Structure and functions of the respiratory organs. Respiratory system Respiratory system diagram

Breath is a set of physiological processes that ensure gas exchange between the body and the external environment and oxidative processes in cells, as a result of which energy is released.

Respiratory organs

Airways Lungs

nasal cavity

nasopharynx

The respiratory organs perform the following functions: airway, respiratory, gas exchange, sound production, odor detection, humoral, participate in lipid and water-salt metabolism, immune.

Nasal cavity formed by bones, cartilage and lined with mucous membrane. A longitudinal partition divides it into right and left halves. In the nasal cavity, the air is warmed (blood vessels), moistened (tears), purified (mucus, villi), and disinfected (leukocytes, mucus). In children, the nasal passages are narrow, and the mucous membrane swells at the slightest inflammation. Therefore, children's breathing, especially in the first days of life, is difficult. There is another reason for this - the accessory cavities and sinuses in children are underdeveloped. For example, the maxillary cavity reaches full development only during the period of changing teeth, the frontal cavity reaches 15 years of age. The nasolacrimal canal is wide, which leads to infection and the occurrence of conjunctivitis. When breathing through the nose, irritation of the nerve endings of the mucous membrane occurs, and the act of breathing itself and its depth are intensified by reflex. Therefore, when breathing through the nose, more air enters the lungs than when breathing through the mouth.

From the nasal cavity through the choanae, air enters the nasopharynx - a funnel-shaped cavity that communicates with the nasal cavity and through the opening of the Eustachian tube connects to the cavity of the middle ear. The nasopharynx performs the function of conducting air.

Larynx - This is not only a section of the airways, but also a voice-forming organ. It also performs a protective function - it prevents food and liquid from entering the respiratory tract.

Epiglottis located above the entrance to the larynx and covers it during swallowing. The narrowest part of the larynx is the glottis, which is limited by the vocal cords. The length of the vocal cords in newborns is the same. By the time of puberty, it is 1.5 cm in girls and 1.6 cm in boys.

Trachea is a continuation of the larynx. This is a tube 10-15 cm long in adults and 6-7 cm in children. Its skeleton consists of 16-20 cartilaginous half-rings that prevent its walls from collapsing. The entire length of the trachea is lined ciliated epithelium and contains many glands that secrete mucus. At the lower end, the trachea is divided into 2 main bronchi.

Walls bronchi supported by cartilaginous rings and lined with ciliated epithelium. In the lungs, the bronchi branch, forming the bronchial tree. The thinnest branches are called bronchioles, which end in convex sacs, the walls of which are formed by a large number of alveoli. The alveoli are intertwined with a dense network of capillaries in the pulmonary circulation. They exchange gases between the blood and alveolar air.

Lungs - This is a paired organ that occupies almost the entire surface of the chest. The lungs consist of the bronchial tree. Each lung has the shape of a truncated cone, the expanded part adjacent to the diaphragm. The tops of the lungs extend beyond the collarbones into the neck area by 2-3 cm. The height of the lungs depends on gender and age and is approximately 21-30 cm in adults, and in children it corresponds to their height. Lung weight also varies with age. In newborns approximately 50 g, junior schoolchildren– 400 g, for adults – 2 kg. The right lung is slightly larger than the left and consists of three lobes, the left has 2 and has a cardiac notch - the seat of the heart.

On the outside, the lungs are covered with a membrane - the pleura - which has 2 layers - pulmonary and parietal. Between them there is a closed cavity - the pleural cavity, with a small amount of pleural fluid, which facilitates the sliding of one leaf over the other during breathing. There is no air in the pleural cavity. The pressure in it is negative - below atmospheric.

Respiratory system person- a set of organs and tissues that ensure the exchange of gases between blood and external environment.

Respiratory system function:

• oxygen entering the body;
• elimination from the body carbon dioxide;
• removal of gaseous metabolic products from the body;
• thermoregulation;
• synthetic: some are synthesized biologically in lung tissue active substances: heparin, lipids, etc.;
• hematopoietic: mast cells and basophils mature in the lungs;
• depositing: the capillaries of the lungs can accumulate large number blood;
• absorption: ether, chloroform, nicotine and many other substances are easily absorbed from the surface of the lungs.

