It is not part of the digestive system. Digestive system: how everything works

Digestive system human is a complex organ system responsible for the breakdown and absorption of nutrients that come with food. The complex of the digestive system includes: the oral cavity, esophagus, stomach, small intestine, large intestine, rectum. In addition, the liver is also part of the digestive system, gall bladder and bile ducts, pancreas. Topographically, the digestive organs include the head, cervical, thoracic, abdominal and pelvic parts of the digestive organs.

The digestive stroke (digestive tube) is understood as a part of the digestive apparatus that has a tubular structure: the esophagus, stomach, small and large intestines. Food enters the digestive system through the mouth, which is the initial organ of digestion. The digestive organs are 12 meters long and work in two phases. The mechanical phase occurs mainly in oral cavity and consists of crushing the food you eat into particles small enough to be swallowed. The chemical phase is the transformation of food into substances that are assimilated by the body, which is achieved by the action of various juices secreted by the digestive glands. The final organ of the digestive system is the anus (anus).

The mouth is the entrance for food and the beginning of the digestive system. The oral cavity is lined with a mucous membrane. Ducts open into it salivary glands... Salivary glands - These three pairs of glands secrete saliva, which moistens and begins to chemically process food. At the bottom of the mouth is the tongue and teeth that chew food. With the help of the tongue, a person tastes and mixes food. The ability to taste allows you to distinguish between sweet, sour, salty and bitter; the sense of smell allows you to distinguish many odors. The taste is perceived by the gustatory endings located on the surface of the tongue; smell - olfactory receptors, which are located in the upper part of the nasal mucosa.

The mouth goes into the pharynx. Swallowing begins voluntarily and continues automatically. During swallowing, the epiglottis closes the entrance to the larynx, and food does not enter the respiratory tract. The epiglottis is a cartilage located between the larynx and the pharynx. The esophagus, a muscular tube lined with mucous membranes, connects the pharynx to the stomach. Food moves through the esophagus thanks to muscle contractions and relaxation - the so-called peristalsis and enters the stomach, passing through the annular muscular sphincter, which opens and closes. The sphincter prevents food from returning to the esophagus.

The stomach is an organ located in the abdominal cavity. He receives food already moistened with saliva and chewed, mixes it with gastric juice and pushes through the pylorus into the duodenum. The cells lining the stomach produce three important substances: mucus, hydrochloric acid and pepsinogen - a precursor of the enzyme pepsin. Mucus envelops the cells of the gastric mucosa. Hydrochloric acid forms an acidic environment in the stomach, which is necessary for the transformation of pepsinogen into pepsin, an enzyme that breaks down proteins. High acidity in the stomach is a good barrier to infection, as it destroys most bacteria.

From the stomach, food enters the initial part of the small intestine - the duodenum - through the pyloric sphincter in portions that the small intestine can digest. The duodenum receives pancreatic enzymes from the pancreas and bile from the liver. These secretions enter the duodenum through the opening, which is located in the center of the eminence - the large duodenal nipple. The mucous membrane of the duodenum over a greater extent has folds with small processes - villi. There are microvilli on the villi. This structure provides better absorption of nutrients. The rest of the small intestine is located below the duodenum and consists of the jejunum and ileum. The absorption of fats and other nutrients mainly takes place here. In general, the small intestine is the part of the digestive tract 4 to 7 meters long, where the pancreas and gastric juice and, bile, and where nutrients are absorbed. The consistency of the intestinal contents gradually changes as the food mass passes through the small intestine.

The liver is a vital organ for the body. It stores glycogen, which is a reserve of energy, and secretes bile, which is necessary for the digestion of fats. Bile is secreted from the liver through the right and left hepatic ducts, which join to form the common hepatic duct. Between meals, the bile produced by the liver is stored and concentrated in the gallbladder.

The gallbladder is an organ located in the lower part of the liver. Food entering the duodenum entails hormonal and nerve signals that cause the gallbladder to contract. As a result, bile is secreted into the duodenum and mixed with its contents.

The large intestine is the last part of the digestive tract. It consists of the cecum, colon and rectum, where water from food is absorbed and feces from undigested foods are formed. The colon is home to many bacteria that break down some substances to help the body absorb food and produce essential nutrients such as vitamin K.

