Human digestive system splitting. Digestive organs. The structure and function of the digestive system

Digestion- a set of processes of mechanical and chemical processing of food into components suitable for absorption into the blood and lymph and participation in metabolism. Digestion products enter the internal environment of the body and are transported to cells, where they are either oxidized with the release of energy, or are used in biosynthesis processes as a building material.

Departments of the human digestive system: oral cavity, pharynx, esophagus, stomach, small and large intestines, anus. The walls of the hollow organs of the digestive tract consist of three shells : external connective tissue, middle muscle and internal - mucosa. The movement of food from one section to another is carried out due to the reduction of the walls of the organs of the tract.

The main functions of the digestive system:

■ secretory (production of digestive juices by the liver and pancreas, the short ducts of which exit into the small intestine; also play an important role in digestion salivary glands and glands located in the walls of the stomach and small intestine);

■ motor , or motor (mechanical processing of food, its movement along the digestive tract and the removal of undigested residues outside the body);

■ suction breakdown products of food and other nutrients into the internal environment of the body - blood and lymph.

Oral cavity. Pharynx

Oral cavity bounded from above by a solid and soft palate, from below - by the jaw-hyoid muscle, on the sides - by the cheeks, in front - by the lips. Behind the oral cavity using throat communicated with by the throat ... V oral cavity are tongue and teeth ... In the oral cavity, the ducts of three pairs of large salivary glands - parotid, sublingual and mandibular.

■ The taste of the food is analyzed in the mouth, then the food is crushed with teeth, enveloped in saliva, and subjected to enzymes.

The mucous membrane of the mouth has many glands of different sizes. Small glands are located shallow in the tissues, large ones are usually removed from the oral cavity and communicate with it by long excretory ducts.

Teeth. An adult usually has 32 teeth: 4 incisors, 2 canines, 4 small molars and 6 large molars on each jaw. The teeth are used to hold, bite off, gnaw and mechanically grind food; they also take part in the formation of speech sounds.

■ Incisors located in the front of the mouth; have straight sharp edges and are suitable for biting off food.

■ Fangs located behind the incisors; have a conical shape; in humans are poorly developed.

■Small molars located behind the canines; have one or two roots and two tubercles on the surface; serve to grind food.

■Large molars located behind small roots; have three (upper molars) or four (lower) roots and four or five tubercles on the surface; serve to grind food.

Tooth comprises root (part of the tooth buried in the jaw socket), necks (part of the tooth buried in the gum) and crowns (the part of the tooth that protrudes into the mouth). Inside the root passes channel expanding into the tooth cavity and filled pulp (loose connective tissue) containing blood vessels and nerves. The pulp produces an alkaline solution that seeps out through the pores of the tooth; this solution is required to neutralize acidic environment formed by bacteria living on the teeth and destroying the tooth.

The base of the tooth is dentine covered on the crown tooth enamel , and on the neck and root - dental cement ... Dentin and cement - types bone tissue. Tooth enamel- the hardest tissue in the human body, in terms of hardness it is close to quartz.

A child about a year old has baby teeth , which then, starting at the age of six, are dropped out and replaced permanent teeth ... Before changing the roots of milk teeth are absorbed. Rudiments permanent teeth are laid even in the uterine period of development. The eruption of permanent teeth ends by 10-12 years; the exception is wisdom teeth, the appearance of which is sometimes delayed up to 20-30 years.

Bite- the closure of the upper incisors with the lower ones; with a correct bite, the upper incisors are located in front of the lower ones, which enhances their cutting action.

Language- a movable muscular organ, covered with a mucous membrane, richly supplied with blood vessels and nerves; comprises body and the back - root ... The body of the tongue forms a lump of food and moves food as it chews, the root of the tongue pushes food in the direction of the pharynx leading to the esophagus. When swallowing food, the opening of the trachea ( breathing tube) is covered by the epiglottis. Language is also organ of taste and participates in the formation speech sounds .

Salivary glands reflexively secrete saliva having weakly alkaline reaction and containing water (98-99%), slime and digestive enzymes. Mucus is a viscous liquid consisting of water, antibodies (bacteria bind) and protein substances - mucin (moistens food as it chews, creating a lump for food to be swallowed) and lysozyme (has a disinfecting effect, destroying the membranes of bacterial cells).

■ Saliva is secreted continuously (up to 1.5-2 liters per day); salivation may increase reflexively (see below). The center of salivation is in the medulla oblongata.

Saliva enzymes: amylase and maltose begin to break down carbohydrates, and lipase - fats; at the same time, complete splitting does not occur due to the short duration of the presence of food in the mouth.

Zev- the hole through which the oral cavity communicates with by the throat ... On the sides of the pharynx there are special formations (accumulations of lymphoid tissue) - tonsils , which contain lymphocytes that perform a protective function.

Pharynx Is a muscular organ that connects the oral cavity with esophagus and nasal cavity- with the larynx. Swallowing - reflex process. During swallowing, the lump of food passes into the pharynx; in this case, the soft palate rises and blocks the entrance to the nasopharynx, and the epiglottis blocks the path to the larynx.

Esophagus

Esophagus — top part alimentary canal; It is a muscle tube about 25 cm long, lined with squamous epithelium from the inside; starts from the pharynx. The muscular layer of the walls of the esophagus in the upper part consists of striated muscle tissue, in the middle and lower part - of smooth muscle tissue. Together with the trachea, the esophagus passes into the chest cavity and at the level of the XI thoracic vertebra opens into the stomach.

The muscular walls of the esophagus can contract, pushing food into the stomach. The contractions of the esophagus are slow peristaltic waves arising in its upper part and extending along the entire length of the esophagus.

Peristaltic wave It is a wave-like cycle of successive contractions and relaxations of small segments of the tube spreading along the digestive tube, forcing food into relaxed areas. Peristaltic waves move food throughout the digestive tract.

Stomach

Stomach- an expanded pear-shaped part of the digestive tube with a volume of 2-2.5 (sometimes up to 4) liters; has a body, a bottom and a pyloric part (a section bordering the duodenum), an inlet and an outlet. Food accumulates in the stomach and lingers for some time (2-11 hours). During this time, it is grinded, mixed with gastric juice, acquiring the consistency of a liquid soup (forms chyme ), and is exposed to the action of hydrochloric acid and enzymes.

■ The main process of digestion in the stomach is hydrolysis of proteins .

Walls stomach are made up of three layers of smooth muscle fibers and are lined with glandular epithelium. Muscle cells the outer layer has a longitudinal direction, the middle layer is circular (circular), the inner layer is oblique. This structure helps to maintain the tone of the walls of the stomach, mixing the food mass with gastric juice and its movement into the intestines.

Mucous membrane the stomach is collected in folds into which the excretory ducts open glands producing gastric juice. The glands are composed of the main (produce enzymes) lining (produce hydrochloric acid) and additional cells (they produce mucus, which is constantly renewed and prevents the digestion of the stomach walls by its own enzymes).

The gastric mucosa also contains endocrine cells producing digestive and other hormones .

■ In particular, the hormone gastrin stimulates the production of gastric juice.

Gastric juice Is a clear liquid, which contains digestive enzymes, 0.5% hydrochloric acid solution (pH = 1-2), mucins (protects the walls of the stomach) and inorganic salts. The acid activates enzymes in gastric juice (in particular, it converts inactive pepsinogen into active pepsin ), denatures proteins, softens fibrous foods and destroys pathogens. Gastric juice is secreted reflexively, 2-3 liters per day.

❖ Enzymes of gastric juice:
■ pepsin breaks down complex proteins into simpler molecules - polypeptides;
■ gelatinase breaks down the connective tissue protein - gelatin;
■ lipase breaks down emulsified milk fats to glycerin and fatty acids;
■ chymosin curdles milk casein.

Salivary enzymes also enter the stomach along with the food lump, where they continue to act for some time. So, amylase break down carbohydrates until the food lump is saturated with gastric juice and neutralization of these enzymes occurs.

The chyme processed in the stomach enters in portions duodenum - the initial section of the small intestine. The exit of chyme from the stomach is controlled by a special annular muscle - gatekeeper .

Small intestine

Small intestine- the longest part of the digestive tract (its length is 5-6 m), occupying the most abdominal cavity... Initial part small intestine — duodenum - has a length of about 25 cm; the ducts of the pancreas and liver open into it. The duodenum passes into skinny , skinny - in ileum .

The muscular layer of the walls of the small intestine is formed by smooth muscle tissue and is capable of peristaltic movements ... The mucous membrane of the small intestine has a large number of microscopic glands (up to 1000 per 1 mm 2), generating intestinal juice , and forms numerous (about 30 million) microscopic outgrowths - villi .

