I will solve the exam biology breathing. Human. Organs, organ systems: digestion, respiration, blood circulation, lymph circulation. Types of airways

Nutrients and food products

Nutrients- proteins, fats, carbohydrates, mineral salts, water and vitamins. Nutrients are found in food products plant and animal origin. They provide the body with all the necessary nutrients and energy.

Water, mineral salts and vitamins are absorbed by the body unchanged. Proteins, fats, and carbohydrates found in food cannot be directly absorbed by the body. They decompose into simpler substances.
The process of mechanical and chemical processing of food and its transformation into simpler and soluble compounds that can be absorbed, transported by blood and lymph and absorbed by the body as plastic and energy material is called digestion.

Digestive organs

Digestive system carries out the process of mechanical and chemical processing of food, absorption of processed substances and removal of undigested and undigested components of food.
In the digestive system there are alimentary canal and digestive glands opening into it with their excretory ducts. The alimentary canal consists of oral cavity, pharynx, esophagus, stomach, small intestine and colon. TO digestive glands include large ones (three pairs salivary glands, liver and pancreas) and many small glands.

Alimentary canal They are a complex tube 8–10 m long and consists of the oral cavity, pharynx, esophagus, stomach, small intestine and colon. The wall of the digestive canal has three layers. 1) Outer the layer is formed by connective tissue and performs a protective function. 2) Average the layer in the oral cavity, pharynx, upper third of the esophagus and rectal sphincter is formed by striated muscle tissue, and in the remaining sections - by smooth muscle tissue. Muscle layer ensures the mobility of the organ and the movement of food gruel through it. 3) Interior(mucous) layer consists of epithelium and connective tissue plate. Derivatives of the epithelium are large and small digestive glands that produce digestive juices.

Digestion in the mouth

IN oral cavity there are teeth and tongue. The ducts of three pairs of large salivary glands and many small ones open into the oral cavity.
Teeth grind food. A tooth consists of a crown, a neck and one or more roots.
The crown of the tooth is covered with hard enamel(the hardest tissue in the body). Enamel protects the tooth from abrasion and penetration of microbes. Roots covered cement. The main part of the crown, neck and root is dentine. Enamel, cement and dentin are types of bone tissue. Inside the tooth there is a small dental cavity filled with soft pulp. It is formed by connective tissue penetrated by vessels and nerves.
An adult has 32 teeth: in each half of the upper and lower jaw 2 incisors, 1 canine, 2 small molars and 3 large molars. Newborns have no teeth. Milk teeth appear by the 6th month and are replaced by permanent teeth by 10–12 years. Wisdom teeth grow in between the ages of 20 and 22.
There are always a lot of microorganisms in the oral cavity that can lead to diseases of the oral cavity, in particular tooth decay ( caries). It is very important to keep the oral cavity clean - rinse your mouth after eating, brush your teeth with special pastes that contain fluoride and calcium.
Language- a mobile muscular organ consisting of striated muscles, supplied with numerous vessels and nerves. The tongue moves food during chewing, participates in wetting it with saliva and swallowing, and serves as an organ of speech and taste. The mucous membrane of the tongue has outgrowths - taste buds, containing taste, temperature, pain and tactile receptors.
Salivary glands- large paired parotid, submandibular and sublingual; as well as a large number of small glands. They open into ducts into the oral cavity and secrete saliva. The secretion of saliva is regulated by the humoral pathway and the nervous system. Saliva can be released not only during eating when the receptors of the tongue and oral mucosa are irritated, but also when seeing tasty food, feeling its smell, etc.
Saliva consists of 98.5–99% water (1–1.5% dry matter). It contains mucin(a mucous protein substance that helps form the food bolus), lysozyme(bactericidal substance), enzymes amylase maltase(splits maltose into two glucose molecules). Saliva has an alkaline reaction, since its enzymes are active in a slightly alkaline environment.
Food remains in the oral cavity for 15–20 seconds. The main functions of the oral cavity are approbation, grinding and wetting of food. In the oral cavity, food is subjected to mechanical and partially chemical processing with the help of teeth, tongue and saliva. Here, the breakdown of carbohydrates by enzymes contained in saliva begins and can continue while the bolus of food moves through the esophagus and for some time in the stomach.
From the mouth, food enters the pharynx and then into the esophagus. Pharynx- a muscular tube located in front of the cervical vertebrae. The pharynx is divided into three parts: nasopharynx, oropharynx and laryngeal part . The respiratory and digestive tracts intersect in the mouth.
Esophagus- a muscular tube 25–30 cm long. The upper third of the esophagus is formed by striated muscle tissue, the rest by smooth muscle tissue. The esophagus passes through an opening in the diaphragm into the abdominal cavity and here it becomes the stomach. The function of the esophagus is to move the bolus of food into the stomach as a result of contractions of the muscular membrane.

Digestion in the stomach

The stomach is a sac-like, expanded part of the digestive tube. Its wall consists of three layers described above: connective tissue, muscle and mucous. The stomach is divided into inlet, fundus, body and outlet. The capacity of the stomach ranges from one to several liters. In the stomach, food is retained for 4–11 hours and is mainly subjected to chemical processing by gastric juice.
Gastric juice produced by the glands of the gastric mucosa (in the amount of 2.0–2.5 l/day). Gastric juice contains mucus, hydrochloric acid and enzymes.
Slime protects the gastric mucosa from mechanical and chemical damage.
Hydrochloric acid(HCl concentration - 0.5%), due to the acidic environment, has a bactericidal effect; activates pepsin, causes denaturation and swelling of proteins, which facilitates their breakdown by pepsin.
Gastric juice enzymes: pepsin gelatinase(hydrolyzes gelatin), lipase(breaks down emulsified milk fats into glycerol and fatty acids), chymosin(curds the milk).
When food does not enter the stomach for a long time, a feeling occurs. hunger. It is necessary to distinguish between the concepts of “hunger” and “appetite”. To eliminate the feeling of hunger, the amount of food consumed is of primary importance. Appetite is characterized by a selective attitude to the quality of food and depends on many psychological factors.
Sometimes, as a result of ingestion of poor-quality food or highly irritating substances, vomit. However, the contents upper sections The intestines return to the stomach and, together with its contents, are expelled through the esophagus into the oral cavity due to antiperistalsis and strong contractions of the diaphragm and abdominal muscles.

