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Respiratory organs and their functions: nasal cavity, larynx, trachea, bronchi, lungs. Human respiratory organs

What can be called the main indicator of human vitality? Of course, we are talking about breathing. A person can go without food and water for some time. Without air, life is not possible at all.

General information

What is breathing? It is the link between the environment and people. If the supply of air is difficult for some reason, then the human heart and respiratory organs begin to function in an enhanced mode. This occurs due to the need to provide sufficient oxygen. Organs are able to adapt to changing environmental conditions.

Scientists were able to establish that the air entering the human respiratory system forms two streams (conditionally). One of them penetrates the left side of the nose. shows that the second one is coming from the right side. Experts have also proven that the arteries of the brain are divided into two streams of air. Thus, the breathing process must be correct. This is very important for maintaining the normal functioning of people. Let's consider the structure of the human respiratory organs.

Important Features

When we talk about breathing, we are talking about a set of processes that are aimed at ensuring a continuous supply of oxygen to all tissues and organs. In this case, substances that are formed during the exchange of carbon dioxide are removed from the body. Breathing is a very complex process. It goes through several stages. The stages of entry and exit of air into the body are as follows:

  1. We are talking about gas exchange between atmospheric air and the alveoli. This stage is considered external respiration.
  2. Exchange of gases carried out in the lungs. It occurs between the blood and alveolar air.
  3. Two processes: the delivery of oxygen from the lungs to the tissues, as well as the transport of carbon dioxide from the latter to the former. That is, we are talking about the movement of gases using the bloodstream.
  4. The next stage of gas exchange. It involves tissue cells and capillary blood.
  5. Finally, internal breathing. This refers to what occurs in the mitochondria of cells.

Main goals

The human respiratory organs remove carbon dioxide from the blood. Their task also includes saturating it with oxygen. If we list the functions of the respiratory organs, then this is the most important.

Additional purpose

There are other functions of the human respiratory organs, among them the following can be distinguished:

  1. Taking part in thermoregulation processes. The fact is that the temperature of the inhaled air affects a similar parameter of the human body. During exhalation, the body releases heat to the external environment. At the same time, it is cooled, if possible.
  2. Taking part in excretory processes. During exhalation, water vapor is eliminated from the body along with air (except carbon dioxide). This also applies to some other substances. For example, ethyl alcohol during alcohol intoxication.
  3. Taking part in immune reactions. Thanks to this function of the human respiratory system, it becomes possible to neutralize some pathologically dangerous elements. These include, in particular, pathogenic viruses, bacteria and other microorganisms. Certain lung cells are endowed with this ability. In this regard, they can be classified as elements of the immune system.

Specific tasks

There are very narrowly focused functions of the respiratory organs. In particular, specific tasks are performed by the bronchi, trachea, larynx, and nasopharynx. Among these narrowly focused functions are the following:

  1. Cooling and warming of incoming air. This task is performed according to the ambient temperature.
  2. Humidification of the air (inhaled), which prevents the lungs from drying out.
  3. Purification of incoming air. In particular, this applies to foreign particles. For example, to dust entering with the air.

The structure of the human respiratory organs

All elements are connected by special channels. Air enters and exits through them. This system also includes the lungs, the organs where gas exchange occurs. The structure of the entire complex and the principle of its operation are quite complex. Let's look at the human respiratory system (pictures below) in more detail.

Information about the nasal cavity

The respiratory tract begins with it. The nasal cavity is separated from the oral cavity. The front is the hard palate, and the back is the soft palate. The nasal cavity has a cartilaginous and bone skeleton. It is divided into left and right parts thanks to a continuous partition. Three turbinates are also present. Thanks to them, the cavity is divided into passages:

  1. Lower.
  2. Average.
  3. Upper.

Exhaled and inhaled air passes through them.

Features of the mucosa

It has a number of devices that are designed to process inhaled air. First of all, it is covered by ciliated epithelium. Its cilia form a continuous carpet. Due to the fact that the eyelashes flicker, dust is quite easily removed from the nasal cavity. The hairs that are located at the outer edge of the holes also help retain foreign elements. contains special glands. Their secretion envelops dust and helps eliminate it. In addition, air humidification occurs.

The mucus that is found in the nasal cavity has bactericidal properties. It contains lysozyme. This substance helps reduce the ability of bacteria to reproduce. It also kills them. The mucous membrane contains many venous vessels. Under different conditions they can swell. If they are damaged, nosebleeds begin. The purpose of these formations is to heat the air stream passing through the nose. Leukocytes leave the blood vessels and end up on the surface of the mucosa. They also perform protective functions. In the process of phagocytosis, leukocytes die. Thus, the mucus that comes out of the nose contains many dead “defenders.” Next, the air passes into the nasopharynx, and from there to other organs of the respiratory system.

Larynx

It is located in the anterior laryngeal part of the pharynx. This is the level of the 4-6th cervical vertebrae. The larynx is formed by cartilage. The latter are divided into paired (sphenoid, corniculate, arytenoid) and unpaired (cricoid, thyroid). In this case, the epiglottis is attached to the upper edge of the last cartilage. During swallowing, it closes the entrance to the larynx. Thus, it prevents food from entering it.

General information about the trachea

It is a continuation of the larynx. It is divided into two bronchi: left and right. The bifurcation is where the trachea branches. It is characterized by the following length: 9-12 centimeters. On average, the transverse diameter reaches eighteen millimeters.

The trachea may include up to twenty incomplete cartilaginous rings. They are connected by fibrous ligaments. Thanks to cartilaginous half-rings, the airways become elastic. In addition, they are made to flow down, therefore, they are easily passable for air.

The membranous posterior wall of the trachea is flattened. It contains smooth muscle tissue (bundles that run longitudinally and transversely). This ensures active movement of the trachea when coughing, breathing, and so on. As for the mucous membrane, it is covered by ciliated epithelium. In this case, the exception is part of the epiglottis and vocal cords. It also has mucous glands and lymphoid tissue.

Bronchi

This is a paired element. The two bronchi into which the trachea is divided enter the left and right lungs. There they branch tree-like into smaller elements, which are included in the pulmonary lobules. Thus, bronchioles are formed. We are talking about even smaller respiratory branches. The diameter of the respiratory bronchioles can be 0.5 mm. They, in turn, form the alveolar ducts. The latter end with corresponding bags.

