I will solve the exam biology respiratory system. Human. Organs, organ systems: digestion, respiration, blood circulation, lymph circulation. Digestion in the stomach

Breathing The process of gas exchange between the body and the environment is called. Human life is closely related to the reactions of biological oxidation and is accompanied by the absorption of oxygen. To maintain oxidative processes, a continuous supply of oxygen is necessary, which is carried by the blood to all organs, tissues and cells, where most of it binds to the end products of cleavage, and the body is released from carbon dioxide. The essence of the process of respiration is the consumption of oxygen and the release of carbon dioxide. (N.E. Kovalev, L.D. Shevchuk, O.I. Shchurenko. Biology for preparatory departments of medical institutes.)

Functions of the respiratory system.

Oxygen is found in the air around us.
It can penetrate the skin, but only in small amounts, completely insufficient to sustain life. There is a legend about Italian children who were painted with gold paint to participate in a religious procession; the story goes on to say that they all died of asphyxiation because "the skin couldn't breathe". On the basis of scientific data, death by asphyxiation is completely excluded here, since the absorption of oxygen through the skin is barely measurable, and the release of carbon dioxide is less than 1% of its release through the lungs. The respiratory system provides oxygen to the body and removal of carbon dioxide. The transport of gases and other substances necessary for the body is carried out with the help of the circulatory system. The function of the respiratory system is only to supply the blood with a sufficient amount of oxygen and remove carbon dioxide from it. The chemical reduction of molecular oxygen with the formation of water is the main source of energy for mammals. Without it, life cannot last more than a few seconds. The reduction of oxygen is accompanied by the formation of CO 2 . The oxygen included in CO 2 does not come directly from molecular oxygen. The use of O 2 and the formation of CO 2 are interconnected by intermediate metabolic reactions; theoretically, each of them last some time. The exchange of O 2 and CO 2 between the body and the environment is called respiration. In higher animals, the process of respiration is carried out through a series of successive processes. 1. The exchange of gases between the environment and the lungs, which is usually referred to as "pulmonary ventilation". 2. Exchange of gases between the alveoli of the lungs and blood (pulmonary respiration). 3. Exchange of gases between blood and tissues. Finally, gases pass within the tissue to the places of consumption (for O 2) and from the places of formation (for CO 2) (cellular respiration). The loss of any of these four processes leads to respiratory disorders and creates a danger to human life.

Anatomy.

The human respiratory system consists of tissues and organs that provide pulmonary ventilation and pulmonary respiration. The airways include: nose, nasal cavity, nasopharynx, larynx, trachea, bronchi and bronchioles. The lungs consist of bronchioles and alveolar sacs, as well as arteries, capillaries and veins of the pulmonary circulation. The elements of the musculoskeletal system associated with breathing include the ribs, intercostal muscles, diaphragm, and accessory muscles of respiration.

Airways.

The nose and nasal cavity serve as conductive channels for air, in which it is heated, humidified and filtered. Olfactory receptors are also enclosed in the nasal cavity.
The outer part of the nose is formed by a triangular bone-cartilaginous skeleton, which is covered with skin; two oval openings on the lower surface - the nostrils - each open into the wedge-shaped nasal cavity. These cavities are separated by a septum. Three light spongy curls (shells) protrude from the side walls of the nostrils, partially dividing the cavities into four open passages (nasal passages). The nasal cavity is lined with a richly vascularized mucosa. Numerous stiff hairs, as well as ciliated epithelial and goblet cells, serve to clean the inhaled air from particulate matter. Olfactory cells lie in the upper part of the cavity.

The larynx lies between the trachea and the root of the tongue. The laryngeal cavity is divided by two mucosal folds that do not fully converge along the midline. The space between these folds - the glottis is protected by a plate of fibrous cartilage - the epiglottis. Along the edges of the glottis in the mucous membrane are fibrous elastic ligaments, which are called the lower, or true, vocal folds (ligaments). Above them are the false vocal folds, which protect the true vocal folds and keep them moist; they also help to hold the breath, and when swallowing, they prevent food from entering the larynx. Specialized muscles stretch and relax the true and false vocal folds. These muscles play an important role in phonation and also prevent any particles from entering the respiratory tract.

The trachea begins at the lower end of the larynx and descends into the chest cavity, where it divides into the right and left bronchi; its wall is formed by connective tissue and cartilage. In most mammals, cartilage forms incomplete rings. The parts adjacent to the esophagus are replaced by a fibrous ligament. The right bronchus is usually shorter and wider than the left. Upon entering the lungs, the main bronchi gradually divide into ever smaller tubes (bronchioles), the smallest of which, the terminal bronchioles, are the last element of the airways. From the larynx to the terminal bronchioles, the tubes are lined with ciliated epithelium.