Digestion in the intestines

The intestine consists of the small intestine (includes the duodenum, jejunum and ileum) and the large intestine (includes the cecum with the appendix, colon and rectum).
Food gruel is taken from the stomach in separate portions through the sphincter ( orbicularis muscle) enters the duodenum. Here the food pulp is exposed chemical action pancreatic juice, bile and intestinal juice.
The largest digestive glands are the pancreas and liver.
Pancreas located behind the stomach on the posterior abdominal wall. The gland consists of an exocrine part that produces pancreatic juice (enters the duodenum through the pancreatic duct), and an endocrine part that secretes the hormones insulin and glucagon into the blood.
Pancreatic juice (pancreatic juice) has an alkaline reaction and contains a number of digestive enzymes: trypsinogen(a proenzyme that passes into trypsin in the duodenum under the influence of enterokinase in intestinal juice), trypsin(in an alkaline environment it breaks down proteins and polypeptides into amino acids), amylase, maltase and lactase(break down carbohydrates) lipase(in the presence of bile, it breaks down fats into glycerol and fatty acids), nucleases(cleave nucleic acids into nucleotides). Secretion of pancreatic juice occurs in quantities (1.5–2 l/day).
Liver located in abdominal cavity under the diaphragm. The liver produces bile, which through the gall bladder duct enters the duodenum.
Bile is produced constantly, therefore, outside the period of digestion, it is collected in gallbladder. There are no enzymes in bile. It is alkaline and contains water, bile acids and bile pigments (bilirubin and biliverdin). Bile provides an alkaline reaction of the small intestine, promotes the separation of pancreatic juice, converts pancreatic enzymes into an active state, emulsifies fats, which facilitates their digestion, promotes the absorption of fatty acids, and enhances intestinal motility.
In addition to participating in digestion, the liver neutralizes toxic substances formed during metabolism or received from the outside. Glycogen is synthesized in liver cells.
Small intestine- the longest part of the digestive tube (5–7 m). Here food substances are almost completely digested, and the products of digestion are absorbed. It is divided into duodenum, jejunum and ileum.
Duodenum(about 30 cm long) has the shape of a horseshoe. In it, food gruel is subjected to the digestive action of pancreatic juice, bile and intestinal gland juice.
Intestinal juice produced by the glands of the mucous membrane of the small intestine. It contains enzymes that complete the breakdown of nutrients: peptidase amylase, maltase, invertase, lactase(break down carbohydrates) lipase(breaks down fats) enterokinase
Depending on the location of the digestive process in the intestine, there are cavity and parietal digestion. Cavity digestion occurs in the intestinal cavity under the influence of digestive enzymes secreted in the digestive juices. Parietal digestion is carried out by enzymes fixed on the cell membrane, at the border of the extracellular and intracellular environments. The membranes form a huge number of microvilli (up to 3000 per cell), on which a powerful layer of digestive enzymes is adsorbed. Pendulum-like movements of the circular and longitudinal muscles help to mix the food gruel; peristaltic wave-like movements of the circular muscles ensure the movement of the gruel to the colon.
Colon has a length of 1.5–2 m, an average diameter of 4 cm and includes three sections: the cecum with the appendix, colon and rectum. At the border of the ileum and cecum there is an ileocecal valve, which acts as a sphincter, which regulates the movement of the contents of the small intestine into the large intestine in separate portions and prevents its reverse movement. The large intestine, like the small intestine, is characterized by peristaltic and pendulum-like movements. The glands of the colon produce a small amount of juice, which does not contain enzymes, but has a lot of mucus necessary for the formation of feces. In the large intestine, water is absorbed, fiber is digested, and feces are formed from undigested food.
Numerous bacteria live in the large intestine. A number of bacteria synthesize vitamins (K and group B). Cellulose-degrading bacteria break down vegetable fiber to glucose acetic acid and other products. Glucose and acids are absorbed into the blood. Gaseous products of microbial activity (carbon dioxide, methane) are not absorbed and are released outside. Putrefaction bacteria in the large intestine destroy unabsorbed protein digestion products. In this case, toxic compounds are formed, some of which penetrate into the blood and are neutralized in the liver. Food debris turns into feces and accumulates in the rectum, which removes feces through the anus.

Suction

Absorption occurs in almost all parts of the digestive system. Glucose is absorbed in the oral cavity, water, salts, glucose, alcohol are absorbed in the stomach, water, salts, glucose, amino acids, glycerin, fatty acids are absorbed in the small intestine, water, alcohol, and some salts are absorbed in the colon.
The main absorption processes occur in lower sections small intestine (in the jejunum and ileum). There are many outgrowths of the mucous membrane - villi which increase the suction surface. The villus contains small capillaries, lymphatic vessels, nerve fibers. The villi are covered with a single layer of epithelium, which facilitates absorption. Absorbed substances enter the cytoplasm of the mucosal cells and then into the blood and lymphatic vessels passing inside the villi.

The mechanisms of absorption of different substances are different: diffusion and filtration (a certain amount of water, salts and small molecules organic matter), osmosis (water), active transport (sodium, glucose, amino acids). Absorption is facilitated by contractions of the villi, pendular and peristaltic movements of the intestinal walls.
Amino acids and glucose are absorbed into the blood. Glycerol dissolves in water and enters the epithelial cells. Fatty acids react with alkalis and form salts, which, in the presence of bile acids, dissolve in water and are also absorbed by epithelial cells. In the villous epithelium, glycerol and fatty acid salts interact to form human-specific fats that enter the lymph.
The absorption process is regulated by the nervous system and humorally (B vitamins stimulate the absorption of carbohydrates, vitamin A stimulates the absorption of fats).