What are alveoli? These are protrusions that look like bubbles, which are located on the walls of the corresponding sacs and passages. Their diameter reaches 0.3 mm, and the number can reach up to 400 million. This makes it possible to create a large breathing surface. This factor significantly affects lung volume. The latter can be increased.

The most important human respiratory organs

They are considered lungs. Serious illnesses associated with them can be life-threatening. The lungs (photos presented in the article) are located in the chest cavity, which is hermetically sealed. Its posterior wall is formed by the corresponding part of the spine and ribs, which are movably attached. Between them are the internal and external muscles.

The chest cavity is separated from the abdominal cavity from below. The abdominal obstruction, or diaphragm, is involved in this. The anatomy of the lungs is not simple. A person has two of them. The right lung includes three lobes. At the same time, the left consists of two. The apex of the lungs is their narrowed upper part, and the expanded lower part is considered the base. The gates are different. They are represented by depressions on the inner surface of the lungs. Blood nerves as well as lymphatic vessels pass through them. The root is represented by a combination of the above formations.

The lungs (the photo illustrates their location), or rather their tissue, consist of small structures. They are called lobules. We are talking about small areas that have a pyramidal shape. The bronchi, which enter the corresponding lobule, are divided into respiratory bronchioles. The alveolar duct is present at the end of each of them. This entire system represents the functional unit of the lungs. It is called the acini.

The lungs are covered with pleura. This is a shell consisting of two elements. We are talking about the outer (parietal) and inner (visceral) lobes (a diagram of the lungs is attached below). The latter covers them and at the same time is the outer shell. It makes a transition to the outer layer of the pleura along the root and represents the inner lining of the walls of the chest cavity. This leads to the formation of a geometrically closed, minute capillary space. We are talking about the pleural cavity. It contains a small amount of the corresponding liquid. She moistens the pleura. This makes it easier for them to slide together. Changes in air in the lungs occur for many reasons. One of the main ones is the change in the size of the pleural and chest cavities. This is the anatomy of the lungs.

Features of the air inlet and outlet mechanism

As mentioned earlier, an exchange occurs between the gas that is in the alveoli and the atmospheric gas. This is due to the rhythmic alternation of inhalations and exhalations. The lungs do not have muscle tissue. For this reason, their intensive reduction is impossible. In this case, the most active role is given to the respiratory muscles. When they are paralyzed, it is not possible to breathe. In this case, the respiratory organs are not affected.

Inspiration is the act of breathing in. We are talking about an active process during which the chest enlarges. Expiration is the act of exhalation. This process is passive. It occurs because the chest cavity becomes smaller.

The respiratory cycle is represented by the phases of inhalation and subsequent exhalation. The diaphragm and external oblique muscles take part in the process of air entry. As they contract, the ribs begin to rise. At the same time, the chest cavity enlarges. The diaphragm contracts. At the same time, it takes a flatter position.

As for the incompressible organs, during the process under consideration they are pushed to the sides and down. During a quiet inhalation, the dome of the diaphragm lowers by about one and a half centimeters. Thus, the vertical size of the thoracic cavity increases. In the case of very deep breathing, auxiliary muscles take part in the act of inhalation, among which the following stand out:

  1. Rhomboids (which elevate the scapula).
  2. Trapezoidal.
  3. Small and large pectorals.
  4. Anterior serratus.

The wall of the chest cavity and the lungs are covered by a serous membrane. The pleural cavity is represented by a narrow gap between the layers. It contains serous fluid. The lungs are always stretched. This is due to the fact that the pressure in the pleural cavity is negative. We are talking about elastic traction. The fact is that lung volume constantly tends to decrease. At the end of a quiet exhalation, almost every respiratory muscle relaxes. In this case, the pressure in the pleural cavity is below atmospheric. For different people, the main role in the act of inhalation is played by the diaphragm or intercostal muscles. In accordance with this, we can talk about different types of breathing:

  1. Reburn.
  2. Diaphragmatic.
  3. Abdomen.
  4. Grudny.

It is now known that the latter type of breathing predominates in women. In men, most cases are abdominal. During quiet breathing, exhalation occurs due to elastic energy. It accumulates during the previous inhalation. As the muscles relax, the ribs can passively return to their original position. If the contractions of the diaphragm decrease, it will return to its previous dome-shaped position. This is due to the fact that the abdominal organs act on it. Thus, the pressure in it decreases.

All of the above processes lead to compression of the lungs. Air comes out of them (passively). Forced exhalation is an active process. The internal intercostal muscles take part in it. Moreover, their fibers go in the opposite direction when compared with external ones. They contract and the ribs move down. The chest cavity also shrinks.

The human respiratory organs include:

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

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

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

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

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

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

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

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

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

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

Paranasal sinuses

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

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

Paranasal sinuses

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

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

Larynx

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

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

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

Trachea

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

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

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

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

Bronchi

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

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

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

Trachea and bronchi

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

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

Respiratory organs: lungs

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

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

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

The structure of the alveoli

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

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

The essence of the breathing process

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

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

Gas exchange across the air-blood barrier

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

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

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

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

Breathing is the link between a person and the environment. If the supply of air is obstructed, the human respiratory organs and heart begin to work harder to provide the necessary amount of oxygen for breathing. The human respiratory and respiratory system is capable of adapting to environmental conditions.

The human respiratory system ensures gas exchange between atmospheric air and the lungs, as a result of which oxygen from the lungs enters the blood and is transferred by the blood to the tissues of the body, and carbon dioxide is transported from the tissues in the opposite direction. At rest, the tissues of an adult’s body consume approximately 0.3 liters of oxygen per minute and produce a slightly smaller amount of carbon dioxide. The ratio of the amount of CO2 formed in its tissues to the amount of 02 consumed by the body is called the respiratory coefficient, the value of which under normal conditions is 0.9. Maintaining a normal level of gas homeostasis of O2 and CO2 in the body in accordance with the rate of tissue metabolism (respiration) is the main function of the respiratory system of the human body.