Lungs

In general, the lungs have the appearance of spongy, sweaty cone-shaped formations lying on both halves of the chest cavity. The smallest structural element of the lung - the lobule consists of the final bronchiole leading to the pulmonary bronchiole and the alveolar sac. The walls of the pulmonary bronchioles and the alveolar sac form depressions called alveoli. This structure of the lungs increases their respiratory surface, which is 50-100 times the surface of the body. The relative size of the surface through which gas exchange occurs in the lungs is greater in animals with high activity and mobility. The walls of the alveoli consist of a single layer of epithelial cells and are surrounded by pulmonary capillaries. The inner surface of the alveolus is coated with a surfactant. The surfactant is believed to be a secretion product of granule cells. A separate alveolus, in close contact with neighboring structures, has the shape of an irregular polyhedron and approximate dimensions up to 250 microns. It is generally accepted that the total surface of the alveoli through which gas exchange takes place depends exponentially on body weight. With age, there is a decrease in the surface area of ​​the alveoli.

Pleura

Each lung is surrounded by a sac called the pleura. The outer (parietal) pleura adjoins the inner surface of the chest wall and the diaphragm, the inner (visceral) covers the lung. The gap between the sheets is called the pleural cavity. When the chest moves, the inner sheet usually slides easily over the outer one. The pressure in the pleural cavity is always less than atmospheric (negative). At rest, intrapleural pressure in humans is on average 4.5 Torr lower than atmospheric pressure (-4.5 Torr). The interpleural space between the lungs is called the mediastinum; it contains the trachea, thymus gland and heart with large vessels, lymph nodes and esophagus.

Blood vessels of the lungs

The pulmonary artery carries blood from the right ventricle of the heart, it divides into right and left branches that go to the lungs. These arteries branch out following the bronchi, supply large lung structures, and form capillaries that wrap around the walls of the alveoli.

The air in the alveolus is separated from the blood in the capillary by the alveolar wall, the capillary wall, and in some cases an intermediate layer in between. From the capillaries, blood flows into small veins, which eventually join and form the pulmonary veins, which deliver blood to the left atrium.
The bronchial arteries of the great circle also bring blood to the lungs, namely, they supply the bronchi and bronchioles, lymph nodes, the walls of blood vessels and the pleura. Most of this blood flows into the bronchial veins, and from there - into the unpaired (right) and semi-unpaired (left). A very small amount of arterial bronchial blood enters the pulmonary veins.

respiratory muscles

The respiratory muscles are those muscles whose contractions change the volume of the chest. Muscles from the head, neck, arms, and some of the upper thoracic and lower cervical vertebrae, as well as the external intercostal muscles connecting rib to rib, raise the ribs and increase the volume of the chest. The diaphragm is a muscular-tendon plate attached to the vertebrae, ribs, and sternum that separates the chest cavity from the abdominal cavity. This is the main muscle involved in normal inspiration. With increased inhalation, additional muscle groups are reduced. With increased exhalation, the muscles attached between the ribs (internal intercostal muscles), to the ribs and lower thoracic and upper lumbar vertebrae, as well as the muscles of the abdominal cavity, act; they lower the ribs and press the abdominal organs against the relaxed diaphragm, thus reducing the capacity of the chest.

Pulmonary ventilation

As long as intrapleural pressure remains below atmospheric pressure, the dimensions of the lungs closely follow those of the chest cavity. The movements of the lungs are made as a result of the contraction of the respiratory muscles in combination with the movement of parts of the chest wall and diaphragm.

Breathing movements

Relaxation of all the muscles associated with breathing puts the chest in a position of passive exhalation. Appropriate muscle activity can translate this position into inhalation or increase exhalation.
Inspiration is created by expansion of the chest cavity and is always an active process. Due to their articulation with the vertebrae, the ribs move up and out, increasing the distance from the spine to the sternum, as well as the lateral dimensions of the chest cavity (costal or thoracic type of breathing). Contraction of the diaphragm changes its shape from dome-shaped to flatter, which increases the size of the chest cavity in the longitudinal direction (diaphragmatic or abdominal type of breathing). Diaphragmatic breathing usually plays the main role in inhalation. Since people are bipedal creatures, with each movement of the ribs and sternum, the center of gravity of the body changes and it becomes necessary to adapt different muscles to this.
During quiet breathing, a person usually has enough elastic properties and the weight of the moved tissues to return them to the position preceding inspiration. Thus, exhalation at rest occurs passively due to a gradual decrease in the activity of the muscles that create the condition for inspiration. Active exhalation may result from contraction of the internal intercostal muscles in addition to other muscle groups that lower the ribs, reduce the transverse dimensions of the chest cavity and the distance between the sternum and spine. Active exhalation can also occur due to contraction of the abdominal muscles, which presses the viscera against the relaxed diaphragm and reduces the longitudinal size of the chest cavity.
The expansion of the lung reduces (temporarily) the total intrapulmonary (alveolar) pressure. It is equal to atmospheric when the air is not moving, and the glottis is open. It is below atmospheric pressure until the lungs are full when inhaling, and above atmospheric pressure when exhaling. Intrapleural pressure also changes during the respiratory movement; but it is always below atmospheric (i.e., always negative).