The respiratory system consists of the lungs and respiratory tract.

Pulmonary contractions are carried out using the intercostal muscles and the diaphragm.

Respiratory tract: nasal cavity, pharynx, larynx, trachea, bronchi and bronchioles.

The lungs consist of pulmonary vesicles - alveoli

Rice. Respiratory system

respiratory tract

nasal cavity

The nasal and pharyngeal cavities are the upper respiratory tract. The nose is formed by a system of cartilage, thanks to which the nasal passages are always open. At the very beginning of the nasal passages there are small hairs that trap large dust particles in the inhaled air.

The nasal cavity is lined from the inside with a mucous membrane penetrated by blood vessels. It contains a large number of mucous glands (150 glands/$cm^2$ of mucous membrane). Mucus prevents the proliferation of microbes. A large number of leukocytes-phagocytes emerge from the blood capillaries onto the surface of the mucous membrane, which destroy the microbial flora.

In addition, the mucous membrane can change significantly in its volume. When the walls of its vessels contract, it contracts, the nasal passages expand, and the person breathes easily and freely.

The mucous membrane of the upper respiratory tract is formed by ciliated epithelium. The movement of the cilia of an individual cell and the entire epithelial layer is strictly coordinated: each previous cilium in the phases of its movement is ahead of the next one for a certain period of time, therefore the surface of the epithelium is wave-like - “flickers”. The movement of the cilia helps keep the airways clear by removing harmful substances.

Rice. 1. Ciliated epithelium of the respiratory system

The olfactory organs are located in the upper part of the nasal cavity.

Function of the nasal passages:

• filtration of microorganisms;
• dust filtration;
• humidification and warming of inhaled air;
• mucus flushes everything filtered into the gastrointestinal tract.

The cavity is divided into two halves by the ethmoid bone. Bone plates divide both halves into narrow, interconnected passages.

Open into the nasal cavity sinuses air-bearing bones: maxillary, frontal, etc. These sinuses are called paranasal sinuses. They are lined with a thin mucous membrane containing a small number of mucous glands. All these septa and shells, as well as numerous accessory cavities of the cranial bones, dramatically increase the volume and surface of the walls of the nasal cavity.

paranasal sinuses

Paranasal sinuses (paranasal sinuses) - air cavities in the bones of the skull, communicating with the nasal cavity.

In humans, there are four groups of paranasal sinuses:

• maxillary (maxillary) sinus - a paired sinus located in the upper jaw;
• frontal sinus - a paired sinus located in the frontal bone;
• ethmoid labyrinth - a paired sinus formed by cells of the ethmoid bone;
• sphenoid (main) - a paired sinus located in the body of the sphenoid (main) bone.

Rice. 2. Paranasal sinuses: 1 - frontal sinuses; 2 - cells of the lattice labyrinth; 3 - sphenoid sinus; 4 - maxillary (maxillary) sinuses.

The exact meaning of the paranasal sinuses is still not known.

Possible functions of the paranasal sinuses:

• reduction in front weight facial bones skulls;
• voice resonators;
• mechanical protection of the head organs during impacts (shock absorption);
• thermal insulation of tooth roots, eyeballs etc. from temperature fluctuations in the nasal cavity during breathing;
• humidification and warming of inhaled air due to slow air flow in the sinuses;
• perform the function of a baroreceptor organ ( additional organ feelings).

Maxillary sinus (maxillary sinus)- paired paranasal sinus, occupying almost the entire body of the maxillary bone. The inside of the sinus is lined with a thin mucous membrane of ciliated epithelium. There are very few glandular (goblet) cells, vessels and nerves in the sinus mucosa.

The maxillary sinus communicates with the nasal cavity through openings on the inner surface of the maxillary bone. IN in good condition the sinus is filled with air.