Villi- this is an outgrowth of the mucous membrane of the gonadal intestine with a height of 0.1-0.5 mm, inside which there are smooth muscle fibers and a well-developed circulatory and lymphatic network. The villi are covered with a monolayer epithelium that forms finger-like outgrowths microvilli (about 1 μm long and 0.1 μm in diameter).

Pa area 1 cm 2 located from 1800 to 4000 villi; together with microvilli, they increase the surface area of ​​the small intestine by more than 30–40 times.

In the small intestine organic matter They are broken down to products that can be assimilated by the cells of the body: carbohydrates - to simple sugars, fats - to glycerol and fatty acids, proteins - to amino acids. It combines two types of digestion: cavity and membrane (parietal).

By using cavity digestion initial hydrolysis of nutrients occurs.

Membrane digestion carried out on the surface microvilli , where the corresponding enzymes are located, and provides the final stage of hydrolysis and the transition to absorption. Amino acids and glucose are absorbed through the villi into the blood; glycerol and fatty acids are absorbed into the epithelial cells of the small intestine, where they synthesize the body's own fats, which enter the lymph and then into the blood.

Of great importance for digestion in the duodenum are pancreatic juice (stands out pancreas ) and bile (secreted liver ).

Intestinal juice has an alkaline reaction and consists of a cloudy liquid part and lumps of mucus containing deflated cells of the intestinal epithelium. These cells are destroyed and release the enzymes contained in them, which are actively involved in the digestion of chyme, breaking it down into products that can be assimilated by the cells of the body.

❖ Intestinal juice enzymes:
■ amylase and maltose catalyze the breakdown of starch and glycogen,
■ invertase completes the digestion of sugars',
■ lactase hydrolyze lactose,
■ enterokinase converts an inactive enzyme trypsinogen into an active one trypsin that breaks down proteins;
■ dipeptidases cleave dipeptides to amino acids.

Pancreas

Pancreas- organ of mixed secretion: its exocrine part develops pancreatic juice, endocrine part develops hormones (see ""), regulating carbohydrate metabolism.

The pancreas is located under the stomach; comprises heads , body and tail and has an ungulate lobular structure; its length is 15-22 cm, weight is 60-100 g.

Head the gland is surrounded by the duodenum, and tail part adjacent to the spleen. The gland has conducting channels that merge into the main and additional ducts, through which pancreatic juice enters the duodenum during digestion. In this case, the main duct at the very entrance to the duodenum (at the Vater's nipple) is connected to the common bile duct (see below).

The activity of the pancreas is regulated by the autonomic nervous system (via the vagus nerve) and humorally (by hydrochloric acid of gastric juice and the hormone secretin).

Pancreatic juice(pancreatic juice) contains nones НСО 3 -, which neutralize gastric hydrochloric acid, and a number of enzymes; has an alkaline reaction, pH = 7.5-8.8.

Pancreatic juice enzymes:
■ proteolytic enzymes trypsin, chymotrypsin and elastase break down proteins to low molecular weight peptides and amino acids;
■ amylase breaks down carbohydrates to glucose;
■ lipase breaks down neutral fats to glycerin and fatty acids;
■ nucleases split nucleic acids to nucleotides.

Liver

Liver- the largest digestive gland associated with the racemic intestine (in an adult, its weight reaches 1.8 kg); located in upper section abdominal cavity, on the right under the diaphragm; consists of four unequal parts. Each lobe consists of granules 0.5-2 mm in size, formed by glandular cells hepatocytes , between which there is connective tissue, blood and lymphatic vessels and bile ducts, merging into one common hepatic duct.

Hepatocytes are rich in mitochondria, elements of the cytoplasmic reticulum and the Golgi complex, ribosomes, and especially glycogen deposits. They (hepatocytes) produce bile (see below), which is secreted into the bile ducts of the liver, and also secretes glucose, urea, proteins, fats, vitamins, etc., entering the blood capillaries.

The hepatic artery, portal vein and nerves enter the liver through the right lobe; on its lower surface is gall bladder with a volume of 40-70 ml, serving for the accumulation of bile and its periodic (during meals) injection into the intestine. The gallbladder duct connects to the common hepatic duct, forming general bile duct , which goes down, merges with the pancreatic duct and opens into the duodenum.

❖The main functions of the liver:

■ synthesis and secretion of bile;

■ metabolic:

- participation in the exchange proteins: synthesis of blood proteins, including those involved in its coagulation - fibrinogen, prothrombin, etc .; deamination of amino acids;

- participation in the exchange carbohydrates : regulating blood sugar levels by synthesis (from excess glucose) and deposition of glycogen under the influence of the hormone insulin, and breakdown of glycogen to glucose (under the influence of the hormone glucagon);

- participation in lipid metabolism: activation lipases , splitting emulsified fats, ensuring the absorption of fats, depositing excess fat;

- participation in the synthesis of cholesterol and vitamins A, B) 2, the deposition of vitamins A, D, K;

- participation in the regulation of water exchange;

■ barrier and protective:

- detoxification (neutralization) and transformation into urea of ​​poisonous decay products of proteins (ammonia, etc.) that enter the bloodstream from the intestines and enter the liver through the portal vein;

- absorption of microbes;

- inactivation of foreign substances;

- removal of hemoglobin breakdown products from the blood;

■ hematopoietic:

- the liver of embryos (2-5 months) performs the function of hematopoiesis;

- the liver of an adult accumulates iron, which is then used to synthesize hemoglobin;

■blood depot (along with the spleen and skin); can deposit up to 60% of all blood.

Bile- a product of the activity of liver cells; is a very complex weakly alkaline mixture of substances (water, salts bile acids, phospholipids, bile pigments, cholesterol, mineral salts, etc.; pH = 6.9-7.7), designed to emulsify fats and activate enzymes for their cleavage; has a yellowish or greenish-brown color, which is determined by bile pigments bilirubin and others, formed during the breakdown of hemoglobin. The liver produces 500-1200 ml of bile per day.

❖ The main functions of bile:
■ creation of an alkaline environment in the intestine;
■ increased motor activity (motility) of the intestine;
■ crushing fat into droplets ( emulsification), which facilitates their splitting;
■ activation of enzymes of intestinal juice and pancreatic juice;
■ facilitating the digestion of fats and other substances insoluble in water;
■ activation of absorption processes in the small intestine;
■ has a destructive effect on many microorganisms. Without bile, fats and fat-soluble vitamins cannot not only be broken down, but also absorbed.

Colon

Colon has a length of 1.5-2 m, a diameter of 4-8 cm and is located in the abdominal cavity and the pelvic cavity. There are four divisions in it: blind intestine with a vermiform appendix - appendix, sigmoid, colonic and straight intestines. At the place of transition of the small intestine to the large intestine is located valve , providing unidirectional movement of intestinal contents. The rectum ends anus surrounded by two sphincters that regulate bowel movement. The internal sphincter is formed by smooth muscles and is under the control of the autonomic nervous system, the external sphincter is formed by the annular striated muscle and is controlled by the central nervous system.

The large intestine produces mucus, but has no villi and is almost devoid of digestive glands. It is inhabited by symbiotic bacteria , synthesizing organic acids, vitamins of groups B and K and enzymes, under the influence of which partial breakdown of fiber occurs. The resulting toxic substances are absorbed into the bloodstream and enter the liver through the portal vein, where they are rendered harmless.

The main functions of the colon: breakdown of fiber (cellulose); absorption of water (up to 95%), mineral salts, vitamins and amino acids produced by microorganisms; the formation of semi-solid feces; moving them into the rectum and reflex excretion through the anus to the outside.

Suction

Suction- a set of processes that ensure the transfer of substances from gastrointestinal tract into the internal environment of the body (blood, lymph); it is attended by cellular organelles: mitochondria, Golgi complex, endoplasmic reticulum.

Substance absorption mechanisms:

■ passive transport (diffusion, osmosis, filtration) carried out without energy consumption, and

Through diffusion (it occurs due to the difference in the concentration of the solute) some salts and small organic molecules; filtration (observed with an increase in pressure as a result of contraction of intestinal smooth muscles) promotes the absorption of the same substances as diffusion; through osmosis water is absorbed; by active transport sodium, glucose, fatty acids, amino acids are absorbed.

The sections of the digestive tract in which absorption occurs. The absorption of various substances is carried out throughout the entire digestive tract, but the intensity of this process in different departments is not the same:

■ in oral cavity absorption is insignificant due to the short-term stay of food here;

■ in stomach glucose is absorbed, partially water and mineral salts, alcohol, certain medications;

■ in small intestine amino acids, glucose, glycerin, fatty acids, etc. are absorbed;

■ in colon water, mineral salts, vitamins, amino acids are absorbed.

❖ The effectiveness of absorption in the intestine is provided by:

■ villi and microvilli (see above), which increase the absorption surface of the small intestine by 30-40 times;

■ high blood flow in the intestinal mucosa.

