Respiration is a complex and continuous biological process, as a result of which the body consumes free electrons and oxygen from the external environment, and releases carbon dioxide and water saturated with hydrogen ions.

The human respiratory system is a set of organs that provide the function of external human respiration (gas exchange between the inhaled atmospheric air and the blood circulating in the pulmonary circulation).

Gas exchange is carried out in the alveoli of the lungs, and is normally aimed at capturing oxygen from the inhaled air and releasing carbon dioxide formed in the body into the external environment.

An adult, being at rest, takes an average of 15-17 breaths per minute, and a newborn child takes 1 breath per second.

Ventilation of the alveoli is carried out by alternating inhalation and exhalation. When you inhale, atmospheric air enters the alveoli, and when you exhale, air saturated with carbon dioxide is removed from the alveoli.

A normal calm breath is associated with the activity of the muscles of the diaphragm and the external intercostal muscles. When you inhale, the diaphragm lowers, the ribs rise, the distance between them increases. The usual calm exhalation occurs to a large extent passively, while the internal intercostal muscles and some abdominal muscles are actively working. When exhaling, the diaphragm rises, the ribs move down, the distance between them decreases.

Types of breathing

The respiratory system performs only the first part of gas exchange. The rest is performed by the circulatory system. There is a deep relationship between the respiratory and circulatory systems.

There are pulmonary respiration, which provides gas exchange between air and blood, and tissue respiration, which performs gas exchange between blood and tissue cells. It is carried out by the circulatory system, since the blood delivers oxygen to the organs and carries away decay products and carbon dioxide from them.

Lung breathing. The exchange of gases in the lungs occurs due to diffusion. The blood that has come from the heart into the capillaries braiding the pulmonary alveoli contains a lot of carbon dioxide, there is little of it in the air of the pulmonary alveoli, so it leaves the blood vessels and passes into the alveoli.

Oxygen enters the blood also through diffusion. But in order for this gas exchange to go on continuously, it is necessary that the composition of gases in the pulmonary alveoli be constant. This constancy is maintained by pulmonary respiration: excess carbon dioxide is removed outside, and oxygen absorbed by the blood is replaced by oxygen from a fresh portion of the outside air.

tissue respiration. Tissue respiration occurs in the capillaries, where the blood gives off oxygen and receives carbon dioxide. There is little oxygen in the tissues, therefore, the breakdown of oxyhemoglobin into hemoglobin and oxygen occurs. Oxygen passes into the tissue fluid and there it is used by cells for the biological oxidation of organic substances. The energy released in this process is used for the vital processes of cells and tissues.

With insufficient oxygen supply to the tissues: the function of the tissue is impaired, because the decay and oxidation of organic substances stops, energy ceases to be released, and cells deprived of energy supply die.

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

Breath types

According to the method of expansion of the chest, two types of breathing are distinguished:

• chest type of breathing(expansion of the chest is made by raising the ribs), more often observed in women;
• abdominal type of breathing(expansion of the chest is produced by flattening the diaphragm,) is more common in men.

Breathing happens:

• deep and superficial;
• frequent and rare.

Special types of respiratory movements are observed with hiccups and laughter. With frequent and shallow breathing, the excitability of the nerve centers increases, and with deep breathing, on the contrary, it decreases.

The system and structure of the respiratory system

The respiratory system includes:

• upper respiratory tract: nasal cavity, nasopharynx, pharynx;
• lower respiratory tract: larynx, trachea, main bronchi and lungs covered with pulmonary pleura.

The symbolic transition of the upper respiratory tract to the lower is carried out at the intersection of the digestive and respiratory systems in the upper part of the larynx. The respiratory tract provides connections between the environment and the main organs of the respiratory system - the lungs.

The lungs are located in the chest cavity, surrounded by the bones and muscles of the chest. The lungs are in hermetically sealed cavities, the walls of which are lined with parietal pleura. Between the parietal and pulmonary pleura is a slit-like pleural cavity. The pressure in it is lower than in the lungs, and therefore the lungs are always pressed against the walls of the chest cavity and take its shape.