The lower part of the pharynx passes into two tubes: the respiratory tube (in front) and the esophagus (in the back). Thus, the pharynx is a common section for the digestive and respiratory systems.

Larynx

The upper part of the breathing tube is the larynx, located in the front of the neck. Most of the larynx is also lined with a mucous membrane of ciliated epithelium.

The larynx consists of movably interconnected cartilages: cricoid, thyroid (forms Adam's apple, or Adam's apple) and two arytenoid cartilages.

Epiglottis covers the entrance to the larynx when swallowing food. The anterior end of the epiglottis is connected to the thyroid cartilage.

Rice. Larynx

The cartilages of the larynx are connected to each other by joints, and the spaces between the cartilages are covered with connective tissue membranes.

voicing

When pronouncing a sound, the vocal cords come together until they touch. With a current of compressed air from the lungs, pressing on them from below, they move apart for a moment, after which, thanks to their elasticity, they close again until the air pressure opens them again.

The resulting oscillations vocal cords and give the sound of a voice. The pitch of the sound is regulated by the degree of tension of the vocal cords. The shades of the voice depend both on the length and thickness of the vocal cords, and on the structure of the oral cavity and nasal cavity, which play the role of resonators.

The thyroid gland is adjacent to the larynx on the outside.

In front, the larynx is protected by the anterior neck muscles.

Trachea and bronchi

The trachea is a breathing tube about 12 cm long.

It is composed of 16-20 cartilaginous half-rings that do not close at the back; half rings prevent the trachea from collapsing during exhalation.

The back of the trachea and the spaces between the cartilaginous half-rings are covered with a connective tissue membrane. Behind the trachea lies the esophagus, the wall of which, during passage food bolus slightly protrudes into its lumen.

Rice. Cross section of the trachea: 1 - ciliated epithelium; 2 - own layer of mucous membrane; 3 - cartilaginous half-ring; 4 - connective tissue membrane

At the level of IV-V thoracic vertebrae, the trachea is divided into two large primary bronchi, extending into the right and left lungs. This place of division is called bifurcation (branching).

The aortic arch bends through the left bronchus, and the right one bends around the azygos vein running from behind to front. According to the expression of old anatomists, “the aortic arch sits astride the left bronchus, and the azygos vein sits on the right.”

Cartilaginous rings located in the walls of the trachea and bronchi make these tubes elastic and non-collapsing, so that air passes through them easily and unhindered. The inner surface of the entire respiratory tract (trachea, bronchi and parts of the bronchioles) is covered with a mucous membrane of multirow ciliated epithelium.

The structure of the respiratory tract ensures warming, humidification and purification of inhaled air. Dust particles move upward with ciliated epithelium and are expelled out with coughing and sneezing. Microbes are neutralized by lymphocytes of the mucous membrane.

lungs

The lungs (right and left) are located in the chest cavity under the protection of the rib cage.

Pleura

Lungs covered pleura.

Pleura- a thin, smooth and moist serous membrane rich in elastic fibers that covers each of the lungs.

Distinguish pulmonary pleura, tightly adherent to lung tissue, and parietal pleura, lining the inside of the chest wall.

At the roots of the lungs, the pulmonary pleura becomes the parietal pleura. Thus, a hermetically closed pleural cavity is formed around each lung, representing a narrow gap between the pulmonary and parietal pleura. The pleural cavity is filled with a small amount of serous fluid, which acts as a lubricant, facilitating the respiratory movements of the lungs.

Rice. Pleura

mediastinum

The mediastinum is the space between the right and left pleural sacs. It is bounded in front by the sternum with costal cartilages, and in the back by the spine.

The mediastinum contains the heart with large vessels, trachea, esophagus, thymus gland, nerves of the diaphragm and thoracic lymphatic duct.

bronchial tree

Deep grooves divide the right lung into three lobes, and the left into two. The left lung on the side facing the midline has a depression with which it is adjacent to the heart.

In every lung with inside includes thick bundles consisting of the primary bronchus, pulmonary artery and nerves, and two pulmonary veins and lymphatic vessels emerge. All these bronchial-vascular bundles, taken together, form lung root. Around the pulmonary roots there are a large number of bronchial lymph nodes.