The rectum is the last link in the colon and digestive tract, which connects the colon to the outside environment. It starts just behind the sigmoid colon and includes the anus. Normally, the rectum is empty as feces accumulate higher in the descending colon. Gradually, the descending colon fills and the feces pass into the rectum, causing the urge to defecate. Anus- This is the opening at the end of the digestive tract through which stool is removed from the body.

Have healthy person all digestive organs function very harmoniously, thanks to fine regulation from the side nervous system and a number of hormonal substances that are formed in the digestive system itself.

DIGESTIVE SYSTEM

DIGESTIVE SYSTEM, a group of body organs dedicated to digestion. In humans, the mouth is the first component of the digestive system, where food is mechanically ground by teeth and processed by saliva (or rather, by the enzymes it contains). This is where the process of breaking down the foods eaten begins. Then the food enters the esophagus, and from there into the stomach. Behind the stomach is the small intestine, which opens into the colon. After the food is swallowed, its further advance is carried out by PERISTALTICS. Walking through digestive organs, food is broken down into its original molecules, which are absorbed by the blood and carried to the tissues of the body. CARBOHYDRATES break down into sugars, PROTEINS - into AMINO ACIDS, and FATS - into FATTY ACIDS and GLYCERIN. Indigestible material, mainly cellulose, passes into the rectum, from where it is periodically excreted through the ANAL OPENING in the form of feces.

Digestion and absorption of nutrients occurs in the digestive tract, which is a convoluted tube about 10 m long; its beginning is in oral cavity, and the ending is in the anus. Food passes through the esophagus (1) into the stomach (2), where it is partially digested. The resulting mushy substance - chyme - enters the duodenum (3), the first section of the long (about 7 m) small intestine... The duodenum receives bile secreted by the gallbladder (4) located in the liver (5) and enzymes from the adrenal glands (6). Absorption occurs mainly in the jejunum and ileum, the next sections of the small intestine (7). All that is left passes into the cecum (8), the cavity from which the large intestine begins. It is adjoined by a vermiform process about 10 cm long - the appendix (9). Water is reabsorbed in the colon (10). In the rectum (11 (feces are formed and accumulate, which are then expelled through the anus) ^).


Scientific and technical encyclopedic dictionary.

See what the "DIGESTIVE SYSTEM" is in other dictionaries:

    DIGESTIVE SYSTEM- DIGESTIVE SYSTEM, b. or m. a complex system of cavities lined with epithelium, which is equipped in certain parts with glands that secrete various enzymes, due to which the digestion and dissolution of food materials absorbed ... Great medical encyclopedia

    Digestive system- ensures the assimilation by the body of the energy it needs as a source of energy, as well as for cell renewal and growth of nutrients. The human digestive apparatus is represented by the digestive tube, large glands of the digestive ... ... Human Anatomy Atlas

    The totality of the digestive organs in animals. Intracellular digestion (phagocytosis) is characteristic of protozoa. In naib, primitive multicellular organisms, food is digested separately. cells; in sponges with choanocytes and pinacocytes, in intestinal ones ... ... Biological encyclopedic dictionary

    The digestive apparatus, the totality of the digestive organs in animals and humans. P. s. provides the body with the necessary energy and building materials for the restoration and renewal of cells and tissues, which are constantly destroyed in ... ... Great Soviet Encyclopedia

    Digestive, gastrointestinal intestinal tract(Gastrointestinal tract), or alimentary tube, a system of organs in real multicellular animals, designed for processing and extracting nutrients from food, absorbing them into the blood and excreting them from the body ... ... Wikipedia

    The totality of the digestive organs in animals and humans. In vertebrates, it is represented by the oral cavity, pharynx, esophagus, stomach, intestines, as well as large digestive glands (liver, pancreas, etc.). * * * ... ... encyclopedic Dictionary

    - (systema digestorium) a set of organs that ensure the processing and assimilation of food necessary for the vital activity of the body. P.'s organs by the village, connected into a single anatomical and functional complex, form digestive tract length ... Medical encyclopedia

    The totality of the digestive organs in animals and humans. In vertebrates, it is represented by the oral cavity, pharynx, esophagus, stomach, intestines, and also cr. digests. glands (liver, pancreas, etc.) ... Natural science. encyclopedic Dictionary

    digestive system- language. linguistic. sublingual. esophagus. goiter. stomach. intestines. intestine. small intestine. duodenum. cecum. pancreas. scar. abomasum ... Ideographic Dictionary of the Russian Language