Entering the lungs, the main bronchi branch, forming a bronchial tree, at the ends of which there are pulmonary vesicles, alveoli. Through the bronchial tree, air reaches the alveoli, where gas exchange occurs between the atmospheric air that has reached the pulmonary alveoli (lung parenchyma) and the blood flowing through the pulmonary capillaries, which ensure the supply of oxygen to the body and the removal of gaseous waste products from it, including carbon dioxide. gas.

Breathing process

Inhalation and exhalation is carried out by changing the size of the chest with the help of the respiratory muscles. During one breath (in a calm state), 400-500 ml of air enters the lungs. This volume of air is called the tidal volume (TO). The same amount of air enters the atmosphere from the lungs during a quiet exhalation.

The maximum deep breath is about 2,000 ml of air. After maximum exhalation, about 1200 ml of air remains in the lungs, called the residual volume of the lungs. After a quiet exhalation, approximately 1,600 ml remains in the lungs. This volume of air is called the functional residual capacity (FRC) of the lungs.

Due to the functional residual capacity (FRC) of the lungs, a relatively constant ratio of oxygen and carbon dioxide is maintained in the alveolar air, since the FRC is several times larger than the tidal volume (TO). Only 2/3 of the airway reaches the alveoli, which is called the volume of alveolar ventilation.

Without external respiration, the human body can usually live up to 5-7 minutes (the so-called clinical death), after which loss of consciousness, irreversible changes in the brain and its death (biological death) occur.

Breathing is one of the few bodily functions that can be controlled consciously and unconsciously.

Functions of the respiratory system

• Respiration, gas exchange. The main function of the respiratory organs is to maintain the constancy of the gas composition of the air in the alveoli: remove excess carbon dioxide and replenish the oxygen carried away by the blood. This is achieved through breathing movements. When inhaling, the skeletal muscles expand the chest cavity, followed by the expansion of the lungs, the pressure in the alveoli decreases and the outside air enters the lungs. When you exhale, the chest cavity decreases, its walls squeeze the lungs and the air comes out of them.
• Thermoregulation. In addition to ensuring gas exchange, the respiratory organs perform another important function: they participate in heat regulation. When breathing, water evaporates from the surface of the lungs, which leads to cooling of the blood and the whole body.
• Voice formation. The lungs create air currents that vibrate the vocal cords of the larynx. Speech is carried out thanks to articulation, which involves the tongue, teeth, lips and other organs that direct sound streams.
• Air purification. The inner surface of the nasal cavity is lined with ciliated epithelium. It secretes mucus that moistens the incoming air. Thus, the upper respiratory tract performs important functions: warming, moisturizing and purifying the air, as well as protecting the body from harmful effects through the air.

Lung tissue also plays an important role in processes such as hormone synthesis, water-salt and lipid metabolism. In the abundantly developed vascular system of the lungs, blood is deposited. The respiratory system also provides mechanical and immune protection against environmental factors.

Breathing regulation

Nervous regulation of breathing. Respiration is regulated automatically by the respiratory center, which is represented by a collection of nerve cells located in different parts of the central nervous system. The main part of the respiratory center is located in the medulla oblongata. The respiratory center consists of the centers of inhalation and exhalation, which regulate the work of the respiratory muscles.

Nervous regulation has a reflex effect on breathing. The collapse of the pulmonary alveoli, which occurs during exhalation, reflexively causes inspiration, and the expansion of the alveoli reflexively causes exhalation. Its activity depends on the concentration of carbon dioxide (CO2) in the blood and on nerve impulses coming from the receptors of various internal organs and skin.A hot or cold stimulus (of the sensory system) of the skin, pain, fear, anger, joy (and other emotions and stressors), physical activity quickly change the nature of the respiratory movements.

It should be noted that there are no pain receptors in the lungs, therefore, in order to prevent diseases, periodic fluorographic examinations are carried out.

Humoral regulation of respiration. During muscular work, oxidation processes are enhanced. Consequently, more carbon dioxide is released into the blood. When blood with an excess of 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 breath holding occurs.