Entering the lungs, the left bronchus is divided into two, and the right - into three branches according to the number of pulmonary lobes. In the lungs, the bronchi form the so-called bronchial tree. With each new “twig” the diameter of the bronchi decreases until they become completely microscopic bronchioles with a diameter of 0.5 mm. The soft walls of the bronchioles contain smooth muscle fibers and no cartilaginous half-rings. There are up to 25 million such bronchioles.

Rice. Bronchial tree

The bronchioles pass into branched alveolar ducts, which end in pulmonary sacs, the walls of which are strewn with swellings - pulmonary alveoli. The walls of the alveoli are penetrated by a network of capillaries: gas exchange occurs in them.

The alveolar ducts and alveoli are entwined with many elastic connective tissue and elastic fibers, which also form the basis of the smallest bronchi and bronchioles, due to which the lung tissue easily stretches during inhalation and collapses again during exhalation.

alveoli

The alveoli are formed by a network of thin elastic fibers. The inner surface of the alveoli is lined with a single layer flat epithelium. The epithelial walls produce surfactant- a surfactant that lines the inside of the alveoli and prevents their collapse.

Under the epithelium of the pulmonary vesicles lies a dense network of capillaries into which the terminal branches of the pulmonary artery are divided. Through the contacting walls of the alveoli and capillaries, gas exchange occurs during breathing. Once in the blood, oxygen binds to hemoglobin and is distributed throughout the body, supplying cells and tissues.

Rice. Alveoli

Rice. Gas exchange in the alveoli

Before birth, the fetus does not breathe through the lungs and the pulmonary vesicles are in a collapsed state; after birth, with the very first breath, the alveoli swell and remain straightened for life, retaining a certain amount of air even with the deepest exhalation.

gas exchange area

The completeness of gas exchange is ensured by the huge surface through which it occurs. Each pulmonary vesicle is an elastic sac measuring 0.25 millimeters. The number of pulmonary vesicles in both lungs reaches 350 million. If we imagine that all pulmonary alveoli are stretched and form one bubble with a smooth surface, then the diameter of this bubble will be 6 m, its capacity will be more than $50 m^3$, and the internal surface will be $113 m^2$ and would thus be approximately 56 times larger than the entire skin surface of the human body.

The trachea and bronchi do not participate in respiratory gas exchange, but are only air-conducting pathways.

physiology of breathing

All vital processes occur with the obligatory participation of oxygen, i.e. they are aerobic. The central nervous system is especially sensitive to oxygen deficiency, and primarily cortical neurons, which die earlier than others in oxygen-free conditions. As is known, the period clinical death should not exceed five minutes. Otherwise, irreversible processes develop in the neurons of the cerebral cortex.

Breath- physiological process of gas exchange in the lungs and tissues.

The entire breathing process can be divided into three main stages:

• pulmonary (external) respiration: gas exchange in the capillaries of the pulmonary vesicles;
• transport of gases by blood;
• cellular (tissue) respiration: gas exchange in cells (enzymatic oxidation of nutrients in mitochondria).

Rice. Pulmonary and tissue respiration

Red blood cells contain hemoglobin, a complex iron-containing protein. This protein is capable of attaching oxygen and carbon dioxide to itself.

Passing through the capillaries of the lungs, hemoglobin attaches 4 oxygen atoms to itself, turning into oxyhemoglobin. Red blood cells transport oxygen from the lungs to body tissues. In tissues, oxygen is released (oxyhemoglobin is converted into hemoglobin) and carbon dioxide is added (hemoglobin is converted into carbohemoglobin). Red blood cells then transport carbon dioxide to the lungs for removal from the body.

Rice. Transport function of hemoglobin

The hemoglobin molecule forms a stable compound with carbon monoxide II ( carbon monoxide). Carbon monoxide poisoning leads to the death of the body due to oxygen deficiency.

mechanism of inhalation and exhalation

Inhale- is an active act, as it is carried out with the help of specialized respiratory muscles.

