group of muscles that tense the vocal cords. The vocal cords themselves are located in the larynx and are directly involved in the formation of speech sounds.

The larynx is formed in such a way that the process of swallowing does not interfere with breathing. It is located at the level of the fourth to seventh cervical vertebrae.

Trachea

The actual extension of the larynx is the trachea. According to the location of the organs in the trachea, the cervical and thoracic parts are divided. The esophagus is adjacent to the trachea. The neurovascular bundle runs very close to it. It includes the carotid artery, vagus nerve and jugular vein.

The trachea branches into two sides. This point of separation is called a bifurcation. The posterior wall of the trachea is flattened. This is where the muscle tissue is located. Its special location allows the trachea to be mobile when coughing. The trachea, like other respiratory organs, is covered with a special mucous membrane - ciliated epithelium.

Bronchi

The branching of the trachea leads to the next paired organ - the bronchi. The main bronchi in the hilum area are divided into lobar bronchi. The right main bronchus is wider and shorter than the left.

At the end of the bronchioles are the alveoli. These are small passages, at the end of which there are special bags. They exchange oxygen and carbon dioxide with small blood vessels. The alveoli are lined from the inside with a special substance. They maintain their surface tension, preventing the alveoli from sticking together. The total number of alveoli in the lungs is approximately 700 million.

Lungs

Of course, all organs of the respiratory system are important, but the lungs are considered the most significant. They directly exchange oxygen and carbon dioxide.

The organs are located in the chest cavity. Their surface is lined with a special membrane called pleura.

The right lung is a couple of centimeters shorter than the left lung. The lungs themselves do not contain muscles.

There are two sections in the lungs:

1. The top.
2. Base.

And also three surfaces: diaphragmatic, costal and mediastinal. They face the diaphragm, ribs, and mediastinum respectively. The surfaces of the lung are separated by edges. The costal and mediastinal regions are separated by the anterior edge. The lower edge separates from the diaphragm area. Each lung is divided into lobes.

The right lung has three of them:

Upper;

Average;

The left one has only two: upper and lower. Between the lobes there are interlobar surfaces. Both lungs have an oblique fissure. It separates the lobes of the organ. The right lung additionally has a horizontal fissure separating the upper and middle lobes.

The base of the lung is expanded, and the upper part is narrowed. On the inner surface of each part there are small indentations called gates. The formations that create the root of the lung pass through them. Lymphatic and blood vessels and bronchi pass through here. In the right lung there is a bronchus, a pulmonary vein, and two pulmonary arteries. In the left there is a bronchus, a pulmonary artery, two pulmonary veins.

In the front of the left lung there is a small depression - the cardiac notch. From below it is limited by a part called the tongue.

The chest protects the lungs from external damage. The chest cavity is sealed, it is separated from the abdominal cavity.

Diseases associated with the lungs greatly affect the general condition of the human body.

Pleura

The lungs are covered with a special film - pleura. It consists of two parts: the outer and inner petals.

The pleural cavity always contains a small amount of serous fluid, which ensures the wetting of the pleural lobes.

The human respiratory system is created in such a way that there is negative air pressure directly in the pleural cavity. It is thanks to this fact, as well as the surface tension of the serous fluid, that the lungs are constantly in an expanded state, and they also accept the respiratory movements of the chest.

Respiratory muscles

Respiratory muscles are divided into inspiratory (producing inhalation) and expiratory (working when exhaling).

The main inspiratory muscles are:

1. Diaphragm.
2. External intercostal.
3. Intercartilaginous internal muscles.

There are also inspiratory accessory muscles (scalenes, trapezius, pectoralis major and minor, etc.)

The intercostal, rectus, hypocostal, transverse, external and internal oblique abdominal muscles are expiratory muscles.

Diaphragm

The diaphragm also plays a significant role in the breathing process. This is a unique plate that separates two cavities: the thoracic and abdominal. It is classified as a respiratory muscle. In the diaphragm itself there is a tendon center and three more muscle areas.

When contraction occurs, the diaphragm moves away from the chest wall. At this time, the volume of the chest cavity increases. The simultaneous contraction of this muscle and the abdominal muscles causes the pressure inside the chest cavity to become less than the external atmospheric pressure. At this moment, air enters the lungs. Then, as a result of muscle relaxation, exhalation occurs

Respiratory mucosa

The respiratory organs are covered with a protective mucous membrane - ciliated epithelium. On the surface of the ciliated epithelium there is a huge number of cilia, constantly carrying out the same movement. Special cells located between them, together with the mucous glands, produce mucus that wets the cilia. Like duct tape, tiny particles of dust and dirt inhaled stick to it. They are transported to the pharynx and removed. In the same way, harmful viruses and bacteria are eliminated.

This is a natural and quite effective self-cleaning mechanism. This shell structure and ability to be cleaned applies to all respiratory organs.

Factors affecting the state of the respiratory system

Under normal conditions, the respiratory system works clearly and smoothly. Unfortunately, it can be easily damaged. Many factors can influence its condition:

1. Cold.
2. Excessively dry air generated in the room as a result of the operation of heating devices.
3. Allergy.
4. Smoking.