Thanks to nervous and humoral regulation, the concentration of carbon dioxide and oxygen in the blood is maintained at a certain level under any conditions.

With problems with external respiration, certain

Vital capacity of the lungs

The vital capacity of the lungs is an important indicator of respiration. If a person takes the deepest breath, and then exhales as much as possible, then the exchange of exhaled air will be the vital capacity of the lungs. The vital capacity of the lungs depends on age, gender, height, and also on the degree of fitness of a person.

To measure the vital capacity of the lungs, use such a device as - SPIROMETER. For a person, not only the vital capacity of the lungs is important, but also the endurance of the respiratory muscles. A person whose lung capacity is small, and even the respiratory muscles are weak, has to breathe often and superficially. This leads to the fact that fresh air remains mainly in the airways and only a small part of it reaches the alveoli.

Breathing and exercise

During physical exertion, breathing, as a rule, increases. The metabolism is accelerated, the muscles require more oxygen.

Devices for the study of respiratory parameters

• capnograph- a device for measuring and graphically displaying the content of carbon dioxide in the air exhaled by a patient over a certain period of time.
• pneumograph- a device for measuring and graphically displaying the frequency, amplitude and form of respiratory movements over a certain period of time.
• Spirograph- a device for measuring and graphically displaying the dynamic characteristics of respiration.
• Spirometer- a device for measuring VC (vital capacity of the lungs).

OUR LUNGS LOVE:

1. Fresh air(with insufficient oxygen supply to the tissues: tissue function is impaired, because the decay and oxidation of organic substances stops, energy ceases to be released, and cells deprived of energy supply die. Therefore, staying in a stuffy room leads to headaches, lethargy, and reduced efficiency ).

2. Exercise(with muscular work, oxidation processes are intensified).

OUR LUNGS DON'T LIKE:

1. Infectious and chronic diseases of the respiratory tract(sinusitis, frontal sinusitis, tonsillitis, diphtheria, influenza, tonsillitis, acute respiratory infections, tuberculosis, lung cancer).

2. Polluted air(car exhausts, dust, polluted air, smoke, vodka fumes, carbon monoxide - all these components have an adverse effect on the body. Hemoglobin molecules that have captured carbon monoxide are deprived of the ability to transfer oxygen from the lungs to tissues for a long time. There is a lack of oxygen in the blood and tissues, which affects the functioning of the brain and other organs).

3. Smoking(narcotic substances contained in nicotine are involved in metabolism and interfere with nervous and humoral regulation, disrupting both. In addition, tobacco smoke substances irritate the mucous membrane of the respiratory tract, which leads to an increase in the mucus secreted by it).

And now let's look at and analyze the respiratory process as a whole, and also trace the anatomy of the respiratory tract and a number of other features associated with this process.

The respiratory system performs the function of gas exchange, delivering oxygen to the body and removing carbon dioxide from it. The airways are the nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles and lungs.

In the upper respiratory tract, the air is warmed, cleaned of various particles and humidified. Gas exchange takes place in the alveoli of the lungs.

nasal cavity It is lined with a mucous membrane, in which two parts differ in structure and function: respiratory and olfactory.

The respiratory part is covered with ciliated epithelium that secretes mucus. Mucus moisturizes the inhaled air, envelops solid particles. The mucous membrane warms the air, as it is abundantly supplied with blood vessels. Three turbinates increase the overall surface of the nasal cavity. Under the shells are the lower, middle and upper nasal passages.

Air from the nasal passages enters through the choanae into the nasal, and then into the oral part of the pharynx and larynx.

Larynx performs two functions - respiratory and voice formation. The complexity of its structure is associated with the formation of voice. The larynx is located at the level of the IV-VI cervical vertebrae and is connected by ligaments to the hyoid bone. The larynx is formed by cartilage. Outside (in men this is especially noticeable), the "Adam's apple", "Adam's apple" - the thyroid cartilage - protrudes. At the base of the larynx is the cricoid cartilage, which is connected by joints to the thyroid and two arytenoid cartilages. The cartilaginous vocal process departs from the arytenoid cartilages. The entrance to the larynx is covered by an elastic cartilaginous epiglottis attached to the thyroid cartilage and hyoid bone by ligaments.