Changes in lung volume

In humans, the lungs occupy about 6% of the volume of the body, regardless of its weight. The volume of the lung does not change in the same way during inspiration. There are three main reasons for this, firstly, the chest cavity increases unevenly in all directions, and secondly, not all parts of the lung are equally extensible. Thirdly, the existence of a gravitational effect is assumed, which contributes to the downward displacement of the lung.
The volume of air inhaled during a normal (non-enhanced) inhalation and exhaled during a normal (non-enhanced) exhalation is called respiratory air. The volume of maximum exhalation after the previous maximum inhalation is called vital capacity. It is not equal to the total volume of air in the lung (total lung volume) because the lungs do not fully collapse. The volume of air that remains in the lung that has collapsed is called residual air. There is additional volume that can be inhaled at maximum effort after a normal inhalation. And the air that is exhaled with maximum effort after a normal exhalation is the expiratory reserve volume. Functional residual capacity consists of expiratory reserve volume and residual volume. This is the air in the lungs in which normal breathing air is diluted. As a result, the composition of the gas in the lungs after one respiratory movement usually does not change dramatically.
Minute volume V is the air inhaled in one minute. It can be calculated by multiplying the mean tidal volume (V t) by the number of breaths per minute (f), or V=fV t . Part V t, for example, air in the trachea and bronchi to the terminal bronchioles and in some alveoli, does not participate in gas exchange, since it does not come into contact with active pulmonary blood flow - this is the so-called "dead" space (V d). The part of V t that is involved in gas exchange with pulmonary blood is called the alveolar volume (VA). From a physiological point of view, alveolar ventilation (V A) is the most essential part of external respiration V A \u003d f (V t -V d), since it is the volume of air inhaled per minute that exchanges gases with the blood of the pulmonary capillaries.

Pulmonary respiration

A gas is a state of matter in which it is evenly distributed over a limited volume. In the gas phase, the interaction of molecules with each other is insignificant. When they collide with the walls of an enclosed space, their movement creates a certain force; this force applied per unit area is called gas pressure and is expressed in millimeters of mercury.

Hygiene advice in relation to the respiratory organs, they include warming the air, cleansing it of dust and pathogens. This is facilitated by nasal breathing. There are many folds on the surface of the mucous membrane of the nose and nasopharynx, which ensure its warming during the passage of air, which protects a person from colds in the cold season. Thanks to nasal breathing, dry air is moistened, settled dust is removed by the ciliated epithelium, and tooth enamel is protected from damage that would occur when cold air is inhaled through the mouth. Through the respiratory organs, pathogens of influenza, tuberculosis, diphtheria, tonsillitis, etc. can enter the body together with air. Most of them, like dust particles, adhere to the mucous membrane of the airways and are removed from them by the ciliary epithelium, and microbes are neutralized by mucus. But some microorganisms settle in the respiratory tract and can cause various diseases.
Proper breathing is possible with the normal development of the chest, which is achieved by systematic physical exercises in the open air, the correct posture while sitting at the table, and a straight posture when walking and standing. In poorly ventilated rooms, the air contains from 0.07 to 0.1% CO 2 , which is very harmful.
Smoking causes great harm to health. It causes permanent poisoning of the body and irritation of the mucous membranes of the respiratory tract. The fact that smokers have lung cancer much more often than non-smokers also speaks about the dangers of smoking. Tobacco smoke is harmful not only to smokers themselves, but also to those who remain in the atmosphere of tobacco smoke - in a residential area or at work.
The fight against air pollution in cities includes a system of purification plants at industrial enterprises and extensive landscaping. Plants, releasing oxygen into the atmosphere and evaporating water in large quantities, refresh and cool the air. The leaves of the trees trap dust, so that the air becomes cleaner and more transparent. Proper breathing and systematic hardening of the body are important for health, for which it is often necessary to be in the fresh air, take walks, preferably outside the city, in the forest.

The respiratory system provides the functions of external respiration, that is, gas exchange between blood and air. Internal, or tissue respiration, is called gas exchange between tissue cells and the fluid surrounding them, and oxidative processes that occur inside cells and lead to energy production.

Gas exchange with air takes place in the lungs. It is aimed at ensuring that oxygen from the air enters the blood (it is captured by hemoglobin molecules, since oxygen dissolves poorly in water), and carbon dioxide dissolved in the blood is released into the air, into the external environment.

An adult at rest takes about 14-16 breaths per minute. With physical or emotional stress, the depth and frequency of breathing may increase.

The airways carry air to the lungs. They begin in the nasal cavity, from there air enters the pharynx through the nasal passages. At the level of the pharynx, the respiratory tract meets the digestive tract. Allocate the nasopharynx and oropharynx (they are separated by the tongue). Below, at the level of the epiglottis, they together form the hypopharynx.

From the laryngopharynx, air goes to the larynx, then to the trachea. The walls of the larynx are formed by several cartilages, between which the vocal cords are stretched. With a calm inhalation and exhalation, the vocal cords are relaxed. When air passes between tense ligaments, sound is produced. A person is able to arbitrarily change the angles of the cartilage and the degree of tension of the ligaments, which makes speech and singing possible.

The conditional border between the upper and lower respiratory tract passes at the level of the larynx.

To upper respiratory tract the oral cavity can also be attributed, since sometimes breathing is carried out through the mouth. Breathing through the nose is more physiological for several reasons:

• Firstly, passing through the convoluted nasal passages, the air has time to warm up, moisturize and be cleaned of dust and bacteria. When the respiratory tract is cooled, the protective ability of the immune system decreases and the risk of getting sick increases;
• Secondly, there are receptors in the nasal cavity that trigger sneezing. This is a complex protective reflex act aimed at removing foreign bodies, harmful chemicals, mucus and other irritants from the respiratory tract;
• Thirdly, there are olfactory receptors in the nasal passages, thanks to which a person distinguishes smells.