Digestive enzymes

Digestive processes are influenced digestive juices, which are produced digestive glands. In this case, proteins are broken down into amino acids, fats into glycerol and fatty acids, and complex carbohydrates- to simple sugars (glucose, etc.). The main role in such chemical processing of food belongs to the enzymes contained in digestive juices. Enzymes- biological catalysts of protein nature produced by the body itself. A characteristic property of enzymes is their specificity: each enzyme acts on a substance or a group of substances only of a certain chemical composition and structure, on a certain type of chemical bond in the molecule.
Under the influence of enzymes, insoluble and incapable of absorption complex substances are broken down into simple, soluble and easily absorbed by the body.
During digestion, food undergoes the following enzymatic effects. Saliva contains amylase(breaks down starch to maltose) and maltase(breaks down maltose into glucose). Gastric juice contains pepsin(breaks down proteins into polypeptides), gelatinase(breaks down gelatin) lipase(breaks down emulsified fats into glycerol and fatty acids), chymosin(curds the milk). Pancreatic juice contains trypsinogen, which is converted into trypsin(breaks down proteins and polypeptides into amino acids), amylase, maltase, lactase, lipase, nuclease(breaks down nucleic acids into nucleotides). Intestinal juice contains peptidase(breaks down polypeptides into amino acids), amylase, maltase, invertase, lactase(break down carbohydrates) lipase, enterokinase(converts trypsinogen to trypsin).
Enzymes are highly active: each enzyme molecule within 2 seconds at 37 °C can lead to the breakdown of about 300 molecules of the substance. Enzymes are sensitive to the temperature of the environment in which they act. In humans, they are most active at a temperature of 37–40 °C. For an enzyme to function, a certain reaction of the environment is required. For example, pepsin is active in an acidic environment, the rest of the listed enzymes are active in weakly alkaline and alkaline environments.

Contribution of I. P. Pavlov to the study of digestion

The study of the physiological foundations of digestion was carried out mainly by I. P. Pavlov (and his students) thanks to the method he developed fistula technique research. The essence of this method is to create, through an operation, an artificial connection of the duct of the digestive gland or the cavity of the digestive organ with the external environment. I.P. Pavlov, performing surgical operations on animals, formed permanent fistulas. With the help of fistulas, he managed to collect pure digestive juices, without food admixtures, measure their quantity and determine chemical composition. The main advantage of this method, proposed by I.P. Pavlov, is that the digestion process is studied in natural conditions existence of an organism on a healthy animal, and the activity of the digestive organs is stimulated by natural food stimuli. Merits of I. P. Pavlov in the study of activity digestive glands got international recognition- he was awarded the Nobel Prize.
In humans, a rubber probe is used to extract gastric juice and duodenal contents, which the subject swallows. Information about the condition of the stomach and intestines can be obtained by illuminating the areas where they are located. x-rays, or method endoscopy(a special device is inserted into the cavity of the stomach or intestines - endoscope, which is equipped with optical and lighting devices that allow you to examine the cavity of the digestive canal and even the ducts of the glands).

Breath

Breath- a set of processes that ensure the supply of oxygen, its use in the oxidation of organic substances and the removal of carbon dioxide and some other substances.
A person breathes by absorbing oxygen from the atmospheric air and releasing carbon dioxide into it. Every cell needs energy to function. The source of this energy is the breakdown and oxidation of organic substances that make up the cell. Proteins, fats, carbohydrates, entering into chemical reactions with oxygen, oxidize (“burn”). In this case, the molecules disintegrate and the internal energy contained in them is released. Without oxygen, metabolic transformations of substances in the body are impossible.
There are no oxygen reserves in the human or animal body. Its continuous intake into the body is ensured by the respiratory system. The accumulation of significant amounts of carbon dioxide as a result of metabolism is harmful to the body. CO 2 is also removed from the body by the respiratory system.
The function of the respiratory system is to supply the blood with sufficient oxygen and remove carbon dioxide from it.
There are three stages of breathing: external (pulmonary) respiration- exchange of gases in the lungs between the body and the environment; transport of gases in the blood from the lungs to the tissues of the body; tissue respiration- gas exchange in tissues and biological oxidation in mitochondria.

External breathing

External breathing provided respiratory system, which consists of lungs(where gas exchange occurs between inhaled air and blood) and respiratory(airborne) ways(through which inhaled and exhaled air passes).
Airways (respiratory) tracts include the nasal cavity, nasopharynx, larynx, trachea and bronchi. The respiratory tract is divided into upper (nasal cavity, nasopharynx, larynx) and lower (trachea and bronchi). They have a hard skeleton, represented by bones and cartilage, and are lined from the inside with a mucous membrane, equipped with ciliated epithelium. Functions respiratory tract: heating and humidification of air, protection from infections and dust.