    - (Latin systema digestorium) carries out the digestion of food through its physical and chemical treatment, absorption of cleavage products through the mucous membrane into the blood and lymph and excretion of unprocessed residues. Contents 1 Composition 2 ... ... Wikipedia

Books

  • Digestive system. Textbook for medical universities in English, Nichiporuk Gennady Ivanovich, Gaivoronsky Ivan Vasilievich, Kurtseva Anna Andreevna, Gaivoronskaya Maria Georgievna. Creation study guide"Digestive system" on English language is a requirement modern system medical education in Russia. Currently in medical ...
  • Digestive system. Textbook for medical schools (specialty "General Medicine") / Digestive system. The manual for medical students, Gayvoronskiy I., Kurtseva A., Gayvoronskaya M. et al. Creation of the textbook "Digestive system" in English is a requirement of the modern system of medical education in Russia. Currently in medical ...

One of the main conditions of life is the intake of nutrients into the body, which are continuously consumed by cells in the course of metabolism. For the body, the source of these substances is food. Digestive system ensures the breakdown of nutrients into simple organic compounds(monomers), which enter the internal environment of the body and are used by cells and tissues as a plastic and energetic material. In addition, the digestive system provides the body with the required amount of water and electrolytes.

Digestive system, or the gastrointestinal tract, is a convoluted tube that begins with the mouth and ends with the anus. It also includes a number of organs that ensure the secretion of digestive juices ( salivary glands, liver, pancreas).

Digestion - it is a set of processes during which food is processed in the gastrointestinal tract and the proteins, fats, carbohydrates contained in it are broken down into monomers and the subsequent absorption of monomers into the internal environment of the body.

Rice. Human digestive system

The digestive system includes:

  • the oral cavity with the organs located in it and the adjacent large salivary glands;
  • pharynx;
  • esophagus;
  • stomach;
  • small and large intestine;
  • pancreas.

The digestive system consists of a digestive tube, the length of which in an adult reaches 7-9 m, and a number of large glands located outside its walls. The distance from the mouth to the anus (in a straight line) is only 70-90 cm. The big difference in size is due to the fact that the digestive system forms many bends and loops.

The oral cavity, pharynx and esophagus, located in the area of ​​the human head, neck and chest cavity, have a relatively straight direction. In the oral cavity, food enters the pharynx, where there is a crossover of digestive and respiratory tract... Then comes the esophagus, through which food mixed with saliva enters the stomach.

In the abdominal cavity is the end of the esophagus, stomach, small, blind, colon, liver, pancreas, in the pelvic area - the rectum. In the stomach, the food mass is exposed to gastric juice for several hours, liquefies, is actively mixed and digested. In the small intestine, food, with the participation of many enzymes, continues to be digested, as a result of which simple compounds are formed that are absorbed into the blood and lymph. Water is absorbed in the large intestine and feces are formed. Undigested and unsuitable for absorption substances are removed to the outside through the anus.

Salivary glands

The mucous membrane of the oral cavity has numerous small and large salivary glands. The large glands include: three pairs of large salivary glands - parotid, submandibular and sublingual. The submandibular and sublingual glands simultaneously secrete mucous and watery saliva; they are mixed glands. The parotid glands secrete only mucous saliva. Maximum allocation, for example, on lemon juice can reach 7-7.5 ml / min. In the saliva of humans and most animals, there are enzymes amylase and maltase, due to which a chemical change in food occurs already in the oral cavity.

The enzyme amylase converts food starch into a disaccharide - maltose, and the latter, under the action of the second enzyme, maltase, is converted into two glucose molecules. Although the enzymes of saliva are highly active, complete breakdown of starch in the oral cavity does not occur, since food is in the mouth for only 15-18 seconds. The saliva reaction is usually slightly alkaline or neutral.

Esophagus

The wall of the esophagus is three-layered. Middle layer consists of developed striated and smooth muscles, when contracted, food is pushed into the stomach. The contraction of the muscles of the esophagus creates peristaltic waves, which, arising in the upper part of the esophagus, propagate along the entire length. In this case, the muscles of the upper third of the esophagus are sequentially reduced first, and then the smooth muscles in the lower sections. When food passes through the esophagus and stretches it, there is a reflex opening of the entrance to the stomach.