To lower respiratory tract include the larynx, trachea, and bronchi. The paths of air and food cross, so food or liquid can enter the trachea. Such an arrangement of the respiratory organs evolutionarily goes back to lungfish, which swallowed air into the stomach for breathing. The entrance to the trachea is blocked by a special cartilage, the epiglottis. During the act of swallowing, the epiglottis descends to prevent food and liquid from entering the lungs.

The trachea is located anterior to the esophagus, it is a tube in the wall of which there are cartilaginous semirings that give the trachea the necessary rigidity so that it does not collapse and air can pass to the lungs. The back wall of the trachea is soft, so when hard lumps pass through the esophagus, it can stretch and not create obstacles to food.

With swelling of the neck (for example, with allergic Quincke's edema), the trachea is protected from compression, unlike the laryngopharynx. Therefore, with swelling of the larynx, a person can suffocate. If the larynx is still open, a rigid tube is inserted into it to allow air to flow. If the larynx is already swollen too much, a tracheotomy is done: an incision in the trachea, into which a breathing tube is inserted.

At the level of the V-VI thoracic vertebrae, the trachea divides into two main bronchi, right and left. The place where the trachea divides is called a bifurcation. The bronchi are similar in structure to the trachea, only the cartilages in their walls are in the form of closed rings. Inside the lungs, the bronchi also branch into smaller bronchioles.

Sometimes foreign bodies still get into the lower respiratory tract. In this case, the mucous membrane is irritated and the person begins to cough to remove the foreign body. If the airways are completely blocked, asphyxia occurs, the person begins to suffocate.

The traditional way to help in such a situation is considered to be blows to the back. However, if you hit a person standing straight, the foreign body will move down under the influence of gravity and most likely block the right main bronchus (it departs from the trachea at a smaller angle). After that, breathing will be restored, but not in full, since only one lung will function. The victim will need hospitalization.

To prevent blockage of the main bronchus, before performing back blows, it is necessary that the victim bend forward. In this case, you should strike between the shoulder blades, making sharp pushing movements from the bottom up.

If, after 5 strokes, the victim continues to suffocate, perform Heimlich (Heimlich) technique: standing behind the victim, put the fist of one hand over the navel and press sharply and strongly with both hands. The Heimlich maneuver can also be performed on a lying person (see figure).

Lungs, gas exchange

The human body has two lungs, right and left. The right has three lobes, the left has two. In general, the left lung is smaller in size, since part of the volume of the chest on the left is occupied by the heart. It is in the lungs that gas exchange takes place between blood and air.

Through the thinnest parts of the respiratory tract, the terminal (final) bronchioles, air enters the alveoli. Alveoli are hollow, thin-walled sacs surrounded by a dense network of capillaries. Bubbles are collected in clusters, which are called alveolar sacs, they form the respiratory sections of the lungs. Each lung contains about 300,000,000 alveoli. This structure allows you to significantly increase the surface area on which gas exchange occurs. In humans, the total surface area of ​​the alveolar walls ranges from 40 m² to 120 m².

Venous blood reaches the alveolar sac through arterioles. Oxygenated arterial blood flows through the venule towards the heart. Oxygen and carbon dioxide move along the concentration gradient by passive diffusion, since the air is relatively high in oxygen and low in carbon dioxide.

Composition of atmospheric air: 21% oxygen, 0.03% carbon dioxide (CO2) and 79% nitrogen. On exhalation, the composition of the air changes as follows: 16.3% oxygen, 4% CO2 and still 79% nitrogen. It can be seen that the concentration of CO2 increases by more than 100 times! At the same time, the oxygen concentration does not change so much, therefore, in order for the air to be breathable again, it is more important to remove excess carbon dioxide from it, rather than saturate it with oxygen.

The walls of the alveoli are coated on the inside with a surfactant, a surfactant that prevents the alveoli from collapsing on exhalation. Surfactant reduces the force of surface tension, it is secreted by special cells, alveolocytes. In inflammatory processes, the composition of the surfactant may change, the alveoli begin to collapse and stick together, the surface area of ​​gas exchange decreases, there is a feeling of lack of air, shortness of breath.

A way to straighten the stuck together alveoli is yawning - another complex reflex act of the respiratory system. Yawning occurs when not enough oxygen is supplied to the brain.

Respiratory movements, lung volumes

The chest cavity is lined from the inside with a smooth serous membrane - the pleura. The pleura has two sheets, one covers the wall of the chest cavity (parietal, or parietal pleura), the other covers the lungs themselves (visceral, or pulmonary pleura). The pleura secrete pleural fluid, which softens the sliding of the lungs and prevents friction. Also, the pleura provides tightness of the pleural cavity, so that breathing is possible.

When inhaling, a person changes the volume of the respiratory cell in two ways: by raising the ribs and by lowering the diaphragm. The ribs have a slanting downward direction, so when the main respiratory muscles are tensed, they rise up, expanding the chest. The diaphragm is a powerful muscle that separates the organs of the chest and abdominal cavities. In a relaxed state, they form a dome, and when tense, it becomes flat and presses down the abdominal organs.