Nasal cavity divided by a partition into two halves. It communicates with the external environment through the nostrils, and from behind with the pharynx through the choanae. The mucous membrane of the nasal cavity has a large number of blood vessels. The blood passing through them warms the air. The glands of the mucous membrane secrete mucus, which moisturizes the walls of the nasal cavity and reduces the activity of bacteria. On the surface of the mucosa there are leukocytes that destroy a large number of bacteria. The ciliated epithelium of the mucous membrane traps and removes dust. When the cilia of the nasal cavities are irritated, a sneezing reflex occurs. Thus, the air in the nasal cavity is warmed, disinfected, moistened and cleaned of dust. In the mucous membrane of the upper part of the nasal cavity there are sensitive olfactory cells that form the organ of smell. From the nasal cavity, air enters the nasopharynx, and from there into the larynx.
Larynx formed by several cartilages: thyroid cartilage(protects the larynx from the front), cartilaginous epiglottis(protects the respiratory tract when swallowing food). The larynx consists of two cavities that communicate through a narrow glottis. The edges of the glottis are formed vocal cords. When you exhale air through the closed vocal cords, they vibrate, accompanied by the appearance of sound. The final formation of speech sounds occurs with the help of the tongue, soft palate and lips When the cilia of the larynx are irritated, a cough reflex occurs. From the larynx, air enters the trachea.
Trachea formed by 16–20 incomplete cartilaginous rings that do not allow it to collapse, and back wall The trachea is soft and contains smooth muscle. This allows food to pass freely through the esophagus, which lies behind the trachea.
At the bottom, the trachea is divided into two main bronchi(right and left), which penetrate the lungs. In the lungs, the main bronchi branch repeatedly into bronchi of the 1st, 2nd, etc. orders, forming bronchial tree. Bronchi of the 8th order are called lobular. They branch into terminal bronchioles, which branch into respiratory bronchioles, which form alveolar sacs consisting of alveoli. Alveoli- pulmonary vesicles having the shape of a hemisphere with a diameter of 0.2–0.3 mm. Their walls consist of single-layer epithelium and are covered with a network of capillaries. Gases are exchanged through the walls of the alveoli and capillaries: oxygen passes from the air into the blood, and CO 2 and water vapor enter the alveoli from the blood.
Lungs- large paired cone-shaped organs located in the chest. The right lung consists of three lobes, the left - of two. The main bronchus and pulmonary artery enter each lung, and two pulmonary veins exit. The outside of the lungs is covered with pulmonary pleura. Gap between shell chest cavity and the pleura (pleural cavity) is filled with pleural fluid, which reduces the friction of the lungs against the chest wall. Pressure in pleural cavity less than atmospheric by 9 mm Hg. Art. and is about 751 mm Hg. Art.
Breathing movements. Not in the lungs muscle tissue, and therefore they cannot actively contract. The active role in the act of inhalation and exhalation belongs to the respiratory muscles: intercostal muscles And diaphragm. When they contract, the volume of the chest increases and the lungs stretch. When the respiratory muscles relax, the ribs drop to their original level, the dome of the diaphragm rises, the volume of the chest, and therefore the lungs, decreases, and the air escapes out. A person makes an average of 15–17 breathing movements per minute. At muscle work breathing increases 2–3 times.
Vital capacity of the lungs. At rest, a person inhales and exhales about 500 cm 3 of air ( tidal volume ). At deep breath a person can inhale about 1500 cm 3 more air ( additional volume). After exhalation, he is able to exhale about 1500 cm 3 more ( reserve volume). These three quantities add up to vital capacity of the lungs(VC) is the greatest amount of air that a person can exhale after a deep breath. Vital vital capacity is measured using a spirometer. It is an indicator of the mobility of the lungs and chest and depends on gender, age, body size and muscle strength. In children 6 years old, vital capacity is 1200 cm 3; in adults - an average of 3500 cm 3; for athletes it is larger: for football players - 4200 cm 3, for gymnasts - 4300 cm 3, for swimmers - 4900 cm 3. The volume of air in the lungs exceeds vital capacity. Even with the deepest exhalation, about 1000 cm3 of residual air remains in them, so the lungs do not collapse completely.
Regulation of breathing. Located in the medulla oblongata respiratory center. One part of its cells is associated with inhalation, the other with exhalation. Impulses are transmitted from the respiratory center through motor neurons to the respiratory muscles and diaphragm, causing alternation of inhalation and exhalation. Inhalation reflexively causes exhalation, exhalation reflexively causes inhalation. The respiratory center is influenced by the cerebral cortex: a person can hold his breath for a while, change its frequency and depth.
The accumulation of CO 2 in the blood causes excitation of the respiratory center, which causes faster and deeper breathing. This is how the humoral regulation of breathing is carried out.
Artificial respiration done in case of respiratory arrest in drowned people, in case of electric shock, carbon monoxide poisoning, etc. They breathe from mouth to mouth or from mouth to nose. Exhaled air contains 16–17% oxygen, which is sufficient to ensure gas exchange, and high content in exhaled air, CO 2 (3–4%) promotes humoral stimulation of the victim’s respiratory center.

Transport of gases

Oxygen is transported to tissues mainly in the composition oxyhemoglobin(HbO 2). A small amount of CO 2 is transported from tissues to the lungs in the composition carbhemoglobin(HbCO 2). Most of the carbon dioxide combines with water to form carbon dioxide. Carbonic acid in tissue capillaries reacts with K + and Na + ions, turning into bicarbonates. As part of potassium bicarbonates in erythrocytes (minor part) and sodium bicarbonates in blood plasma (most part), carbon dioxide is transferred from tissues to the lungs.

Gas exchange in the lungs and tissues

A person breathes atmospheric air with a high oxygen content (20.9%) and low content carbon dioxide (0.03%), and exhales air in which O 2 is 16.3%, and CO 2 is 4%. Nitrogen and inert gases that make up the air do not participate in respiration, and their content in inhaled and exhaled air is almost the same.
In the lungs, oxygen from the inhaled air passes through the walls of the alveoli and capillaries into the blood, and CO2 from the blood enters the alveoli of the lungs. The movement of gases occurs according to the laws of diffusion, according to which gas penetrates from a medium containing more of it into a medium containing less of it. Gas exchange in tissues also occurs according to the laws of diffusion.
Respiratory hygiene. To strengthen and develop the respiratory organs, proper breathing (inhalation is shorter than exhalation), breathing through the nose, development of the chest (the wider it is, the better), and combating bad habits(smoking), clean air.
An important task is to protect the air environment from pollution. One of the conservation measures is the landscaping of cities and towns, as plants enrich the air with oxygen and clean it of dust and harmful impurities.

Immunity

Immunity- a way to protect the body from genetically foreign substances and infectious agents. The body's defense reactions are provided by cells - phagocytes, as well as proteins - antibodies. Antibodies are produced by cells that are formed from B lymphocytes. Antibodies are formed in response to the appearance of foreign proteins in the body - antigens. Antibodies bind to antigens, neutralizing their pathogenic properties.
There are several types of immunity.
Natural innate(passive) - due to the transfer of ready-made antibodies from mother to child through the placenta or during breastfeeding.
Natural acquired(active) - due to the production of one’s own antibodies as a result of contact with antigens (after illness).
Acquired passive- created by introducing ready-made antibodies into the body ( healing serum). Therapeutic serum is a preparation of antibodies from the blood of a specifically previously infected animal (usually a horse). The serum is administered to a person already infected with the infection (antigens). The introduction of therapeutic serum helps the body fight infection until it develops its own antibodies. This immunity does not last long - 4–6 weeks.
Acquired active- created by introduction into the body vaccines(an antigen represented by weakened or killed microorganisms or their toxins), resulting in the production of corresponding antibodies in the body. This immunity lasts a long time.

Circulation

Circulation- blood circulation in the body. Blood can perform its functions only by circulating in the body.
Circulatory system: heart(central circulatory organ) and blood vessels(arteries, veins, capillaries).

Structure of the heart

Heart- a hollow four-chambered muscular organ. The size of the heart is approximately the size of the fist. The average weight of the heart is 300 g.