The stomach is located in the left hypochondrium, in the epigastric region, and is an extension of the digestive tube with well-developed muscular walls. Its shape can change depending on the phase of digestion. Length empty stomach about 18-20 cm, the distance between the walls of the stomach (between the greater and lesser curvature) is 7-8 cm. A moderately full stomach has a length of 24-26 cm, the greatest distance between the greater and lesser curvatures is 10-12 cm. depending on the food and liquid taken from 1.5 to 4 liters. The stomach relaxes during the act of swallowing and remains relaxed throughout the entire meal. After eating, the state occurs increased tone required to start the process of mechanical processing of food: grinding and mixing the chyme. This process is carried out due to peristaltic waves, which arise approximately 3 times per minute in the area of ​​the esophageal sphincter and propagate at a speed of 1 cm / s towards the exit to the duodenum. At the beginning of the digestion process, these waves are weak, but as digestion in the stomach ends, they increase both in intensity and frequency. As a result, a small portion of the chyme is adjusted to the exit from the stomach.

The inner surface of the stomach is covered with a mucous membrane that forms a large number of folds. It contains the glands that secrete gastric juice. These glands are composed of main, accessory, and parietal cells. The main cells produce enzymes of gastric juice, the lining cells produce hydrochloric acid, and the additional cells produce mucoid secretions. The food is gradually soaked in gastric juice, mixed and crushed with contraction of the stomach muscles.

Gastric juice - clear colorless liquid, which has an acidic reaction due to the presence of hydrochloric acid in the stomach. It contains enzymes (proteases) that break down proteins. The main protease is pepsin, which is secreted by cells in an inactive form - pepsinogen. Under the influence of hydrochloric acid, pepsinogen is converted into pepsin, which breaks down proteins into polypeptides of varying complexity. Other proteases have specific effects on gelatin and milk protein.

Under the influence of lipase, fats are broken down into glycerol and fatty acids. Gastric lipase can only act on emulsified fats. Of all food products, only milk contains emulsified fat, so only that fat is broken down in the stomach.

In the stomach, the breakdown of starch, which has begun in the oral cavity, continues under the influence of saliva enzymes. They act in the stomach until the food bolus is saturated with acidic gastric juice, since hydrochloric acid stops the action of these enzymes. In humans, a significant part of the starch is broken down by the saliva ptyalin in the stomach.

In gastric digestion, hydrochloric acid plays an important role, which activates pepsinogen to pepsin; causes swelling of protein molecules, which contributes to their enzymatic breakdown, promotes curdling milk to casein; has a bactericidal effect.

2-2.5 liters of gastric juice are secreted per day. On an empty stomach, a small amount of it is secreted, containing mainly mucus. After eating, the secretion gradually increases and is kept at a relatively high level 4-6 hours

The composition and amount of gastric juice depends on the amount of food. The largest amount of gastric juice is secreted in protein food, less - for carbohydrate, and even less - for fatty. Normally, gastric juice has an acidic reaction (pH = 1.5-1.8), which is due to hydrochloric acid.

Small intestine

The human small intestine starts from the pylorus of the stomach and is divided into the duodenum, the jejunum and the ileum. The length of the small intestine of an adult reaches 5-6 m.The shortest and widest is the 12-intestine (25.5-30 cm), the lean one is 2-2.5 m, the ileum is 2.5-3.5 m. Thickness the small intestine is constantly decreasing along its course. The small intestine forms loops, which are covered in front by a large omentum, and from above and from the sides are limited by the large intestine. In the small intestine, the chemical processing of food and the absorption of products of its breakdown continue. Mechanical mixing and movement of food in the direction of the large intestine occurs.

The wall of the small intestine has a structure typical of the gastrointestinal tract: the mucous membrane, the submucosa, in which the clusters are located lymphoid tissue, glands, nerves, blood and lymphatic vessels, muscularis, and serous membrane.

The muscular membrane consists of two layers - inner circular and outer - longitudinal, separated by a layer of loose connective tissue, in which the nerve plexuses, blood and lymphatic vessels are located. Due to these muscle layers, mixing and movement of intestinal contents towards the exit occurs.

The smooth, moisturized serous membrane facilitates the sliding of the viscera relative to each other.

The glands perform a secretory function. As a result of complex synthetic processes, they produce mucus that protects the mucous membrane from injury and the action of secreted enzymes, as well as various biologically active substances and primarily enzymes necessary for digestion.