This system consists of a single complex of bone, cartilage, connective and muscle tissues of the chest, the respiratory tract (air section of the lungs), which ensures the movement of air between the external environment and the air space of the alveoli, as well as lung tissue (respiratory section of the lungs), which has high elasticity and extensibility. The respiratory system includes its own nervous apparatus, which controls the respiratory muscles of the chest, sensory and motor fibers of the neurons of the autonomic nervous system, which have terminals in the tissues of the respiratory organs. The place of gas exchange between the human body and the external environment is the alveoli of the lungs, the total area of ​​which reaches an average of 100 m2.

Alveoli (about 3.108) are located at the end of the small airways of the lungs, have a diameter of approximately 0.3 mm and are in close contact with the pulmonary capillaries. Blood circulation between the tissue cells of the human body that consume O2 and produce CO2, and the lungs, where these gases are exchanged with atmospheric air, is carried out by the circulatory system.

Functions of the respiratory system. In the human body, the respiratory system performs respiratory and non-respiratory functions. The respiratory function of the system maintains gas homeostasis of the internal environment of the body in accordance with the level of metabolism of its tissues. With the inhaled air, dust microparticles enter the lungs, which are retained by the mucous membrane of the respiratory tract and then removed from the lungs with the help of protective reflexes (coughing, sneezing) and mucociliary cleansing mechanisms (protective function).

The non-respiratory functions of the system are caused by processes such as synthesis (surfactant, heparin, leukotrienes, prostaglandins), activation (angiotensin II) and inactivation (serotonin, prostaglandins, norepinephrine) of biologically active substances, with the participation of alveolocytes, mast cells and the endothelium of the capillaries of the lungs (metabolic function ). The epithelium of the mucous membrane of the respiratory tract contains immunocompetent cells (T- and B-lymphocytes, macrophages) and mast cells (histamine synthesis), which provide the protective function of the body. Through the lungs, water vapor and molecules of volatile substances are removed from the body with exhaled air (excretory function), as well as a small part of the heat from the body (thermoregulatory function). The respiratory muscles of the chest are involved in maintaining the position of the body in space (postural-tonic function). Finally, the nervous apparatus of the respiratory system, the muscles of the glottis and upper respiratory tract, as well as the muscles of the chest are involved in human speech activity (speech production function). The main respiratory function of the respiratory system is realized in the processes of external respiration, which are the exchange of gases (O2, CO2 and N2) between the alveoli and the external environment, the diffusion of gases (O2 and CO2) between the alveoli of the lungs and the blood (gas exchange). Along with external respiration, the body carries out the transport of respiratory gases in the blood, as well as gas exchange of 02 and CO2 between the blood and tissues, which is often called internal (tissue) respiration.

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

Studies have also shown that in the artery of the human brain, the air received is also divided into two streams. The breathing process 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.

The human respiratory system includes the trachea, lungs, bronchi, lymphatic, and vascular systems. They also include the nervous system and respiratory muscles, 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 exit of air from the lungs. The most important organ of the entire respiratory system is the lungs, between which the heart is located.

Respiratory system

Nasal cavity

- the main channel for air entering the respiratory tract. Divided into two parts by the osteochondral nasal septum. The interior of each cavity is formed by bony pits and projections called septa, and is covered with a mucous membrane consisting of numerous hairs, or cilia, and mucus-secreting glands. The nose cleans the inhaled air: thanks to the cilia, it traps fine dust that is in the air, and with the help of sputum it creates protection against possible infections, as it destroys microorganisms in the air we breathe.

The mucous membrane prevents too dry air from entering the body and provides it with the necessary humidity. In addition, its blood vessels maintain an optimal temperature in the nasal cavity, and the folds of the inner wall retain and warm the inhaled air.

Oral cavity

- This is one of the main parts of the digestive system, but it is also the respiratory tract, in addition, it is involved in speech formation. It is limited to the lips, the inside of the cheeks, the base of the tongue and the palate.

The function of the oral cavity in the process of breathing is insignificant, since the nostrils are much better adapted for this purpose. Nevertheless, it serves as an inlet and outlet for air in cases where there is a great need to saturate the lungs with oxygen. For example, when we make great physical efforts or when the nostrils become blocked due to injury or a cold.

The oral cavity is involved in speech production, as the tongue and teeth articulate the sounds produced by the vocal cords in the larynx.

Trachea

is a tube connecting the larynx and bronchi. The trachea is about 12-15 cm long. The trachea, unlike the lungs, is 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. At the end, the trachea bifurcates into two bronchi. The bifurcation of the trachea is called bifurcation. At the beginning of the trachea, the thyroid gland adjoins it. At 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 muscle-cartilaginous tissue with a fibrous structure. The trachea consists of 18-20 rings of cartilaginous tissue, thanks to which the trachea is flexible.

Pharynx

is a tube that originates in the nasal cavity. The digestive and respiratory tracts intersect in the pharynx. 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 the 5-7 vertebrae of the neck. 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 cleanse and humidify it. The oral cavity 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.

Larynx

- a respiratory organ connecting the trachea and pharynx. The voice box is located in the larynx. The larynx is located in the area of ​​4-6 vertebrae of the neck and is attached to the hyoid bone with the help of ligaments. 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: corniculate, sphenoid, arytenoid. The connection between the joints is provided by ligaments and joints. Between the cartilages there are membranes that also serve as a connection.

Bronchi

are tubes formed as a result of bifurcation of the trachea. Each of the main bronchi then branches into smaller bronchi that go to different areas or lobes of the lungs.

The bronchi that penetrate the lobes of the lungs are called lobar bronchi, and there are three of them in the right lung and two in the left. Further, the lobar bronchi continue to branch and narrow, dividing into segmental bronchi, and finally turn into tubes with a diameter of less than 1 mm - bronchioles.

Bronchioles distribute oxygen through their endings, the pulmonary alveoli, a kind of bubbles in which gas exchange takes place, that is, the exchange of carbon dioxide for oxygen.

Lungs -

main respiratory organs. They are shaped like a cone. 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 through the alveoli. Blood enters the lungs from the veins thanks to 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 regeneration process to take place, and to receive nutrients from the blood that the body needs. Covering the lungs is the pleura, consisting of two lobes separated by a cavity (pleural cavity).

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

The main source of energy for all human tissues is processes aerobic (oxygen) oxidation organic substances that occur in the mitochondria of cells and require a constant supply of oxygen.

Breath- this is a set of processes that ensure the supply of oxygen to the body, its use in the oxidation of organic substances and the removal of carbon dioxide and some other substances from the body.

