Common organ of the respiratory and digestive systems. Human digestive and respiratory systems

The nervous system is the commander of our body, a kind of control system that has a complex organization. The nervous system can be divided into the central nervous system, represented by the brain and spinal cord, and the peripheral nervous system, represented by peripheral nerves(Fig. 35).

There are many ways of transmitting nerve impulses, but we will consider the simplest one. The nervous system consists mainly of neurons that have processes, with the help of which the impulse is transmitted, something like telephone wires (Fig. 35).

The central nervous system consists of the brain and spinal cord, it is the command and thought center, where the nuclei and numerous nerve networks are located. An idea is formed in the cerebral cortex to raise a hand, take a step with a foot, or express any emotions (Fig. 36).

The signal from the cerebral cortex, passing through many complex structures, enters spinal cord, there it exits through the roots and goes to the muscles that move, for example, an arm or leg (Fig. 37).

We must not forget that nerves can be not only motor, but also sensitive. We touch the hot mug, get burned and remove our hand. This is because the nerve impulse from the receptors of neurons located in the thickness of the skin feeds information to the brain.

The brain, in turn, instantly transmits information to the motor neuron, and we immediately remove our hand from the hot object so as not to get burned (Fig. 38). Fedor already has two systems, but for some reason there are still no movements.

Respiratory system. A person, like most living beings on our planet, cannot do without air, namely the oxygen that it contains. Oxygen in the air is 21% (Fig. 39).

The properties of oxygen are very diverse, and one of its most important properties is the ability to oxidize. With the help of oxygen, vital biochemical processes take place in the body, so a person cannot survive without air. In the absence of oxygen, the brain dies first, after about 5-6 minutes.

How to deliver oxygen to all vital organs? How will oxygen help the muscles move? Oxygen enters through the nose and through the mouth, through the trachea, through the bronchi, into the alveoli of our lungs (Fig. 40.41).

Oxygen is involved in the conversion of energy, if there is no oxygen, then the energy for muscle movement will not be released and the muscle will not be able to contract. When there is an intense load on the muscular system, for example, a long run without sufficient preparation, then you may have noticed that the muscles begin to hurt (Fig. 42).

Due to the lack of oxygen in the muscles, pyruvic acid is converted according to the oxygen-free type, so lactic acid is released and the muscles hurt. Has it happened? Now you know why. Here Fedor has oxygen for the processes of releasing energy and moving the body, but !!! The very material from which we will receive energy, it does not exist, what to do? We need to find out where this material for energy comes from.

Digestive system. This is exactly the system (Fig. 43) that supplies our body with the material for life: proteins, fats, carbohydrates, vitamins and all the necessary minerals. A person is born weighing 3.5 kg, so why is the weight 70 kg by the age of 23? Weight is gained from the food we eat. No wonder they say that "we are what we eat." The way it is. What does the digestive system consist of (Fig. 43)?

First of all, this system is oral cavity, pharynx, esophagus, stomach, large and small intestines. There are also auxiliary organs that, in addition to digestion, perform other functions. These include the liver, pancreas, salivary glands. The main organic substances, as mentioned, are proteins, fats and carbohydrates.

Proteins (Fig. 44) are involved in the structure of our body, they work as enzymes. In an emergency, other very important functions are used to generate energy.

Carbohydrates (Fig. 45) are simple and complex. Simple carbohydrates are found in the greatest quantity in sweets, and complex carbohydrates are found in porridge and bread. Simple carbohydrates are quickly digested and converted into energy or, in excess, are converted into fats. Carbohydrates are easy to break down, and a sufficient amount of energy is released.

Fats (Fig. 46) have a storage function. All the energy that is not used is stored as fat in our body.

The food contains a different composition of proteins, fats, carbohydrates and minerals. You can find out about the amount of these substances in the product by looking at the label with reverse side(Fig. 47).

Now let's see how food passes through the digestive system (Fig. 48). Here a person ate something, having thoroughly chewed it - (1). Then the food goes through the pharynx into the esophagus - (2). From there it enters the stomach, where the gastric juice processes what is eaten - (3). Then the food passes into the small intestine (which is approximately 7 meters long), where its absorption begins - (4). In the large intestine, all the remaining water is absorbed and feces are formed - (5). Through the rectum, feces are removed from the body - (6). Total time digestion can reach up to 15 hours or more.

The main function of the respiratory organs is to provide the tissues of the human body with oxygen and release them from carbon dioxide. Along with this, the respiratory organs are involved in voice formation, smell and other functions. In the respiratory system, there are organs that perform air conduction (nasal cavity, nasopharynx, larynx, trachea, bronchi) and gas exchange functions (lungs). In the process of respiration, atmospheric oxygen is bound by blood and delivered to the cells and tissues of the body. Inside cellular respiration provides the release of energy necessary to maintain life processes. The resulting carbon dioxide (CO2) is transported by the blood to the lungs and removed with exhaled air.

The entry of air into the lungs (inhalation) is the result of contraction of the respiratory muscles and an increase in lung capacity. Exhalation occurs due to relaxation of the respiratory muscles. Therefore, the respiratory cycle consists of inhalation and exhalation. Breathing occurs continuously due to nerve impulses coming from the respiratory center located in the medulla oblongata. The respiratory center is automatic, but its work is controlled by the cerebral cortex.

Efficiency external respiration can be estimated by the value of pulmonary ventilation, i.e. the volume of air passing through the respiratory tract. An adult person inhales and exhales an average of about 500 cm 3 of air in one respiratory cycle. This volume is called respiratory. With an additional (after a normal breath) maximum breath, you can inhale another 1500-2000 cm 3 of air. This is an additional volume of inspiration. After a calm exhalation, you can additionally exhale about 1500-3000 cm 3 of air. This is the extra expiratory volume. The vital capacity of the lungs is equal to the total value of the respiratory and additional volumes of inhalation and exhalation (3-5 liters). The vital capacity of the lungs is determined by spirometry.

Digestive system

The human digestive system consists of a digestive tube (8-9 m long) and large digestive glands closely related to it - the liver, pancreas, salivary glands (large and small). The digestive system begins with the oral cavity and ends with anus. The essence of digestion is the physical and chemical processing of food, as a result of which it becomes possible for the absorption of nutrients through the walls of the digestive tract and their entry into the blood or lymph. Nutrients include proteins, fats, carbohydrates, water, and minerals. In the digestive apparatus, complex physicochemical transformations of food occur: from the formation of a food bolus in the oral cavity to the absorption and removal of its undigested residues. These processes are carried out as a result of the motor, suction and secretory functions of the digestive apparatus. All three of these digestive functions are regulated by the nervous and humoral (through hormones) pathways. The nerve center that regulates digestive functions, as well as food motivation, is located in the hypothalamus (interbrain), and hormones are mostly formed in the gastrointestinal tract itself.

The primary chemical and physical processing of food takes place in the oral cavity. So, under the action of saliva enzymes - amylase and maltase - hydrolysis (splitting) of carbohydrates occurs at a pH (acid-base) balance of 5.8-7.5. Salivation occurs reflexively. It intensifies when we smell pleasant odors, or, for example, when foreign particles enter the oral cavity. The volume of salivation is 0.5 ml per minute at rest (this facilitates speech motor function) and 5 ml per minute during meals. Saliva also has bactericidal properties. Physical processing of food includes grinding (chewing) and the formation of a food bolus. In addition, taste sensations are formed in the oral cavity. In this, saliva also plays an important role, which in this case acts as a solvent. There are four primary taste sensations: sour, salty, sweet, bitter. They are unevenly distributed on the surface of the tongue.