If the lifting of the ribs plays an important role in the process of inhalation, this type of breathing is called thoracic, it is typical for women. In men, the abdominal (diaphragmatic) type of breathing predominates more often, in which the diaphragm tension plays the main role in inhalation.

Due to the fact that the pleural cavity is airtight, and the volume of the chest increases, the pressure in the pleural cavity during inspiration drops and becomes lower than atmospheric pressure (conditionally, such pressure is called negative). Air begins to enter the lungs due to the difference in pressure through the respiratory tract.

If the tightness of the pleura is broken (this can happen with a fracture of the ribs or a penetrating wound), air will not enter the lungs, but into the pleural cavity. A collapse of the lung or its lobe may even occur, since atmospheric pressure will act from the outside, not straightening, but, on the contrary, compressing the lung tissue. The penetration of gas into the pleural cavity is called pneumothorax. Gas exchange in a collapsed lung is impossible, therefore, when the chest is injured, it is very important to ensure the tightness of the pleural cavity as soon as possible. For this, sealed bandages are used, a piece of oilcloth, polyethylene, thin rubber, etc. is applied directly to the wound.

If the intensity of ventilation needs to be increased, auxiliary muscles join the work of the main respiratory muscles: muscles of the neck, chest, and some spinal muscles. Since many of them are attached to the bones of the girdle of the upper limbs, to facilitate breathing, people lean on their hands to fix the girdle of the limbs. Similar postures can be observed in sick people with an asthma attack.

Exhalation at rest is passive. There are respiratory muscles with which you can make a sharp (forced) exhalation. These are mainly the abdominal muscles: when tensed, they squeeze the abdominal organs, pushing up the diaphragm.

At rest, the lungs are ventilated unevenly, the tops of the lungs are the worst ventilated. This is compensated by the fact that the tops are more abundantly supplied with blood than the bases. The quiet expiratory volume averages 0.5 liters. There are reserve volumes of inhalation and exhalation, if necessary, a person begins to breathe hard, take deep breaths and forced exhalations. At the same time, the volume of air in the lungs will increase several times.

The maximum volume that a person can exhale after taking a deep breath is called vital capacity (VC) and is about 4.5 liters. At the same time, a certain amount of air always remains in the airways, even after a complete exhalation (otherwise the airways would collapse). This air makes up the residual volume, about 1.5 liters.

Spirography is used to study the function of external respiration. An example of a spirogram is shown in the figure:

tissue respiration

In the tissues of the body, where the oxygen concentration is less than in the lungs, oxygen molecules leave the erythrocytes into the blood and then enter the tissue fluid. Oxygen is poorly soluble in water, so it is released by red blood cells gradually.

Tissue cells release CO2 into the blood through the tissue fluid, which is highly soluble in water and does not require hemoglobin to be carried.

Thus, the transport of gases occurs passively, without energy consumption. Effective gas exchange between blood and tissue is possible only in capillaries, since their wall is rather thin, and the blood flow rate is rather slow.

It is important to remember that the ultimate goal of the respiratory system is to ensure the supply of oxygen into the cell, since it is the aerobic oxidation of glucose that is the source of energy for humans. The process of obtaining energy occurs inside the cell organelles, mitochondria.

Glucose undergoes several stages of oxidation under the action of respiratory enzymes, resulting in the formation of ATP molecules, water and carbon dioxide. ATP is a universal energy carrier that is used in almost all processes in the cell.

Breathing regulation

The respiratory center is located in the medulla oblongata, it regulates the depth and frequency of breaths. Receptors on its surface respond mainly to an increase in the concentration of CO2 in the blood. That is, if the air has a normal concentration of oxygen, but the content of carbon dioxide is increased (hyperdrop) the person will experience severe discomfort. There will be shortness of breath, dizziness, suffocation, the person will lose consciousness. For many people, elevated CO2 causes panic.

With hyperventilation of the lungs (too frequent and deep breathing), CO2 is washed out of the blood, which also leads to dizziness and sometimes to loss of consciousness, because the breathing regulation system “goes astray”.

There are also receptors that respond to a decrease or increase in oxygen in the blood. At hypoxia(lack of oxygen) there is lethargy, lethargy and confusion. After a while, euphoria sets in, which is replaced by stupor and loss of consciousness.

Signals from the respiratory center are sent to the intercostal muscles and the diaphragm. With an excess of carbon dioxide, the frequency of respiratory movements increases to a greater extent, and with a lack of oxygen, their depth.

Cough receptors are located in the upper respiratory tract, trachea and large bronchi, in the pleura. In response to mucosal irritation, they trigger a cough reflex to get rid of the irritant. There are no cough receptors in the small bronchi and bronchioles, so if the inflammatory process is localized in the terminal sections of the respiratory tract, it is not accompanied by a cough.

The mucus that is secreted during inflammation, after a while reaches the large bronchi and begins to irritate them, the cough reflex starts. Distinguish between productive and unproductive cough. A productive cough produces sputum. If there is not enough mucus, or if it is too viscous and difficult to separate, the cough is not productive.

To facilitate the discharge of sputum, thinning drugs, mucolytics are used. To prevent people from suffering from a strong cough, antitussive drugs are used that reduce the sensitivity of receptors or inhibit the center of the cough reflex.