Features of the absorption of various substances:

■ proteins absorbed into the blood in the form of amino acid solutions;

■ carbohydrates absorbed mainly in the form of glucose; most intensively glucose is absorbed in the upper intestine. Blood flowing from the intestine is directed through the portal vein to the liver, where most of glucose is converted into glycogen and stored in reserve;

■ fats absorbed mainly into the lymphatic capillaries of the villi of the small intestine;

■ water is absorbed into the blood (most intensively - 1 liter in 25 minutes - in the large intestine);

■ mineral salts absorbed into the blood in the form of solutions.

Digestion regulation

The digestion process lasts from 6 to 14 hours (depending on the composition and amount of food). Regulation and strict coordination of actions (motor, secretory and absorption) of all organs of the digestive system in the process of digestion are carried out with the help of nervous and humoral mechanisms.

■ The physiology of digestion was studied in detail by I.P. Pavlov, who developed new method study of gastric secretion. For these works I.P. Pavlov was awarded Nobel Prize(1904).

The essence of the method of I.P. Pavlova: a part of the stomach of an animal (for example, a dog) is surgically isolated so that all autonomic nerves and she had full digestive function, but so that food does not get into it. A fistula tube is implanted into this part of the stomach, through which the secreted gastric juice is discharged to the outside. By collecting this juice and determining its qualitative and quantitative composition, it is possible to establish the main features of the digestion process at any stage.

Food center- a set of structures located in the central nervous system that regulate food intake; includes nerve cells centers of hunger and satiety located in the hypothalamus, centers of chewing, swallowing, sucking, salivation, secretion of gastric and intestinal juice located in the medulla oblongata, as well as neurons of the reticular formation and certain areas of the cerebral cortex.

■ The food center is excited and inhibited nerve impulses coming from receptors of the gastrointestinal tract, vision, smell, hearing, etc., as well as humoral agents (hormones and other biologically active substances) supplied to it with blood.

❖ Regulation of salivation — complex reflex ; includes unconditioned and conditioned reflex components.

■ Unconditioned salivary reflex: when food enters the oral cavity with the help of located in this cavity receptors taste, temperature and other properties of food are recognized. From receptors along sensory nerves, excitation is transmitted to salivation center located in the medulla oblongata. From him the team goes to salivary glands , as a result of which saliva is released, the quantity and quality of which is determined physical properties and the amount of food.

■ Conditioned reflex reaction(carried out with the participation of the cerebral hemispheres of the brain): salivation that occurs when there is no food in the mouth, but when you see or smell well-known food or when you mention this food in conversation (while the type of food that we have never tasted , does not cause salivation).

Regulation of gastric acid secretion — complex reflex (includes conditioned reflex and unconditioned components) and humoral .

■ The regulation of secretion is carried out in a similar (complex reflex and humoral) manner bile and pancreatic juice .

■ Conditioned reflex reaction(carried out with the participation of the cerebral cortex): the secretion of gastric juice begins long before food enters the stomach when thinking about food, smelling it, seeing a set table, etc. Such I.P. Pavlov called it "hot" or "appetizing"; it prepares the stomach for eating.

■ Noise, reading, extraneous conversations inhibit the conditioned reflex reaction. Stress, irritation, rage intensify, and fear and melancholy inhibit gastric acid secretion and gastric motility (motor activity).

■ Unconditioned reflex: increased secretion of gastric juice as a result of mechanical irritation with food (a 1 also chemical irritation with spices, pepper, mustard) of the receptors in the mouth and stomach.

■ Humoral regulation: the release of the gastric mucosa (under the influence of food digestion products) hormones (gastrin, etc.), which enhance the secretion of hydrochloric acid and pepsin. Humoral agents - secretin (formed in the duodenum) and cholecystokinin stimulating the formation of digestive enzymes.

❖ Phases of gastric secretion: cephalic (cerebral), gastric, intestinal.

■ Cephalic phase- the first phase of gastric secretion, proceeding under the control of conditioned and unconditioned reflexes. Lasts about 1.5-2 hours after eating.

■ Gastric phase- the second phase of secretion of juice, during which the secretion of gastric juice is regulated by hormones (gastrin, histamine) formed in the stomach itself and supplied with blood flow to its glandular cells.

■Intestinal phase- the third phase of secretion of juice, during which the secretion of gastric juice is regulated chemicals, formed in the intestine and entering the glandular cells of the stomach with the blood stream.

❖Regulation of intestinal juice secretion — unconditional reflex and humoral .

■ Reflex regulation: the mucous membrane of the small intestine begins to reflexively secrete intestinal juice as soon as the acidic food gruel enters the initial part of the intestine.

■ Humoral regulation: secretion (under the influence of weak hydrochloric acid) by the inner layer lining the small intestine, hormones cholecystokinin and secretin stimulating the secretion of pancreatic juice and bile. The regulation of the digestive system is closely related to the mechanisms of formation of targeted eating behavior based on hunger, or appetite .

The organs of the gastrointestinal tract are arranged in such a way that a person receives from food everything necessary for his life. What kind important functions do the digestive organs? Thanks to their well-coordinated work, toxins and poisons do not enter the bloodstream. In addition, the digestive system protects a person from some infectious diseases and allows his body to synthesize vitamins on its own.

The structure and function of the digestive system

The digestive tract consists of the following links:

• oral cavity with salivary glands;
• pharynx;
• esophagus;
• stomach;
• liver;
• colon and small intestine;
• pancreas.

Body name	Structural features	Functions performed
Oral cavity	Tongue, teeth	Grinding, analysis and softening of the food lump
Esophagus	Muscular, serous membranes, epithelium	Motor, protective and secretory functions
Stomach	Has a large number of blood vessels	Digestion of the food lump
Duodenum	Includes the ducts of the liver and pancreas	Moving the food lump along the digestive tract
Liver	Has veins and arteries that are responsible for the blood supply to the organ	Distribution of nutrients, synthesis of various substances and neutralization of toxins, production of bile
Pancreas	Located under the stomach	Excretion with enzymes of a special secret that modifies nutrients
Small intestine	It is laid in loops, the walls of this organ can contract, there are villi on the inner mucous membrane that increase its area	Absorption of split nutrients
Large intestine (with anus and straight section)	The walls of the organ are made up of muscle fibers	Completion of the digestion process, as well as water absorption, feces formation and bowel movement through the act of defecation

The digestive tract looks like a tube that is seven to nine meters long. Some glands are located outside the walls of the system, but interact with it and perform general functions... Interestingly, the gastrointestinal tract is long, but fits inside human body thanks to a huge number bends and loops of the intestines.

Digestive system functions

The structure of the human digestive organs, of course, is of considerable interest, however, the functions that they perform are also curious. First, the lump of food enters the pharynx through the mouth. Then it moves to other parts of the gastrointestinal tract along the esophagus.

Food crushed in the mouth and processed with saliva enters the stomach. In the abdominal cavity are the organs of the final segment of the esophagus, as well as the pancreas and liver.

The duration of the stay of food in the stomach depends on its type, but is no more than a few hours. The food in the specified organ interacts with gastric juice, as a result of which it becomes very liquid, it is mixed, and later digested.

Further, the mass enters the small intestine. Thanks to enzymes (enzymes), nutrients are converted into elemental compounds, which are absorbed into circulatory system, before going through filtration in the liver. Leftover food moves into the large intestine, where fluid is absorbed and feces are formed. Through bowel movements, processed food is expelled from the human body.

The importance of saliva and esophagus in the digestive system

The organs of the digestive system cannot function normally without the participation of saliva. Small and large salivary glands are located on the mucous membrane of the oral cavity, where food initially gets. The large salivary glands are near auricles, under the tongue and jaws. The glands located near the auricles produce mucus, and the other two types produce a mixed secret.

The saliva flow can be very intense. So, when using lemon juice, up to 7.5 ml of this liquid is released per minute. It contains amylase and maltase. These enzymes activate the digestive process already in the oral cavity: starch under the action of amylase is converted to maltose, which is then modified by maltase to glucose. Most of the saliva is water.

The food lump is in the mouth for up to twenty seconds. During this time period, starch cannot fully dissolve. Saliva, as a rule, has either a slightly alkaline or neutral reaction. In addition, this liquid contains a special protein, lysozyme, which has disinfecting properties.

The human digestive organs include the esophagus, which follows the pharynx. If you imagine its wall in section, you can see three layers. The middle layer is made up of muscle and can contract, which makes it possible for the food bolus to travel from the pharynx to the stomach.

When food passes along the esophagus, the sphincter of the stomach is triggered. This muscle prevents the reverse movement of the food bolus and holds it in the specified organ. If it does not work well, then the processed masses are thrown back into the esophagus, which leads to heartburn.