After swallowing, food enters the stomach. Depending on the composition of the food is in the stomach for different times. Bread and meat are digested in 2-3 hours, fats - 7-8 hours. In the stomach, liquid and solid food components gradually form a semi-liquid slurry - chyme. Gastric juice is very complex composition, as it is a secretion product of three types of gastric glands. It contains enzymes: pepsinogens that break down proteins; lipases that break down fats, etc. In addition, gastric juice contains hydrochloric acid (HC1), which gives the juice an acidic reaction (0.9-1.5), and mucus (mucopolysaccharides), which protects the stomach wall from self-digestion.

Almost complete emptying of the stomach occurs 2-3 hours after a meal. At the same time, it begins to contract in the mode of 3 times per minute (duration of contractions from 2 to 20 seconds). The stomach secretes 1.5 liters of gastric juice daily.

Digestion in the duodenum is even more difficult due to the fact that three digestive juices enter there - bile, pancreatic juice and own intestinal juice. In the duodenum, chyme is exposed to the action of enzymes that hydrolyze fats, carbohydrates, proteins, and nucleic acids; The pH in this case is 7.5-8.5. The most active enzymes are pancreatic juice. Bile facilitates the digestion of fats by turning them into an emulsion. In the duodenum, carbohydrates are further broken down.

In the small intestine (jejunum and ileum), three interrelated processes are combined - cavity (extracellular) digestion, parietal (membrane) and absorption. Together they represent the stages of the digestive-transport conveyor. The chyme moves along small intestine at a speed of 2.5 cm per minute and digested in it for 5-6 hours. The intestine contracts 13 times per minute, which contributes to the mixing and splitting of food. The cells of the intestinal epithelium are covered with microvilli, which are outgrowths 1-2 microns high. Their number is huge - from 50 to 200 million per 1 mm 2 of the surface of the intestine. The total area of ​​the intestine due to this increases to 400 m 2 . Enzymes are adsorbed in the pores between microvilli.

Intestinal juice contains a complete set of enzymes that break down proteins, fats, carbohydrates, nucleic acids. These enzymes carry out parietal digestion. Through the microvilli, simple molecules of these substances are also absorbed into the blood and lymph. So, proteins are absorbed into the blood in the form of amino acids, carbohydrates - in the form of glucose and other monosaccharides, and fats - in the form of glycerol and fatty acids into the lymph and partially into the blood.

The process of digestion ends in the large intestine. The glands of the large intestine secrete mucus. In the large intestine, due to the bacteria that inhabit it, fermentation of fiber and putrefaction of proteins occur. When proteins rot, a number of toxic products are formed, which, being absorbed into the blood, are decontaminated in the liver.

The liver performs a barrier (protective) function, synthesizing substances harmless to the body from toxic substances. In the large intestine, active absorption of water and the formation of feces are completed. The microflora (bacteria) of the large intestine carries out the biosynthesis of some biologically active substances(for example, vitamins B and K).

abstract

Anatomy

Topic: Digestive and respiratory systems human

General overview of the digestive system

The digestive system is a tube and large digestive glands located near its walls. The digestive tube has well-defined extensions (oral cavity, stomach) and a large number of bends and loops. The length of the alimentary canal or tube is 8-12 meters. The alimentary canal begins with the oral opening (3), which opens into the oral cavity (2), the oral cavity opens into the pharynx (4). In the pharynx, the digestive and respiratory tract. The esophagus (8) carries food from the pharynx to the stomach (9). The stomach passes into the small intestine, which begins with the duodenum (15). AT duodenum the pancreatic duct (14) and the common bile duct (11) open. The duodenum passes into the jejunum (16, 19), the jejunum passes into the ileum (26). The ileum passes into the large intestine.

The large intestine is divided into the caecum (24) with the appendix (25), the ascending colon (20), the transverse colon (22), the descending colon (21), the sigmoid colon (27) and the rectum (28), which ends with a sphincter ( 29). The length of the entire large intestine is 1.5-2 m.

The oral cavity and its parts

oral cavity (cavum oris ) is divided into 2 sections: the vestibule of the mouth (1) and the actual oral cavity (3). The vestibule of the mouth is limited by the lips in front and cheeks from the sides, teeth and gums from the inside.

The oral cavity is located medially from the teeth and gums (3) and communicates with the vestibule (1) through the gaps between the teeth of the upper and mandible. top wall oral cavities form a hard and soft palate covered with a mucous membrane. The soft palate joins behind the hard palate. The soft palate has a narrow process at the back - the uvula. Two pairs of folds extend from the soft palate on the sides and downwards - the arches. Between the arches are palatine tonsils (4). The bottom of the oral cavity is the diaphragm of the mouth, formed by a pair of maxillohyoid muscle (5) fused along the midline, on which the tongue lies. At the point of transition of the mucous membrane to the lower surface of the tongue, its frenulum is formed. On the sides of the frenulum at the top of the sublingual papillae, the ducts of the sublingual and submandibular salivary glands open. The mucosa contains a large number of simple salivary glands.

The oral cavity in the posterior part communicates with the pharyngeal cavity through the pharynx, which is bounded from above by the soft palate, the palatine arches serve as its walls, and the root of the tongue is below.

The structure of the language. Salivary glands

language (lingua ) is a muscular organ. It is formed by striated muscle tissue covered with a mucous membrane. In the tongue, a narrow front part is distinguished - the top of the tongue (15), a wide back part - the root of the tongue (5). The middle part is the body of the tongue(14). The mucous membrane of the tongue is covered with stratified epithelium, forming papillae of various shapes. There are filiform (13), cone-shaped, leaf-shaped (9), mushroom-shaped (11) and grooved papillae (10). In the thickness of the epithelium of the leaf-shaped, mushroom-shaped, grooved papillae are taste buds - groups of receptor taste cells. The filiform papillae are the most abundant and give the tongue a velvety appearance. In the mucous membrane of the root of the tongue there is lymphoid tissue, which forms the lingual tonsil.

The muscles of the tongue are divided into external and own. External muscles turn the tongue to the sides, own muscles change its shape: shorten and thicken. The ducts of 3 pairs of large salivary glands open into the oral cavity: parotid (weight 30g) on ​​the buccal mucosa; submandibular (16g) and sublingual (5g) under the tongue in the meat area. Small salivary glands (labial, cervical, lingual, palatine) are located in the corresponding parts of the oral mucosa.

The total amount of saliva secreted per day is 1-2 liters. (depending on the nature of the food).