❖ Human breathing includes:
■ ventilation;
■ gas exchange in the lungs;
■ transportation of gases by blood;
■ gas exchange in tissues;
■ cellular respiration (biological oxidation).

The differences in the composition of the alveolar and inhaled air are explained by the fact that in the alveoli, oxygen continuously diffuses into the blood, and carbon dioxide enters the alveoli from the blood. Differences in the composition of the alveolar and exhaled air are explained by the fact that during exhalation, the air leaving the alveoli mixes with the air contained in the respiratory tract.

Structure and Functions of the respiratory organs

❖ Respiratory system person includes:

■ airways - nasal cavity (it is separated from the oral cavity in front by the hard palate and in the back by the soft palate), nasopharynx, larynx, trachea, bronchi;

■ lungs , consisting of alveoli and alveolar ducts.

Nasal cavity initial part of the respiratory tract; has paired holes - nostrils through which air penetrates; located at the outer edge of the nostrils hairs , delaying the penetration of large dust particles. The nasal cavity is divided by a septum into right and left halves, each of which consists of an upper, middle and lower nasal passages .

Mucous membrane nasal passages covered ciliated epithelium , highlighting slime , which glues dust particles together and has a detrimental effect on microorganisms. Cilia the epithelium constantly fluctuates and contributes to the removal of foreign particles along with mucus.

■The mucous membrane of the nasal passages is abundantly supplied blood vessels , which helps warm and humidify the inhaled air.

■ The epithelium also contains receptors responsive to different odors.

Air from the nasal cavity through the internal nasal openings - choanae - Fall into nasopharynx and further into larynx .

Larynx- a hollow organ, formed by several paired and unpaired cartilages, interconnected by joints, ligaments and muscles. The largest of the cartilages is thyroid - consists of two quadrangular plates connected at the front at an angle. In men, this cartilage protrudes slightly forward, forming Adam's apple . Located above the entrance to the larynx epiglottis - a cartilaginous plate that covers the entrance to the larynx during swallowing.

The laryngeal cavity is covered mucous membrane , forming two pairs folds which block the entrance to the larynx during swallowing and (lower pair of folds) cover vocal cords .

Vocal cords in front they are attached to the thyroid cartilage, and behind - to the left and right arytenoid cartilages, while between the ligaments a glottis . When the cartilage moves, the ligaments come closer together and stretch or, conversely, diverge, changing the shape of the glottis. During breathing, the ligaments are separated, and during singing and speech they almost close, leaving only a narrow gap. Air passing through this gap causes vibration of the edges of the ligaments, which generates sound . In formation speech sounds the tongue, teeth, lips and cheeks are also involved.

Trachea- a tube about 12 cm long, extending from the lower edge of the larynx. It is formed by 16-20 cartilaginous half rings , the open soft part of which is formed by dense connective tissue and faces the esophagus. The inside of the trachea is lined ciliated epithelium , whose cilia remove dust particles from the lungs into the pharynx. At the level of 1V-V thoracic vertebrae, the trachea is divided into left and right bronchi .

Bronchi similar in structure to the trachea. Entering the lung, the bronchi branch, forming bronchial "tree" . The walls of the small bronchi ( bronchioles ) consist of elastic fibers, between which smooth muscle cells are located.

Lungs- a paired organ (right and left), occupying most of the chest and tightly adjacent to its walls, leaving room for the heart, large vessels, esophagus, trachea. The right lung consists of three lobes, the left - of two.

The chest cavity is lined on the inside parietal pleura . On the outside, the lungs are covered with a dense membrane - pulmonary pleura . There is a narrow gap between the pulmonary and parietal pleura - pleural cavity , filled with fluid that reduces friction between the lungs and the walls of the chest cavity when breathing. The pressure in the pleural cavity is below atmospheric, which creates suction force , pressing the lungs to the chest. Since lung tissue is elastic and capable of stretching, the lungs are always in an expanded state and follow the movements of the chest.

Bronchial tree in the lungs it branches into passages with sacs, the walls of which are formed by many (about 350 million) pulmonary vesicles - alveoli . Outside, each alveolus is surrounded by a thick network of capillaries . The walls of the alveoli consist of a single-layer squamous epithelium, covered from the inside with a layer of surfactant - surfactant . Through the walls of the alveoli and capillaries occurs gas exchange between the inhaled air and the blood: oxygen passes from the alveoli into the blood, and carbon dioxide enters the alveoli from the blood. Surfactant accelerates the diffusion of gases through the wall and prevents the “collapse” of the alveoli. The total gas exchange surface of the alveoli is 100-150 m2.

The exchange of gases between the alveoli and blood occurs due to diffusion . There is always more oxygen in the alveoli than in the blood capillaries, so it passes from the alveoli to the capillaries. On the contrary, there is more carbon dioxide in the blood than in the alveoli, so it moves from the capillaries to the alveoli.

Breathing movements

Ventilation- this is a constant change of air in the alveoli of the lungs, necessary for gas exchange of the body with the external environment and ensured by regular movements of the chest during inhale And exhale .

Inhale carried out actively , due to the reduction external oblique intercostal muscles and diaphragm (the dome-shaped tendon-muscular septum separating the chest cavity from the abdominal cavity).

The intercostal muscles lift the ribs and move them slightly to the sides. When the diaphragm contracts, its dome flattens and moves the abdominal organs down and forward. As a result, the volume of the chest cavity and lungs, following the movements of the chest, increases. This leads to a drop in pressure in the alveoli, and atmospheric air is sucked into them.

Exhalation with quiet breathing is carried out passively . When the external oblique intercostal muscles and diaphragm relax, the ribs return to their original position, the volume of the chest decreases, and the lungs return to their original shape. As a result, the air pressure in the alveoli becomes higher than atmospheric pressure, and it flows out.

Exhalation during physical activity it becomes active . Participating in its implementation internal oblique intercostal muscles, abdominal wall muscles and etc.

Average respiratory rate for an adult - 15-17 per minute. During physical activity, the respiratory rate can increase 2-3 times.

The role of breathing depth. When breathing deeply, air has time to penetrate more alveoli and stretch them. As a result, gas exchange conditions improve and the blood is additionally saturated with oxygen.

Lung capacity

Pulmonary volume- the maximum amount of air that the lungs can hold; in an adult it is 5-8 liters.