The outer lining of the heart is pericardium. It consists of two leaves: one forms pericardial sac, the other - the outer shell of the heart - epicardium. Between the pericardial sac and the epicardium there is a cavity filled with fluid to reduce friction during heart contraction. Middle layer of the heart - myocardium. It consists of striated muscle tissue of a special structure. The heart muscle is formed by striated muscle tissue of a special structure ( cardiac muscle tissue). In it, neighboring muscle fibers are interconnected by cytoplasmic bridges. Intercellular connections do not interfere with the conduction of excitation, due to which the heart muscle is able to contract quickly. IN nerve cells And skeletal muscles ah, each cell is excited in isolation. Inner lining of the heart - endocardium. It lines the cavity of the heart and forms the valves - valves.
The human heart consists of four chambers: 2 atria(left and right) and 2 ventricles(left and right). Muscular wall ventricles (especially the left) are thicker than the wall of the atria. IN right half Venous blood flows in the heart, and arterial blood flows in the left.
Between the atria and ventricles there are flap valves(between the left - double-leaf, between the right - tricuspid). Between the left ventricle and the aorta and between the right ventricle and the pulmonary artery there are semilunar valves(consist of three sheets resembling pockets). Heart valves allow blood to flow in only one direction: from the atria to the ventricles, and from the ventricles to the arteries.
The heart muscle has the property of automaticity. Automaticity of the heart- its ability to contract rhythmically without external stimulation under the influence of impulses arising within itself. The automatic contraction of the heart continues even when it is isolated from the body.

Work of the heart

The function of the heart is to pump blood from the veins to the arteries. The heart contracts rhythmically: contractions alternate with relaxations. Contraction of the heart is called systole, and relaxation is called diastole. Cardiac cycle - a period covering one contraction and one relaxation. It lasts 0.8 s and consists of three phases: Phase I - contraction (systole) of the atria - lasts 0.1 s; Phase II - contraction (systole) of the ventricles - lasts 0.3 s; Phase III - general pause - both atria and ventricles are relaxed - lasts 0.4 s.
At rest, the heart rate of an adult is 60–80 times per minute, in athletes 40–50, in newborns 140. During physical activity, the heart contracts more often, while the duration of the general pause decreases. The amount of blood ejected by the heart in one contraction (systole) is called systolic blood volume. It is 120–160 ml (60–80 ml for each ventricle). The amount of blood ejected by the heart in one minute is called minute volume. It is 4.5–5.5 liters.
Electrocardiogram(ECG) - recording of bioelectric signals from the skin of the arms and legs and from the surface of the chest. The ECG reflects the condition of the heart muscle.
When the heart pumps, sounds called heart sounds are produced. In some diseases, the nature of the tones changes and noise appears.

Vessels

The walls of arteries and veins consist of three layers: interior(thin layer of epithelial cells), average(a thick layer of elastic fibers and smooth muscle cells) and outer(loose connective tissue and nerve fibers). Capillaries consist of a single layer of epithelial cells.

Arteries- vessels through which blood flows from the heart to organs and tissues. The walls consist of three layers. The following types of arteries are distinguished: elastic arteries (large vessels closest to the heart), muscular arteries (medium and small arteries that resist blood flow and thereby regulate blood flow to the organ) and arterioles (the last branches of the artery that turn into capillaries).
Capillaries - thin vessels, in which fluids, nutrients and gases are exchanged between blood and tissues. Their wall consists of a single layer of epithelial cells. The length of all capillaries in the human body is about 100,000 km. At the junction of arteries and capillaries there are clusters of muscle cells that regulate the lumen of blood vessels. At rest, 20–30% of a person’s capillaries are open.
The movement of fluid through the capillary wall occurs as a result of the difference in the hydrostatic pressure of the blood and the hydrostatic pressure of the surrounding tissue, as well as under the influence of the difference in the osmotic pressure of the blood and intercellular fluid. At the arterial end of the capillary, substances dissolved in the blood are filtered into tissue fluid. At its venous end, blood pressure decreases, the osmotic pressure of plasma proteins promotes the flow of fluid and metabolic products back into the capillaries.
Vienna- vessels through which blood flows from organs to the heart. Their walls (like those of arteries) consist of three layers, but they are thinner and poorer in elastic fibers. Therefore, the veins are less elastic. Most veins are equipped with valves that prevent reverse current blood.

Systemic and pulmonary circulation

The vessels in the human body form two closed circulatory systems. There are large and small circles of blood circulation. Vessels great circle supply blood to organs, small vessels ensure gas exchange in the lungs.
Systemic circulation: arterial (oxygenated) blood flows from the left ventricle of the heart through the aorta, then through the arteries, arterial capillaries to all organs; from the organs, venous blood (saturated with carbon dioxide) flows through the venous capillaries into the veins, from there through the superior vena cava (from the head, neck and arms) and the inferior vena cava (from the torso and legs) into the right atrium.
Pulmonary circulation: venous blood flows from the right ventricle of the heart through the pulmonary artery into a dense network of capillaries entwining the pulmonary vesicles, where the blood is saturated with oxygen, then arterial blood flows through the pulmonary veins into the left atrium. In the pulmonary circulation, arterial blood flows through the veins, venous blood through the arteries.

Movement of blood through vessels

Blood moves through the vessels due to contractions of the heart, creating a difference in blood pressure in different parts vascular system. Blood flows from a place where its pressure is higher (arteries) to where its pressure is lower (capillaries, veins). At the same time, the movement of blood through the vessels depends on the resistance of the vessel walls. The amount of blood passing through an organ depends on the pressure difference in the arteries and veins of that organ and the resistance to blood flow in its vasculature. The speed of blood flow is inversely proportional to the total cross-sectional area of the vessels. The speed of blood flow in the aorta is 0.5 m/s, in the capillaries - 0.0005 m/s, in the veins - 0.25 m/s.

The heart contracts rhythmically, so blood enters the vessels in portions. However, blood flows continuously in the vessels. The reasons for this are the elasticity of the walls of blood vessels.
The pressure created by the heart is not enough to move blood through the veins. This is facilitated by the valves of the veins, which ensure blood flow in one direction; contraction of nearby skeletal muscles, which compress the walls of the veins, pushing blood towards the heart; the suction effect of large veins with an increase in the volume of the chest cavity and negative pressure in it.