The structure of the pharynx

pharynx (pharynx ) is the initial part of the digestive tube and respiratory tract. It is located in the head and neck region, has a funnel-shaped shape and a length of 12-15 cm. Three parts are distinguished at the pharynx: the upper - nasal, the middle - oral and the lower guttural. The nasopharynx (2) communicates with the nasal cavity through the choanae. The oropharynx (6) communicates with the oral cavity (3) through the pharynx. The hypopharynx (8) in its anterior part communicates with the larynx through its upper opening. On the side walls of the nasopharynx at the level of the choanae, there is a paired pharyngeal opening of the auditory (Eustachian) tubes, which connect the pharynx on each side with the middle ear cavity and help maintain pressure in it at atmospheric pressure. Near the opening of the auditory tubes, between it and the palatine curtain, there is a tubal tonsil. On the border between the upper and posterior walls of the pharynx is the unpaired pharyngeal tonsil. These tonsils form the pharyngeal lymphoid ring.

The walls of the pharynx are built from several layers and are lined with ciliated and stratified squamous epithelium. The muscular membrane consists of circular muscles - pharyngeal constrictors and longitudinal muscles - pharyngeal lifters, which move the food bolus to the esophagus.

The epiglottis separates the respiratory and food tract, which closes the entrance to the larynx when swallowing.

Structure of teeth, dental formula

A person has two sets of teeth - milk and permanent. The teeth are located in the alveoli of the upper and lower jaws. Milk teeth (20 teeth) appear in early childhood. They are replaced by permanent

teeth (32 teeth). Each tooth has a crown, neck and root. The crown is located above the gum (1). The neck (5) is located on the border between the root and the crown. The root (6) is located in the alveolus, it ends with a tip (10), on which there is a small hole through which the vessels and nerves (9) enter the tooth. Inside the tooth there is a small cavity, it contains the dental pulp, in which the blood vessels and nerves branch (4). Each tooth has one root (incisors and canines); two or three roots (near molars). The substance of the tooth includes enamel (2), cementum (7) and dentin (3). According to the shape of the crown and the number of roots, the following forms of teeth are distinguished: incisors, canines, small and large molars. The closure of the upper and lower teeth is called an overbite. The number of teeth is usually denoted by the dental formula. It looks like a fraction. The numerator of the fraction is the upper jaw, the denominator is the lower jaw. In an adult, it is 2 1 2 3 / 2 1 2 3. The formula of milk teeth is 2 1 0 2/ 2 1 0 2.

The eruption of milk teeth occurs from 6-7 months until the end of the 2nd, the beginning of the 3rd year. The change of milk teeth to permanent ones begins at the age of 7-7.5 years and ends, basically, by 12-12.5 years. The third large molars erupt by 20-25 years and later.

The structure of the esophagus. Mediastinum

Esophagus ) is a 30 cm long tube that starts at a level between V and VII cervical vertebrae and ends at level X I thoracic vertebra.

The esophagus is divided into: cervical, thoracic, abdominal parts. The cervical part is located behind the trachea, the thoracic part is located next to the back of the aorta, the abdominal part is under the diaphragm (see figure).

On its way to the stomach, the esophagus has three narrowings - the first when the pharynx passes into the esophagus; the second is on the border between IV and V thoracic vertebrae; the third - at the level of the aperture of the diaphragm. The walls of the esophagus have 3 membranes: mucous, muscular and adventitial. The mucous membrane has longitudinal folds.

The mediastinum ) part of the chest cavity, lying behind the sternum. The anterior border of the mediastinum is the posterior surface of the sternum, the posterior - thoracic region spine, lower - diaphragm. At the top, the mediastinum connects to the neck through the superior thoracic inlet. On the right and on the left, the mediastinum borders on the pleural cavity. The border between them is the mediastinal pleura. Distinguish between superior and inferior mediastinum. At the bottom is the heart and pericardium. The conditional frontal plane passing through the trachea divides the mediastinum into anterior and posterior. Located in the front thymus, superior vena cava, aortic arch, trachea and main bronchi, heart and pericardium. In the back esophagus, thoracic aorta, esophagus, vagus nerves, sympathetic trunks and their branches.

The structure of the stomach

stomach ) an elongated, curved bag with a capacity of 1.5 to 4 liters. At the top is the entrance to the stomach - the cardiac section (5). To the right of the entrance to the stomach is an expanded part - the bottom or vault (1). Down from the bottom is the most expanded part - the body of the stomach (4). The right convex edge forms the greater curvature of the stomach (7), the left concave edge forms the lesser curvature (6). The narrow right part of the stomach forms a pylorus - pylorus (10), passing into the duodenum (8,9,11).

The wall of the stomach has membranes: mucous, submucosal, muscular and serous. In the gastric mucosa there are folds, gastric fields and pits into which the ducts of the gastric glands open. The number of gastric glands reaches 24 million. There are own glands of the stomach, located in the area of ​​the bottom and body, and pyloric. Own glands contain chief cells that produce enzymes and parietal secrete hydrochloric acid and mucous membranes. The pyloric glands contain parietal and mucous cells.

From greater curvature the greater omentum begins, located anterior to the organs abdominal cavity behind the anterior abdominal wall.

The structure of the small intestine

The small intestine ) starts from the pylorus of the stomach and ends with the confluence of the blind part of the colon. The length of the small intestine ranges from 2.2 to 4.4 m.

The small intestine is divided into three parts: the duodenum ( duodenum), lean (jejunum) and iliac (ileum ). About 2/5 of the length of the small intestine belongs to the jejunum and about 3/5 to the ileum.

The wall of the small intestine consists of a serous membrane (3), muscular (2), mucous membrane (1). The mucous membrane forms circular folds (6) and a huge number of microscopic outgrowths - villi, there are about 4-5 million of them. There are depressions between the villi - crypts. The surface of the mucous membrane and villi are covered with epithelium. On the surface of epitheliocytes there is a brush border formed by a huge number of microvilli (up to 1500-3000 on the surface of each epithelial cell). Each villus contains 1-2 arterioles, which break up into capillaries. In the center of each villus there is a lymphatic capillary.

In the mucous membrane there are single lymphoid nodules (4), in the middle section of the intestine there are accumulations of lymphoid nodes in the form of plaques (Peyer's patches).

The small intestine has a mesentery, so it is very mobile, which ensures the promotion and mixing of the contents of the intestine.

The structure of the large intestine

Large intestine (intestinum crassum ) continues the small intestine and extends to the anus. The large intestine has the appearance of a frame or rim, bordering the abdominal cavity on the right, top and left, so it was called the colon - ( colon ).

In the large intestine, 6 parts are distinguished: the initial part is the caecum (6), 7-8 cm long; ascending part of the colon, 14-18 cm long; transverse part of the colon, 30-80 cm long; descending part of the colon, 25 cm long; sigmoid colon; rectum, 15-18 cm long. In the caecum and colon, the longitudinal muscle layer is assembled in the form of three ribbons (2) that go to the rectum. Due to the fact that the ribbons are shorter than the intestine itself, its walls between the ribbons form protrusions haustra (3). There are fatty processes on the ribbons (1). The folds of the mucous membrane have a crescent shape (4). From the lower part of the caecum, a appendix (8) departs. There is an ileocecal valve (5) at the confluence of the ileum with the cecum. The rectum has 2 bends and ends with the anus - the anus.

The caecum, appendix, transverse and sigmoid lie intraperitoneally, i.e. have a mesentery and are mobile.