The respiratory muscles include intercostal muscles and diaphragm. When inhaling deeply, the muscles of the neck, chest and abs are used.

The lungs themselves do not have muscles. They are not able to stretch and contract on their own. The lungs only follow the chest, which expands thanks to the diaphragm and intercostal muscles.

During inhalation, the diaphragm lowers by 3-4 cm, as a result of which the volume of the chest increases by 1000-1200 ml. In addition, the diaphragm moves the lower ribs to the periphery, which also leads to an increase in the capacity of the chest. Moreover, the stronger the contraction of the diaphragm, the more the volume of the thoracic cavity increases.

The intercostal muscles, contracting, raise the ribs, which also causes an increase in the volume of the chest.

The lungs, following the stretching chest, themselves stretch, and the pressure in them drops. As a result, a difference is created between the pressure atmospheric air and pressure in the lungs, air rushes into them - inhalation occurs.

Exhalation, Unlike inhalation, it is a passive act, since muscles do not take part in its implementation. When the intercostal muscles relax, the ribs lower under the influence of gravity; the diaphragm, relaxing, rises, taking its usual position, and the volume of the chest cavity decreases - the lungs contract. Exhalation occurs.

The lungs are located in a hermetically sealed cavity formed by the pulmonary and parietal pleura. In the pleural cavity the pressure is below atmospheric (“negative”). Due to negative pressure, the pulmonary pleura is pressed tightly against the parietal pleura.

A decrease in pressure in the pleural space is the main reason for the increase in lung volume during inhalation, that is, it is the force that stretches the lungs. Thus, during an increase in the volume of the chest, the pressure in the interpleural formation decreases, and due to the pressure difference, air actively enters the lungs and increases their volume.

During exhalation, the pressure in the pleural cavity increases, and due to the pressure difference, air escapes and the lungs collapse.

Chest breathing carried out mainly by the external intercostal muscles.

Abdominal breathing carried out by the diaphragm.

Men have abdominal breathing, while women have thoracic breathing. However, regardless of this, both men and women breathe rhythmically. From the first hour of life, the breathing rhythm is not disturbed, only its frequency changes.

A newborn baby breathes 60 times per minute, the frequency of an adult is breathing movements at rest it is about 16−18. However, during physical activity, emotional arousal or increased body temperature, the respiratory rate may increase significantly.

Vital capacity of the lungs

Vital capacity of the lungs (VC)- this is the maximum amount of air that can enter and exit the lungs during maximum inhalation and exhalation.

The vital capacity of the lungs is determined by the device spirometer.

In an adult healthy person Vital capacity varies from 3500 to 7000 ml and depends on gender and on indicators of physical development: for example, chest volume.

Vital fluid consists of several volumes:

1. Tidal volume (TO)- this is the amount of air that enters and leaves the lungs during quiet breathing (500-600 ml).
2. Inspiratory reserve volume (IRV)) is the maximum amount of air that can enter the lungs after a quiet inhalation (1500 - 2500 ml).
3. Expiratory reserve volume (ERV)- this is the maximum amount of air that can be removed from the lungs after a quiet exhalation (1000 - 1500 ml).

regulation of breathing

Breathing is regulated by nerves and humoral mechanisms, which come down to ensuring the rhythmic activity of the respiratory system (inhalation, exhalation) and adaptive respiratory reflexes, that is, changing the frequency and depth of respiratory movements that take place under changing environmental conditions or internal environment body.

The leading respiratory center, as established by N. A. Mislavsky in 1885, is the respiratory center located in the medulla oblongata.

Respiratory centers are found in the hypothalamus region. They take part in the organization of more complex adaptive respiratory reflexes necessary when the conditions of the organism’s existence change. In addition, the respiratory centers are located in the cerebral cortex, carrying out higher forms adaptation processes. Availability respiratory centers in the cerebral cortex is evidenced by the formation of respiratory conditioned reflexes, changes in the frequency and depth of respiratory movements that occur at different emotional states, as well as voluntary changes in breathing.