Blood pressure and pulse

Blood pressure- the pressure at which blood is held in a blood vessel. Most high pressure in the aorta, less in large arteries, even less in capillaries and lowest in veins.
A person's blood pressure is measured using a mercury or spring tonometer in the brachial artery (blood pressure). Maximum (systolic) pressure- pressure during ventricular systole (110–120 mm Hg). Minimum (diastolic) pressure- pressure during ventricular diastole (60–80 mm Hg). Pulse pressure- difference between systolic and diastolic pressure. An increase in blood pressure is called hypertension, decrease - hypotension. Promotion blood pressure occurs during heavy physical activity, a decrease occurs with large blood losses, severe injuries, poisoning, etc. With age, the elasticity of the walls of the arteries decreases, so the pressure in them becomes higher. The body regulates normal blood pressure by introducing or removing blood from blood depots (spleen, liver, skin) or by changing the lumen of blood vessels.
The movement of blood through the vessels is possible due to the pressure difference at the beginning and end of the blood circulation. Blood pressure in the aorta and large arteries is 110–120 mmHg. Art. (that is, 110–120 mm Hg above atmospheric), in arteries - 60–70, in the arterial and venous ends of the capillary - 30 and 15, respectively, in the veins of the extremities 5–8, in large veins of the thoracic cavity and at the confluence them into the right atrium is almost equal to atmospheric (when inhaling, slightly lower than atmospheric, when exhaling, slightly higher).
Arterial pulse- rhythmic vibrations of arterial walls as a result of blood entering the aorta during left ventricular systole. The pulse can be detected by touch where the arteries lie closer to the surface of the body: in the area of the radial artery of the lower third of the forearm, in the superficial temporal artery and the dorsal artery of the foot.

Lymphatic system

Lymph- colorless liquid; formed from tissue fluid that has leaked into the lymphatic capillaries and vessels; contains 3–4 times less proteins than blood plasma; lymph reaction is alkaline. It contains fibrinogen, so it can clot. Lymph does not contain red blood cells; small quantities contain white blood cells that penetrate from the blood capillaries into the tissue fluid.

Lymphatic system includes lymphatic vessels(lymphatic capillaries, large lymphatic vessels, lymphatic ducts - the largest vessels) and The lymph nodes. Lymph circulation: tissues, lymphatic capillaries, lymphatic vessels with valves, lymph nodes, thoracic and right lymphatic ducts, large veins, blood, tissue. Lymph moves through the vessels due to rhythmic contractions of the walls of large lymphatic vessels, the presence of valves in them, contraction of skeletal muscles, and the suction action of the thoracic duct during inhalation.
Functions of the lymphatic system: additional outflow of fluid from organs; hematopoietic and protective functions(V lymph nodes lymphocytes multiply and pathogens are phagocytosed, as well as immune bodies are produced); participation in metabolism (absorption of fat breakdown products).

Regulation of the activity of the heart and blood vessels

The activity of the heart and blood vessels is controlled through nervous and humoral regulation. At nervous regulation central nervous system may decrease or increase heart rate and constrict or dilate blood vessels. These processes are regulated by the parasympathetic and sympathetic nervous systems, respectively. At humoral regulation Hormones are released into the blood. Acetylcholine reduces heart rate, dilates blood vessels. Adrenalin stimulates the heart, constricts the lumen of blood vessels. An increase in the content of potassium ions in the blood depresses, and calcium increases the work of the heart. Lack of oxygen or excess carbon dioxide in the blood leads to vasodilation. Damage to blood vessels causes their narrowing as a result of the release of special substances from platelets.
Diseases of the circulatory system in most cases, they arise due to poor nutrition, frequent stressful conditions, physical inactivity, smoking, etc. Preventive measures cardiovascular diseases are physical exercise And healthy image life.

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

Respiratory system function:

oxygen entering the body;

removal of carbon dioxide from the body;

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 amounts 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 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

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 in the inhaled air.

The nasal cavity is lined internally with mucous membrane, permeated 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 nose 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:

decrease in the mass of the anterior facial bones of the skull;

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 sensory organ).

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. Under normal conditions, 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.

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 the passage of a bolus of food, 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. Inner surface The entire respiratory tract (trachea, bronchi and parts of the bronchioles) is covered with a mucous membrane of multirow ciliated epithelium.

The design of the respiratory tract ensures warming, humidification and purification of the air inhaled. Dust particles move upward through the 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 serous fluid, which plays the role of 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 and 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.

Each lung contains thick bundles on the inside, 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 exchange of gases 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 of atmospheric air and the 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; in an adult, the resting respiratory rate is about 16-18. However, during physical activity, emotional arousal, or when body temperature rises, 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 a healthy adult, vital capacity varies from 3500 to 7000 ml and depends on gender and indicators physical development: for example, chest volume.

Vital fluid consists of several volumes:

Tidal volume (TO)- this is the amount of air that enters and leaves the lungs during quiet breathing (500-600 ml).

Inspiratory reserve volume (IRV)) is the maximum amount of air that can enter the lungs after a quiet inhalation (1500 - 2500 ml).

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 nervous and humoral mechanisms, which boil down to ensuring the rhythmic activity of the respiratory system (inhalation, exhalation) and adaptive breathing reflexes, that is, changes in the frequency and depth of respiratory movements that take place under changing conditions external environment 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. The presence of respiratory centers in the cerebral cortex is proven by the formation of conditioned respiratory reflexes, changes in the frequency and depth of respiratory movements that occur in 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 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.

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

Respiratory system function:

oxygen entering the body;
removal of carbon dioxide from the body;
removal of gaseous metabolic products from the body;
thermoregulation;
synthetic: some biologically active substances are synthesized in lung tissue: heparin, lipids, etc.;
hematopoietic: mast cells and basophils mature in the lungs;
depositing: the capillaries of the lungs can accumulate large amounts 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 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

Airways

NASAL CAVITY

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 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.

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.

PARANARY SINUSES

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.

VOTE FORMATION

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.

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).

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.

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.

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. All these bronchial-vascular bundles, taken together, form lung root. Around the pulmonary roots there are a large number of bronchial lymph nodes.

Rice. Bronchial tree

ALVEOLI

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

Rice. Alveoli

Rice. Gas exchange in the alveoli

GAS EXCHANGE AREA

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 you know, the period of 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.

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.

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

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.

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 a healthy adult, 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:

Tidal volume (TO)- this is the amount of air that enters and leaves the lungs during quiet breathing (500-600 ml).
Inspiratory reserve volume (IRV)) is the maximum amount of air that can enter the lungs after a quiet inhalation (1500 - 2500 ml).
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 nervous 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 conditions of the external environment 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 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, respiratory centers are located in the cerebral cortex, carrying out higher forms of adaptation processes. The presence of respiratory centers in the cerebral cortex is proven by the formation of conditioned respiratory reflexes, changes in the frequency and depth of respiratory movements that occur in 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 narrowing of the bronchi, while the 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.