The structure of the liver. bile ducts

Liver (hepar ) is the largest gland in the human body, its weight is about 1.5 kg. The liver is located in the abdominal cavity on the right under the diaphragm, in the right hypochondrium. There are two surfaces of the liver: the upper - diaphragmatic and lower - visceral. From above, the liver is covered with peritoneum, which forms a series of ligaments: coronal (1), falciform (4), round (7). The crescent ligament divides the upper surface into two lobes: the greater right (5) and the smaller left (6). On the lower surface of the liver there are two longitudinal and one transverse furrow. They divide the liver into right, left, quadrate, and caudate lobes. In the transverse furrow there are gates of the liver; through them vessels and nerves enter and the hepatic ducts exit. Between the square and right lobes of the liver is the gallbladder (9). The liver consists of lobules with a diameter of 1.5 mm, similar to a prism. Interlobular veins, arteries and bile ducts are located in the layers between the lobules, forming the hepatic triad. The bile capillaries gather into the bile ducts, which give rise to the right and left hepatic ducts. The ducts merge to form the common hepatic duct, which joins with the cystic duct and is called the bile duct.

The liver lies mesoperitoneally its upper and lower surfaces are covered by the peritoneum, and the posterior edge is adjacent to the posterior wall of the abdominal cavity and is not covered by the peritoneum.

The peritoneum is parietal and visceral. Pancreas

Peritoneum (peritoneum ) and the peritoneal cavity limited by it is located in the abdominal cavity. It is a thin serous membrane covered with epithelial cells - mesothelium. Allocate the parietal peritoneum, lining the inside of the abdominal wall and visceral, covering the stomach, liver, spleen, small intestine and other organs. The peritoneal cavity contains serous fluid.

Depending on how the organ is completely or partially covered by the peritoneum, there are organs that lie intra- or mesoperitoneally. In men, the abdominal cavity is closed; in women, it communicates with the external environment through the fallopian tubes and uterus.

Pancreas ( pancreas ) lies behind the stomach, its length is 15-20 cm. It contains the head (13), located inside the bend of the duodenum, the body (8) and the tail (7), reaching the gate of the spleen (1).

The pancreas is a mixed gland and consists of two parts. The exocrine part produces pancreatic juice (500-700 ml per day), the endocrine part forms and releases into the blood hormones (insulin and glucagon) that regulate carbohydrate and fat metabolism.

The pancreatic ducts (main and accessory) open on the duodenal mucosa on the major and minor papillae.

external nose and nasal cavity

External nose (nasus externus ) is located in the middle of the face, has different shape depending on individual, age and racial characteristics. It stands out: the upper part - the root; middle part - back; the end of the nose is the apex. It consists of soft tissues and bone and cartilage framework. In the cartilaginous part, there are: lateral cartilage, cartilage of the wings, cartilage of the nasal septum.

nasal cavity ( cavum nasi ) is divided by a longitudinal septum into right and left halves. There are three turbinates on the side walls: upper (3); middle (2) and lower (4), hanging down into the nasal cavity. Between the shells are the nasal passages: upper, middle and lower, into which the air-bearing sinuses of the skull open. The nasolacrimal canal opens into the lower passage; in the middle - maxillary and frontal (1) sinuses and anterior cells of the ethmoid bone; and in the upper - sphenoid sinuses (5). Olfactory receptors (olfactory region) are located in the mucous membrane covering the superior turbinates and the upper part of the nasal septum. The zone of the inferior and middle turbinates, where there are no olfactory receptors, is called the respiratory region. There is a ciliated epithelium with a large number of glandulocytes that secrete mucus.

The mucous membrane is rich in blood vessels that form plexuses located directly under the mucous membrane and therefore very vulnerable.

The structure of the larynx

Larynx (larynx ) is at the level IV-VI cervical vertebrae. On the sides of it are the lobes of the thyroid gland, behind - the pharynx. In front, the larynx is covered with the muscles of the neck, and below it borders on the trachea (11,12). The larynx is formed by hyaline cartilages (thyroid, cricoid, arytenoid) and elastic cartilages (horn-shaped, sphenoid, granular - 3 and epiglottis - 1).

The thyroid cartilage (6) is unpaired and consists of two plates connected at an angle (7): straight in men and obtuse in women. This ledge is called the Adam's apple or Adam's apple. Below the thyroid cartilage lies the cricoid cartilage (9). Inward from the thyroid cartilage are the arytenoid cartilages. On their top sit small horn-shaped. In the thickness of the muscles of the larynx are sphenoid cartilages. From above, the larynx is covered by the epiglottis (1).

Cartilages are connected to each other by joints and ligaments. After 20–25 years, ossification of the cricoid, thyroid, and arytenoid cartilages begins.

The structure of the trachea and bronchi. bronchial tree

The larynx passes into the trachea, which begins at the level VII cervical vertebra and ending at the level V thoracic vertebra, where the trachea divides into the right and left main bronchi (8 - tracheal bifurcation).

The right main bronchus (9) is shorter and wider than the left, it enters the gate of the right lung. The left main bronchus (10) is longer, it departs steeply to the left and enters the gate of the left lung.

The length of the trachea is up to 15 cm. It is based on 16-20 hyaline cartilaginous half-rings, open at the back (5). From the outside, the trachea is covered with a connective tissue membrane, from the inside - by a mucous membrane containing ciliated epithelium. The main bronchi go to the corresponding lung, where they branch out to form the bronchial tree.

The main bronchi are divided into lobar bronchi. There are three lobar bronchi in the right lung and two in the left. The lobar bronchi are divided into segmental and other smaller bronchi, in each lung there are 22-23 branching orders. As the diameter of the bronchi decreases, the cartilaginous plates are replaced by elastic ones, and the thickness of the muscle layer increases.

The last stage of bronchial division is the terminal bronchioles with a diameter of about 0.5 mm. (usually 8th branch order).

The structure of the lungs

Lung (pulmo ) a paired organ in the form of a cone with a thickened base (12) and top (3). Each lung is covered with pleura. The lungs have three surfaces: costal, diaphragmatic and mediastinal. On the mediastinal surface are the gates of the lungs, through which the bronchi, blood vessels, and nerves pass.

Each lung is divided into lobes by deep slits (7.8). The right lung has three lobes: upper (6), middle (10) and lower (11), the left lung has two lobes - lower and upper. There is a cardiac notch in the left lung (9). The right lung is approximately 10% larger in volume than the left.

In the lobes of the lung, segments are isolated, the segments are divided into lobules. Each lobule includes a lobular bronchus, which divides into terminal (terminal) bronchioles.

The structural and functional unit of the lung is the acinus. Acinus (cluster) is a branching of the terminal bronchiole into respiratory bronchioles, alveolar ducts and alveoli. Alveoli are thin-walled vesicles separated by a septum 2-8 microns thick. The septum contains a dense network of blood capillaries and elastic fibers. The respiratory surface of all alveoli is 40-120 square meters.

Pleura

Pleura p a (pleura ) is a serous membrane that covers the lungs, the walls of the chest cavity and the mediastinum.