The mucous membrane of the small intestine forms numerous circular folds, thereby increasing the absorption surface of the mucous membrane. The size and number of folds decreases towards the colon. The surface of the mucous membrane is dotted with intestinal villi and crypts (depressions). Villi (4-5 million) 0.5-1.5 mm long carry out parietal digestion and absorption. The villi are outgrowths of the mucous membrane.

In providing the initial stage of digestion, a large role belongs to the processes occurring in the duodenum. On an empty stomach, its contents have a slightly alkaline reaction (pH = 7.2-8.0). When portions of the acidic contents of the stomach pass into the intestine, the reaction of the contents of the duodenum becomes acidic, but then due to the alkaline secretions of the pancreas, small intestine and bile entering the intestine, it becomes neutral. In a neutral environment, gastric enzymes stop acting.

In humans, the pH of the contents of the duodenal ulcer ranges from 4 to 8.5. The higher its acidity, the more pancreatic juice, bile and intestinal secretions are secreted, the evacuation of stomach contents into the duodenum and its contents into the jejunum slows down. As you move through the duodenum, the food content is mixed with secretions entering the intestine, the enzymes of which, already in the duodenum, hydrolyze nutrients.

Pancreatic juice does not enter the duodenum constantly, but only during meals and for some time after that. The amount of juice, its enzymatic composition and the duration of excretion depend on the quality of the food received. The greatest amount of pancreatic juice is secreted for meat, least of all for fat. 1.5-2.5 liters of juice is released per day at an average rate of 4.7 ml / min.

The duct of the gallbladder opens into the lumen of the duodenum. Bile secretion occurs 5-10 minutes after a meal. Under the influence of bile, all enzymes of the intestinal juice are activated. Bile enhances locomotor activity intestines, promoting mixing and movement of food. In the duodenum, 53-63% of carbohydrates and proteins are digested, fats are digested in smaller quantities. In the next section of the digestive tract - the small intestine - further digestion continues, but to a lesser extent than in the duodenum. Basically, the suction process takes place here. Final cleavage nutrient occurs on the surface of the small intestine, i.e. on the same surface where suction takes place. This breakdown of nutrients is called parietal or contact digestion, in contrast to cavity digestion that occurs in the cavity. alimentary canal.

In the small intestine, the most intense absorption occurs 1-2 hours after a meal. The absorption of monosaccharides, alcohol, water and mineral salts occurs not only in the small intestine, but also in the stomach, although to a much lesser extent than in the small intestine.

Colon

The large intestine is the final part of the human digestive tract and consists of several sections. Its beginning is considered to be the cecum, at the border of which the small intestine flows into the large intestine with the ascending section.

The large intestine is subdivided into the cecum with the appendix, the ascending colon, the transverse colon, the descending colon, the sigmoid colon, and the rectum. Its length ranges from 1.5-2 m, its width reaches 7 cm, then the large intestine gradually decreases to 4 cm in the descending colon.

The contents of the small intestine pass into the large intestine through a narrow slit-like opening, which is located almost horizontally. At the confluence of the small intestine into the large intestine, there is a complex anatomical device - a valve equipped with a muscular circular sphincter and two "lips". This valve, which closes the hole, looks like a funnel facing its narrow part into the lumen of the cecum. The valve periodically opens, allowing the contents to flow in small portions into the large intestine. With an increase in pressure in the cecum (with stirring and advancement of food), the "lips" of the valve close, and access from the small intestine to the large intestine is terminated. Thus, the valve prevents backflow of the contents of the large intestine into the small intestine. The length and width of the caecum are approximately equal (7-8 cm). A vermiform appendix (appendix) departs from the lower wall of the cecum. Its lymphoid tissue - structure immune system... The cecum passes directly into the ascending colon, then the transverse colon, the descending colon, sigmoid and straight, which ends in the anus (anus). The length of the rectum is 14.5-18.7 cm. In front, the rectum with its wall adjoins in men to the seminal vesicles, the vas deferens and the section of the bottom of the bladder lying between them, even lower to prostate, in women, the rectum is bordered in front of back wall the vagina throughout its entire length.

The whole process of digestion in an adult lasts 1-3 days, of which longest time falls on the stay of food debris in the colon. Its motility provides a reservoir function - the accumulation of contents, the absorption of a number of substances from it, mainly water, its promotion, the formation feces and their removal (defecation).

