The structure of the respiratory system. Respiratory organs and their functions: nasal cavity, larynx, trachea, bronchi, lungs

All life on Earth exists for a set of solar heat and energy that reaches the surface of our planet. All animals and humans have adapted to extract energy from organic substances synthesized by plants. In order to use the energy of the Sun contained in the molecules of organic substances, it must be released by oxidizing these substances. Most often, air oxygen is used as an oxidizing agent, since it makes up almost a quarter of the volume of the surrounding atmosphere.

Unicellular protozoa, coelenterates, free-living flat and round worms breathe the entire surface of the body. Special respiratory organs - pinnate gills appear in marine annelids and aquatic arthropods. The respiratory organs of arthropods are tracheae, gills, leaf-shaped lungs located in the recesses of the body cover. The respiratory system of the lancelet is represented gill slits penetrating the wall of the anterior intestine - the pharynx. In fish, under the gill covers are located gills, abundantly penetrated by the smallest blood vessels. In terrestrial vertebrates, the respiratory organs are lungs. The evolution of respiration in vertebrates followed the path of increasing the area of ​​the lung septa involved in gas exchange, improving transport systems for delivering oxygen to cells located inside the body, and developing systems that provide ventilation of the respiratory organs.

The structure and functions of the respiratory system

A necessary condition for the vital activity of an organism is a constant gas exchange between the organism and the environment. The organs through which inhaled and exhaled air circulate are combined into a respiratory apparatus. The respiratory system is formed by the nasal cavity, pharynx, larynx, trachea, bronchi and lungs. Most of them are airways and serve to carry air into the lungs. The process of gas exchange takes place in the lungs. When breathing, the body receives oxygen from the air, which is carried by the blood throughout the body. Oxygen is involved in complex oxidative processes of organic substances, in which the energy necessary for the body is released. The end products of decomposition - carbon dioxide and partially water - are excreted from the body into the environment through the respiratory system.

Functions of the respiratory system

• Providing cells of the body with oxygen O 2.
• Removal from the body of carbon dioxide CO 2, as well as some end products of metabolism (water vapor, ammonia, hydrogen sulfide).

nasal cavity

The airways begin at nasal cavity, which through the nostrils is connected to the environment. From the nostrils, air passes through the nasal passages lined with mucous, ciliated and sensitive epithelium. The external nose consists of bone and cartilage formations and has the shape of an irregular pyramid, which varies depending on the structural features of a person. The composition of the osseous skeleton of the external nose includes the nasal bones and the nasal part of the frontal bone. The cartilaginous skeleton is a continuation of the bone skeleton and consists of hyaline cartilages of various shapes. The nasal cavity has a lower, upper and two side walls. The lower wall is formed by the hard palate, the upper one by the ethmoid plate of the ethmoid bone, the lateral one by the upper jaw, the lacrimal bone, the orbital plate of the ethmoid bone, the palatine bone and the sphenoid bone. The nasal cavity is divided into right and left parts by the nasal septum. The nasal septum is formed by a vomer, a perpendicular plate of the ethmoid bone, and is complemented in front by a quadrangular cartilage of the nasal septum.

On the side walls of the nasal cavity there are turbinates - three on each side, which increases the inner surface of the nose, with which the inhaled air comes into contact.

The nasal cavity is formed by two narrow and sinuous nasal passages. Here the air is warmed, humidified and freed from dust particles and microbes. The membrane lining the nasal passages consists of cells that secrete mucus and cells of the ciliated epithelium. With the movement of cilia, mucus, along with dust and microbes, is sent out of the nasal passages.

The inner surface of the nasal passages is richly supplied with blood vessels. The inhaled air enters the nasal cavity, is heated, moistened, cleaned of dust and partially neutralized. From the nasal cavity, it enters the nasopharynx. Then the air from the nasal cavity enters the pharynx, and from it - into the larynx.

Larynx

Larynx- one of the divisions of the airways. Air enters here from the nasal passages through the pharynx. There are several cartilages in the wall of the larynx: thyroid, arytenoid, etc. At the moment of swallowing food, the neck muscles raise the larynx, and the epiglottal cartilage descends and the larynx closes. Therefore, food only enters the esophagus and does not enter the trachea.

In the narrow part of the larynx are located vocal cords, in the middle between them is the glottis. As air passes through, the vocal cords vibrate, producing sound. The formation of sound occurs on exhalation with the movement of air controlled by a person. The following are involved in the formation of speech: the nasal cavity, lips, tongue, soft palate, facial muscles.