The pleura that lines the wall of the chest cavity is called the parietal pleura. In the parietal pleura, a costalpart, diaphragmatic and mediastinal.Between the parietal and visceral there is a narrow gap - the pleural cavity, containing a small amount of serous fluid. In places where one part of the parietal pleura passes into another, there are so-called pleural sinuses, into which the edges of the lungs enter during maximum inspiration. The deepest sinus is the costal-phrenic sinus, formed at the junction of the anterior part of the costal pleura to the diaphragmatic one. The second is diaphragmatic - mediastinal, paired, located in the sagittal direction between the diaphragm and the mediastinal pleura. The third - costal-mediastinal, paired, lies along the vertical axis in front at the point of transition of the costal pleura to the mediastinal. In these recesses, fluid accumulates during inflammation of the pleura. The right and left pleural cavities are separated and do not communicate with each other (they are separated by the mediastinum). Distinguish between superior and inferior mediastinum. At the bottom is the heart and pericardium. The conditional frontal plane passing through the trachea divides the mediastinum into anterior and posterior.

In the anterior is the thymus gland, superior vena cava, aortic arch, trachea and main bronchi, heart and pericardium. In the posterior esophagus, thoracic aorta, esophagus, vagus nerves, sympathetic trunks and their branches.

The space between the organs of the mediastinum is filled with loose connective tissue.

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Obreumova N.I., Petrukhin A.S. Fundamentals of anatomy, physiology and hygiene of children and adolescents. Tutorial for students of the defectological faculty of higher education. ped. textbook establishments. - M.: Publishing Center "Academy", 2009.

Nutrients and foods

Nutrients are 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, carbohydrates found in food cannot be directly absorbed by the body. They break down into simpler substances.
The process of mechanical and chemical processing of food and its transformation into simpler and more soluble compounds that can be absorbed, carried by blood and lymph and assimilated by the body as a plastic and energy material is called digestion.

Digestive organs

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

alimentary canal They are a complexly modified tube 8–10 m long and consist of the oral cavity, pharynx, esophagus, stomach, small intestine and large intestine. The wall of the alimentary canal has three layers. one) Outer layer is formed by connective tissue and performs a protective function. 2) Average the layer in the oral cavity, in the pharynx, in the upper third of the esophagus and in the sphincter of the rectum is formed by striated muscle tissue, and in the remaining sections - by smooth muscle tissue. The muscular layer provides the mobility of the organ and the movement of food pulp along it. 3) Interior(mucus) 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

AT oral cavity teeth and tongue are present. 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, neck and one or more roots.
The crown of the tooth is covered with hard enamel(most hard tissue organism). Enamel protects the tooth from abrasion and microbial penetration. Roots are covered cement. The main part of the crown, neck and root is dentine. Enamel, cementum and dentin are types of bone tissue. Inside the tooth there is a small tooth cavity filled with soft pulp. It is formed by connective tissue, penetrated by blood vessels and nerves.
An adult has 32 teeth: in each half of the upper and lower jaws, there are 2 incisors, 1 canine, 2 small molars and 3 large molars. Newborns don't have teeth. Milk teeth appear by the 6th month and by the age of 10-12 are replaced by permanent ones. Wisdom teeth grow by the age of 20-22.
There are always a lot of microorganisms in the oral cavity that can lead to diseases of the oral cavity organs, in particular to tooth decay ( caries). It is very important to keep the oral cavity clean - rinse your mouth after eating, brush your teeth with special pastes, which include fluorine and calcium.
Language- a mobile muscular organ, consisting of striated muscles, equipped with numerous vessels and nerves. The tongue moves food in the process of chewing, participates in wetting it with saliva and swallowing, 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 with 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 meals when the receptors of the tongue and oral mucosa are irritated, but also when seeing tasty food, smelling it, etc.
Saliva consists of 98.5–99% water (1–1.5% solids). It contains mucin(mucous protein substance that helps the formation of the food bolus), lysozyme(bactericidal agent), enzymes amylase maltase(breaks down maltose into two molecules of glucose). Saliva has an alkaline reaction, since its enzymes are active in a slightly alkaline environment.
Food stays in the mouth for 15-20 seconds. The main functions of the oral cavity are approbation, grinding and wetting of food. In the oral cavity, food undergoes 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 during the movement of the food bolus through the esophagus and for some time in the stomach.
From the mouth, food passes into 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 pharynx. In the oral part, the respiratory and digestive tracts intersect.
Esophagus- a muscular tube 25–30 cm long. The upper third of the esophagus is formed by striated muscle tissue, the rest is smooth muscle tissue. The esophagus passes through an opening in the diaphragm into the abdominal cavity, where it passes into the stomach. The function of the esophagus is the movement of the food bolus 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. In the stomach, there is an entrance, a bottom, a body and an exit. The capacity of the stomach is from one to several liters. In the stomach, food is delayed for 4-11 hours and is mainly subjected to chemical processing. gastric juice.
Gastric juice produce 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 cleavage by pepsin.
Enzymes of gastric juice: pepsin gelatinase(hydrolyzes gelatin) lipase(breaks down emulsified milk fats into glycerol and fatty acid), chymosin(curdles milk).
With a prolonged lack of food in the stomach, there is a feeling hunger. It is necessary to distinguish between the concepts of "hunger" and "appetite". To eliminate the feeling of hunger, the amount of food absorbed 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. In this case, the contents of the upper intestines return to the stomach and, together with its contents, are thrown out through the esophagus into the oral cavity due to antiperistalsis and strong contractions of the diaphragm and abdominal muscles.

Digestion in the intestine

The intestine consists of the small intestine (includes the duodenum, jejunum, and ileum) and the large intestine (includes the caecum with appendix, colon, and rectum).
From the stomach, food gruel in separate portions through the sphincter (circular muscle) enters the duodenum. Here, the food slurry is exposed to the chemical action of pancreatic juice, bile and intestinal juice.
The largest digestive glands are the pancreas and the liver.
Pancreas located behind the stomach on the back abdominal wall. The gland consists of an exocrine part that produces pancreatic juice (enters the duodenum through the excretory duct of the pancreas), 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 in the duodenum under the influence of intestinal juice enterokinase into trypsin), trypsin(in an alkaline environment it breaks down proteins and polypeptides to amino acids), amylase, maltase and lactase(break down carbohydrates) lipase(breaks down fats into glycerol and fatty acids in the presence of bile), nucleases(break down nucleic acids into nucleotides). The secretion of pancreatic juice is carried out in an amount (1.5–2 l / day).
Liver located in the abdominal cavity below the diaphragm. The liver produces bile, which through the bile duct duct enters the duodenum.
Bile is produced constantly, therefore, outside the period of digestion, it is collected in gallbladder. Bile contains no enzymes. It is alkaline, 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, activates pancreatic enzymes, 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 that are formed during metabolism or come from outside. Glycogen is synthesized in liver cells.
Small intestine- the longest part of the digestive tube (5–7 m). Here, nutrients are almost completely digested, and digestion products are absorbed. It is divided into duodenal, lean and iliac.
Duodenum(about 30 cm long) has the shape of a horseshoe. In it, the food slurry is subjected to the digestive action of pancreatic juice, bile and juice of the intestinal glands.
intestinal juice produced by the glands of the mucous membrane of the small intestine. It contains enzymes that complete the process of breaking down nutrients: peptidase amylase, maltase, invertase, lactase(break down carbohydrates) lipase(breaks down fats) enterokinase
Depending on the localization of the digestive process in the intestine, there are abdominal and parietal digestion. Cavitary 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. The pendulum movements of the annular and longitudinal muscles contribute to the mixing of the food slurry, the peristaltic wave-like movements of the annular muscles ensure the movement of the slurry to the large intestine.
Colon has a length of 1.5–2 m, an average diameter of 4 cm and includes three sections: the caecum with the appendix, the colon and rectum. On the border of the ileum and caecum there is an ileocecal valve that acts as a sphincter that 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 movements. The glands of the large intestine 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-destroying bacteria break down plant fiber into 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 products of protein digestion. In this case, toxic compounds are formed, some of which penetrate the bloodstream and are neutralized in the liver. Food residues turn into feces, accumulate in the rectum, which carries out the excretion of 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 in the stomach, water, salts, glucose, amino acids, glycerol, fatty acids in the small intestine, water, alcohol, some salts in the colon.
The main processes of absorption occur in the lower parts of the small intestine (in the jejunum and ileum). There are many outgrowths of the mucosa - 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 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 of organic substances), osmosis (water), active transport (sodium, glucose, amino acids). Absorption is facilitated by contractions of the villi, pendulum and peristaltic movements of the intestinal walls.
Amino acids and glucose are absorbed into the blood. Glycerin dissolves in water and enters the epithelial cells. Fatty acids react with alkalis, form salts, which, in the presence of bile acids dissolve in water and are also absorbed by epithelial cells. In the villus epithelium, glycerol and fatty acid salts interact to form human-specific fats that enter the lymph.
The process of absorption is regulated by the nervous system and humorally (vitamins of group B 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 - into 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 group of substances of only a certain chemical composition and structure, on a certain type of chemical bond in a 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 into maltose) and maltase(breaks down maltose to 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(curdles milk). Pancreatic juice contains trypsinogen, which is converted to trypsin(breaks down proteins and polypeptides to 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 for 2 s at 37 °C can lead to the breakdown of about 300 molecules of a substance. Enzymes are sensitive to the temperature of the environment in which they operate. In humans, they are most active at a temperature of 37–40 °C. For the enzyme to work, a certain reaction of the environment is required. For example, pepsin is active in an acidic environment, while the other enzymes listed are active in weakly alkaline and alkaline environments.