A1. Gas exchange between blood and atmospheric air

happens 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) air dehumidification

A5. The larynx protects from food getting into it:

1) arytenoid cartilage

3) epiglottis

4) thyroid cartilage

A6. The respiratory surface of the lungs increases

1) bronchi

2) bronchioles

3) eyelashes

4) alveoli

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

1) diffusion from an area with lower gas concentration to an area with 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 breaks 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 lung mobility

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 concentrations of oxygen and carbon dioxide in the blood and tissues

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

4) difference in air pressure in the lungs and pleural cavity

IN 1. Select the processes occurring during gas exchange in the lungs

1) diffusion of oxygen from blood into tissues

2) formation of carboxyhemoglobin

3) 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

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

A) larynx

B) bronchi

D) bronchioles

B) nasopharynx

D) lungs

The set of organs that provide the function external breathing: gas exchange between inhaled atmospheric air and circulating blood.

Breath- a set of processes that ensure the body’s need for oxygen and the release of carbon dioxide. The supply of oxygen from the atmosphere to cells is necessary for oxidation substances, which results in the release energy , necessary for the body. Without breathing a person can live up to 5-7 minutes , followed by loss of consciousness, irreversible changes in the brain and death.

Stages of breathing

1) external breathing - delivering air to the lungs

2) gas exchange in the lungs between the alveolar air and the blood of the capillaries of the ICC

3) transport of gases by blood

4) gas exchange in tissues between the blood of the BCC capillaries and tissue cells

5) fabric respiration - bio-oxidation in cell mitochondria

Breathing functions

Providing the body with oxygen and its participation in OVR

Removing part of the gaseous metabolic products: CO 2, H 2 O, NH 3, H 2 S and others

Oxidation of organic matter with release of energy

Breathing rate

An adult at rest has an average of 14 respiratory movements per minute, but it can undergo significant fluctuations of 10-18.

In children 20-30; in infants 30-40; in newborns 40-60

Tidal volume 400-500ml - volume of air during inhalation/exhalation at rest.

After a calm inhalation, you can inhale additionally inspiratory reserve volume 1500 ml.

After a calm exhalation, you can exhale additionally reserve volume 1500ml.

Vital capacity of the lungs 3500ml – maximum inhalation after maximum exhalation. The sum of tidal volume and inspiratory and expiratory reserve volume.

Functional residual capacity 3000ml - remains after a calm exhalation.

Residual volume 1500ml remains in the lungs after maximum exhalation.

Alveolar air constantly fills the alveoli of the lungs during quiet breathing. The sum of residual and reserve volumes. Equal to 2500ml, it participates in gas exchange

Classification of breathing types according to the method of chest expansion:

- chest : expansion of the chest by raising the ribs, more often in women.

- abdominal : expansion of the chest by flattening the diaphragm, more often in men.

Airway types:

System upper : nasal cavity, nasopharynx, oropharynx, partially oral cavity.

System lower : larynx, trachea, bronchial tree.

Symbolic transition the upper respiratory tract to the lower is carried out at the intersection of the digestive and respiratory systems in upper part of the larynx .

Upper respiratory tract

Nasal cavity divided by a septum (cartilage, bipod) into 2 halves and at the back, due to joan goes into nasopharynx . The accessory cavities of the nose are sinuses - frontal, sphenoid and maxillary (Highmorova). The inner surface of the nasal cavity is lined mucous membrane , the top layer of which is formed ciliated epithelium .

Mucus has bactericidal properties: it, with microorganisms and dust settled on it, is removed from the body by the movement of cilia, clearing and humidifying the incoming air. Thanks to blood vessels , the air is warming up.

Superior turbinate forms olfactory cavity , on the walls of the mucous membrane of which there are special olfactory nerve cells. The endings are there too olfactory nerve .

Opens into the nasal cavity nasolacrimal duct , removing excess tear fluid.

Pharynx– muscular tube covered with mucous membrane, 12-15 cm. The connecting link between the respiratory and digestive systems: informs the cavity nose And mouth , And esophagus With larynx Yu . Adjacent to the lateral walls of the pharynx carotid arteries and jugular veins. Lymphoid tissue accumulates at the entrance to the pharynx, forming tonsils . 3 parts:

Upper nasopharynx communicates with the nasal cavity using the choanae.

Average oropharynx communicates with the oral cavity through the pharynx.

Lower hypopharynx communicates with the larynx.

Lower respiratory tract

Larynx contains voice apparatus and connects the pharynx to the trachea. Located on the level 4-6 cervical vertebrae and is connected by ligaments to hyoid bone . When swallowing, the entrance to the larynx is closed by cartilage epiglottis .

Trachea- windpipe, continuation of the larynx. Looks like a tube 11-13cm , which consists of 16-20 cartilaginous half rings , the back of which is smooth muscle textile. They are connected to each other by fibrous ligaments formed by dense fibrous connective tissue.

Mucous membrane the larynx and trachea are lined ciliated epithelium , rich in lymphoid tissue and mucous glands.

Bronchi- branches windpipe. The lower end of the trachea is level 5th thoracic vertebra divided by 2 main bronchi , which go to gate the corresponding lung. The right bronchus is wider and shorter (8 rings), and the left one is narrower and longer (12 rings). They are moving away from them

- equity bronchi of the 1st order according to the number of lung lobes: 3 in the right and 2 in the left.

- zonal bronchi of the 2nd order

- segmental bronchi 3rd order

They branch repeatedly, forming bronchial tree . As the diameter of the bronchus decreases, the cartilaginous rings are replaced by plates and disappear into bronchioles .

Large particles inhaled foreign bodies are removed using cough ; and dust particles or microorganisms - due to cilia vibrations epithelial cells that provide advancement bronchial secretion towards the trachea.

Lungs

Paired cone-shaped elastic spongy organs occupying almost the entire volume chest cavity . On the inner surface there is gates where the bronchus, nerves, lymphatic vessels pass, pulmonary veins and arteries that together form lung root.