The autonomic nervous system innervates the walls of the bronchi. Their smooth muscles are supplied with centrifugal fibers of the vagus and sympathetic nerves. Vagus nerves cause contraction of the bronchial muscles and narrowing of the bronchi, and sympathetic nerves relax the bronchial muscles and dilate the bronchi.

Humoral regulation: in exhalation is carried out reflexively in response to an increase in the concentration of carbon dioxide in the blood.

In one day, an adult inhales and exhales tens of thousands of times. If a person cannot breathe, then he only has seconds.

The importance of this system for humans can hardly be overestimated. You need to think about how the human respiratory system works, what its structure and functions are, before health problems may arise.

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The structure of the human respiratory system

The pulmonary system can be considered as one of the most significant in human body. It includes functions aimed at absorbing oxygen from the air and removing carbon dioxide. Normal operation breathing is especially important for children.

The anatomy of the respiratory organs stipulates that they can be divided into two groups:

• airways;
• lungs.

Upper respiratory tract

When air enters the body, it passes through the mouth or nose. It moves further through the pharynx, entering the trachea.

The upper respiratory tract includes paranasal sinuses nose, as well as the larynx.

The nasal cavity is divided into several sections: lower, middle, upper and general.

Inside, this cavity is covered with ciliated epithelium, which warms the incoming air and cleans it. There is a special mucus here that has protective properties that help fight infection.

The larynx is a cartilaginous formation that is located in the space from the pharynx to the trachea.

Lower respiratory tract

When inhalation occurs, air moves inward and enters the lungs. At the same time, from the pharynx at the beginning of its journey it ends up in the trachea, bronchi and lungs. Physiology classifies them as the lower respiratory tract.

In the structure of the trachea, it is customary to distinguish the cervical and thoracic parts. It is divided into two parts. It, like other respiratory organs, is covered with ciliated epithelium.

The lungs are divided into sections: apex and base. This organ has three surfaces:

• diaphragmatic;
• mediastinal;
• costal

The lung cavity is protected, in short, by the rib cage on the sides and the diaphragm below the abdominal cavity.

Inhalation and exhalation are controlled by:

• diaphragm;
• intercostal respiratory muscles;
• intercartilaginous internal muscles.

Functions of the respiratory system

The most important function of the respiratory organs is as follows: supply the body with oxygen in order to sufficiently ensure its vital functions, as well as withdraw from human body carbon dioxide and other breakdown products, performing gas exchange.

The respiratory system also performs a number of other functions:

1. Creating air flow to ensure voice formation.
2. Obtaining air for odor recognition.
3. The role of breathing is also that it provides ventilation to maintain optimal body temperature;
4. These organs are also involved in the blood circulation process.
5. Implemented protective function against the threat of being hit pathogens along with the inhaled air, including when a deep breath occurs.
6. To a small extent external breathing promotes the removal of waste substances from the body in the form of water vapor. In particular, dust, urea and ammonia can be removed in this way.
7. The pulmonary system performs blood deposition.

IN the latter case The lungs, thanks to their structure, are able to concentrate a certain volume of blood, giving it to the body when the overall plan requires it.

Human breathing mechanism

The breathing process consists of three processes. The following table explains this.

The flow of oxygen into the body can occur through the nose or mouth. It then passes through the pharynx, larynx and into the lungs.

Oxygen enters the lungs as one of the components of air. Their branched structure allows O2 gas to dissolve in the blood through the alveoli and capillaries, forming unstable chemical compounds with hemoglobin. Thus, in a chemically bound form, oxygen moves through circulatory system throughout the body.

The regulation scheme provides that O2 gas gradually enters the cells, being released from its connection with hemoglobin. At the same time, carbon dioxide exhausted by the body takes its place in transport molecules and is gradually transferred to the lungs, where it is removed from the body during exhalation.

Air enters the lungs because their volume periodically increases and decreases. The pleura is attached to the diaphragm. Therefore, when the latter expands, the volume of the lungs increases. By taking in air, internal respiration occurs. If the diaphragm contracts, the pleura pushes waste carbon dioxide out.