Stomach

This organ is the next link of the digestive system after the esophagus and is localized in the epigastric region. The parameters of the stomach are determined by its contents. An organ free from food has a length of no more than twenty centimeters and a distance between the walls from seven to eight centimeters. If the stomach is moderately filled with food, then its length will increase to twenty-five centimeters, and its width - up to twelve centimeters.

The capacity of an organ is variable and depends on its contents. It ranges from one and a half to four liters. When the act of swallowing is performed, the muscles of the stomach relax until the end of the meal. But all this time, his muscles are at the ready. Their importance cannot be overstated. The food is frayed, and thanks to the movement of the muscles, it is processed. The digested food bolt moves to the small intestine.

Gastric juice is a clear liquid with an acidic reaction due to the presence of hydrochloric acid in its composition. It contains the following groups of enzymes:

• proteases that break down proteins into polypeptide molecules;
• lipases affecting fats;
• amylases converting complex carbohydrates into simple sugars.

The production of gastric juice is usually carried out during the consumption of food and lasts for a period of four to six hours. Up to 2.5 liters of this liquid are released in 24 hours.

Small intestine

This segment of the digestive system is made up of the following links:

• the duodenum;
• skinny intestine;
• the intestine.

The small intestine is "packed" in loops, which makes it fit in the abdominal cavity. He is responsible for continuing the food processing process, mixing it and then routing it to the thick section. The glands located in the tissues of the small intestine produce a secretion that protects its mucous membrane from damage.

In the duodenum, the medium is slightly alkaline, but with the penetration of the mass from the stomach into it, it changes downward. In this zone there is a pancreatic duct, the secret of which alkalizes the food lump. It is here that the enzymes of the gastric juice stop their action.

Colon

This section of the gastrointestinal tract is considered the final, its length is approximately two meters. It has the largest lumen, however, at the descending colonic region, the width of this organ decreases from seven to four centimeters. The structure of the large intestine includes several zones.

Most of the time, the food bolus resides in the large intestine. The process of digesting food itself takes from one to three hours. In the large intestine, the accumulation of contents, the absorption of substances and liquids, their movement along the tract, the creation and elimination of feces are carried out.

Typically, food reaches the large intestine about three hours after the end of the meal. This segment of the digestive system fills up within one day, and then gets rid of food debris in 1-3 days.

In the large intestine, the absorption of nutrients produced by the microflora that lives in this section, as well as an impressive part of water and various electrolytes, is carried out.

The effect of alcohol on the gastrointestinal tract

The negative effect of alcohol on the state of the gastrointestinal tract begins in the oral cavity. High concentrations of ethanol provoke a decrease in saliva secretion. This liquid has bactericidal properties, that is, it disinfects plaque microorganisms. With a decrease in its amount, the oral cavity becomes a suitable place for the development of diseases. Carcinoma of the throat and oral cavity is, unfortunately, common among drinkers.

With the regular use of alcohol, the body's defense mechanisms deteriorate. Their poor quality work affects the functioning of the gastrointestinal tract. First of all, the esophagus suffers. A person who has encountered alcohol addiction, often there are difficulties with swallowing, and sometimes food that has entered the stomach is thrown back into the esophagus.

An addiction can lead to the development of gastritis and a deterioration in secretory function. Ethanol negatively affects the functioning of the pancreas. In addition, frequent alcohol consumption increases the risk of pancreatitis, which can be acute or chronic.

The most famous consequence of alcohol addiction is cirrhosis. Unfortunately, it often develops into liver cancer. Cirrhosis is not the only disease that develops in people who are alcohol dependent. There are also pathologies such as hepatomegaly and hepatitis. Their treatment requires a competent approach.

Thus, the digestive system consists of several links, the well-coordinated work of which largely depends on human health. It is thanks to the gastrointestinal tract that the body receives all the nutrients it needs for normal life.

The liver plays an important role: it disinfects toxins and other harmful compounds that enter it through the portal vein. She spends tremendous energy on her work. Since this organ is considered a kind of "filter", the state of human health largely depends on the quality of its work.

The negative effects of alcohol on the digestive system cannot be underestimated. Regular use drinks containing ethanol provokes the development of various diseases of the gastrointestinal tract, which cannot always be cured. Addiction to addiction is bad for the body as a whole.

The digestive tract consists of the following sections: the upper, consisting of the mouth and larynx, the middle, consisting of the esophagus and stomach, and the lower, the small and large intestine.

Upper digestive tract

Mouth

Mouth- the first part of the digestive tract. It contains: hard and soft palate, lips, muscles, teeth, salivary glands and tongue.
The hard and soft palate forms the upper wall of the mouth. The hard palate is formed by the upper jaw and palatine bone and lies in front of the mouth. The soft palate is composed of muscles and lies at the back of the mouth, forming an arch with the uvula.

Lips- extremely mobile formations - are the entrance to the oral cavity. They are composed of muscle tissue and have an abundant blood supply that ensures their color, and many nerve endings that allow them to determine the temperature of food and liquids entering the mouth.

Muscles - There are three main facial muscles involved in chewing:

1. Cheek muscles
2. Chewing muscles on the sides of the face
3. Temporal muscles

Teeth... Children have 20 deciduous teeth, which are replaced by 32 permanent teeth in the period from 6 to 25 years. An adult has 16 upper teeth growing from the dental cells of the upper jaw, and 16 - in the lower jaw.

There are three types of teeth:

1. Front incisors
2. Cone-shaped canines
3. Posterior premolar and molar teeth, flatter than the rest.

Salivary glands- contain cells that produce a thick, watery liquid - saliva. Saliva is made up of water, mucus, and the enzyme salivary amylase.

There are three pairs of salivary glands:

1. Ear, located under the ears
2. Sublingual
3. Submandibular

Language- formed by skeletal muscles and attached to the hyoid bone and mandible. Its surface is covered with small papillae with sensitive cells. Because of this, they are called taste buds.

Pharynx

The pharynx connects the digestive and respiratory systems and has three parts:

1. The nasopharynx is a conduit for air inhaled through the nose. Rather associated with respiratory system than with the digestive system.
2. The oropharynx is located behind the soft palate and nasopharynx and is a conduit for air, food, and fluid through the mouth.
3. The laryngopharynx is an extension of the oropharynx, leading further into the digestive tract.

The tonsils in the throat and the adenoids on the back of the nose protect the body from infection through food, fluid, and air.

Middle and lower digestive tract

The middle and lower parts of the digestive tract are a single structure from the esophagus to the anus. Throughout its course, it changes in accordance with its functions.

The digestive tract is made up of four main layers:

1. The peritoneum is a dense outer layer that secretes a lubricant that allows the organs of the digestive system to glide.
2. Muscle layers - The muscle fibers are arranged in two layers. The inner layer is the circular layer of the muscular membrane, the outer layer is longitudinal. The contraction and relaxation of these muscles is called peristalsis and is a wave-like movement that propels food through the digestive tract.
3. Submucosa - consists of loose connective tissue containing elastic fibers, lymphatic vessels and nerves that are involved in the life of the digestive tract, nourishing it and ensuring its sensitivity.

Esophagus

The esophagus is a long tube (about 25 cm) that runs from the pharynx to the stomach. It lies behind the trachea, in front of the spine. The empty esophagus is flat. The muscle structure allows it to expand when ingested. The muscle layer contracts, pushing food down the esophagus (peristalsis) through an annular muscle called the cardiac sphincter into the stomach.

Stomach

The stomach is a comma-shaped bag and lies under the diaphragm on the left side. The lining of the stomach has many folds that allow it to stretch when full and contract when the stomach is empty. In the same layer lie the gastric glands, which produce gastric juice that dissolves food.

The muscular layer of the digestive tract is the thickest in the stomach, since here it moves during the digestion of food. At the end of the stomach is another annular muscle - the pyloric sphincter. It controls the passage of digested food to the lower digestive system.

Small intestine

The small intestine is by no means small. It is about 6 meters long. It curls up around itself and fills the abdominal cavity.

The general structure of the small intestine is the same as that of others. digestive organs except that it has tiny protective villi on its inner mucosa. They contain glands that produce digestive juices; blood capillaries that take nutrients from digested food; lymphatic capillaries, called milky vessels, that absorb food fats.

The small intestine is also connected with additional organs of the digestive system. The gallbladder and pancreas connect to the small intestine in the duodenum, respectively, by the bile and pancreas ducts.

Colon

The large intestine is wider and shorter than the small intestine. It is about 1.5 meters long and is divided into 5 sections.

• The cecum is separated from the ileum of the small intestine by the ileocecal sphincter. Attached to the cecum is an appendix formed by lymphatic tissue. It is not involved in digestion, but it protects the system from infections.
• The colon is divided into four parts: ascending, transverse and descending, the position of which corresponds to the names, and the sigmoid, which connects the colon to the rectum.
• The rectum comes from sigmoid colon and lies next to the sacrum.
• The anal canal is a continuation of the rectum.
• The intestine ends with the anus, formed by two muscles: the internal and external sphincters.