Trachea

The larynx goes into trachea(windpipe), which has the shape of a tube about 12 cm long, in the walls of which there are cartilaginous semi-rings that do not allow it to subside. Its back wall is formed by a connective tissue membrane. The tracheal cavity, like the cavity of other airways, is lined with ciliated epithelium, which prevents dust and other foreign bodies from penetrating into the lungs. The trachea occupies a middle position, behind it is adjacent to the esophagus, and on the sides of it are neurovascular bundles. In front, the cervical region of the trachea is covered by muscles, and at the top it is also covered by the thyroid gland. The thoracic trachea is covered in front by the handle of the sternum, the remnants of the thymus gland and vessels. From the inside, the trachea is covered with a mucous membrane containing a large amount of lymphoid tissue and mucous glands. When breathing, small particles of dust adhere to the moistened mucosa of the trachea, and the cilia of the ciliated epithelium move them back to the exit from the respiratory tract.

The lower end of the trachea divides into two bronchi, which then branch many times, enter the right and left lungs, forming a "bronchial tree" in the lungs.

Bronchi

In the thoracic cavity, the trachea divides into two bronchus- left and right. Each bronchus enters the lung and there it divides into bronchi of smaller diameter, which branch into the smallest air-bearing tubes - bronchioles. As a result of further branching, bronchioles pass into extensions - alveolar passages, on the walls of which there are microscopic protrusions called pulmonary vesicles, or alveoli.

The walls of the alveoli are built from a special thin single-layer epithelium and are densely braided with capillaries. The total thickness of the wall of the alveoli and the wall of the capillary is 0.004 mm. Through this thinnest wall, gas exchange occurs: oxygen enters the blood from the alveoli, and carbon dioxide comes back. There are hundreds of millions of alveoli in the lungs. Their total surface in an adult is 60–150 m 2. due to this, a sufficient amount of oxygen enters the blood (up to 500 liters per day).

Lungs

Lungs occupy almost the entire cavity of the chest cavity and are elastic spongy organs. In the central part of the lung there are gates, where the bronchus, pulmonary artery, nerves enter, and the pulmonary veins exit. The right lung is divided by furrows into three lobes, the left into two. Outside, the lungs are covered with a thin connective tissue film - the pulmonary pleura, which passes to the inner surface of the wall of the chest cavity and forms the parietal pleura. Between these two films is a pleural space filled with fluid that reduces friction during breathing.

Three surfaces are distinguished on the lung: the outer, or costal, medial, facing the other lung, and the lower, or diaphragmatic. In addition, two edges are distinguished in each lung: anterior and inferior, separating the diaphragmatic and medial surfaces from the costal. Posteriorly, the costal surface without a sharp border passes into the medial. The anterior edge of the left lung has a cardiac notch. Its gates are located on the medial surface of the lung. The gates of each lung include the main bronchus, the pulmonary artery, which carries venous blood to the lung, and the nerves that innervate the lung. Two pulmonary veins exit the gates of each lung, which carry arterial blood to the heart, and lymphatic vessels.

The lungs have deep grooves dividing them into lobes - upper, middle and lower, and in the left two - upper and lower. The dimensions of the lung are not the same. The right lung is slightly larger than the left, while it is shorter and wider, which corresponds to a higher standing of the right dome of the diaphragm due to the right-sided location of the liver. The color of normal lungs in childhood is pale pink, while in adults they acquire a dark gray color with a bluish tint - a consequence of the deposition of dust particles that enter with air. The lung tissue is soft, delicate and porous.

Lung gas exchange

In the complex process of gas exchange, three main phases are distinguished: external respiration, gas transfer by blood, and internal, or tissue, respiration. External respiration unites all the processes occurring in the lung. It is carried out by the respiratory apparatus, which includes the chest with the muscles that set it in motion, the diaphragm and the lungs with the airways.

The air that enters the lungs during inhalation changes its composition. The air in the lungs gives up some of the oxygen and is enriched with carbon dioxide. The content of carbon dioxide in the venous blood is higher than in the air in the alveoli. Therefore, carbon dioxide leaves the blood in the alveoli and its content is less than in the air. First, oxygen dissolves in the blood plasma, then binds to hemoglobin, and new portions of oxygen enter the plasma.