It is impossible to inhibit the cough reflex if there is a large amount of sputum in the bronchi. In this case, its discharge will be difficult, and it can clog the lumen of the bronchi. Previously, heroin was used as antitussive drops for children.

human respiratory system- a set of organs and tissues that provide in the human body the exchange of gases between the blood and the environment.

Function of the respiratory system:

• intake of oxygen into the body;
• excretion of carbon dioxide from the body;
• excretion of gaseous products of metabolism from the body;
• thermoregulation;
• synthetic: some biologically active substances are synthesized in the tissues of the lungs: heparin, lipids, etc.;
• hematopoietic: mast cells and basophils mature in the lungs;
• deposition: the capillaries of the lungs can accumulate a large amount of 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 airways.

Pulmonary contractions are carried out with the help of the intercostal muscles and the diaphragm.

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

The lungs are made up of pulmonary vesicles alveoli.

Rice. Respiratory system

Airways

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 of 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/ Withm2 cm2 mucous membrane). Mucus prevents the growth of microbes. A large number of leukocytes-phagocytes that destroy the microbial flora come out of the blood capillaries to the surface of the mucous membrane.

In addition, the mucous membrane can vary 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 by a certain period of time, therefore the surface of the epithelium is undulatingly mobile - “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 the inhaled air;
• mucus washes away everything filtered into the gastrointestinal tract.

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

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

SINSINS OF THE NOSE

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

LARYNX

The upper part of the respiratory tube is the larynx, located in front of the neck. Most of the larynx is also lined with a mucous membrane of ciliated (ciliary) 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 at the time of swallowing food. The front end of the epiglottis is connected to the thyroid cartilage.

Rice. Larynx

The cartilages of the larynx are interconnected by joints, and the spaces between the cartilages are covered with connective tissue membranes.

VOICE PRODUCTION

The thyroid gland is attached to the outside of the larynx.

Anteriorly, the larynx is protected by the anterior muscles of the neck.

TRACHEA AND BRONCH

The trachea is a breathing tube about 12 cm long.

It is made up of 16-20 cartilaginous semirings that do not close behind; 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 the passage of the food bolus, protrudes slightly into its lumen.

Rice. Cross section of the trachea: 1 - ciliated epithelium; 2 - own layer of the 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 bronchus, going to the right and left lungs. This place of division is called a bifurcation (branching).

The aortic arch bends through the left bronchus, and the right bronchus bends around the unpaired vein going from behind to the front. In the words of old anatomists, "the aortic arch sits astride the left bronchus, and the unpaired 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 multi-row ciliated epithelium.

The device of the respiratory tract provides warming, moistening and purification of the air coming with inhalation. Dust particles move upward with ciliated epithelium and are removed outside with coughing and sneezing. Microbes are rendered harmless by mucosal lymphocytes.

lungs

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

PLEURA

Lungs covered pleura.

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

Distinguish lung pleura, tightly fused with lung tissue, and parietal pleura, lining the inside of the chest wall.

At the roots of the lungs, the pulmonary pleura passes into 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 that facilitates 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.

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

BRONCHIAL TREE

The right lung is divided by deep furrows into three lobes, and the left into two. The left lung, on the side facing the midline, has a recess with which it is adjacent to the heart.

Thick bundles consisting of the primary bronchus, pulmonary artery and nerves enter each lung from the inside, and two pulmonary veins and lymphatic vessels exit each. All these bronchial-vascular bundles, taken together, form lung root. A large number of bronchial lymph nodes are located around the pulmonary roots.

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 "branch", the diameter of the bronchi decreases until they become completely microscopic bronchioles with a diameter of 0.5 mm. In the soft walls of the bronchioles there are smooth muscle fibers and no cartilaginous semirings. There are up to 25 million such bronchioles.

Rice. bronchial tree

Bronchioles pass into branched alveolar passages, which end in lung sacs, the walls of which are strewn with swellings - pulmonary alveoli. The walls of the alveoli are permeated with 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.

ALVEOLAS

Alveoli are formed by a network of the finest elastic fibers. The inner surface of the alveoli is lined with a single layer of squamous epithelium. The walls of the epithelium produce surfactant- a surfactant that lines the inside of the alveoli and prevents them from collapsing.

Under the epithelium of the pulmonary vesicles lies a dense network of capillaries, into which the terminal branches of the pulmonary artery break. Through the adjoining walls of the alveoli and capillaries, gas exchange occurs during respiration. Once in the blood, oxygen binds to hemoglobin and spreads 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 first breath, the alveoli swell and remain straightened for life, retaining a certain amount of air even with the deepest exhalation.

GAS EXCHANGE AREA

respiratory physiology

All life processes proceed with the obligatory participation of oxygen, that is, they are aerobic. Particularly sensitive to oxygen deficiency is the central nervous system, and primarily cortical neurons, which die earlier than others in oxygen-free conditions. As you know, the period of clinical death should not exceed five minutes. Otherwise, irreversible processes develop in the neurons of the cerebral cortex.