Between the arytenoids and the inner surface of the thyroid cartilage are vocal cords, consisting of elastic fibers of connective tissue. Sound is produced by the vibration of the vocal cords. The larynx takes part only in the formation of sound. Lips, tongue, soft palate, paranasal sinuses take part in articulate speech. The larynx changes with age. Its growth and function are associated with the development of the gonads. The size of the larynx in boys during puberty increases. The voice changes (mutates).

Air enters the trachea from the larynx.

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

The trachea divides into two elastic main bronchi. The right bronchus is shorter and wider than the left. The main bronchi branch into smaller bronchi - bronchioles. The bronchi and bronchioles are lined with ciliated epithelium. The bronchioles contain secretory cells that produce enzymes that break down surfactant, a secret that helps maintain the surface tension of the alveoli, preventing them from collapsing when exhaled. It also has a bactericidal effect.

Lungs, paired organs located in the chest cavity. The right lung has three lobes, the left has two. The lobes of the lung, to a certain extent, are anatomically isolated areas with a bronchus that ventilates them and their own vessels and nerves.

The functional unit of the lung is the acinus, a branching system of one terminal bronchiole. This bronchiole is divided into 14-16 respiratory bronchioles, forming up to 1500 alveolar passages, bearing up to 20,000 alveoli. The pulmonary lobule consists of 16-18 acini. Segments are made up of lobules, lobes are made up of segments, and a lung is made up of lobes.

Outside, the lung is covered with an internal pleura. Its outer layer (parietal pleura) lines the chest cavity and forms a sac in which the lung is located. Between the outer and inner sheets is the pleural cavity, filled with a small amount of fluid that facilitates the movement of the lungs during breathing. The pressure in the pleural cavity is less than atmospheric and is about 751 mm Hg. Art.

When inhaling, the chest cavity expands, the diaphragm descends, and the lungs expand. When exhaling, the volume of the chest cavity decreases, the diaphragm relaxes and rises. The respiratory movements involve the external intercostal muscles, the muscles of the diaphragm, and the internal intercostal muscles. With increased breathing, all the muscles of the chest are involved, lifting the ribs and sternum, the muscles of the abdominal wall.

Tidal volume is the amount of air inhaled and exhaled by a person at rest. It is equal to 500 cm 3.

Extra volume - the amount of air that a person can inhale after a normal breath. This is another 1500 cm 3.

The reserve volume is the amount of air that a person can exhale after a normal exhalation. It is equal to 1500 cm 3. All three quantities make up the vital capacity of the lungs.

Residual air is the amount of air that remains in the lungs after the deepest exhalation. It is equal to 1000 cm 3.

Respiratory movements are controlled by the respiratory center of the medulla oblongata. The center has departments of inhalation and exhalation. From the center of inhalation, impulses are sent to the respiratory muscles. There is a breath. From the respiratory muscles, impulses enter the respiratory center along the vagus nerve and inhibit the inspiratory center. There is an exhalation. The activity of the respiratory center is affected by the level of blood pressure, temperature, pain and other stimuli. Humoral regulation occurs when the concentration of carbon dioxide in the blood changes. Its increase excites the respiratory center and causes quickening and deepening of breathing. The ability to arbitrarily hold your breath for a while is explained by the controlling influence on the breathing process of the cerebral cortex.

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

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

Breathing is one of the most basic properties of any living organism. Its great importance is difficult to overestimate. About how important normal breathing is, a person thinks only when it suddenly becomes difficult, for example, when a cold has appeared. If without food and water a person is still able to live for some time, then without breathing - a matter of seconds. In one day, an adult makes more than 20,000 breaths and the same number of exhalations.

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

How does a person breathe?

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 respiration and how are the respiratory organs arranged?

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

The main role of the former is the unhindered delivery of air to the lungs. The respiratory tract of a person begins with the nose, but the process itself can also occur through the mouth if the nose is blocked. However, nasal breathing is preferable, because 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 respiration:

• external respiration;
• transport of gases with the bloodstream;
• internal (cellular) respiration;

When inhaling through the nose or mouth, the 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.