The transition of oxygen and carbon dioxide from one medium to another occurs due to diffusion from a higher concentration to a lower one. Although diffusion proceeds slowly, the surface of contact of blood with air in the lungs is so large that it completely provides the necessary gas exchange. It has been calculated that complete gas exchange between blood and alveolar air can occur in a time that is three times shorter than the residence time of blood in the capillaries (i.e., the body has significant reserves of oxygen supply to tissues).

Venous blood, once in the lungs, gives off carbon dioxide, is enriched with oxygen and turns into arterial blood. In a large circle, this blood diverges through the capillaries to all tissues and gives oxygen to the cells of the body, which constantly consume it. There is more carbon dioxide released by the cells as a result of their vital activity here than in the blood, and it diffuses from the tissues into the blood. Thus, arterial blood, having passed through the capillaries of the systemic circulation, becomes venous and the right half of the heart goes to the lungs, where it is again saturated with oxygen and releases carbon dioxide.

In the body, respiration is carried out with the help of additional mechanisms. The liquid media that make up the blood (its plasma) have a low solubility of gases in them. Therefore, in order for a person to exist, he would need to have a heart 25 times more powerful, lungs 20 times more powerful and pump more than 100 liters of liquid (and not five liters of blood) in one minute. Nature has found a way to overcome this difficulty by adapting a special substance, hemoglobin, to carry oxygen. Thanks to hemoglobin, blood is able to bind oxygen 70 times, and carbon dioxide - 20 times more than the liquid part of the blood - its plasma.

Alveolus- a thin-walled bubble with a diameter of 0.2 mm filled with air. The wall of the alveoli is formed by a single layer of flat epithelial cells, along the outer surface of which a network of capillaries branches. Thus, gas exchange occurs through a very thin partition formed by two layers of cells: the walls of the capillary and the walls of the alveoli.

Gas exchange in tissues (tissue respiration)

The exchange of gases in the tissues is carried out in the capillaries according to the same principle as in the lungs. Oxygen from the tissue capillaries, where its concentration is high, passes into the tissue fluid with a lower oxygen concentration. From the tissue fluid, it penetrates into the cells and immediately enters into oxidation reactions, so there is practically no free oxygen in the cells.

Carbon dioxide, according to the same laws, comes from the cells, through the tissue fluid, into the capillaries. The released carbon dioxide promotes the dissociation of oxyhemoglobin and itself enters into combination with hemoglobin, forming carboxyhemoglobin transported to the lungs and released into the atmosphere. In the venous blood flowing from the organs, carbon dioxide is both in a bound and in a dissolved state in the form of carbonic acid, which easily decomposes into water and carbon dioxide in the capillaries of the lungs. Carbonic acid can also combine with plasma salts to form bicarbonates.

In the lungs, where venous blood enters, oxygen saturates the blood again, and carbon dioxide from a zone of high concentration (pulmonary capillaries) passes into a zone of low concentration (alveoli). For normal gas exchange, the air in the lungs is constantly replaced, which is achieved by rhythmic attacks of inhalation and exhalation, due to the movements of the intercostal muscles and the diaphragm.

Transport of oxygen in the body

The meaning of breathing.

Breath is a set of physiological processes that provide gas exchange between the body and the environment ( external respiration), and oxidative processes in cells, as a result of which energy is released ( internal breathing). Exchange of gases between blood and atmospheric air ( gas exchange) - carried out by the respiratory organs.

Food is the source of energy in the body. The main process that releases the energy of these substances is the oxidation process. It is accompanied by the binding of oxygen and the formation of carbon dioxide. Considering that there are no oxygen reserves in the human body, its continuous supply is vital. The cessation of oxygen access to the cells of the body leads to their death. On the other hand, carbon dioxide formed in the process of oxidation of substances must be removed from the body, since the accumulation of a significant amount of it is life-threatening. The absorption of oxygen from the air and the release of carbon dioxide is carried out through the respiratory system.

The biological significance of respiration is:

• providing the body with oxygen;
• removal of carbon dioxide from the body;
• oxidation of organic compounds of BJU with the release of energy necessary for a person to live;
• removal of end products of metabolism ( vapors of water, ammonia, hydrogen sulfide, etc.).

The respiratory system combines organs that perform air (oral cavity, nasopharynx, larynx, trachea, bronchi) and respiratory, or gas exchange (lungs), functions.