In a healthy person, the food mass 3-3.5 hours after ingestion begins to enter the colon, which is filled within 24 hours and is completely emptied in 48-72 hours.

The large intestine absorbs glucose, vitamins, amino acids produced by bacteria in the intestinal cavity, up to 95% of water and electrolytes.

The content of the cecum makes small and long movements in one direction or the other due to the slow contractions of the intestine. The colon is characterized by several types of contractions: small and large pendulum-like, peristaltic and antiperistaltic, propulsive. The first four types of contractions provide mixing of the contents of the intestine and increase the pressure in its cavity, which helps to thicken the contents by absorbing water. Strong propulsive contractions occur 3-4 times a day and move intestinal contents to the sigmoid colon. The undulating contractions of the sigmoid colon mix the feces into the rectum, the stretching of which causes nerve impulses that are transmitted along the nerves to the center of defecation in spinal cord... From there, impulses are directed to the anal sphincter. The sphincter relaxes and contracts voluntarily. The center of defecation in children in the first years of life is not controlled by the cerebral cortex.

Microflora in the digestive tract and its function

The large intestine is abundantly populated with microflora. The macroorganism and its microflora constitute a single dynamic system. The dynamism of the endoecological microbial biocenosis of the digestive tract is determined by the number of microorganisms that enter it (in humans, about 1 billion microbes are ingested orally per day), the intensity of their reproduction and death in the digestive tract and the removal of microbes from it in the feces (in humans, normally 10 12-10 14 microorganisms).

Each of the sections of the digestive tract has a characteristic number and set of microorganisms. Their number in the oral cavity, despite the bactericidal properties of saliva, is large (I0 7 -10 8 per 1 ml of oral fluid). The contents of the stomach of a healthy person on an empty stomach are often sterile due to the bactericidal properties of pancreatic juice. In the contents of the colon, the number of bacteria is maximum, and 1 g of feces of a healthy person contains 10 billion or more microorganisms.

The composition and number of microorganisms in the digestive tract depends on endogenous and exogenous factors. The first includes the influence of the mucous membrane of the alimentary canal, its secretions, motility and the microorganisms themselves. The second - the nature of the diet, factors external environment taking antibacterial drugs. Exogenous factors influence directly and indirectly through endogenous factors. For example, the intake of a particular food changes the secretory and motor activity of the digestive tract, which forms its microflora.

Normal microflora - eubiosis - performs a number of important functions for the macroorganism. Its participation in the formation of the immunobiological reactivity of the organism is extremely important. Eubiosis protects macroorganism from the introduction and reproduction of pathogenic microorganisms in it. Disruption of the normal microflora during illness or as a result of prolonged administration of antibacterial drugs often entails complications caused by the rapid multiplication in the intestines of yeast, staphylococcus, proteus and other microorganisms.

The intestinal microflora synthesizes vitamins K and group B, which partially cover the body's need for them. The microflora also synthesizes other substances important for the body.

Bacterial enzymes break down cellulose, hemicellulose and pectins undigested in the small intestine, and the resulting products are absorbed from the intestine and are included in the body's metabolism.

Thus, normal microflora the intestine is not only involved in the final link of the digestive processes and carries protective function but from dietary fiber(plant material indigestible by the body - cellulose, pectin, etc.) produces a number of important vitamins, amino acids, enzymes, hormones and other nutrients.

Some authors highlight the heat-generating, energy-generating and stimulating functions of the large intestine. In particular, G.P. Malakhov notes that microorganisms living in the large intestine, during their development, release energy in the form of heat, which heats venous blood and adjacent internal organs. And it is formed in the intestine during the day, according to various sources, from 10-20 billion to 17 trillion microbes.

Like all living things, microbes have a glow around them - bioplasm, which charges water and electrolytes absorbed in the large intestine. It is known that electrolytes are among the best accumulators and energy carriers. These energy-rich electrolytes, along with the flow of blood and lymph, are carried throughout the body and give their high energy potential to all cells of the body.

Our body has special systems that are stimulated by various influences of the external environment. By means of mechanical irritation of the sole of the foot, all vital important organs; by means of sound vibrations, special zones on the auricle associated with the entire body are stimulated, light stimuli through the iris of the eye also stimulate the entire body and diagnostics are carried out along the iris, and there are certain areas on the skin that are associated with internal organs, the so-called Zakharyin zones - Geza.