Together they form a single functional system.

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

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

The process of respiration 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 enters from the alveoli into the vessels, and carbon dioxide returns back. Both alveoli and capillaries consist of a single layer of epithelium, which allows gases to easily penetrate into 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 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 the cells, it first penetrates into the intercellular space, and then directly into the cell.

The main purpose of respiration is the generation of energy in the 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 when you exhale, respectively, decreases. At rest, a person uses only 5 percent of the total volume of the lungs.

Functions of the respiratory system

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

In the process of 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 participants in other important functions of the body, in particular, they are directly involved in the formation of speech sounds, as well as 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 the temperature of his body. Exhaled gases lower body temperature.

Excretory processes also partially involve the organs of the respiratory system. Some water vapor is also released.

The structure of the respiratory organs, 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 releases 200 g of carbon dioxide. However, if physical activity increases, then 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, in the process of breathing, dust, ammonia and urea are removed from the body.

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

Respiratory organs: description

All respiratory organs are interconnected.

Nose

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

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

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

The nose is divided into bone and cartilage sections. The nasal septum separates the right and left halves.

From the inside, 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 veins. 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. The cartilages of the larynx are:

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

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

The joints of the body provide its mobility. The larynx has many different ligaments. There is also a whole group of muscles that strain the vocal cords. In the larynx are the vocal cords themselves, which are most 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 from the fourth to the seventh cervical vertebrae.

Trachea

The actual continuation of the larynx is the trachea. According to the location, respectively, the organs in the trachea are divided into the cervical and thoracic parts. The esophagus is adjacent to the trachea. Very close to it passes the neurovascular bundle. 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 region of the gate are divided into lobar. 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 it is the lungs that are considered the most significant. They directly exchange oxygen and carbon dioxide.

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

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

The lungs are divided into two sections:

1. Top.
2. Base.

As well as three surfaces: diaphragmatic, costal and mediastinal. They are turned respectively to the diaphragm, ribs, mediastinum. The surfaces of the lung are separated by edges. The costal and mediastinal regions are separated by the anterior margin. The lower edge separates from the diaphragm area. Each lung is divided into lobes.

The right lung has three of them:

Upper;

Medium;

The left has only two: top and bottom. Between the lobes are interlobar surfaces. Both lungs have an oblique fissure. She shares shares in the body. 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 depressions called gates. Formations pass through them, creating the root of the lung. Here are the lymphatic and blood vessels, bronchi. In the right lung it is a bronchus, pulmonary vein, two pulmonary arteries. In the left - bronchus, pulmonary artery, two pulmonary veins.

In 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 - the pleura. It consists of two parts: outer and inner petal.

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

The human respiratory system is designed in such a way that negative air pressure is present directly in the pleural cavity. It is due to this fact, as well as the surface tension of the serous fluid, that the lungs are constantly in a straightened state, and they also receive respiratory movements of the chest.

respiratory muscles

Respiratory muscles are divided into inspiratory (inhale) and expiratory (work during exhalation).

The main inspiratory muscles are:

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

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

Intercostal, rectus, hypochondrium, transverse, external and internal oblique muscles of the abdomen are expiratory muscles.

Diaphragm

The diaphragm also plays an important role in the breathing process. This is a unique plate that separates two cavities: chest and abdomen. It belongs to the respiratory muscles. In the diaphragm itself, a tendon center and three more muscle areas are distinguished.

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 leads to the fact that the pressure inside the chest cavity becomes less than the external atmospheric pressure. At this point, air enters the lungs. Then, as a result of muscle relaxation, exhalation is carried out

The mucous membrane of the respiratory system

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 that constantly carry 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 that have been inhaled by inhalation 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 fairly effective self-cleaning mechanism. This structure of the shell and the ability to cleanse extends 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 affect her 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 cilia of the epithelium can significantly slow down, or even stop altogether.

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

At first, 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, a general uncomfortable condition.