The main function of the respiratory organs is to ensure gas exchange between air and blood by diffusion of oxygen and carbon dioxide through the walls of the pulmonary alveoli into the blood capillaries. In addition, the respiratory organs are involved in sound production, odor detection, the production of certain hormone-like substances, in lipid and water-salt metabolism, and in maintaining the body's immunity.

In the airways, purification, moistening, warming of the inhaled air, as well as the perception of smell, temperature and mechanical stimuli take place.

A characteristic feature of the structure of the respiratory tract is the presence of a cartilaginous base in their walls, as a result of which they do not collapse. The inner surface of the respiratory tract is covered with a mucous membrane, which is lined with ciliated epithelium and contains a significant number of glands that secrete mucus. The cilia of the epithelial cells, moving against the wind, bring foreign bodies out along with the mucus.

General characteristics of the respiratory system

The most important indicator of human viability can be called breath. A person can do without water and food for some time, but life is impossible without air. Breathing is the link between a person and the environment. If the air flow is obstructed, then respiratory organs I am a person and the heart begins to work in an enhanced mode, which provides the necessary amount of oxygen for breathing. The human respiratory and respiratory system is capable of adapt to environmental conditions.

Scientists have established an interesting fact. The air that enters respiratory system of a person, conditionally forms two streams, one of which passes into the left side of the nose and penetrates into left lung, the second stream penetrates the right side of the nose and feeds into right lung.

Also, studies have shown that in the artery of the human brain there is also a separation into two streams of air received. Process breathing must be correct, which is important for normal life. Therefore, it is necessary to know about the structure of the human respiratory system and respiratory organs.

Breathe-helping machine human includes trachea, lungs, bronchi, lymphatics, and vascular system. They also include the nervous system and respiratory muscles, the pleura. The human respiratory system includes the upper and lower respiratory tract. Upper respiratory tract: nose, pharynx, oral cavity. Lower respiratory tract: trachea, larynx and bronchi.

The airways are necessary for the entry and removal of air from the lungs. The most important organ of the entire respiratory system is lungs between which the heart is located.

Respiratory system

Lungs- the main organs of respiration. They are cone shaped. The lungs are located in the chest area, located on either side of the heart. The main function of the lungs is gas exchange, which occurs with the help of the alveoli. The lungs receive blood from the veins through the pulmonary arteries. Air penetrates through the respiratory tract, enriching the respiratory organs with the necessary oxygen. Cells need to be supplied with oxygen in order for the process to take place. regeneration, and nutrients from the blood needed by the body. Covers the lungs - the pleura, consisting of two petals, separated by a cavity (pleural cavity).

The lungs include the bronchial tree, which is formed by bifurcation trachea. The bronchi, in turn, are divided into thinner ones, thus forming segmental bronchi. bronchial tree ends with very small pouches. These sacs are many interconnected alveoli. Alveoli provide gas exchange respiratory system. The bronchi are covered with epithelium, which in its structure resembles cilia. Cilia remove mucus to the pharyngeal region. Promotion is promoted by coughing. The bronchi have a mucous membrane.

Trachea is a tube that connects the larynx and bronchi. The trachea is about 12-15 see Trachea, in contrast to the lungs - an unpaired organ. The main function of the trachea is to carry air into and out of the lungs. The trachea is located between the sixth vertebra of the neck and the fifth vertebra of the thoracic region. In the end trachea bifurcates into two bronchi. The bifurcation of the trachea is called a bifurcation. At the beginning of the trachea, the thyroid gland adjoins it. On the back of the trachea is the esophagus. The trachea is covered by a mucous membrane, which is the basis, and it is also covered by muscular-cartilaginous tissue, a fibrous structure. The trachea is made up of 18-20 rings of cartilage, thanks to which the trachea is flexible.

Larynx- a respiratory organ that connects the trachea and pharynx. The voice box is located in the larynx. The larynx is in the area 4-6 vertebrae of the neck and with the help of ligaments attached to the hyoid bone. The beginning of the larynx is in the pharynx, and the end is a bifurcation into two tracheas. The thyroid, cricoid, and epiglottic cartilages make up the larynx. These are large unpaired cartilages. It is also formed by small paired cartilages: horn-shaped, wedge-shaped, arytenoid. The connection of the joints is provided by ligaments and joints. Between the cartilages are membranes that also perform the function of connection.