The structure of additional organs

The liver, gallbladder and pancreas are also part of the digestive system. They also have functions associated with other systems that make them important connecting links in the body.

Liver

The liver is the largest internal organ. It lies directly below the diaphragm in the upper right abdomen. The liver has a larger right side and a smaller left side. The parts of the liver are called lobes; right lobe associated with the gallbladder channel. The liver is one of the most important connecting links in the body, which has an abundant blood supply. It receives oxygenated blood through the hepatic artery, which is a branch of the descending aorta, and venous blood with nutrients through the hepatic portal vein, which is part of the portal circulation. As a result, the liver performs many functions, not all of which are related to the digestive system.

• Filtration - the blood of the hepatic portal vein is filtered through the liver; old and damaged red blood cells and other unnecessary substances, including excess proteins, are removed from it.
• Detoxification - The liver removes toxins from the blood such as drugs and alcohol.
• Breakdown - The liver breaks down damaged, dead blood cells to form bilirubin, which is involved in the production of bile. The liver also destroys unnecessary particles(toxins and excess proteins), forming urea, which is eliminated from the body in the form of urine.
• Storage - The liver stores a certain amount of vitamins, glycogen and iron, which the body receives from food for later use, such as muscle glycogen.
• Production - The liver produces bile, which is stored in the gallbladder. Bile helps maintain body temperature by producing heat and destroys damaged and dead red blood cells, resulting in breakdown products in the liver.

Gall bladder

The gallbladder resembles sadness in shape. It is located just above the duodenum and below the liver and is connected to both organs by tributaries. The gallbladder receives bile from the liver for storage until the duodenum needs it to digest food. Bile is composed of water, bile salts used in digestion, and bile pigments, including bilirubin, which gives feces their characteristic color. Gallstones formed from large particles bile, which can block its passage into the duodenum; in this case, severe pain occurs.

Pancreas

The pancreas is a long, thin organ that lies across the left side of the abdomen.

This gland has a twofold function:

• It is endocrine, i.e. produces hormones that are released into the bloodstream as part of the excretory system.
• She is exocrine. those. produces a liquid substance - pancreatic juice, which flows through the ducts into the duodenum and participates in digestion. Pancreatic juice is made up of water, minerals and enzymes.

In carrying out its functions, the digestive system relies on the interaction of all its parts.

Digestive system functions

Swallowing

This includes eating, chewing, and crushing food in your mouth. The food takes the form of a soft ball called a bolus.

This process involves:

• Lips - The nerve endings of the lips evaluate the temperature of food and liquid entering the mouth, and the movements of the muscles of the upper and lower lips ensure their tight closure.
• Teeth - incisors can bite off large pieces of food; sharp fangs tearing food apart; molars rub it.
• Muscles - the cheek muscles move the cheeks inward; chewing muscles lift lower jaw to the top, thereby pressing on the food in the mouth; the temporal muscles close the mouth.
• Saliva - Binds and moisturizes food, preparing it for swallowing. Saliva dissolves food so that we can taste it, and it also cleans the mouth and teeth.
• Tongue - feels the taste of food, moving it around the mouth during chewing, before moving the finished lump into back mouth to swallow. The papillae on the surface of the tongue have tiny nerves that determine if we want to continue by sending a signal to the brain to interpret the taste.
• Pharynx - The muscles in the pharynx contract and propel the bolus down into the esophagus. During swallowing, all other pathways are closed. The soft palate rises and covers the nasopharynx. The epiglottis closes the entrance to the trachea. Thus, this muscle coordination ensures the correct direction of food movement.

Digestion

Digestion is the breakdown of food into tiny particles that can be absorbed by cells.

In digestion, 2 processes can be distinguished:

• Mechanical digestion is the chewing of food to crush and form food lumps (boluses) that occur in the mouth.
• Chemical digestion, which is the breakdown of food by digestive juices containing enzymes, which takes place in the mouth, stomach and duodenum. During this time, the food lump is transformed into a chyme.
• The saliva produced in the mouth by the salivary glands contains the enzyme amylase. In the mouth, amylase begins the breakdown of carbohydrates.
• In the stomach, the glands present produce gastric juices, which contain the enzyme pepsin. It breaks down proteins.
• The stomachs also produce hydrochloric acid, which stops the action of salivary amylase and also kills harmful particles that enter the stomach. When the level of acidity in the stomach reaches a certain level, the pyloric sphincter passes a small portion of the digested food into the first section of the lower digestive tract - the duodenum.
• Pancreatic juices from the pancreas through the duct enter the duodenum. They contain enzymes. Lipase breaks down fats, amylase continues to digest carbohydrates, trypsin breaks down proteins.
• In the duodenum itself, the villi of the mucous membrane produce digestive juices; they contain the enzymes maltose, sucrose and lactose, which break down sugar, and erepsin, which completes the processing of proteins.
• At the same time, bile produced in the liver and stored in gallbladder, enters the duodenum. Bile breaks down fats into smaller particles during the emulsification process.

In the process of digestion, the food we eat undergoes a series of changes from a solid food in the mouth to a bolus and liquid chyme. Carbohydrates, proteins and fats must be broken down by enzymes for the following processes to occur.

Absorption

Absorption is the process of transferring nutrients from the digestive system into the bloodstream to carry them throughout the body. Absorption takes place in the stomach, small intestine and colon.

• From the stomach, a limited amount of water, alcohol and drugs go directly into the blood stream and are carried through the body.
• During peristaltic movements of the muscles of the small intestine, the chyme passes through the duodenum, jejunum and ileum. At the same time, the villi of the mucous membrane ensure the absorption of digested nutrients. The villi contain blood capillaries that take digested carbohydrates, proteins, vitamins, minerals and water into the blood stream. The villi also contain lymphatic capillaries called milky vessels that absorb digested fats before they enter the bloodstream. The blood carries the obtained substances throughout the body in accordance with its requests and after that it is cleared by the liver, leaving excess nutrients in it for storage. When the chyme reaches the end of the duodenum, most of the nutrients have already been absorbed by the blood and lymph, leaving only indigestible food particles, water and a small amount of nutrients.
• When the chyme reaches the ileum, the end of the small intestine, the ileocecal sphincter allows it to pass into the large intestine and closes to prevent it from returning. All the nutrients remaining in it are absorbed, and feces are obtained from the remains. Peristaltic movements of the muscles push them up the colon and into the rectum. The rest of the water is absorbed along the way.

Excretion

Excretion is the removal of indigestible food debris from the body.

When the faeces reach the rectum, we reflexively feel the need to empty the intestines. Peristaltic movements push the feces through the anal canal and the internal sphincter relaxes. The movements of the external sphincter are arbitrary, and at this moment we can choose to empty the intestines or close the muscle until a more appropriate moment.

This whole process takes from several hours to several days, depending on its complexity. Nutritious, dense foods take longer to digest and stay in the stomach longer than lighter, softer foods. Absorption occurs over the next few hours, followed by excretion. All of these processes are more effective if the body is not overloaded. The digestive system needs rest, when blood from the muscles can move to it, which is why we feel sleepy after eating, and when too much physical activity we suffer from indigestion.

Possible violations

Possible disorders of the digestive system from A to Z:

• ANOREXIA - lack of appetite, leading to exhaustion, and in severe cases- to death.
• APPENDICITIS - inflammation of the appendix. Acute appendicitis occurs suddenly and the appendix is ​​surgically removed. Chronic appendicitis can last for several months without the need for surgery.
• CROWN DISEASE - see ILEITIS.
• BULIMIA is a binge eating disorder that causes people to vomit and / or take laxatives. Like anorexia, bulimia is a psychological problem and normal food intake can only be restored once it is eliminated.
• LOSS - displacement of an organ, such as the rectum.
• GASTRITIS is an irritation or inflammation of the stomach. May be caused by eating certain foods or drinks.
• GASTROENTERITIS - inflammation of the stomach and intestines, leading to vomiting and diarrhea. Dehydration and exhaustion can occur very quickly, so care must be taken to replenish lost fluids and nutrients.
• HEMORRHOUS is swelling of the veins in the anus that causes pain and discomfort. Bleeding from these veins can lead to anemia due to iron loss.
• GLUTEN DISEASE - intolerance to gluten (a protein found in wheat).
• A HERNIA is a rupture in which an organ extends beyond its protective sheath. Colon hernia is common in men.
• DIARRHEA - too frequent bowel movements as a result of a peristaltic "attack", leading to dehydration and exhaustion, as the body does not receive a large amount of water and nutrients.
• DYSENTERIA is an infection of the colon resulting in severe diarrhea.
• Jaundice - yellow skin staining, which in adults is a sign of a serious illness. Yellow Caused by bilirubin, which is produced when red blood cells in the liver break down.
• GALL STONES - Solid formations of bile particles in the gallbladder that can cause bile to enter the duodenum. In difficult cases, removal of the gallbladder is sometimes required.
• CONSTITUTION - Irregular bowel movements due to dry, hard feces when too much water is absorbed.
• IKOTA - repeated involuntary spasms of the diaphragm.
• ILEITIS - inflammation of the ileum. Another name is Crohn's disease.
• ACID REGULATION - a condition when the contents of the stomach, together with hydrochloric acid and digestive juices, return to the esophagus, causing a burning sensation.
• Colitis is an inflammation of the colon that leads to diarrhea. In this case, there is a stool with blood and mucus due to damage to the mucous membrane.
• METEORISM - the presence of air in the stomach and intestines that has been swallowed with food. May be associated with certain foods that gas during digestion.
• INDIGENOUS - pain associated with eating certain foods that are difficult to digest. It can also be caused by overeating, hunger, or other causes.
• OBESITY - being overweight as a result of overeating.
• PROCTITIS is an inflammation of the rectal lining, causing both pain when passing feces and the need to empty the intestines.
• INTESTINAL CANCER - colon cancer. It can form in any part of it and block permeability.
• ESOPHAGEAL CARCINOMA - malignant tumor along the length of the esophagus. Most often occurs in the lower esophagus in middle-aged men.
• Mucous colitis is a disease usually associated with severe stress... Symptoms are alternating periods of diarrhea and constipation.
• LIVER CIRROSIS - hardening of the liver, usually caused by alcohol abuse.
• ESOPHAGITIS is an inflammation of the esophagus, often characterized by heartburn (burning sensation in the chest).
• Ulcer - opening the surface of any part of the body. It usually occurs in the digestive tract, where its lining is disrupted due to an excess of acid in the digestive juices.

Harmony

The efficient functioning of the digestive system ensures that the cells, tissues, organs and systems of the body receive the optimal amount of nutrients and water. The digestive system, in addition to the state of its own components, depends on its connections with other systems.

Liquid

The body loses about 15 liters of fluid per day: through the kidneys with urine, through the lungs when exhaling, through the skin with sweat and feces. The body produces about a third of a liter of water per day during the production of energy in cells. Therefore, the body's minimum need for water - a little more than a liter - allows you to maintain fluid balance and avoid dehydration. Drinking water prevents constipation: when feces stagnates in the intestines, most of the water is absorbed and it dries up. This makes bowel movements difficult, painful, and can strain the lower digestive tract. Constipation affects other body systems as well, leading to skin laxity if toxins in the faeces are retained in the body.

Nutrition

The task of the digestive system is to break down food into substances that can be absorbed by the body - part of the natural process of maintaining life. Food can be divided into:

1. Carbohydrates - are broken down to glucose and carried by the blood to the liver. The liver directs some of the glucose to the muscles, and it is oxidized during energy production. Some of the glucose is stored in the liver as glycogen and is sent to the muscles later. The rest of the glucose is carried by the blood stream to the cells, its excess is deposited in the form of fats. There are fast-depleting carbohydrates: in sugar, candy and most instant foods, which provide a short burst of energy, and slow-depleting: in grains, vegetables and fresh fruits, which provide a longer charge.
2. Proteins (proteins) - are broken down into amino acids, which provide growth and recovery of the body. The proteins that we get from eggs, cheese, meat, fish, soy, lentils and legumes are broken down into different amino acids during digestion. Then these amino acids are absorbed by the blood and enter the liver, after which they are either removed or used by the cells. The liver cells convert them into plasma proteins; proteins change; are broken down (unnecessary proteins are destroyed and pass into urea, which enters the kidneys with blood and is removed from there in the form of urine).
3. Fats - enter the lymphatic system through the milk vessels during emulsification, before entering the bloodstream through the lymphatic ducts. They are another source of energy and material for the formation of cells. Excess fats removed from the blood and deposited. There are two main sources of fat: hard fats from dairy products and meat, and soft fats from vegetables, nuts, and fish. Hard fats are not as healthy as soft fats.
4. Vitamins A, B, C, D, E and K are absorbed from the digestive system and participate in all processes in the body. Excess vitamins can be stored in the body until needed, such as during a diet. Vitamins A and BJ2 are stored in the liver, vitamins A, D, E and K, fat soluble- in fat cells.
5. Minerals (iron, calcium, soda, chlorine, potassium, phosphorus, magnesium, fluorine, zinc, selenium, etc.) are absorbed like vitamins and are also necessary for various processes in the body. Excess minerals are not absorbed and are removed either c. feces, or urine through the kidneys.
6. Fiber is a dense, fibrous carbohydrate that cannot be digested. The insoluble fiber found in wheat bran, fruits and vegetables makes it easier for faeces to pass through the colon, increasing their mass. This mass absorbs water, making the feces softer. The muscle layer of the large intestine is stimulated and waste products are removed from the body more quickly, reducing the risk of constipation and infection.
   It is clear that in order to fulfill my functions, the digestive system requires a balanced supply of nutrients. Ignoring the body's need for food leads to rapid dehydration into exhaustion. Over time, it leads to even more major changes which result in illness or even death.

Recreation

The body needs rest so that the digestive system can process the food it receives. Before and immediately after eating, the body needs a short period of rest for the digestive tract to do its job. The digestive system requires an abundant flow of blood to function naturally and efficiently. During rest, a large volume of blood can flow to the alimentary canal from other systems. If the body remains active during and immediately after a meal, not enough blood is involved in the digestion process. Due to ineffective digestion, heaviness, nausea, flatulence, indigestion occur. Rest also provides time for nutrient absorption. In addition, after a good rest, the cleansing of the body is much more effective.

Activity

Activity becomes possible when food and liquid have been crushed, digested, and assimilated. During digestion, proteins, fats and carbohydrates obtained from food are broken down so that, after being absorbed, they can be used for energy production in cells (cellular metabolism). When the body is deficient in nutrients, it uses up reserves from muscle, liver and fat cells. Eating more food than is necessary leads to weight gain and less food to weight loss. The energy value of products is calculated in kilocalories (Kcal) or kilojoules (kJ). 1 kcal = 4.2 kJ; average daily requirement for a woman and 2550 kcal / 10 600 kJ for a man. To maintain body weight, it is necessary to measure the amount of food consumed with the body's need for energy. The amount of energy required for each person varies according to age, gender, physique and physical activity... It changes during pregnancy, lactation, or illness. The body responds with a feeling of hunger to the growing need for energy. However, this feeling often misleads us, and we eat out of boredom, out of habit, in company or simply because of the availability of food. In addition, we very often ignore satiety signals and indulge ourselves.

Air

The air from the atmosphere contains oxygen, which is necessary to activate the energy obtained from food. The way we breathe determines the amount of activated energy and must correlate with the needs of the body. When the body needs a lot of energy, breathing becomes more frequent, with a decrease in this need, it slows down significantly. It is important to breathe more calmly during meals so that too much air does not enter the digestive tract, and to breathe faster when it is necessary to activate the energy received from food. Although breathing is an involuntary process carried out by the respiratory and nervous systems, we can control its quality to some extent. If more attention was paid to the art of breathing, the body would be much less susceptible to stress and injury, which in turn would prevent the occurrence of many diseases or alleviate their syndromes (mucous colitis is significantly relieved by proper breathing).

With increasing age, the body's energy needs change: children need more energy than older people. With aging, the processes in the body slow down, and this is reflected in the need for food, which changes in proportion to the decrease in the level of activity. Middle-aged people are often overweight because they ignore the need to reduce their food intake. Changing your eating habits can be difficult, especially when associated with pleasure. In addition, age affects digestion: it becomes difficult due to a decrease in the absorption of nutrients.

Colour

The digestive tract takes up a large part of the body, stretching from the mouth down to the anus. It goes through five chakras, from the fifth to the first. Thus, the digestive system is associated with the colors corresponding to these chakras:

• Blue, the color of the fifth chakra, is associated with the throat.
• Green - the color of the fourth chakra - brings the system to harmony.
• Yellow, associated with the third chakra, cleanses by affecting the stomach, liver, pancreas and small intestine, aids in digestion and absorption of nutrients.
• Orange - the color of the second chakra - continues the cleansing process and helps to remove waste products through the small and large intestines.
• Red - the color of the first chakra - affects excretion by preventing the lower digestive system from lethargy.

Knowledge

Knowing what role the digestive system plays in general health organism is the key to healthy eating... In addition, when we understand our body's signals, it is easier to achieve a balance between physical and psychological needs for food. Children intuitively know what they need to eat and when, and when left alone with adequate food and water supplies, they never go hungry or overeat. Starting to live according to the laws of society, which, in general, do not take into account the needs of the digestive system, we very quickly lose this ability. What is the point in not having breakfast, given that it is in the morning that we need the most nutrients for the whole day? Why eat a three-course dinner at the end of the day when we don't need any energy for about 12 more hours?