Worth noting: a person needs 300 ml of oxygen within one minute. During the same time, there is a need to remove 200 ml of carbon dioxide outside the body. However, these figures are only valid in a situation where a person does not experience severe physical activity. If maximum inhalation occurs, they will increase many times over.

May occur various types breathing:

1. At chest breathing inhalation and exhalation are carried out due to the efforts of the intercostal muscles. Moreover, during inhalation rib cage expands and also rises slightly. Exhalation is performed in the opposite way: the cell contracts while simultaneously lowering slightly.
2. Abdominal breathing looks different. The inhalation process is carried out due to the expansion of the abdominal muscles with a slight rise of the diaphragm. When you exhale, these muscles contract.

The first of them is most often used by women, the second by men. In some people, both the intercostal and abdominal muscles may be used during breathing.

Diseases of the human respiratory system

Such diseases usually fall into one of the following categories:

1. In some cases, the cause may be an infectious infection. The cause may be microbes, viruses, bacteria, which, once in the body, have a pathogenic effect.
2. Some people have allergic reactions, which are expressed in various breathing problems. There can be many reasons for such disorders, depending on the type of allergy a person has.
3. Autoimmune diseases are very dangerous to health. In this case, the body perceives its own cells as pathogens and begins to fight them. In some cases, the result may be a disease of the respiratory system.
4. Another group of diseases are those that are hereditary. In this case, we are talking about the fact that at the genetic level there is a predisposition to certain diseases. However, by paying sufficient attention to this issue, in most cases the disease can be prevented.

To monitor the presence of a disease, you need to know the signs by which you can determine its presence:

• cough;
• dyspnea;
• pain in the lungs;
• feeling of suffocation;
• hemoptysis.

Cough is a reaction to mucus accumulated in the bronchi and lungs. IN different situations it can vary in nature: with laryngitis it can be dry, with pneumonia it can be wet. If we are talking about ARVI diseases, the cough can periodically change its character.

Sometimes when coughing, the patient experiences pain, which can occur either constantly or when the body is in a certain position.

Shortness of breath can manifest itself in different ways. Subjective intensifies at times when a person experiences stress. Objective is expressed in a change in the rhythm and force of breathing.

Importance of the respiratory system

The ability of people to speak is largely based on proper breathing.

This system also plays a role in the body's thermoregulation. Depending on the specific situation, this makes it possible to increase or decrease body temperature to the desired extent.

In addition to carbon dioxide, breathing also removes some other waste products from the human body.

In this way, a person is given the opportunity to distinguish different odors by inhaling air through the nose.

Thanks to this system of the body, gas exchange occurs between humans and environment, supplying organs and tissues with oxygen and removing waste carbon dioxide from the human body.

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

The diagram of the human respiratory system includes the respiratory tract - upper and lower:

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

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

Nasal cavity

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

1. The frame consists of many small bones on which cartilage is attached. It depends on their shape and size appearance human nose.


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

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

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

Paranasal sinuses

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

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

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

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

Larynx

After passing through the nasal cavity and nasopharynx (or oral cavity, if a person breathes through the mouth), air enters the larynx. This is a tube-shaped organ of very complex anatomy, which consists of cartilage, ligaments and muscles. This is where the vocal cords are located, thanks to which we can produce sounds of different frequencies. Functions of the larynx - conduction of air, formation of voice.

Structure:

1. The larynx is located at the level of 4–6 cervical vertebrae.
2. Its anterior surface is formed by the thyroid and cricoid cartilages. The posterior and upper parts are the epiglottis and small wedge-shaped cartilages.
3. The epiglottis is the “lid” that covers the larynx during swallowing. This device is needed to prevent food from entering the airways.
4. The inside of the larynx is lined with single-layer respiratory epithelium, the cells of which have thin villi. They move, directing mucus and dust particles towards the throat. Thus, the airways are constantly cleansed. Only the surface of the vocal cords is lined stratified epithelium, this makes them more resistant to damage.
5. There are receptors in the thickness of the mucous membrane of the larynx. When these receptors are irritated by foreign bodies, excess mucus or waste products of microorganisms, a reflex cough occurs. This is a protective reaction of the larynx aimed at cleansing its lumen.