Tidal volume of the lungs- this is the volume of air entering the lungs in one breath during quiet breathing (on average about 500 cm3).

Inspiratory reserve volume- the volume of air that can be additionally inhaled after a quiet inhalation (about 1500 cm 3).

Expiratory reserve volume- the volume of air that can be exhaled^ after a calm exhalation with volitional tension (approximately 1500 cm3).

Vital capacity of the lungs is the sum of the tidal volume of the lungs, the expiratory reserve volume and the inspiratory reserve volume; on average it is 3500 cm 3 (for athletes, in particular swimmers, it can reach 6000 cm 3 or more). It is measured using special instruments - a spirometer or spirograph - and is graphically presented in the form of a spirogram.

Residual volume- the amount of air that remains in the lungs after maximum exhalation.

Transfer of gases by blood

Oxygen is carried in the blood in two forms - in the form oxy-hemoglobin (about 98%) and in the form of dissolved O 2 (about 2%).

Blood oxygen capacity- the maximum amount of oxygen that can be absorbed by one liter of blood. At a temperature of 37 °C, 1 liter of blood can contain up to 200 ml of oxygen.

Transport of oxygen to body cells carried out hemoglobin (Hb) blood located in red blood cells . Hemoglobin binds oxygen, turning into oxyhemoglobin :

Hb + 4O 2 → HbO 8.

Blood transfer of carbon dioxide:

■ in dissolved form (up to 12% CO 2);

■ most of the CO 2 does not dissolve in the blood plasma, but penetrates into red blood cells, where it interacts (with the participation of the enzyme carbonic anhydrase) with water, forming unstable carbonic acid:

CO 2 + H 2 O ↔ H 2 CO 3,

which then dissociates into the H + ion and the bicarbonate ion HCO 3 -. HCO 3 ions pass from red blood cells into blood plasma, from which they are transported to the lungs, where they again penetrate into red blood cells. In the capillaries of the lungs, the reaction (CO 2 + H 2 O ↔ H 2 CO 3) in red blood cells shifts to the left, and HCO 3 ions eventually turn into carbon dioxide and water. Carbon dioxide enters the alveoli and exits as part of the exhaled air.

Exchange of gases in tissues

Exchange of gases in tissues occurs in the capillaries of the systemic circulation, where the blood gives off oxygen and receives carbon dioxide. In tissue cells, the concentration of oxygen is lower than in capillaries (since it is constantly utilized in tissues). Therefore, oxygen passes from the blood vessels into the tissue fluid, and with it into the cells, where it enters into oxidation reactions. For the same reason, carbon dioxide from the cells enters the capillaries, is transported by the blood stream through the pulmonary circulation to the lungs and is excreted from the body. After passing through the lungs, venous blood becomes arterial and enters the left atrium.

Breathing regulation

❖ Breathing is regulated:
■ cerebral cortex,
■ respiratory center located in the medulla oblongata and pons,
■ nerve cells of the cervical spinal cord,
■ nerve cells of the thoracic spinal cord.

Respiratory center- this is a region of the brain that is a collection of neurons that ensure the rhythmic activity of the respiratory muscles.

■ The respiratory center is subordinate to the overlying parts of the brain located in the cerebral cortex; this allows you to consciously change the rhythm and depth of breathing.

■ The respiratory center regulates the functioning of the respiratory system according to the reflex principle.

❖ Neurons of the respiratory center are divided into inhalation neurons and exhalation neurons .

Inhalation neurons transmit excitation to the nerve cells of the spinal cord, which control the contraction of the diaphragm and external oblique intercostal muscles.

Expiratory neurons are excited by receptors of the airways and alveoli with an increase in lung volume. Impulses from these receptors enter the medulla oblongata, causing inhibition of inspiratory neurons. As a result, the respiratory muscles relax and exhalation occurs.

Humoral regulation of respiration. During muscular work, CO 2 and under-oxidized metabolic products (lactic acid, etc.) accumulate in the blood. This leads to an increase in the rhythmic activity of the respiratory center and, as a consequence, to increased ventilation of the lungs. As the concentration of CO 2 in the blood decreases, the tone of the respiratory center decreases: an involuntary temporary holding of breath occurs.

Sneeze- a sharp, forced exhalation of air from the lungs through closed vocal cords, occurring after stopping breathing, closing the glottis and a rapid increase in air pressure in the chest cavity, caused by irritation of the nasal mucosa with dust or strong-smelling substances. Along with air and mucus, irritants of the mucous membrane are also released.

Cough differs from sneezing in that the main air flow comes out through the mouth.

Respiratory hygiene

♦ Correct breathing:

■ you need to breathe through your nose ( nasal breathing), since its mucous membrane is rich in blood and lymphatic vessels and has special cilia, warming, purifying and moisturizing the air and preventing the penetration of microorganisms and dust particles into the respiratory tract (if nasal breathing is difficult, headaches appear and fatigue quickly sets in);

■ inhalation should be shorter than exhalation (this promotes productive mental activity and normal perception of moderate physical activity);

■ during increased physical activity, a sharp exhalation should be made at the moment of greatest effort.

❖ Conditions for proper breathing:

■ well-developed chest; lack of stoop, sunken chest;

■ maintaining correct posture: the body position should be such that breathing is not difficult;

■ hardening the body: you should spend a lot of time in the fresh air, perform various physical exercises and breathing exercises, engage in sports that develop the respiratory muscles (swimming, rowing, skiing, etc.);

■ maintaining an optimal gas composition of the indoor air: regularly ventilate the premises, sleep in the summer with the windows open, and in the winter with the vents open (staying in a stuffy, unventilated room can cause headaches, lethargy, and deterioration in well-being).

Dust Hazard: Pathogenic microorganisms and viruses settle on dust particles, which can cause infectious diseases. Large dust particles can mechanically injure the walls of the pulmonary vesicles and airways, complicating gas exchange. Dust containing particles of lead or chromium can cause chemical poisoning.

The effect of smoking on the respiratory system. Smoking is one of the links in the chain of causes of many respiratory diseases. In particular, irritation of the pharynx, larynx, and trachea by tobacco smoke can cause chronic inflammation of the upper respiratory tract and dysfunction of the vocal apparatus; in severe cases, excessive smoking causes lung cancer.