Special care

The way the digestive system is treated affects the health of the entire body. A cared-for digestive system will take care of the entire body. It prepares "fuel" for the body, and the quality and quantity of this "fuel" correlates with the time it takes to grind, digest and assimilate food. Stress destroys the balance needed to efficiently produce fuel and is one of the main causes of digestive upset. Stress kind of turns off the digestive system until the situation returns to normal. In addition, it affects the feeling of hunger. Some people eat to calm down, others lose their appetite in stressful situations.

For the well-being of the digestive system, you need the following:

• Regular meals to provide the body with enough energy to perform its functions.
• Balanced nutrition for a healthy body.
• At least a liter of water a day to avoid dehydration.
• Fresh, unprocessed food containing the maximum amount of nutrients.
• Allocated time to eat to avoid indigestion.
• Time for regular bowel movements.
• Avoid increased activity immediately after eating.
• Eat when you are hungry, not out of boredom or habit.
• Chew food thoroughly for mechanical digestion to be effective.
• Avoid stressful situations which can adversely affect digestion, absorption and excretion.
• Avoid sources of free radicals - fried foods - that cause premature aging.

Think about how often you “gulp down” food, eat on the run, or even skip meals, and then eat fast food when hungry, but too tired, lazy, or busy to cook a normal meal. No wonder so many people have digestive problems!

The digestive system has a number of functions:

-mechanical function, or crushing of food, is carried out with the help of teeth in the oral cavity and due to mixing in the stomach and small intestine, as well as transportation of the food lump through the digestive tract due to contraction of the muscular membrane (peristalsis);

-secretory function consists in the synthesis and secretion of digestive enzymes by the digestive glands;

-chemical function consists in chemical processing food (digestion) with the help of digestive enzymes. Primary chemical processing of food begins in the mouth and ends in the small intestine, where the final chemical processing takes place. In the large intestine and at the border of the large and small intestines the intestinal microflora lives- symbiotic microorganisms that help us digest plant and dairy foods;

- suction function ensures the absorption of digestive products into the blood and lymph. Partial absorption of carbohydrates begins in the oral cavity, continues in the stomach, where protein breakdown products begin to be absorbed. The main absorption occurs in the small intestine. It should be noted that lipid digestion products are absorbed into the lymph;

-excretory function- allocation of undigested food and waste products;

-endocrine- the release of digestive hormones.

Oral cavity, or oral cavity(fig. 1)

Rice. 1.Oral cavity and pharynx: 1 - upper and 2 - lower lips; 3 - pharynx; 4 - language; 5 - palatine and 6 - palatine-pharyngeal arch; 7 - palatine tonsil; 8 - tongue; 9 - soft and 10 - hard palate; 11 - gums

Teeth(fig. 2). The main function is the capture and primary mechanical processing of food (grinding).

In humans, two types of teeth are distinguished, depending on the time of appearance:

-baby teeth(temporary). A child has 20 milk teeth, functioning until they are replaced with permanent teeth at the age of 7 to 13-14 years. On each half of the jaw there are 2 incisors, 1 canine, 2 large molars;

-permanent teeth... A person has 32 permanent teeth: in each half of the jaw there are 2 incisors, 1 canine, 2 small molars and 3 large molars.

Rice. 2.Tooth structure diagram: I - enamel; 2 - dentin; 3 - tooth pulp; 4 - gum; 5 - cement; 6 - periodontium; 7 -bone; I - tooth crown; II - the neck of the tooth; III - tooth root; IV - root canal

Language... A mobile muscular organ, dressed with a mucous membrane, richly supplied with blood vessels and nerves.

The mucous membrane is rich in taste buds - papillae(fig. 3). Distinguish: filiform and mushroom papillae- scattered over the entire upper surface of the tongue; papillae, surrounded by a roller, - in the amount of 7-11 are located on the border of the body and the root of the tongue; leaf-shaped papillae - well visible at the edges of the tongue. There are no papillae on the underside of the tongue.

The tongue is involved in the process of sucking, swallowing, articulating speech, is an organ of taste (mushroom and leaf-shaped papillae perceive sour, sweet and salty taste, and the papillae with a roller is bitter).

Rice. 3.Language: 1 - the root of the tongue; 2 - filiform, 3 - mushroom, 4 - surrounded by a roller and 5 - leaf-shaped papillae; 6 - blind fossa; 7 - palatal-lingual fold; 8 - palatine and 9 - lingual tonsils; 10 - epiglottis

Pharynx

The muscular organ connecting the oral cavity with the esophagus and the nasal cavity with the larynx, i.e. in the pharynx the digestive and respiratory tracts intersect... The pharynx is divided into three parts: nasopharynx, oropharynx and laryngeal part... In the throat are located six tonsils... Nasopharynx through choanas communicated with nasal cavity... On the side walls are holes of the auditory (Eustachian) tubes that connect it to the cavity middle ear, helping to equalize the pressure in the middle ear with external pressure. Tonsils perform an important protective and partly hematopoietic function. A sharp increase in the tonsils is the first sign of angina, scarlet fever, diphtheria.

Esophagus

It is a muscle tube about 25 cm long (Fig. 4). It begins without sharp boundaries from the pharynx at the level of the VI cervical vertebra and at the level of the XI thoracic vertebra opens into the stomach. The muscular membrane has features: in the upper third it consists of striated muscles, a in the lower third - only from smooth muscles... The main function of the esophagus is to carry the food bolus into the stomach. Partially, the esophagus performs a protective function with the help of three narrowings (it is in these narrowings that accidentally swallowed foreign objects very often get stuck). It does not have its own digestive glands; saliva enzymes carry out digestion. It has an alkaline environment.

Rice. 4.The structure of the esophagus wall. Mucous (I), muscular (II) and serous (III) membranes: 1 - multilayer squamous epithelium; 2 - own and 3 - muscle layers of the mucous membrane; 4 - submucosal layer; 5 - mucous gland; 6 - a layer of circular and longitudinal (7) muscles

Stomach

The only expanded part of the digestive tube with a volume of up to 5 liters (Fig. 5). Distinguish entrance (cardiac part), bottom, body and exit (gatekeeper). At the entrance and exit there are circular muscles-closures (sphincters)... The muscular layer has three types of muscles: longitudinal, annular and oblique.

The stomach performs several functions: mechanical processing of food by stirring, temporary storage and chemical processing of food, and partial absorption. Chemical processing of food is carried out by gastric juice secreted own glands. Gastric juice It has acidic environment(pH 2). Glands consist of three types of cells: the main secreting digestive enzymes, lining releasing hydrochloric acid, and additional secreting mucus.

Rice. 5.The stomach with an open anterior wall (A) and its muscular membrane (B): 1 - cardiac part; 2 - cardiac opening; 3 - the bottom of the stomach; 4 - the body of the stomach; 5 - small and 6 - great curvature stomach; 7 - pyloric (pyloric) part; 8 - gatekeeper; 9 - gatekeeper hole; 10 - muscular layer; 11 - longitudinal (outer) layer; 12 - circular layer; 13 - the sphincter of the gatekeeper; 14 - oblique fibers

Small intestine

The longest part of the digestive tract (up to 5 m) is divided into three parts: duodenum, skinny and ileum... A characteristic feature is the presence villi formed by the mucous membrane (Fig. 6, 7). The villi have microvilli formed by epithelium of the villi. On the border with the stomach and large intestine, there are sphincters... Ducts open into the duodenum pancreas and gallbladder.

Rice. 6.The mucous membrane of the small intestines. A - skinny; B - ileum: 1 - muscular membrane; 2 - mesentery; 3 - serous membrane; 4 - single follicles; 5 - circular folds; 6 - mucous membrane; 7 - group follicles

Rice. 7.Diagram of the structure of the villi of the small intestine: 1- intestinal epithelial cells; 2- goblet cells; 3 -central lymphatic sinus; 4 - arteriole; 5 - venule; 6 - blood capillaries

The small intestine is the organ in which the breakdown of proteins, fats and carbohydrates is finally completed and the products of their cleavage are absorbed as well as salts and water. Digestion occurs under the influence intestinal juice allocated intestinal glands, pancreatic juice secreted by the pancreas, and bile... There is cavity and parietal digestion.

Colon

It has a length of up to 2 m and a diameter of up to 5-7 cm. It consists of three sections: the cecum with a vermiform appendix (Fig. 8), the colon and rectum. There are a large number of symbiotic bacteria here. The main functions of the large intestine are the absorption of water and the formation of feces. Due to the presence of bacteria, there is fermentation of fiber and decay of proteins, a number of bacteria synthesize vitamins.