Pharynx is a tube that originates in the nasal cavity. The pharynx crosses the digestive and respiratory tracts. The pharynx can be called the link between the nasal cavity and the oral cavity, and the pharynx also connects the larynx and esophagus. The pharynx is located between the base of the skull and 5-7 neck vertebrae. The nasal cavity is the initial section of the respiratory system. Consists of the external nose and nasal passages. The function of the nasal cavity is to filter the air, as well as to purify and moisten it. Oral cavity This is the second way air enters the human respiratory system. The oral cavity has two sections: posterior and anterior. The anterior section is also called the vestibule of the mouth.

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.

Human respiration is a complex physiological mechanism that ensures the exchange of oxygen and carbon dioxide between cells and the external environment.

Oxygen is constantly absorbed by cells and at the same time there is a process of removing carbon dioxide from the body, which is formed as a result of biochemical reactions occurring in the body.

Oxygen is involved in the oxidation reactions of complex organic compounds with their final decomposition to carbon dioxide and water, during which the energy necessary for life is formed.

In addition to the vital gas exchange, external respiration provides other important functions in the body, for example, the ability to sound production.

This process involves the muscles of the larynx, respiratory muscles, vocal cords and oral cavity, and it itself is possible only when exhaling. The second important "non-respiratory" function is sense of smell.

Oxygen in our body is contained in a small amount - 2.5 - 2.8 liters, and about 15% of this volume is in a bound state.

At rest, a person consumes approximately 250 ml of oxygen per minute and removes about 200 ml of carbon dioxide.

Thus, when breathing stops, the supply of oxygen in our body is enough for only a few minutes, then damage and cell death occur, and the cells of the central nervous system suffer first of all.

For comparison: a person can live without water for 10-12 days (in the human body, the water supply, depending on age, is up to 75%), without food - up to 1.5 months.

With intense physical activity, oxygen consumption increases dramatically and can reach up to 6 liters per minute.

Respiratory system

The function of respiration in the human body is carried out by the respiratory system, which includes the organs of external respiration (upper respiratory tract, lungs and chest, including its bone-cartilaginous frame and neuromuscular system), organs for the transport of gases by blood (the vascular system of the lungs, heart) and regulatory centers that ensure the automatism of the respiratory process.

Rib cage

The thorax forms the walls of the chest cavity, which houses the heart, lungs, trachea, and esophagus.

It consists of 12 thoracic vertebrae, 12 pairs of ribs, sternum and connections between them. The anterior wall of the chest is short, it is formed by the sternum and costal cartilages.

The back wall is formed by the vertebrae and ribs, the vertebral bodies are located in the chest cavity. The ribs are connected to each other and to the spine by movable joints and take an active part in breathing.

The spaces between the ribs are filled with intercostal muscles and ligaments. From the inside, the chest cavity is lined with parietal, or parietal, pleura.

respiratory muscles

The respiratory muscles are divided into those that inhale (inspiratory) and those that exhale (expiratory). The main inspiratory muscles include the diaphragm, external intercostal and internal intercartilaginous muscles.

The accessory inspiratory muscles include the scalene, sternocleidomastoid, trapezius, pectoralis major and minor.

The expiratory muscles include the internal intercostal, rectus, subcostal, transverse, as well as the external and internal oblique muscles of the abdomen.

The mind is the master of the senses, and the breath is the master of the mind.

Diaphragm

Since the abdominal septum, the diaphragm, is extremely important in the process of breathing, we will consider its structure and functions in more detail.

This extensive curved (bulge upward) plate completely delimits the abdominal and thoracic cavities.

The diaphragm is the main respiratory muscle and the most important organ of the abdominal press.

In it, a tendon center and three muscle parts are distinguished with names according to the organs from which they begin, respectively, the costal, sternal and lumbar regions are distinguished.

During contraction, the dome of the diaphragm moves away from the chest wall and flattens, thereby increasing the volume of the chest cavity and decreasing the volume of the abdominal cavity.

With simultaneous contraction of the diaphragm with the abdominal muscles, intra-abdominal pressure increases.

It should be noted that the parietal pleura, pericardium and peritoneum are attached to the tendon center of the diaphragm, that is, the movement of the diaphragm displaces the organs of the chest and abdominal cavity.

Airways

The airway refers to the path that air travels from the nose to the alveoli.