Some respiratory diseases

Airborne method of infection. When talking, exhaling forcefully, sneezing, coughing, droplets of liquid containing bacteria and viruses enter the air from the patient’s respiratory system. These droplets remain in the air for some time and can enter the respiratory system of others, transferring pathogens there. The airborne method of infection is typical for influenza, diphtheria, whooping cough, measles, scarlet fever, etc.

Flu- an acute, epidemic-prone viral disease transmitted by airborne droplets; more often observed in winter and early spring. It is characterized by the toxicity of the virus and the tendency to change its antigenic structure, rapid spread, and the danger of possible complications.

Symptoms: fever (sometimes up to 40 ° C), chills, headache, painful movements of the eyeballs, pain in muscles and joints, difficulty breathing, dry cough, sometimes vomiting and hemorrhagic phenomena.

Treatment; bed rest, drinking plenty of fluids, using antiviral drugs.

Prevention; hardening, mass vaccination of the population; To prevent the spread of influenza, sick people should cover their nose and mouth with gauze bandages folded in four when communicating with healthy people.

Tuberculosis- a dangerous infectious disease that has various forms and is characterized by the formation of foci of specific inflammation in the affected tissues (usually in the tissues of the lungs and bones) and a pronounced general reaction of the body. The causative agent is the tuberculosis bacillus; spreads by airborne droplets and dust, less commonly - through contaminated food (meat, milk, eggs) from sick animals. Revealed when fluorography . In the past, it had a massive distribution (this was facilitated by constant malnutrition and unsanitary conditions). Some forms of tuberculosis can be asymptomatic or undulating, with periodic exacerbations and remissions. Possible symptoms; fatigue, general malaise, loss of appetite, shortness of breath, periodically low-grade fever (about 37.2 °C), constant cough with sputum production, in severe cases - hemoptysis, etc. Prevention; regular fluorographic examinations of the population, maintaining cleanliness in homes and streets, landscaping the streets to purify the air.

Fluorography- examination of the chest organs by photographing an image from a luminous X-ray screen behind which the subject is located. It is one of the methods for studying and diagnosing lung diseases; allows timely detection of a number of diseases (tuberculosis, pneumonia, lung cancer, etc.). Fluorography must be done at least once a year.

First aid for gas poisoning

Help with carbon monoxide or household monoxide poisoning. Carbon monoxide (CO) poisoning causes headaches and nausea; Vomiting, convulsions, loss of consciousness may occur, and in case of severe poisoning, death from cessation of tissue respiration; Domestic gas poisoning is in many ways similar to carbon monoxide poisoning.

In case of such poisoning, the victim must be taken out into fresh air and an ambulance must be called. In case of loss of consciousness and cessation of breathing, artificial respiration and chest compressions should be performed (see below).

First aid for respiratory arrest

Respiratory cessation can occur as a result of a respiratory disease or as a result of an accident (poisoning, drowning, electric shock, etc.). If it lasts more than 4-5 minutes, it can lead to death or severe disability. In such a situation, only timely pre-medical assistance can save a person’s life.

■ When blockage of the pharynx a foreign body can be reached with your finger; removal of a foreign body from the trachea or bronchi only possible with the help of special medical equipment.

■ When drowning It is necessary to remove water, sand and vomit from the airways and lungs of the victim as quickly as possible. To do this, the victim needs to be placed with his stomach on his knee and with sharp movements, squeeze his chest. Then you should turn the victim onto his back and begin artificial respiration .

Artificial respiration: you need to free the victim’s neck, chest and stomach from clothing, place a hard cushion or hand under his shoulder blades and tilt his head back. The rescuer should be on the side of the victim at his head and, holding his nose and holding his tongue with a handkerchief or napkin, periodically (every 3-4 s) quickly (in 1 s) and forcefully, after a deep breath, blow air from his mouth through gauze or handkerchief in the victim’s mouth; at the same time, out of the corner of your eye you need to monitor the victim’s chest: if it expands, it means that air has entered the lungs. Then you need to press on the victim’s chest and force exhalation.

■ You can use the mouth-to-nose breathing method; at the same time, the rescuer blows air into the victim’s nose with his mouth, and tightly clamps his hand over his mouth.

■ The amount of oxygen in the exhaled air (16-17%) is quite sufficient to ensure gas exchange in the victim’s body; and the presence of 3-4% carbon dioxide in it promotes humoral stimulation of the respiratory center.

Indirect cardiac massage. If the victim's heart stops, he should be placed on his back must be on a hard surface and free your chest from clothing. Then the rescuer should stand upright or kneel at the side of the victim, place one palm on the lower half of his sternum so that the fingers are perpendicular to it, and place the other hand on top; in this case, the rescuer’s arms should be straight and positioned perpendicular to the victim’s chest. The massage should be performed with quick (once per second) thrusts, without bending your elbows, trying to bend the chest towards the spine in adults - by 4-5 cm, in children - by 1.5-2 cm.

■ Indirect cardiac massage is performed in combination with artificial respiration: first, the victim is given 2 breaths of artificial respiration, then 15 presses on the sternum in a row, then again 2 breaths of artificial respiration and 15 presses, etc.; After every 4 cycles, the victim’s pulse should be checked. Signs of successful revival are the appearance of a pulse, constriction of the pupils, and pinkening of the skin.

■ One cycle may also consist of one breath of artificial respiration and 5-6 chest compressions.

The respiratory system is a set of organs and anatomical structures that ensure the movement of air from the atmosphere into the lungs and back (breathing cycles inhalation - exhalation), as well as gas exchange between the air entering the lungs and the blood.

Respiratory organs are the upper and lower respiratory tract and lungs, consisting of bronchioles and alveolar sacs, as well as arteries, capillaries and veins of the pulmonary circulation.

The respiratory system also includes the chest and respiratory muscles (the activity of which ensures stretching of the lungs with the formation of inhalation and exhalation phases and changes in pressure in the pleural cavity), as well as the respiratory center located in the brain, peripheral nerves and receptors involved in the regulation of breathing .

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.

Diffusion- a process as a result of which gas tends from an area of ​​higher concentration to an area where its concentration is low.

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

In addition, the respiratory organs are involved in sound production, smell detection, the production of certain hormone-like substances, lipid and water-salt metabolism, and maintaining the body's immunity. In the airways, the inhaled air is cleansed, moistened, warmed, as well as the perception of temperature and mechanical stimuli.