The 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 developed by him fistula technique research. The essence of this method is to create by 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 admixture of food, measure their quantity and determine chemical composition. The main advantage of this method, proposed by I. P. Pavlov, is that the process of digestion is studied in the natural conditions of the existence of the organism, on a healthy animal, and the activity of the digestive organs is excited by natural food stimuli. The merits of IP Pavlov in studying the activity of the digestive glands received international recognition - he was awarded the Nobel Prize.
In humans, a rubber probe is used to extract gastric juice and the contents of the duodenum, which the subject swallows. Information about the state of the stomach and intestines can be obtained by translucent areas of their location with X-rays, or by the 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.
Humans breathe by taking in oxygen from the air and releasing carbon dioxide into it. Every cell needs energy to live. 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, are oxidized ("burn out"). In this case, the disintegration of molecules occurs and the internal energy contained in them is released. Without oxygen, metabolic transformations of substances in the body are impossible.
There are no reserves of oxygen in the body of humans and animals. Its continuous intake into the body is provided by the respiratory system. The accumulation of a significant amount of carbon dioxide as a result of metabolism is harmful to the body. Removal of CO 2 from the body is also carried out by the respiratory organs.
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 respiration: external (lung) breathing- exchange of gases in the lungs between the body and the environment; transport of gases by the blood from the lungs to the tissues of the body; tissue respiration- gas exchange in tissues and biological oxidation in mitochondria.

external respiration

External respiration provided respiratory system, which consists of lungs(where gas exchange takes place between the inhaled air and the blood) and respiratory(air-bearing) ways(through which the inhaled and exhaled air passes).
Airways (respiratory) 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 solid skeleton, represented by bones and cartilage, and are lined from the inside with a mucous membrane, equipped with ciliated epithelium. Functions of the respiratory tract: heating and humidifying the air, protection against infections and dust.

nasal cavity divided by a partition into two halves. It communicates with the external environment through the nostrils, and 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 mucous glands secrete mucus that moisturizes the walls of the nasal cavity and reduces the vital activity of bacteria. On the surface of the mucosa are leukocytes that destroy a large number of bacteria. The ciliated epithelium of the mucosa retains and removes dust. When the cilia of the nasal cavities are irritated, a sneeze reflex occurs. Thus, in the nasal cavity, the air 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 air is exhaled 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. Air enters the trachea from the larynx.
Trachea formed by 16-20 incomplete cartilaginous rings that do not allow it to subside, and the posterior wall of the trachea is soft and contains smooth muscles. This allows food to pass freely through the esophagus, which lies behind the trachea.
At the bottom, the trachea divides into two main bronchus(right and left), which penetrate the lungs. In the lungs, the main bronchi branch many times into the bronchi of the 1st, 2nd, etc. orders, forming bronchial tree. The bronchi of the 8th order are called lobular. They branch into terminal bronchioles, and those into respiratory bronchioles, which form alveolar sacs made up of alveoli. Alveoli- pulmonary vesicles, having the shape of a hemisphere with a diameter of 0.2–0.3 mm. Their walls consist of a single-layer epithelium and are covered with a network of capillaries. Through the walls of the alveoli and capillaries, gases are exchanged: 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 has three lobes, the left has two. The main bronchus and pulmonary artery pass into each lung, and two pulmonary veins. Outside, the lungs are covered with a pulmonary pleura. The gap between the lining of the chest cavity and the pleura (pleural cavity) is filled with pleural fluid, which reduces the friction of the lungs against the chest wall. The pressure in the pleural cavity is less than atmospheric by 9 mm Hg. Art. and is about 751 mm Hg. Art.
Breathing movements. The lungs do not have muscle tissue, and therefore they cannot actively contract. An active role in the act of inhalation and exhalation belongs to the respiratory muscles: intercostal muscles and diaphragm. With their contraction, the volume of the chest increases and the lungs are stretched. When the respiratory muscles relax, the ribs descend to their original level, the dome of the diaphragm rises, the volume of the chest, and therefore the lungs, decreases, and the air comes out. A person makes an average of 15-17 respiratory movements per minute. During muscular work, breathing quickens by 2-3 times.
Vital capacity of the lungs. At rest, a person inhales and exhales about 500 cm3 of air ( tidal volume). With a deep breath, a person can inhale about 1500 cm 3 of 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(WELCOME) is the largest number air that a person can exhale after taking a deep breath. VC is measured with 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 of age, VC is 1200 cm 3; in adults - an average of 3500 cm 3; for athletes, it is greater: for football players - 4200 cm 3, for gymnasts - 4300 cm 3, for swimmers - 4900 cm 3. The volume of air in the lungs exceeds the VC. Even with the deepest exhalation, about 1000 cm3 of residual air remains in them, so the lungs do not completely collapse.
Breathing regulation. 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 along the motor neurons to the respiratory muscles and diaphragm, causing an 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 leads to an increase and deepening of breathing. This is how the humoral regulation of respiration is carried out.
Artificial respiration done when breathing stops in drowned people, in case of electric shock, poisoning carbon monoxide and so on. They breathe from mouth to mouth or from mouth to nose. The exhaled air contains 16-17% oxygen, which is sufficient to ensure gas exchange, and the high content of CO 2 in the exhaled air (3-4%) contributes to the humoral stimulation of the respiratory center of the victim.