All this has an extremely negative impact on the state of the respiratory system. In this case, the movement of the epithelial cilia can slow down significantly, or even stop altogether.

Harmful microorganisms and dust are no longer removed, resulting in a risk of infection.

Initially, this manifests itself in the form of a cold, and here the upper respiratory tract is primarily affected. There is a violation of ventilation in the nasal cavity, there is a feeling of nasal congestion and a general discomfort.

In the absence of correct and timely treatment, the paranasal sinuses will be involved in the inflammatory process. In this case, sinusitis occurs. Then other signs of respiratory diseases appear.

Cough occurs due to excessive irritation of cough receptors in the nasopharynx. The infection easily passes from the upper to the lower passages and the bronchi and lungs are affected. Doctors say in this case that the infection has “sank” lower. This is fraught with serious diseases such as pneumonia, bronchitis, and pleurisy. Medical institutions strictly monitor the condition of equipment intended for anesthesia and respiratory procedures. This is done to avoid infection of patients. There are SanPiN (SanPiN 2.1.3.2630-10) that must be observed in hospitals.

Like any other system of the body, the respiratory system should be taken care of: treated in a timely manner if a problem arises, and also avoid the negative influence of the environment, as well as bad habits.

The human respiratory organs include:

• nasal cavity;
• paranasal sinuses;
• larynx;
• trachea;
• bronchi;
• lungs.

Let's look at the structure of the respiratory organs and their functions. This will help to better understand how diseases of the respiratory system develop.

The external nose, which we see on a person’s face, consists of thin bones and cartilage. On top they are covered with a small layer of muscle and skin. The nasal cavity is limited in front by the nostrils. On the reverse side of the nasal cavity there are openings - choanae, through which air enters the nasopharynx.

The nasal cavity is divided in half by the nasal septum. Each half has an inner and outer wall. On the side walls there are three projections - the turbinates, separating the three nasal passages.

There are openings in the two upper passages, through which there is a connection with the paranasal sinuses. The lower passage opens the mouth of the nasolacrimal duct, through which tears can enter the nasal cavity.

The entire nasal cavity is covered from the inside with a mucous membrane, on the surface of which lies ciliated epithelium, which has many microscopic cilia. Their movement is directed from front to back, towards the choanae. Therefore, most of the mucus from the nose enters the nasopharynx and does not come out.

In the area of ​​the upper nasal passage there is the olfactory region. Sensitive nerve endings are located there - olfactory receptors, which through their processes transmit the received information about odors to the brain.

The nasal cavity is well supplied with blood and has many small vessels carrying arterial blood. The mucous membrane is easily vulnerable, so nosebleeds are possible. Particularly severe bleeding occurs when damaged by a foreign body or when the venous plexuses are injured. Such plexuses of veins can quickly change their volume, leading to nasal congestion.

Lymphatic vessels communicate with the spaces between the membranes of the brain. In particular, this explains the possibility of rapid development of meningitis in infectious diseases.

The nose performs the function of conducting air, smelling, and is also a resonator for the formation of voice. The important role of the nasal cavity is protective. The air passes through the nasal passages, which have a fairly large area, and is warmed and moistened there. Dust and microorganisms partially settle on the hairs located at the entrance to the nostrils. The rest are transmitted to the nasopharynx with the help of epithelial cilia, and are removed from there by coughing, swallowing, and blowing the nose. The mucus of the nasal cavity also has a bactericidal effect, that is, it kills some of the microbes that get into it.

Paranasal sinuses

The paranasal sinuses are cavities that lie in the bones of the skull and are connected to the nasal cavity. They are covered from the inside with mucous membranes and have the function of a vocal resonator. Paranasal sinuses:

• maxillary (maxillary);
• frontal;
• wedge-shaped (main);
• cells of the ethmoid bone labyrinth.

Paranasal sinuses

The two maxillary sinuses are the largest. They are located in the thickness of the upper jaw under the orbits and communicate with the middle passage. The frontal sinus is also paired, located in the frontal bone above the eyebrow and has the shape of a pyramid, with the apex facing down. Through the nasofrontal canal it also connects to the middle passage. The sphenoid sinus is located in the sphenoid bone on the posterior wall of the nasopharynx. In the middle of the nasopharynx, the openings of the cells of the ethmoid bone open.

The maxillary sinus communicates most closely with the nasal cavity, therefore, often after the development of rhinitis, sinusitis appears when the path of outflow of inflammatory fluid from the sinus to the nose is blocked.

Larynx

This is the upper respiratory tract, which is also involved in the formation of the voice. It is located approximately in the middle of the neck, between the pharynx and trachea. The larynx is formed by cartilage, which is connected by joints and ligaments. In addition, it is attached to the hyoid bone. Between the cricoid and thyroid cartilages there is a ligament, which is cut in case of acute laryngeal stenosis to provide air access.

The larynx is lined with ciliated epithelium, and on the vocal cords the epithelium is stratified squamous, quickly renewed and allowing the ligaments to be resistant to constant stress.

Under the mucous membrane of the lower part of the larynx, below the vocal cords, there is a loose layer. It can swell quickly, especially in children, causing laryngospasm.