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 paths to the lower ones and the bronchi and lungs are already affected. Doctors say in this case that the infection has "descended" below. This is fraught with serious diseases, such as pneumonia, bronchitis, pleurisy. In medical institutions, the condition of equipment intended for anesthetic and respiratory procedures is strictly monitored. 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: treat it in time if a problem occurs, and also avoid the negative influence of the environment, as well as bad habits.

The system for conducting air through our body has a complex structure. Nature has created a mechanism for delivering oxygen to the lungs, where it enters the blood, so that it is possible to exchange gases between the environment and all the cells of our body.

The scheme of the human respiratory system means the respiratory tract - upper and lower:

• The upper ones are the nasal cavity, including the paranasal sinuses, and the larynx, a voice-forming organ.
• The lower ones are the trachea and the bronchial tree.
• The respiratory organs are the lungs.

Each of these components is unique in its functions. Together, all these structures work as one well-coordinated mechanism.

nasal cavity

The first structure through which air passes when inhaling is the nose. Its structure:

1. The frame consists of many small bones on which cartilage is attached. The appearance of a person's nose depends on their shape and size.


2. Its cavity, according to anatomy, communicates with the external environment through the nostrils, while with the nasopharynx through special openings in the bone base of the nose (choana).
3. On the outer walls of both halves of the nasal cavity, 3 nasal passages are located from top to bottom. Through openings in them, the nasal cavity communicates with the paranasal sinuses and the lacrimal duct of the eye.
4. From the inside, the nasal cavity is covered with a mucous membrane with a single-layer epithelium. She has many hairs and cilia. In this area, the air is sucked in, and also warmed and humidified. The hairs, cilia, and mucus layer in the nose act as an air filter, trapping dust particles and trapping microorganisms. The mucus secreted by epithelial cells contains bactericidal enzymes that can destroy bacteria.

Another important function of the nose is olfactory. In the upper parts of the mucous membrane there are receptors for the olfactory analyzer. This area has a different color from the rest of the mucous membranes.

The olfactory zone of the mucous membrane is colored yellowish. From the receptors in its thickness, a nerve impulse is transmitted to specialized areas of the cerebral cortex, where the sense of smell is formed.

Paranasal sinuses

In the thickness of the bones that take part in the formation of the nose, there are voids lined from the inside with a mucous membrane - the paranasal sinuses. They are filled with air. This markedly reduces the weight of the skull bones.

The nasal cavity, together with the sinuses, takes part in the process of voice formation (the air resonates, and the sound becomes louder). There are such paranasal sinuses:

• Two maxillary (maxillary) - inside the bone of the upper jaw.
• Two frontal (frontal) - in the cavity of the frontal bone, above the superciliary arches.
• One wedge-shaped - at the base of the sphenoid bone (it is located inside the skull).
• Cavities within the ethmoid bone.

All these sinuses communicate with the nasal passages through openings and channels. This leads to the fact that the inflammatory exudate from the nose enters the sinus cavity. The disease quickly spreads to nearby tissues. As a result, their inflammation develops: sinusitis, frontal sinusitis, sphenoiditis and ethmoiditis. These diseases are dangerous for their consequences: in advanced cases, pus melts the walls of the bones, entering the cranial cavity, causing irreversible changes in the nervous system.

Larynx

After passing through the nasal cavity and nasopharynx (or oral cavity, if a person breathes through the mouth), the air enters the larynx. It is a tubular organ of a very complex anatomy, which consists of cartilage, ligaments and muscles. It is here that the vocal cords are located, thanks to which we can make sounds of different frequencies. The functions of the larynx are air conduction, voice formation.

Structure:

1. The larynx is located at the level of 4-6 cervical vertebrae.
2. Its anterior surface is formed by the thyroid and cricoid cartilages. The back and upper parts are the epiglottis and small wedge-shaped cartilages.
3. The epiglottis is a "lid" that closes the larynx during a sip. This device is necessary so that food does not enter the airways.
4. From the inside, the larynx is lined with a single-layer respiratory epithelium, the cells of which have thin villi. They move by directing mucus and dust particles towards the throat. Thus, there is a constant purification of the airways. Only the surface of the vocal cords is lined with stratified epithelium, which makes them more resistant to damage.
5. There are receptors in the thickness of the mucous membrane of the larynx. When these receptors are irritated by foreign bodies, excess mucus, or waste products of microorganisms, a reflex cough occurs. This is a protective reaction of the larynx, aimed at cleansing its lumen.