Gas transport

Oxygen is transported to tissues mainly in the composition oxyhemoglobin(HbO 2). A small amount of CO 2 is transported from the 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 bicarbonate in erythrocytes (a minor part) and sodium bicarbonate in blood plasma (most), carbon dioxide is transported 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 a low carbon dioxide content (0.03%), and exhales air in which O 2 is 16.3%, and CO 2 is 4%. Nitrogen and inert gases, which are part of the air, do not participate in respiration, and their content in the 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 a gas penetrates from an environment where it is contained more into an environment with a lower content of it. Gas exchange in tissues also takes place according to the laws of diffusion.
Respiratory hygiene. For the strengthening and development of the respiratory organs, proper breathing (inhalation is shorter than exhalation), breathing through the nose, development of the chest (the wider it is, the better), fighting bad habits(smoking), clean air.
An important task is to protect the air environment from pollution. One of the protection measures is the landscaping of cities and towns, as plants enrich the air with oxygen and purify it from dust and harmful impurities.

Immunity

Immunity- a way to protect the body from genetically alien substances and infectious agents. Protective reactions of the body 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 congenital(passive) - due to the transfer of ready-made antibodies from mother to child through the placenta or when breastfeeding.
natural acquired(active) - due to the production of own antibodies as a result of contact with antigens (after illness).
Acquired Passive- created by the introduction of ready-made antibodies into the body ( therapeutic serum). Therapeutic serum is a preparation of antibodies from the blood of a previously infected animal (usually a horse). Serum is administered to a person already infected with an infection (antigens). The introduction of therapeutic serum helps the body fight infection until it produces its own antibodies. Such immunity does not last long - 4-6 weeks.
Acquired Active- created by the introduction into the body vaccines(an antigen represented by weakened or killed microorganisms or their toxins), resulting in the production of appropriate antibodies in the body. Such immunity lasts for 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 organ of blood circulation) and blood vessels(arteries, veins, capillaries).

The structure of the heart

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

Outer shell of the heart pericardium. It consists of two sheets: 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 contraction of the heart. Middle layer of the heart myocardium. It consists of striated muscle tissue of a special structure. The heart muscle is made up of striated muscle tissue of a special structure ( cardiac muscle tissue). In it, adjacent 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 rapidly. In nerve cells and skeletal muscle, each cell fires 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 atrial(left and right) and 2 ventricles(left and right). The muscular wall of the ventricles (especially the left one) is thicker than the wall of the atria. Venous blood flows in the right side of the heart, arterial blood flows in the left side.
Between the atria and ventricles are flap valves(between the left - bivalve, between the right - tricuspid). Between the left ventricle and the aorta and between the right ventricle and the pulmonary artery are semilunar valves(consist of three sheets resembling pockets). The valves of the heart ensure the movement of blood in only one direction: from the atria to the ventricles, and from the ventricles to the arteries.
The heart muscle has the property of automation. Automatism of the heart- its ability to contract rhythmically without external stimuli under the influence of impulses that arise in itself. Automatic contraction of the heart continues even when it is isolated from the body.

The 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 - a general pause - both the atria and the ventricles are relaxed - lasts 0.4 s.
At rest, the heart rate of an adult is 60–80 times per 1 min, for athletes 40–50, for newborns 140. physical activity the heart contracts more often, while the duration of the total pause decreases. The amount of blood ejected by the heart in one contraction (systole) is called the 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 the minute volume of blood. It is 4.5–5.5 liters.
Electrocardiogram(ECG) - recording of bioelectrical 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 beats, sounds are produced that are called heart sounds. In some diseases, the nature of the tones changes and noises appear.

Vessels

The walls of arteries and veins consist of three layers: interior(thin layer epithelial cells), average(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 that carry blood from the heart to organs and tissues. The walls are made up of three layers. The following types of arteries are distinguished: elastic type arteries (large vessels closest to the heart), muscular type 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 passing 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 of the human body is about 100,000 km. In places where the arteries pass into the capillaries, there are accumulations of muscle cells that regulate the lumen of the vessels. At rest, 20–30% of capillaries are open in humans.
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 contributes to the flow of fluid and metabolic products back into the capillaries.
Vienna Vessels that carry blood from the 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 have valves that prevent backflow of blood.

Large and small circles of blood circulation

Vessels in the human body form two closed systems circulation. Allocate large and small circles of blood circulation. The vessels of the large circle supply blood to the organs, the vessels of the small circle provide 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 trunk and legs) to the right atrium.
Small circle of blood circulation: venous blood flows from the right ventricle of the heart through pulmonary artery into a dense network of capillaries braiding 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.

The movement of blood through the vessels

Blood moves through the vessels due to contractions of the heart, creating a difference in blood pressure in different parts of the vascular system. Blood flows from 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 rate of blood flow is inversely proportional to the total cross-sectional area of ​​the vessels. The blood flow velocity 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 in the vessels continuously. The reasons for this - in the elasticity of the walls of blood vessels.
For the movement of blood through the veins, one pressure created by the heart is not enough. This is facilitated by the valves of the veins, which ensure the flow of blood in one direction; contraction of nearby skeletal muscles, which compress the walls of the veins, pushing blood towards the heart; suction action of large veins with an increase in the volume of the chest cavity and negative pressure in it.

Blood pressure and pulse

Blood pressure is the pressure at which blood is in a blood vessel. The pressure is highest in the aorta, less in the large arteries, even less in the capillaries, and lowest in the veins.
Human 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 is the difference between systolic and diastolic pressure. An increase in blood pressure is called hypertension, lowering - hypotension. Raise blood pressure occurs with heavy physical exertion, a decrease - with large blood loss, 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 withdrawing 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 at the end of the circle of blood circulation. Blood pressure in the aorta and large arteries is 110–120 mm Hg. Art. (that is, 110-120 mm Hg above atmospheric), in the 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 the large veins of the chest cavity and at the confluence them into the right atrium is almost equal to atmospheric (when inhaling, slightly lower than atmospheric, while exhaling, slightly higher).
arterial pulse- rhythmic oscillations of the walls of the arteries as a result of blood entering the aorta during left ventricular systole. The pulse can be felt to the touch where the arteries lie closer to the surface of the body: in the area of ​​\u200b\u200bthe radial artery lower third 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; alkaline reaction of the lymph. It contains fibrinogen, so it is able to coagulate. There are no erythrocytes in the lymph, leukocytes are contained in small quantities, penetrating 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, tissues. Lymph moves through the vessels due to the rhythmic contractions of the walls of large lymphatic vessels, the presence of valves in them, the contraction of skeletal muscles, the suction action of the thoracic duct during inspiration.
Functions lymphatic system: additional outflow of fluid from organs; hematopoietic and protective functions (in lymph nodes there is a multiplication of lymphocytes and phagocytosis of pathogens, as well as the production of immune bodies); 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 by nervous and humoral regulation. At nervous regulation the central nervous system can decrease or increase the heart rate, constrict or dilate blood vessels. These processes are regulated respectively by the parasympathetic and sympathetic nervous systems. At humoral regulation hormones are released into the blood. Acetylcholine reduces heart rate, dilates blood vessels. Adrenalin stimulates the work of the heart, narrows the lumen of blood vessels. An increase in the content of potassium ions in the blood depresses, and calcium enhances the work of the heart. Lack of oxygen or excess of 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. Prevention measures cardiovascular disease are physical exercises and healthy lifestyle life.