They are divided into airways located outside the chest cavity (these are the nasal passages, pharynx, larynx and trachea) and intrathoracic airways (trachea, main and lobar bronchi).

The process of respiration can be conditionally divided into three stages:

External, or pulmonary, human respiration;

Transport of gases by blood (transportation of oxygen by blood to tissues and cells, while removing carbon dioxide from tissues);

Tissue (cellular) respiration, which is carried out directly in cells in special organelles.

External respiration of a person

We will consider the main function of the respiratory apparatus - external respiration, in which gas exchange occurs in the lungs, that is, the supply of oxygen to the respiratory surface of the lungs and the removal of carbon dioxide.

In the process of external respiration, the respiratory apparatus itself takes part, including the airways (nose, pharynx, larynx, trachea), lungs and inspiratory (respiratory) muscles, which expand the chest in all directions.

It is estimated that the average daily ventilation of the lungs is about 19,000-20,000 liters of air, and more than 7 million liters of air pass through the human lungs per year.

Pulmonary ventilation provides gas exchange in the lungs and is supplied by alternating inhalation (inspiration) and exhalation (expiration).

Inhalation is an active process due to the inspiratory (respiratory) muscles, the main of which are the diaphragm, external oblique intercostal muscles and internal intercartilaginous muscles.

The diaphragm is a muscle-tendon formation that delimits the abdominal and thoracic cavities, with its contraction, the volume of the chest increases.

With calm breathing, the diaphragm moves down by 2-3 cm, and with deep forced breathing, the excursion of the diaphragm can reach 10 cm.

When inhaling, due to the expansion of the chest, the volume of the lungs passively increases, the pressure in them becomes lower than atmospheric pressure, which makes it possible for air to penetrate into them. During inhalation, air initially passes through the nose, pharynx, and then enters the larynx. Nasal breathing in humans is very important, because when air passes through the nose, the air is moistened and warmed. In addition, the epithelium lining the nasal cavity is able to retain small foreign bodies that enter with air. Thus, the airways also perform a cleansing function.

The larynx is located in the anterior region of the neck, from above it is connected to the hyoid bone, from below it passes into the trachea. In front and from the sides are the right and left lobes of the thyroid gland. The larynx is involved in the act of breathing, protection of the lower respiratory tract and voice formation, consists of 3 paired and 3 unpaired cartilages. Of these formations, the epiglottis plays an important role in the process of breathing, which protects the respiratory tract from foreign bodies and food. The larynx is conventionally divided into three sections. In the middle section are the vocal cords, which form the narrowest point of the larynx - the glottis. The vocal cords play a major role in the process of sound production, and the glottis plays a major role in breathing practice.

Air enters the trachea from the larynx. The trachea begins at the level of the 6th cervical vertebra; at the level of the 5th thoracic vertebrae, it divides into 2 main bronchi. The trachea itself and the main bronchi consist of open cartilaginous semicircles, which ensures their constant shape and prevents them from collapsing. The right bronchus is wider and shorter than the left, is located vertically and serves as a continuation of the trachea. It is divided into 3 lobar bronchi, as the right lung is divided into 3 lobes; left bronchus - into 2 lobar bronchi (the left lung consists of 2 lobes)

Then the lobar bronchi divide dichotomously (in two) into bronchi and bronchioles of smaller sizes, ending with respiratory bronchioles, at the end of which there are alveolar sacs, consisting of alveoli - formations in which, in fact, gas exchange occurs.

In the walls of the alveoli there is a large number of tiny blood vessels - capillaries, which serve for gas exchange and further transportation of gases.

The bronchi with their branching into smaller bronchi and bronchioles (up to the 12th order, the wall of the bronchi includes cartilaginous tissue and muscles, this prevents the bronchi from collapsing during exhalation) outwardly resemble a tree.

Terminal bronchioles approach the alveoli, which are a branching of the 22nd order.

The number of alveoli in the human body reaches 700 million, and their total area is 160 m2.

By the way, our lungs have a huge reserve; at rest, a person uses no more than 5% of the respiratory surface.

Gas exchange at the level of the alveoli is continuous, it is carried out by the method of simple diffusion due to the difference in the partial pressure of gases (the percentage of the pressure of various gases in their mixture).

The percentage pressure of oxygen in the air is about 21% (in the exhaled air its content is approximately 15%), carbon dioxide - 0.03%.