Trachea

The trachea begins from the lower edge of the cricoid cartilage. This organ is classified as the lower respiratory tract. It ends at the level of 5–6 thoracic vertebrae at the site of its bifurcation (bifurcation).

Structure of the trachea:

1. The tracheal framework forms 15–20 cartilaginous half-rings. They are connected at the back by a membrane that is adjacent to the esophagus.
2. At the site of the division of the trachea into the main bronchi there is a protrusion of the mucous membrane that deviates to the left. This fact determines that foreign bodies that end up here are more often found in the right main bronchus.
3. The mucous membrane of the trachea has good absorption. This is used in medicine to perform intratracheal administration of drugs by inhalation.

Bronchial tree

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

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

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

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

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

Lungs

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

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

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

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

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

On the inner surface of the lung is located its gate - this includes the main bronchi, vessels and nerves (all these structures form the root of the lung). Right human lung consists of three lobes, and the left one - of two. This is due to the fact that the place of the third lobe of the left lung is occupied by the heart.

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

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

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

Respiratory system- a system of organs that conduct air and participate in gas exchange between the body and the environment.

The respiratory system consists of pathways carrying air - the nasal cavity, trachea and bronchi, and the respiratory part itself - the lungs. Having passed through nasal cavity, the air is warmed, moistened, purified and enters first the nasopharynx, and then into the oral part of the pharynx and, finally, into its laryngeal part. Air can get here if we breathe through our mouths. However, in this case it is not cleaned or warmed, so we easily catch colds.

From the laryngeal part of the pharynx, air enters the larynx. The larynx is located in the front of the neck, where the contours of the laryngeal eminence are visible. In men, especially thin men, a protruding protrusion, the Adam's apple, is clearly visible. Women do not have such a protrusion. The vocal cords are located in the larynx. The direct continuation of the larynx is the trachea. From the neck area, the trachea passes into the thoracic cavity and at the level of 4-5 thoracic vertebrae is divided into the left and right bronchi. In the region of the roots of the lungs, the bronchi are divided first into lobar bronchi, then into segmental bronchi. The latter are divided into even smaller ones, forming the bronchial tree of the right and left bronchi.

The lungs are located on either side of the heart. Each lung is covered with a moist, shiny membrane called the pleura. Each lung is divided into lobes by grooves. The left lung is divided into 2 lobes, the right - into three. Lobes consist of segments, segments of lobules. Continuing to divide inside the lobules, the bronchi pass into the respiratory bronchioles, on the walls of which many small vesicles are formed - alveoli. This can be compared to a bunch of grapes hanging at the end of each bronchus. The walls of the alveoli are intertwined with a dense network of tiny capillaries and represent a membrane through which gas exchange occurs between the blood flowing through the capillaries and the air entering the alveoli during breathing. In both lungs of an adult there are over 700 million alveoli, their total respiratory surface exceeds 100 m2, i.e. approximately 50 times larger than the surface of the body!

The pulmonary artery, branching in the lung according to the division of the bronchi down to the smallest blood vessels, brings oxygen-poor venous blood from the right ventricle of the heart to the lung. As a result of gas exchange, venous blood enriched with oxygen, turns into arterial and returns through two pulmonary veins back to the heart into its left atrium. This blood path is called the pulmonary or pulmonary circulation.

For each breath, about 500 ml of air enters the lungs. With the deepest breath, you can inhale about 1500 ml additionally. The volume of air passing through the lungs in 1 minute is called the minute volume of respiration. Normally it is 6-9 liters. In athletes, when running, it increases to 25-30 liters.

Literature.
Popular medical encyclopedia. Editor-in-Chief B.V. Petrovsky. M.: Soviet Encyclopedia, 1987-704s, pp. 620

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