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

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

• pulmonary (external) breathing: 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. Lung and tissue respiration

Red blood cells contain hemoglobin, a complex iron-containing protein. This protein is able to attach 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 the tissues of the body. In the tissues, oxygen is released (oxyhemoglobin is converted to hemoglobin) and carbon dioxide is added (hemoglobin is converted to carbohemoglobin). The 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 INHALE AND EXHAUST

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

The respiratory muscles are intercostal muscles and diaphragm. Deep inhalation uses the muscles of the neck, chest and abs.

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

The diaphragm during inspiration drops by 3-4 cm, as a result of which the volume of the chest increases by 1000-1200 ml. In addition, the diaphragm pushes the lower ribs to the periphery, which also leads to an increase in chest capacity. Moreover, the stronger the contraction of the diaphragm, the more the volume of the chest 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 of the chest, stretch themselves, and the pressure in them drops. As a result, a difference is created between the pressure of atmospheric air and the pressure in the lungs, air rushes into them - inspiration 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 descend under the action of gravity; the diaphragm, relaxing, rises, taking its usual position, and the volume of the chest cavity decreases - the lungs contract. There is an exhalation.

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 the negative pressure, the pulmonary pleura is tightly pressed against the parietal pleura.

A decrease in pressure in the pleural space is the main reason for the increase in lung volume during inspiration, that is, it is the force that stretches the lungs. So, 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 expiration, the pressure in the pleural cavity increases, and due to the difference in pressure, the air escapes, the lungs collapse.

chest breathing carried out mainly due to the external intercostal muscles.

abdominal breathing carried out by the diaphragm.

In men, the abdominal type of breathing is noted, and in women - chest. However, regardless of this, both men and women breathe rhythmically. From the first hour of life, the rhythm of breathing is not disturbed, only its frequency changes.

A newborn child breathes 60 times per minute, in an adult, the frequency of respiratory movements at rest is about 16-18. However, during physical exertion, emotional arousal, or with an increase in body temperature, the respiratory rate can increase significantly.

vital lung capacity

Vital capacity (VC) 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, VC varies from 3500 to 7000 ml and depends on gender and on indicators of physical development: for example, chest volume.

ZhEL consists of several volumes:

1. Tidal volume (TO)- this is the amount of air that enters and exits 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 breath (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).

breathing regulation

Respiration is regulated by nervous and humoral mechanisms, which are reduced to ensuring the rhythmic activity of the respiratory system (inhalation, exhalation) and adaptive respiratory reflexes, that is, a change in the frequency and depth of respiratory movements that occur under changing environmental conditions or the internal environment of the 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. They take part in the organization of more complex adaptive respiratory reflexes, which are necessary when the conditions of the organism's existence change. In addition, the respiratory centers are also located in the cerebral cortex, carrying out the highest forms of adaptive processes. The presence of respiratory centers in the cerebral cortex is proved by the formation of conditioned respiratory reflexes, changes in the frequency and depth of respiratory movements that occur during various 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. The vagus nerves cause contraction of the bronchial muscles and constriction of the bronchi, while the sympathetic nerves relax the bronchial muscles and dilate the bronchi.

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

A1. Gas exchange between blood and atmospheric air

happening in

1) alveoli of the lungs

2) bronchioles

3) fabrics

4) pleural cavity

A2. Breathing is a process

1) obtaining energy from organic compounds with the participation of oxygen

2) energy absorption during the synthesis of organic compounds

3) the formation of oxygen during chemical reactions

4) simultaneous synthesis and decomposition of organic compounds.

A3. The respiratory organ is not:

1) larynx

2) trachea

3) oral cavity

4) bronchi

A4. One of the functions of the nasal cavity is:

1) retention of microorganisms

2) enrichment of blood with oxygen

3) air cooling

4) dehumidification

A5. The larynx protects against food entering it:

1) arytenoid cartilage

3) epiglottis

4) thyroid cartilage

A6. The respiratory surface of the lungs is increased

1) bronchi

2) bronchioles

3) eyelashes

4) alveoli

A7. Oxygen enters the alveoli and from them into the blood

1) diffusion from an area with a lower gas concentration to an area with a higher concentration

2) diffusion from an area with a higher gas concentration to an area with a lower concentration

3) diffusion from body tissues

4) under the influence of nervous regulation

A8. A wound that violates the tightness of the pleural cavity will lead to

1) inhibition of the respiratory center

2) restriction of lung movement

3) excess oxygen in the blood

4) excessive mobility of the lungs

A9. The cause of tissue gas exchange is

1) the difference in the amount of hemoglobin in the blood and tissues

2) the difference in the concentrations of oxygen and carbon dioxide in the blood and tissues

3) different rates of transition of oxygen and carbon dioxide molecules from one medium to another

4) air pressure difference in the lungs and pleural cavity

IN 1. Select the processes that occur during gas exchange in the lungs

1) diffusion of oxygen from blood to tissues

2) formation of carboxyhemoglobin

3) the formation of oxyhemoglobin

4) diffusion of carbon dioxide from cells into the blood

5) diffusion of atmospheric oxygen into the blood

6) diffusion of carbon dioxide into the atmosphere

IN 2. Establish the correct sequence of passage of atmospheric air through the respiratory tract

A) larynx

B) bronchi

D) bronchioles

B) nasopharynx

D) lungs

Biology [A complete guide to preparing for the exam] Lerner Georgy Isaakovich

5.1.3 Structure and functions of the respiratory system

The main terms and concepts tested in the examination paper: alveoli, lungs, alveolar air, inhalation, exhalation, diaphragm, gas exchange in the lungs and tissues, diffusion, respiration, respiratory movements, respiratory center, pleural cavity, regulation of respiration.