Video "Gas exchange in the lungs":

calm exhalation- passive process due to several factors.

After the cessation of contraction of the inspiratory muscles, the ribs and sternum descend (due to gravity) and the chest decreases in volume, respectively, intrathoracic pressure increases (becomes higher than atmospheric pressure) and air rushes out.

The lungs themselves have elastic elasticity, which is aimed at reducing the volume of the lungs.

This mechanism is due to the presence of a film lining the inner surface of the alveoli, which contains a surfactant - a substance that provides surface tension inside the alveoli.

So, when the alveoli are overstretched, the surfactant limits this process, trying to reduce the volume of the alveoli, while at the same time not allowing them to subside completely.

The mechanism of elastic elasticity of the lungs is also provided by the muscle tone of the bronchioles.

Active process involving accessory muscles.

During deep expiration, the abdominal muscles (oblique, rectus and transverse) act as expiratory muscles, with the contraction of which the pressure in the abdominal cavity increases and the diaphragm rises.

The auxiliary muscles that provide exhalation also include the intercostal internal oblique muscles and the muscles that flex the spine.

External respiration can be assessed using several parameters.

Respiratory volume. The amount of air that enters the lungs at rest. At rest, the norm is approximately 500-600 ml.

The volume of inhalation is slightly larger, since less carbon dioxide is exhaled than oxygen is supplied.

Alveolar volume. The part of the tidal volume that participates in gas exchange.

Anatomical dead space. It is formed mainly due to the upper respiratory tract, which are filled with air, but do not themselves participate in gas exchange. It makes up about 30% of the respiratory volume of the lungs.

Inspiratory reserve volume. The amount of air that a person can additionally inhale after a normal breath (can be up to 3 liters).

Expiratory reserve volume. Residual air that can be exhaled after a quiet expiration (up to 1.5 liters in some people).

Breathing rate. The average is 14-18 respiratory cycles per minute. It usually increases with physical activity, stress, anxiety, when the body needs more oxygen.

Minute volume of lungs. It is determined taking into account the respiratory volume of the lungs and the respiratory rate per minute.

Under normal conditions, the duration of the exhalation phase is approximately 1.5 times longer than the inhalation phase.

Of the characteristics of external respiration, the type of respiration is also important.

It depends on whether breathing is carried out only with the help of an excursion of the chest (thoracic, or costal, type of breathing) or the diaphragm takes the main part in the process of breathing (abdominal, or diaphragmatic, type of breathing).

Breathing is above consciousness.

For women, the thoracic type of breathing is more characteristic, although breathing with the participation of the diaphragm is physiologically more justified.

With this type of breathing, the lower sections of the lungs are better ventilated, the respiratory and minute volume of the lungs increases, the body expends less energy on the breathing process (the diaphragm moves more easily than the bone and cartilage frame of the chest).

Breathing parameters throughout a person's life are automatically adjusted, depending on the needs at a certain time.

The respiratory control center consists of several links.

As the first link in regulation the need to maintain a constant level of oxygen and carbon dioxide tension in the blood.

These parameters are constant; with severe disorders, the body can exist for only a few minutes.

The second link of regulation- peripheral chemoreceptors located in the walls of blood vessels and tissues that respond to a decrease in the level of oxygen in the blood or to an increase in the level of carbon dioxide. Irritation of chemoreceptors causes a change in the frequency, rhythm and depth of breathing.

The third link of regulation- the actual respiratory center, which consists of neurons (nerve cells) located at various levels of the nervous system.

There are several levels of the respiratory center.

spinal respiratory center, located at the level of the spinal cord, innervates the diaphragm and intercostal muscles; its significance is in changing the force of contraction of these muscles.

Central respiratory mechanism(rhythm generator), located in the medulla oblongata and the pons, has the property of automatism and regulates breathing at rest.

Center located in the cerebral cortex and hypothalamus, ensures the regulation of breathing during physical exertion and in a state of stress; the cerebral cortex allows you to arbitrarily regulate breathing, produce an unauthorized breath hold, consciously change its depth and rhythm, and so on.

One more important point should be noted: a deviation from the normal rhythm of breathing is usually accompanied by changes in other organs and systems of the body.

Simultaneously with a change in the respiratory rate, the heart rate is often disturbed and blood pressure becomes unstable.

We offer to watch the video a fascinating and informative film "The Miracle of the Respiratory System":

Breathe properly and stay healthy!