Trachea

The lower respiratory tract begins with the trachea. It continues with the larynx and then passes into the bronchi. The organ looks like a hollow tube consisting of cartilaginous half-rings tightly connected to each other. The length of the trachea is about 11 cm.

Below, the trachea forms two main bronchi. This zone is an area of ​​bifurcation (bifurcation), it has many sensitive receptors.

The trachea is lined with ciliated epithelium. Its feature is its good absorption ability, which is used for inhalation of drugs.

For laryngeal stenosis, in some cases a tracheotomy is performed - the anterior wall of the trachea is cut and a special tube is inserted through which air enters.

Bronchi

This is a system of tubes through which air passes from the trachea to the lungs and back. They also have a cleansing function.

The bifurcation of the trachea is located approximately in the interscapular area. The trachea forms two bronchi, which go to the corresponding lung and there are divided into lobar bronchi, then into segmental, subsegmental, lobular, which are divided into terminal bronchioles - the smallest of the bronchi. This entire structure is called the bronchial tree.

Terminal bronchioles have a diameter of 1–2 mm and pass into the respiratory bronchioles, from which the alveolar ducts begin. At the ends of the alveolar ducts there are pulmonary vesicles - alveoli.

Trachea and bronchi

The inside of the bronchi is lined with ciliated epithelium. The constant wave-like movement of the cilia brings up the bronchial secretion - a liquid continuously produced by the glands in the wall of the bronchi and washing away all impurities from the surface. This removes microorganisms and dust. If there is an accumulation of thick bronchial secretions, or a large foreign body enters the lumen of the bronchi, they are removed using a protective mechanism aimed at cleansing the bronchial tree.

In the walls of the bronchi there are ring-shaped bundles of small muscles that are able to “block” the flow of air when it is contaminated. This is how it arises. In asthma, this mechanism begins to work when a substance common to a healthy person, for example, plant pollen, is inhaled. In these cases, bronchospasm becomes pathological.

Respiratory organs: lungs

A person has two lungs located in the chest cavity. Their main role is to ensure the exchange of oxygen and carbon dioxide between the body and the environment.

How are the lungs structured? They are located on the sides of the mediastinum, in which the heart and blood vessels lie. Each lung is covered with a dense membrane - the pleura. Between its leaves there is normally a little fluid, which allows the lungs to slide relative to the chest wall during breathing. The right lung is larger than the left. Through the root, located on the inside of the organ, the main bronchus, large vascular trunks, and nerves enter it. The lungs consist of lobes: the right one has three, the left one has two.

The bronchi, entering the lungs, are divided into smaller and smaller ones. The terminal bronchioles become alveolar bronchioles, which divide and become alveolar ducts. They also branch out. At their ends there are alveolar sacs. Alveoli (respiratory vesicles) open on the walls of all structures, starting with the respiratory bronchioles. The alveolar tree consists of these formations. The branches of one respiratory bronchiole ultimately form the morphological unit of the lungs - the acinus.

The structure of the alveoli

The alveolar orifice has a diameter of 0.1 - 0.2 mm. The inside of the alveolar vesicle is covered with a thin layer of cells lying on a thin wall - a membrane. Outside, a blood capillary is adjacent to the same wall. The barrier between air and blood is called aerohematic. Its thickness is very small - 0.5 microns. An important part of it is the surfactant. It consists of proteins and phospholipids, lines the epithelium and maintains the rounded shape of the alveoli during exhalation, preventing the penetration of microbes from the air into the blood and liquids from the capillaries into the lumen of the alveoli. Premature babies have poorly developed surfactant, which is why they often have breathing problems immediately after birth.

The lungs contain vessels from both circulation circles. The arteries of the great circle carry oxygen-rich blood from the left ventricle of the heart and directly feed the bronchi and lung tissue, like all other human organs. The arteries of the pulmonary circulation bring venous blood from the right ventricle to the lungs (this is the only example when venous blood flows through the arteries). It flows through the pulmonary arteries, then enters the pulmonary capillaries, where gas exchange occurs.

The essence of the breathing process

The exchange of gases between the blood and the external environment that takes place in the lungs is called external respiration. It occurs due to the difference in the concentration of gases in the blood and air.

The partial pressure of oxygen in air is greater than in venous blood. Due to the pressure difference, oxygen penetrates from the alveoli into the capillaries through the air-hematic barrier. There it joins red blood cells and spreads through the bloodstream.

Gas exchange across the air-blood barrier

The partial pressure of carbon dioxide in venous blood is greater than in air. Because of this, carbon dioxide leaves the blood and is released with exhaled air.

Gas exchange is a continuous process that continues as long as there is a difference in the content of gases in the blood and the environment.

During normal breathing, about 8 liters of air pass through the respiratory system per minute. With stress and diseases accompanied by increased metabolism (for example, hyperthyroidism), pulmonary ventilation increases and shortness of breath appears. If increased breathing fails to maintain normal gas exchange, the oxygen content in the blood decreases - hypoxia occurs.

Hypoxia also occurs in high altitude conditions, where the amount of oxygen in the external environment is reduced. This leads to the development of mountain sickness.