The lung is divided by grooves into shares : right for three, left for two. Shares are divided into bronchopulmonary segments , formed by pulmonary in slices , separated from each other by connective tissue layers. One lobule is formed by 12-18 acini. Acinus – structural and functional lung unit, a system of branches of one terminal bronchiole ending in alveoli.

Alveolus - the end part of the breathing apparatus in the form of a thin-walled bubble. They are densely braided capillary network in such a way that each capillary is in contact with several alveoli. The inner surface is represented flat single layer epithelium and permeated with elastic fibers. Cells secrete lubricant into the cavity of the alveoli phospholipid nature - surfactant , which prevents walls from sticking together and has bactericidal properties. Alveolar macrophages .

The outside of the lungs is covered pleura , consisting of 2 sheets:

Interior visceral merges with lung tissue, going into the furrows

Outer parietal fuses with the walls of the chest cavity. It is divided into three parts: costal, diaphragmatic and mediastinal.

Between them there is a closed pleural cavity with a small amount serous fluid . It reduces friction between the layers of the pleura during inhalation and exhalation and creates a negative pressure below atmospheric , so the lungs are always stretched and do not collapse.

Acts of inhalation and exhalation

Lung tissue does not contain muscle tissue, so changes in HA volume are achieved through the work of skeletal muscles. Diaphragm descends, expanding the chest; external intercostal contract, raising the ribs. Thanks to elasticity lungs and a closed interpleural cavity with pressure below atmospheric, lungs passively stretch , the air pressure in the alveoli decreases, which leads to the absorption of atmospheric air. Inhalation is active process , because always requires the participation of muscles.

Quiet exhalation occurs passively: when the external intercostal spaces and the diaphragm relax under the force of gravity, the HA lowers and exhalation occurs. Forced exhalation requires the participation of the internal intercostal and abdominal wall muscles.

Fill out an application to prepare for the Unified State Exam in biology or chemistry

Brief feedback form

Tip 1. Divide questions about breathing into different blocks

Very difficult for students Unified State Exam in Biology are questions about breathing. Many cannot separate at all:

gas exchange

breathing mechanism

transport of gases by blood.

Even the process gas exchange Many people have the wrong idea, thinking that it only goes to the lungs. Gas exchange also occurs in tissues. Understanding the topic is complicated by the different approaches to it in textbooks.

Tip 2. Be aware of the general structure of breathing as a process

I always remind you that breath how the process is divided into external and internal, as well as the transport of gases by blood. I explain external breathing using the mechanisms of inhalation and exhalation as an example. I also look at gas exchange in the lungs here.

Tip 3: Mention diffusion often.

Often students do not indicate that gas exchange is based on diffusion. And this is very important. In this case, where a certain gas diffuses is of great importance. If gas exchange occurs in the lungs, we must say that oxygen from the cavity of the alveoli goes into the capillaries, and carbon dioxide in the opposite direction. If gas exchange occurs in tissues, do not forget about the intermediary between all cells and capillaries: tissue fluid. And here we also need to mention diffusion.

Tip 4. Be prepared for unexpected wording

Compiled by Unified State Exam in Biology They may ask: “How do breathing movements proceed under conditions of calm inhalation and exhalation?” (I quote the text of the question). The question is formulated cunningly, as if the student is being pushed to the idea that during physical activity breathing is completely different. However, the breathing mechanism itself does not change, just more muscles are involved. It seems to me that the compilers simply want to confuse the student with this “free breath”. Imagine that such words are not in the question; in fact, the student was asked about how inhalation and exhalation occur. This is what should be answered.

Tip 5: Mention the intercostal muscles

I always tell students that general formulations must be used in the Unified State Examination. But this needs to be done subtly, which is not always possible. In FIPI's response we do not see a word about external intercostal muscles, although they are meant when speaking about the contraction of the intercostal muscles during inhalation. Of course, you can write in detail: the external intercostal muscles contract when you inhale, the internal ones contract when you exhale. However, it is better to mention that when you exhale, the external intercostal muscles also relax. It is these that the compilers of FIPI mean by “intercostal muscles.”

Tip 6. Remember the value of the diaphragm and chest volume

The compilers of the Unified State Examination standardly mention contraction of the diaphragm. In the very first point, for which the student will receive 1 point, the compilers write about increasing the volume of the chest - this is a very important idea. The contraction of the diaphragm helps increase the volume of the chest. But not only that. In my classes, I always say that the contraction of the external intercostal muscles also contributes to lifting. It is they who raise the chest, in which there is more room for inhalation.

Tip 7. Comment on the elasticity of the lungs and pressure in the pleural cavity

How do you get a second point for this question? We need to write about what lungs stretch thanks to their elasticity. We have another related FIPI question about the structure and functions of the lungs. In my classes I talk about the fact that the alveoli of the lungs consist not only of epithelial tissue, they also have stretchable elastic fibers at the base.

Moreover, it is known that the pressure inside the pleural cavity is negative. It turns out that the lungs stretch not only due to their elasticity - this is also facilitated by low pressure in the pleural cavity.

After stretching the lungs, the pressure in them becomes lower, even less than atmospheric. This is easy to understand: the contraction of the diaphragm and muscles led to the fact that more free space appeared in the lungs. That's why the pressure dropped sharply. All this occurs during inhalation and contributes to it.

Tip 8. Understand the importance of negative pressure in the pleural cavity

The wall of the alveoli expands strongly and easily “sticks” to the wall of the chest cavity precisely thanks to negative pressure in the pleural cavity. We can say that the lungs, stretching, follow the movement of the intercostal muscles and the diaphragm. It is unlikely that this would happen if the pressure in the pleural cavity increased.

Tip 9. Clearly understand the location of the pleural cavity

The student must clearly understand where he is pleural cavity- between the pulmonary and parietal pleura. IN Unified State Exam in Biology They may even ask about what first aid should be provided to a person with a lung injury and depressurization of the pleural cavity. As you exhale, you need to restore the tightness using rubberized fabric or just plastic bags, tightly closing the wound.

Tip 10. Be prepared to describe the mechanism of exhalation

How does exhalation occur? Naturally, the intercostal muscles relax, as does the diaphragm. However, I am saying that the external intercostal muscles are relaxing, but the internal ones are contracting. In this case, the chest descends, which leads to a decrease in the volume of the chest cavity and lungs. The air pressure in the alveolar cavity increases. All these processes ensure exhalation.