Respiratory system performs the vital function of gas exchange, delivery of oxygen to the body and removal of carbon dioxide.

It consists of the nasal cavity, pharynx, larynx, trachea and bronchi.

In the region of the pharynx, the oral and nasal cavities are connected. Functions of the pharynx: moving food from the oral cavity into the esophagus and carrying air from the nasal cavity (or mouth) to the larynx. The pharynx crosses the respiratory and digestive tracts.

The larynx connects the pharynx to the trachea and contains the vocal apparatus.

The trachea is a cartilaginous tube about 10-15 cm long. In order to prevent food from entering the trachea, a so-called palatine veil is located at its entrance. Its purpose is to block the path to the trachea every time you swallow food.

The lungs consist of bronchi, bronchioles and alveoli surrounded by a pleural sac.

How does gas exchange take place?

During inhalation, air is drawn into the nose, in the nasal cavity the air is cleaned and moistened, then it goes down through the larynx into the trachea. The trachea divides into two tubes - the bronchi. Through them, air enters the right and left lungs. The bronchi branch into many tiny bronchioles that end in alveoli. Through the thin walls of the alveoli, oxygen enters the blood vessels. This is where the pulmonary circulation begins. Oxygen is picked up by hemoglobin, which is contained in red blood cells, and oxygenated blood is sent from the lungs to the left side of the heart. The heart pushes blood into the blood vessels, big circle blood circulation, from where oxygen is distributed throughout the body through the arteries. As soon as the oxygen from the blood is used up, the blood through the veins enters the right side of the heart, the systemic circulation ends, and from there - back to the lungs, the pulmonary circulation ends. When you exhale, carbon dioxide is removed from the body.

With each breath, not only oxygen enters the lungs, but also dust, microbes and other foreign objects. On the walls of the bronchi there are tiny villi that trap dust and germs. In the walls of the airways, special cells produce mucus that helps clean and lubricate these villi. Contaminated mucus is excreted through the bronchi to the outside and coughed up.

Breathing yogic techniques are aimed at cleansing the lungs and increasing their volume. For example, Ha-exit, stepped exhalations, punching and tapping of the lungs, full yogic breathing: upper clavicular, costal or thoracic and diaphragmatic or abdominal. It is believed that abdominal breathing is more “correct and beneficial” for human health. The diaphragm is a domed muscular structure that separates chest from the abdominal cavity and is also involved in respiration. When you inhale, the diaphragm goes down, filling the lower part of the lungs, when you exhale, the diaphragm rises. Why is diaphragmatic breathing correct? Firstly, most of the lungs are involved, and secondly, the internal organs are massaged. The more we fill our lungs with air, the more actively we oxygenate the tissues of our body.

Digestive system.

The main divisions of the alimentary canal are: oral cavity, pharynx, esophagus, stomach, small intestine and large intestine, liver and pancreas.

The digestive system performs the functions of mechanical and chemical processing of food, absorption of digested proteins, fats and carbohydrates into the blood and lymph and excretion of undigested substances from the body.

You can describe this process in another way: digestion is the consumption of energy contained in foods in order to increase or rather maintain one's own ever-decreasing energy at a certain level. The release of energy from foods occurs in the process of splitting food. We recall the lectures of Marva Vagarshakovna Oganyan, the concept of phytocalories, which products contain energy, which do not.

Let's go back to the biological process. In the oral cavity, food is crushed, moistened with saliva, and then enters the pharynx. Through the pharynx and esophagus, which passes through the chest and diaphragm, the crushed food enters the stomach.

In the stomach, food mixes with gastric juice active ingredients which is hydrochloric acid and digestive enzymes. Peptin breaks down proteins into amino acids, which are immediately absorbed into the blood through the walls of the stomach. Food stays in the stomach for 1.5-2 hours, where it softens and dissolves under the influence of an acidic environment.

The next stage: partially digested food enters the small intestine - the duodenum. Here, on the contrary, the environment is alkaline, suitable for the digestion and breakdown of carbohydrates. The duct from the pancreas, which ejects pancreatic juice, and the duct from the liver, which ejects bile, passes into the duodenum. It is in this section of the digestive system that food is digested under the influence of pancreatic juice and bile, and not in the stomach, as many people think. In the small intestine, most of the absorption of nutrients through the intestinal wall into the blood and lymph takes place.

Liver. barrier function the liver to purify the blood from the small intestine, so along with useful substances for the body, they are absorbed and not useful, such as: alcohol, medications, toxins, allergens, etc., or more dangerous: viruses, bacteria, microbes.

The liver is the main "laboratory" for the breakdown and synthesis of a large amount of organic substances, it can be said that the liver is a kind of pantry of the body's nutrients, as well as a chemical factory, "built-in" between two systems - digestion and blood circulation. An imbalance in the action of this complex mechanism is the cause of numerous diseases of the digestive tract and of cardio-vascular system. There is the closest connection between the digestive system, liver and blood circulation. The colon and rectum complete the digestive tract. In the large intestine, water is mainly absorbed and feces are formed from food gruel (chyme). Through the rectum, everything that is not needed is removed from the body.

Nervous system

The nervous system includes the brain and spinal cord, as well as nerves, ganglions, plexuses. All of the above primarily consists of nervous tissue, which:

is able to be excited under the influence of irritation from the internal or external environment for the body and conduct excitation in the form of a nerve impulse to various nerve centers for analysis, and then transmit the “order” developed in the center to the executive organs to perform the response of the body in the form of movement (movement in space) or changes in organ function.

The brain is part of the central system located inside the skull. Consists of a number of organs: the cerebrum, cerebellum, brainstem and medulla oblongata. Each part of the brain has its own functions.

The spinal cord forms the distribution network of the central nervous system. It lies inside the spinal column, and all the nerves that form the peripheral nervous system depart from it.

Peripheral nerves - are bundles, or groups of fibers that transmit nerve impulses. They can be ascending, i.e. transmit sensations from the whole body to the central nervous system, and descending, or motor, i.e. bring the teams nerve centers to all parts of the body.

Some components of the peripheral system have distant connections with the central nervous system; they function with very limited CNS control. These components work independently and make up the autonomic or autonomic nervous system. It governs the functioning of the heart, lungs, blood vessels and other internal organs. The digestive tract has its own internal autonomic system.

The anatomical and functional unit of the nervous system is the nerve cell - the neuron. Neurons have processes, with the help of which they are connected to each other and to innervated formations (muscle fibers, blood vessels, glands). offshoots nerve cell have different functional significance: some of them conduct irritation to the body of the neuron - these are dendrites, and only one process - the axon - from the body of the nerve cell to other neurons or organs. The processes of neurons are surrounded by membranes and combined into bundles, which form the nerves. The shells isolate the processes of different neurons from each other and contribute to the conduction of excitation.

Irritation is perceived by the nervous system through the sense organs: eyes, ears, organs of smell and taste, and special sensitive nerve endings - receptors located in the skin, internal organs, vessels, skeletal muscles and joints. They transmit signals through the nervous system to the brain. The brain analyzes the transmitted signals and forms a response.