Airways

The airways of the respiratory system begin with the external nose and nasal cavity. The nasal cavity is divided by the osteochondral septum into two parts: right and left. The inner surface of the cavity, lined with mucous membrane, equipped with cilia and penetrated by blood vessels, is covered with mucus, which retains (and partially neutralizes) microbes and dust. Thus, the air in the nasal cavity is purified, neutralized, warmed and moistened. This is why you need to breathe through your nose.

Over the course of a lifetime, the nasal cavity retains up to 5 kg of dust

Having passed pharyngeal part airways, air enters the next organ larynx, having the shape of a funnel and formed by several cartilages: the thyroid cartilage protects the larynx in front, the cartilaginous epiglottis closes the entrance to the larynx when swallowing food. If you try to speak while swallowing food, it can get into your airways and cause suffocation.

When swallowing, the cartilage moves upward and then returns to its original place. With this movement, the epiglottis closes the entrance to the larynx, saliva or food goes into the esophagus. What else is there in the larynx? Vocal cords. When a person is silent, the vocal cords diverge; when he speaks loudly, the vocal cords are closed; if he is forced to whisper, the vocal cords are slightly open.

  1. Trachea;
  2. Aorta;
  3. Main left bronchus;
  4. Right main bronchus;
  5. Alveolar ducts.

The length of the human trachea is about 10 cm, the diameter is about 2.5 cm

From the larynx, air enters the lungs through the trachea and bronchi. The trachea is formed by numerous cartilaginous half-rings located one above the other and connected by muscle and connective tissue. The open ends of the semirings are adjacent to the esophagus. In the chest, the trachea divides into two main bronchi, from which secondary bronchi branch, which continue to branch further to the bronchioles (thin tubes with a diameter of about 1 mm). The branching of the bronchi is a rather complex network called the bronchial tree.

The bronchioles are divided into even thinner tubes - alveolar ducts, which end in small thin-walled (the thickness of the walls is one cell) sacs - alveoli, collected in clusters like grapes.

Mouth breathing causes deformation of the chest, hearing impairment, disruption of the normal position of the nasal septum and the shape of the lower jaw

The lungs are the main organ of the respiratory system

The most important functions of the lungs are gas exchange, supplying oxygen to hemoglobin, and removing carbon dioxide, or carbon dioxide, which is the end product of metabolism. However, the functions of the lungs are not limited to this alone.

The lungs are involved in maintaining a constant concentration of ions in the body; they can remove other substances from it, except toxins (essential oils, aromatic substances, “alcohol plume”, acetone, etc.). When you breathe, water evaporates from the surface of the lungs, which cools the blood and the entire body. In addition, the lungs create air currents that vibrate the vocal cords of the larynx.

Conventionally, the lung can be divided into 3 sections:

  1. pneumatic (bronchial tree), through which air, like a system of canals, reaches the alveoli;
  2. the alveolar system in which gas exchange occurs;
  3. circulatory system of the lung.

The volume of inhaled air in an adult is about 0 4-0.5 liters, and the vital capacity of the lungs, that is, the maximum volume, is approximately 7-8 times greater - usually 3-4 liters (in women less than in men), although in athletes it can exceed 6 liters

  1. Trachea;
  2. Bronchi;
  3. Apex of the lung;
  4. Upper lobe;
  5. Horizontal slot;
  6. Average share;
  7. Oblique slot;
  8. Lower lobe;
  9. Heart tenderloin.

The lungs (right and left) lie in the chest cavity on either side of the heart. The surface of the lungs is covered with a thin, moist, shiny membrane, the pleura (from the Greek pleura - rib, side), consisting of two layers: the inner (pulmonary) covers the surface of the lung, and the outer (parietal) covers the inner surface of the chest. Between the sheets, which almost touch each other, there is a hermetically closed slit-like space called the pleural cavity.

In some diseases (pneumonia, tuberculosis), the parietal layer of the pleura can grow together with the pulmonary layer, forming so-called adhesions. In inflammatory diseases accompanied by excessive accumulation of fluid or air in the pleural fissure, it expands sharply and turns into a cavity

The spindle of the lung protrudes 2-3 cm above the collarbone, extending into the lower region of the neck. The surface adjacent to the ribs is convex and has the greatest extent. The inner surface is concave, adjacent to the heart and other organs, convex and has the greatest extent. The inner surface is concave, adjacent to the heart and other organs located between the pleural sacs. On it there is the gate of the lung, a place through which the main bronchus and pulmonary artery enter the lung and two pulmonary veins exit.

Each lung is divided into lobes by pleural grooves: the left into two (upper and lower), the right into three (upper, middle and lower).

Lung tissue is formed by bronchioles and many tiny pulmonary vesicles of the alveoli, which look like hemispherical protrusions of the bronchioles. The thinnest walls of the alveoli are a biologically permeable membrane (consisting of a single layer of epithelial cells surrounded by a dense network of blood capillaries), through which gas exchange occurs between the blood in the capillaries and the air filling the alveoli. The inside of the alveoli is coated with a liquid surfactant (surfactant), which weakens the forces of surface tension and prevents the complete collapse of the alveoli during exit.

Compared to the lung volume of a newborn, by the age of 12 the lung volume increases 10 times, by the end of puberty - 20 times

The total thickness of the walls of the alveoli and capillary is only a few micrometers. Thanks to this, oxygen easily penetrates from the alveolar air into the blood, and carbon dioxide easily penetrates from the blood into the alveoli.

Respiratory process

Breathing is a complex process of gas exchange between the external environment and the body. The inhaled air differs significantly in composition from the exhaled air: oxygen, a necessary element for metabolism, enters the body from the external environment, and carbon dioxide is released out.

Stages of the respiratory process

  • filling the lungs with atmospheric air (pulmonary ventilation)
  • the transition of oxygen from the pulmonary alveoli into the blood flowing through the capillaries of the lungs, and the release of carbon dioxide from the blood into the alveoli, and then into the atmosphere
  • delivery of oxygen by blood to tissues and carbon dioxide from tissues to lungs
  • oxygen consumption by cells

The processes of air entering the lungs and gas exchange in the lungs are called pulmonary (external) respiration. Blood brings oxygen to cells and tissues, and carbon dioxide from tissues to the lungs. Constantly circulating between the lungs and tissues, blood thus ensures a continuous process of supplying cells and tissues with oxygen and removing carbon dioxide. In the tissues, oxygen leaves the blood to the cells, and carbon dioxide is transferred from the tissues to the blood. This process of tissue respiration occurs with the participation of special respiratory enzymes.