Trachea

From the lower edge of the cricoid cartilage begins the trachea. This organ belongs to the lower respiratory tract. It ends at the level of 5–6 thoracic vertebrae at the site of its bifurcation (bifurcation).

The structure of the trachea:

1. The framework of the trachea forms 15–20 cartilaginous semirings. Behind, they are connected by a membrane that is adjacent to the esophagus.
2. At the point of division of the trachea into the main bronchi, there is a protrusion of the mucous membrane, which deviates to the left. This fact determines that foreign bodies that get here are more often found in the right main bronchus.
3. The mucous membrane of the trachea has good absorbability. It is used in medicine for intratracheal administration of drugs, by inhalation.

bronchial tree

The trachea divides into two main bronchi - tubular formations consisting of cartilage tissue that enter the lungs. The walls of the bronchi form cartilaginous rings and connective tissue membranes.

Inside the lungs, the bronchi are divided into lobar bronchi (second order), which, in turn, bifurcate several times into bronchi of the third, fourth, etc. up to the tenth order - terminal bronchioles. They give rise to respiratory bronchioles, components of the pulmonary acini.

Respiratory bronchioles pass into the respiratory passages. Alveoli are attached to these passages - sacs filled with air. It is at this level that gas exchange occurs, air cannot seep into the blood through the walls of the bronchioles.

Throughout the tree, bronchioles are lined from the inside with respiratory epithelium, and their wall is formed by cartilage elements. The smaller the caliber of the bronchus, the less cartilage tissue in its wall.

Smooth muscle cells appear in small bronchioles. This causes the ability of bronchioles to expand and narrow (in some cases even spasm). This happens under the influence of external factors, impulses of the autonomic nervous system and some pharmaceuticals.

Lungs

The human respiratory system also includes the lungs. In the thickness of the tissues of these organs, gas exchange occurs between air and blood (external respiration).

Under the path of simple diffusion, oxygen moves to where its concentration is lower (into the blood). By the same principle, carbon monoxide is removed from the blood.

The exchange of gases through the cell is carried out due to the difference in the partial pressure of gases in the blood and the cavity of the alveoli. This process is based on the physiological permeability of the walls of the alveoli and capillaries to gases.

These are parenchymal organs that are located in the chest cavity on the sides of the mediastinum. The mediastinum contains the heart and large vessels (pulmonary trunk, aorta, superior and inferior vena cava), esophagus, lymphatic ducts, sympathetic nerve trunks, and other structures.

The chest cavity is lined from the inside with a special membrane - the pleura, its other sheet covers each lung. As a result, two closed pleural cavities are formed, in which a negative (relative to atmospheric) pressure is created. This provides the person with the opportunity to inhale.

Its gate is located on the inner surface of the lung - this includes the main bronchi, vessels and nerves (all these structures form the root of the lung). The human right lung has three lobes, while the left lung has two. This is due to the fact that the place of the third lobe of the left lung is occupied by the heart.

The parenchyma of the lungs consists of alveoli - cavities with air up to 1 mm in diameter. The walls of the alveoli are formed by connective tissue and alveolocytes - specialized cells that are able to pass oxygen and carbon dioxide bubbles through themselves.

From the inside, the alveolus is covered with a thin layer of a viscous substance - a surfactant. This fluid begins to be produced in the fetus at the 7th month of intrauterine development. It creates a surface tension force in the alveolus, which prevents it from subsiding during exhalation.

Together, the surfactant, the alveolocyte, the membrane on which it lies, and the wall of the capillary form an air-blood barrier. Microorganisms do not penetrate through it (normal). But if an inflammatory process (pneumonia) occurs, the capillary walls become permeable to bacteria.