Respiratory system performs the function of gas exchange, delivering oxygen to the body and removing carbon dioxide from it. The airways are the nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles and lungs. In the upper respiratory tract, the air is warmed, cleaned of various particles and humidified. Gas exchange takes place in the alveoli of the lungs. In the nasal cavity, which is lined with mucous membrane and covered with ciliary epithelium, mucus is secreted. It moisturizes the inhaled air, envelops solid particles. The mucous membrane warms the air, because. it is richly supplied with blood vessels. Air through the nasal passages enters the nasopharynx and then into the larynx.

Larynx performs two functions - respiratory and voice formation. The complexity of its structure is associated with the formation of voice. In the larynx are vocal cords, consisting of elastic fibers of connective tissue. Sound is produced by the vibration of the vocal cords. The larynx takes part only in the formation of sound. Lips, tongue, soft palate, paranasal sinuses take part in articulate speech. The larynx changes with age. Its growth and function are associated with the development of the gonads. The size of the larynx in boys during puberty increases. The voice changes (mutates). Air enters from the larynx into trachea.

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

The trachea divides into two elastic main bronchus. The main bronchi branch into smaller bronchi called bronchioles. The bronchi and brochioles are lined with ciliated epithelium. The bronchioles lead to the lungs.

Lungs - paired organs located in the chest cavity. The lungs are made up of pulmonary sacs called alveoli. The wall of the alveolus is formed by a single-layer epithelium and is braided with a network of capillaries into which atmospheric air enters. Between the outer layer of the lung and the chest pleural cavity, filled with a small amount of fluid that reduces friction when moving the lungs. It is formed by two sheets of pleura, one of which covers the lung, and the other lines the chest from the inside. The pressure in the pleural cavity is less than atmospheric and is about 751 mm Hg. Art. When inhaling The chest cavity expands, the diaphragm descends, and the lungs expand. When exhaling the volume of the chest cavity decreases, the diaphragm relaxes and rises. The respiratory movements involve the external intercostal muscles, the muscles of the diaphragm, and the internal intercostal muscles. With increased breathing, all the muscles of the chest are involved, lifting the ribs and sternum, the muscles of the abdominal wall.

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

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

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

Oxygen is transported to tissues as part of oxyhemoglobin. Carbohemoglobin transports a small amount of carbon dioxide from the tissues to the lungs. Most of it forms carbonic acid with water, which in turn forms potassium and sodium bicarbonates. They carry carbon dioxide to the lungs.

EXAMPLES OF TASKS

A1. Gas exchange between blood and atmospheric air

happening in

1) lung alveoli 3) tissues

2) bronchioles 4) pleural cavity

A2. Breathing is a process

1) obtaining energy from organic compounds with the participation of oxygen

2) energy absorption during the synthesis of organic compounds

3) the formation of oxygen during chemical reactions

4) simultaneous synthesis and decomposition of organic compounds.

A3. The respiratory organ is not:

1) larynx

3) oral cavity

A4. One of the functions of the nasal cavity is:

1) retention of microorganisms

2) enrichment of blood with oxygen

3) air cooling

4) dehumidification

A5. The larynx protects against food entering it:

1) arytenoid cartilage 3) epiglottis

A6. The respiratory surface of the lungs is increased

1) bronchi 3) cilia

2) bronchioles 4) alveoli

A7. Oxygen enters the alveoli and from them into the blood

1) diffusion from an area with a lower gas concentration to an area with a higher concentration

2) diffusion from an area with a higher gas concentration to an area with a lower concentration

3) diffusion from body tissues

4) under the influence of nervous regulation

A8. A wound that violates the tightness of the pleural cavity will lead to

1) inhibition of the respiratory center

2) restriction of lung movement

3) excess oxygen in the blood

4) excessive mobility of the lungs

A9. The cause of tissue gas exchange is

1) the difference in the amount of hemoglobin in the blood and tissues

2) the difference in the concentrations of oxygen and carbon dioxide in the blood and tissues

3) different rates of transition of oxygen and carbon dioxide molecules from one medium to another

4) air pressure difference in the lungs and pleural cavity

Part B

IN 1. Select the processes that occur during gas exchange in the lungs

1) diffusion of oxygen from blood to tissues

2) formation of carboxyhemoglobin

3) the formation of oxyhemoglobin

4) diffusion of carbon dioxide from cells into the blood

5) diffusion of atmospheric oxygen into the blood

6) diffusion of carbon dioxide into the atmosphere

IN 2. Establish the correct sequence of passage of atmospheric air through the respiratory tract

A) larynx B) bronchi D) bronchioles

B) nasopharynx D) lungs E) trachea

Part C

C1. How will the violation of the tightness of the pleural cavity of one lung affect the work of the respiratory system?

C2. What is the difference between pulmonary and tissue gas exchange?

SZ. Why do respiratory diseases complicate the course of cardiovascular diseases?