Rice. eight.The cecum with the appendix (appendix): 1 - appendix (appendix); 2 - opening of the appendix; 3 - cecum; 4 - opening of the small intestine; 5 - large intestine; 6 - colon

Digestive glands

Salivary glands ... The salivary glands secrete saliva, which consists of protein secretion(serous) and mucous component... Protein secretion is secreted parotid glands, slimy - palatine and posterior lingual; submandibular and sublingual is a mixed secret. The main components of saliva are: mucin- mucous protein substance, lysozyme- bactericidal substance, amylase enzymes and maltase.

Distinguish small and large salivary glands... Small ones include labial, buccal, dental, lingual, palatine... These glands are located in the corresponding areas of the oral mucosa. There are three pairs of large salivary glands: parotid, submandibular and sublingual; they lie outside the mucous membrane of the mouth, but the excretory ducts open into the oral cavity.

Liver - the largest gland (weight up to 1.5 kg). Most is located in the right hypochondrium, the smaller one extends into the left side of the abdominal cavity. The main secret that the liver secretes into the digestive system is bile. Bile emulsifies fats, activates the fat-breaking enzymes of the pancreas, but does not contain enzymes. In the liver, carbohydrates are converted to glycogen. The liver also performs a barrier function, neutralizing toxic substances that appear in the body during metabolism. Outside of the digestion process, bile collects in the gallbladder.

Pancreas - The digestive gland is 20 cm long and 4 cm wide, located behind the stomach. The pancreas belongs to the glands of the mixed type. The exocrine part produces pancreatic juice containing trypsinogen, amylase, maltase, lactase, lipase, nuclease. The endocrine part produces hormones: insulin and glucagon.

Digestive enzymes

The main function of the digestive system - the digestive - is performed by specialized proteins - digestive enzymes. In each section of the digestive tract, specific enzymes function that facilitate the digestion of certain substances.

Digestive enzymes

Glands	Enzymes	What is splitting	Final product
		Starch. Glycogen	Maltose
	Maltase	Maltose	Two glucose molecules
Stomach glands
		Milk protein	Denaturation - curdling
Pancreas		Protein. Peptides	Dipeptides. Amino acids
			Maltose
			Fatty acid. Glycerol
Liver and gallbladder	Bile salts and alkalis of bile do not contain digestive enzymes	Digestive enzyme activation, fat emulsification, absorption of fatty acids
Small intestine glands	Suharase	Sucrose	Fructose. Glucose
	Maltase	Maltose
			Glucose. Galactose
	Phosphatase	Organic phosphates	Free phosphate

Vitamins

Vitamins call a group of biologically active organic compounds of various chemical nature, entering the body with food of plant and animal origin. Some vitamins are synthesized intestinal microbial flora... Vitamins are present in food in negligible amounts, and the body also needs them in small quantities, but at the same time they play a very important role in metabolic processes, often being an integral part of enzymes. In the absence of any vitamin or its precursor in the body, a disease occurs - avitaminosis... But, although vitamins are important for the body, an overdose (intoxication) of them due to taking in high doses also leads to painful manifestations and is called hypervitaminosis.

Vitamins are divided into two groups depending on the solvents in which they dissolve: fat soluble(vitamins A, D, E, K) and water soluble(vitamins of group B, PP, C, etc.).

The digestive system includes organs that carry out mechanical and chemical processing of food, the absorption of nutrients and water into the blood or lymph, the formation and removal of undigested food residues. The digestive system consists of the alimentary canal and digestive glands, information about which is shown in the figure.

Let's consider schematically the passage of food through the digestive tract.

Food first goes into oral cavity which is limited by the jaws: upper (fixed) and lower (mobile). In the jaws are teeth - organs that serve to bite off and grind (chew) food. An adult has 28-32 teeth. An adult tooth consists of a soft part - a pulp penetrated blood vessels and nerve endings. The pulp is surrounded by dentin, a bone-like substance. Dentin forms the basis of the tooth - it consists of most of the crown (the part of the tooth protruding above the gum), the neck (the part of the tooth located at the border of the gums) and the root (the part of the tooth located deep in the jaw). The crown of the tooth is covered with tooth enamel, the hardest substance the human body, which serves to protect the tooth from external influences(increased wear and tear, pathogenic microbes, excessively cold or hot food, etc. factors).

Teeth according to their purpose, they are divided into: incisors, canines and molars. The first two types of teeth serve for biting off food and have a sharp surface, and the last one for chewing it and for this has a wide chewing surface. An adult has 4 canines and an incisor, and the rest of the teeth are molars.

In the oral cavity, in the process of chewing food, it is not only crushed, but also mixed with saliva, turns into a food bolt. This mixing in the mouth is done with the tongue and cheek muscles.

The mucous membrane of the oral cavity contains sensitive nerve endings - receptors, with the help of which it perceives the taste, temperature, texture and other qualities of food. Excitation from receptors is transmitted to the centers medulla oblongata... As a result, according to the laws of the reflex, the salivary, gastric and pancreas begin to be included in the work sequentially, then the above-described act of chewing and swallowing occurs. Swallowing Is an act characterized by the pushing of food into the pharynx with the help of the tongue and further, as a result of the contraction of the muscles of the larynx, into the esophagus.

Pharynx- a funnel-shaped canal lined with mucous membrane. The upper wall of the pharynx is fused with the base of the skull, at the border between the VI and VII cervical vertebrae of the pharynx, narrowing, passes into the esophagus. Food enters the esophagus from the oral cavity through the pharynx; in addition, air passes through it, coming from the nasal cavity and from the mouth to the larynx. (There is an intersection of the digestive and respiratory tract in the pharynx).

Esophagus- a cylindrical muscular tube located between the pharynx and the stomach, 22-30 cm long. The esophagus is lined with a mucous membrane, in its submucosa there are numerous own glands, the secret of which moisturizes food during its passage through the esophagus into the stomach. The movement of the food lump along the esophagus occurs due to the wave-like contractions of its wall - the contraction of individual areas alternates with their relaxation.

From the esophagus, food enters the stomach. Stomach- reminiscent of appearance retort, an expandable organ that is part of the digestive tract and is located between the esophagus and the duodenum. It connects with the esophagus through the cardiac opening, and with the duodenum through the opening of the pylorus. The inside of the stomach is covered with a mucous membrane, which contains glands that produce mucus, enzymes and hydrochloric acid.

The stomach is a reservoir for absorbed food, which is mixed in it and partially digested under the influence of gastric juice. Produced by the gastric glands located in the gastric mucosa, gastric juice contains hydrochloric acid and the enzyme pepsin; these substances take part in the chemical processing of food entering the stomach during the process of digestion. Here, under the influence of gastric juice, proteins are broken down.

This - along with the stirring effect of the muscle layers of the stomach on food - turns it into a partially digested semi-liquid mass (chyme), which then enters duodenum... Mixing chyme with gastric juice and its subsequent expulsion into the small intestine is carried out by contraction of the muscles of the stomach walls.

Small intestine occupies most of the abdominal cavity and is located there in the form of loops. Its length reaches 4.5 m. The small intestine, in turn, is divided into the duodenum, the jejunum and the ileum. It is here that most of the processes of food digestion and absorption of its contents take place. The area of ​​the inner surface of the small intestine is increased by the presence of a large number of finger-like outgrowths called villi.

Near the stomach is the duodenum, which is secreted in the small intestine, since the cystic duct of the gallbladder and the pancreatic duct flow into it.

The duodenum is the first of the three sections of the small intestine. Starts from gatekeeper stomach and reaches the jejunum. The duodenum receives bile from the gallbladder (through the common bile duct) and pancreatic juice from the pancreas.

In the walls of the duodenum there are a large number of glands that secrete a mucus-rich alkaline secretion that protects the duodenum from the effects of acidic chyme entering it from the stomach.

Lean intestine- part of the small intestine. The jejunum makes up about two-fifths of the entire small intestine. It connects the duodenum and ileum.

Small intestine contains many glands that secrete intestinal juice. This is where the main food digestion and absorption of nutrients into the lymph and blood take place. The movement of the chyme in the small intestine occurs due to the longitudinal and transverse contractions of the muscles of its wall.

From the small intestine, food enters colon 1.5 m long, which begins with a bag-shaped protrusion - cecum, from which a 15 cm process (appendix) departs. It is believed to have some protective function. Colon intestine- the main part of the colon, which consists of four sections: the ascending, transverse, descending and sigmoid colon.

The large intestine mainly absorbs water, electrolytes and fiber, and ends with the rectum, which collects undigested food. Intestine straight- the terminal part of the large intestine (about 12 cm long), which starts from the sigmoid colon and ends with an anus.

During the act of defecation, feces pass through the rectum. Further, this undigested food through anus(anus) is excreted from the body.