Biological meanings of respiration

  • providing the body with oxygen
  • removal of carbon dioxide
  • oxidation of organic compounds with the release of energy necessary for human life
  • removal of metabolic end products (water vapor, ammonia, hydrogen sulfide, etc.)

Mechanism of inhalation and exhalation. Inhalation and exhalation occur through movements of the chest (thoracic breathing) and the diaphragm (abdominal breathing). The ribs of a relaxed chest fall down, thereby reducing its internal volume. Air is forced out of the lungs, similar to air being forced out of an air pillow or mattress under pressure. By contracting, the respiratory intercostal muscles raise the ribs. The chest expands. The diaphragm, located between the chest and abdominal cavity, contracts, its tubercles are smoothed out, and the volume of the chest increases. Both pleural layers (pulmonary and costal pleura), between which there is no air, transmit this movement to the lungs. A vacuum occurs in the lung tissue, similar to that which appears when an accordion is stretched. Air enters the lungs.

The respiratory rate of an adult is normally 14-20 breaths per 1 minute, but with significant physical activity it can reach up to 80 breaths per 1 minute

When the respiratory muscles relax, the ribs return to their original position and the diaphragm loses tension. The lungs compress, releasing exhaled air. In this case, only a partial exchange occurs, because it is impossible to exhale all the air from the lungs.

During quiet breathing, a person inhales and exhales about 500 cm 3 of air. This amount of air constitutes the tidal volume of the lungs. If you take an additional deep breath, about 1500 cm 3 of air will enter the lungs, called the inspiratory reserve volume. After a calm exhalation, a person can exhale about 1500 cm 3 of air - the reserve volume of exhalation. The amount of air (3500 cm 3), which consists of the tidal volume (500 cm 3), the inspiratory reserve volume (1500 cm 3), and the exhalation reserve volume (1500 cm 3), is called the vital capacity of the lungs.

Out of 500 cm 3 of inhaled air, only 360 cm 3 passes into the alveoli and releases oxygen into the blood. The remaining 140 cm 3 remains in the airways and does not participate in gas exchange. Therefore, the airways are called “dead space”.

After a person exhales a tidal volume of 500 cm3) and then exhales deeply (1500 cm3), there is still approximately 1200 cm3 of residual air volume left in his lungs, which is almost impossible to remove. Therefore, lung tissue does not sink in water.

Within 1 minute, a person inhales and exhales 5-8 liters of air. This is the minute volume of breathing, which during intense physical activity can reach 80-120 liters per minute.

In trained, physically developed people, the vital capacity of the lungs can be significantly greater and reach 7000-7500 cm 3 . Women have a smaller lung capacity than men

Gas exchange in the lungs and transport of gases by blood

The blood that flows from the heart into the capillaries that encircle the pulmonary alveoli contains a lot of carbon dioxide. And in the pulmonary alveoli there is little of it, therefore, thanks to diffusion, it leaves the bloodstream and passes into the alveoli. This is also facilitated by the internally moist walls of the alveoli and capillaries, consisting of only one layer of cells.

Oxygen also enters the blood due to diffusion. There is little free oxygen in the blood, because it is continuously bound by hemoglobin found in red blood cells, turning into oxyhemoglobin. The blood that has become arterial leaves the alveoli and travels through the pulmonary vein to the heart.

In order for gas exchange to take place continuously, it is necessary that the composition of gases in the pulmonary alveoli be constant, which is maintained by pulmonary respiration: excess carbon dioxide is removed outside, and oxygen absorbed by the blood is replaced with oxygen from a fresh portion of the outside air

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

A lot of carbon dioxide accumulates in tissues. It enters the tissue fluid, and from it into the blood. Here, carbon dioxide is partially captured by hemoglobin, and partially dissolved or chemically bound by salts of the blood plasma. Venous blood carries it into the right atrium, from there it enters the right ventricle, which pushes the venous circle through the pulmonary artery and closes. In the lungs, the blood again becomes arterial and, returning to the left atrium, enters the left ventricle, and from it into the systemic circulation.

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 simultaneously increase.

Due to the amazing property of hemoglobin to combine with oxygen and carbon dioxide, the blood is able to absorb these gases in significant quantities

100 ml of arterial blood contains up to 20 ml of oxygen and 52 ml of carbon dioxide

Effect of carbon monoxide on the body. Hemoglobin in red blood cells can combine with other gases. Thus, hemoglobin combines with carbon monoxide (CO), carbon monoxide formed during incomplete combustion of fuel, 150 - 300 times faster and stronger than with oxygen. Therefore, even with a small content of carbon monoxide in the air, hemoglobin combines not with oxygen, but with carbon monoxide. At the same time, the supply of oxygen to the body stops, and the person begins to suffocate.

If there is carbon monoxide in the room, a person suffocates because oxygen does not enter the body tissues

Oxygen starvation - hypoxia- can also occur when the hemoglobin content in the blood decreases (with significant blood loss), or when there is a lack of oxygen in the air (high in the mountains).

If a foreign body enters the respiratory tract or swelling of the vocal cords due to disease, respiratory arrest may occur. Choking develops - asphyxia. When breathing stops, artificial respiration is performed using special devices, and in their absence, using the “mouth to mouth”, “mouth to nose” method or special techniques.

Breathing regulation. The rhythmic, automatic alternation of inhalations and exhalations is regulated from the respiratory center located in the medulla oblongata. From this center, impulses: travel to the motor neurons of the vagus and intercostal nerves, which innervate the diaphragm and other respiratory muscles. The work of the respiratory center is coordinated by the higher parts of the brain. Therefore, a person can hold or intensify their breathing for a short time, as happens, for example, when talking.

The depth and frequency of breathing is affected by the content of CO 2 and O 2 in the blood. These substances irritate chemoreceptors in the walls of large blood vessels, nerve impulses from them enter the respiratory center. With an increase in CO2 content in the blood, breathing deepens; with a decrease in CO2, breathing becomes more frequent.