The large intestine has a special system through which it stimulates the entire body. Each section of the large intestine stimulates separate body... When the intestinal diverticulum is filled with food gruel, microorganisms begin to proliferate in it, releasing energy in the form of bioplasma, which stimulates this area, and through it on the organ associated with this area. If this area is clogged with fecal stones, then there is no stimulation, and the function of this organ slowly begins to fade, then the development of a specific pathology. Especially often, fecal deposits are formed in the folds of the large intestine, where the movement of fecal masses slows down (the place of transition of the small intestine into the large, ascending bend, descending bend, bend of the sigmoid colon). The place of transition of the small intestine to the large one stimulates the nasopharyngeal mucosa; upward bend - thyroid gland, liver, kidneys, gallbladder; descending - bronchi, spleen, pancreas, bends of the sigmoid colon - ovaries, bladder, genitals.

In the life of any living creature, the digestion process plays a gigantic role. And this is not surprising at all, since any animal or person receives everything it needs for its growth and development from food. After undergoing mechanical and chemical processing, it becomes a valuable source of protein, fats, carbohydrates and minerals. For all this, the digestive organs are responsible, the structure and meaning of which we will today be relatively detailed.

Oral cavity

The basis of the oral cavity is represented not only by the bones of the skull, but also by the muscles. It is limited by the palate, cheeks and lips. The red color of the latter is due to a dense network of blood vessels that are located just under their thin and delicate skin. The oral cavity contains numerous ducts of the salivary glands.

Saliva is one of the most important components of normal digestion. It not only moistens food for its easier passage through the esophagus, but also neutralizes some of the microflora, which inevitably enters the human or animal body from the external environment. What other organs of human digestion are there?

Language

It is a mobile muscular organ, richly innervated, with a dense network of blood vessels. He is responsible not only for mechanical movement and mixing of the food mass during chewing, but also for its assessment. taste(due to taste buds) and temperature. It is the tongue that signals that the food is too hot or cold, and therefore can be dangerous to the body.

Teeth

They are derivatives of the skin, ensure the capture and grinding of food, contribute to the intelligibility and euphony of a person's speech. Distinguish between incisors, canines, small and large molars. Each tooth is located in a separate cell, the alveolus. It is attached to it with a small layer of connective tissue.

Pharynx

It is a purely muscular organ with a fibrous core. It is in the pharynx that the digestive organs intersect with respiratory system... In an average adult, the length of this organ is about 12 - 15 cm. It is generally accepted that the pharynx is divided into three sections: the nasopharynx, the oropharynx and the laryngeal part.

The importance of the initial section of the digestive system

Many for some reason completely forget that the initial sections of the digestive tract are extremely important for all stages of digestion, which takes place in the human and animal body. So, already the primary grinding of food not only facilitates its subsequent swallowing, but also significantly increases the degree of its general assimilation.

In addition, saliva (as we said above) has some bactericidal effect, it contains enzymes that break down starch (amylase). In the initial sections of the digestive tract, there is a huge amount of lymphoid tissue (tonsils), which is responsible for the retention and destruction of most of the pathogenic agents that can enter the human or animal body.

In general, the very structure of the digestive system presupposes the presence of a very large amount of lymphoid tissue. As you can understand, this is far from accidental: this is how the body protects itself from a huge volume of pathogenic and conditionally pathogenic microorganisms that enter it with food.

Esophagus

Like the pharynx, it is a muscular organ with a well-developed fibrous base. In an adult, this organ is approximately 25 centimeters long. Anatomists say that it is subdivided into three parts at once: cervical, thoracic and abdominal. It has three perfectly visible narrowings that appear immediately after birth. So, there is a particularly pronounced area at the place where the diaphragm passes.

It is in this place that small children get stuck swallowed by them foreign objects, so the structure of the digestive system is not always rational.

The inner part of the organ is represented by a well-developed mucous membrane. Since the esophagus is innervated by the vegetative part of the nervous system, the intensity of the mucous glands is not always consistent with the situation: food often gets stuck in the esophagus, since it has a weak ability to peristalsis, and the amount of lubricant is small.

What are the structure and functions of the digestive organs, which are directly involved in the processing and assimilation of food nutrients?

Stomach

The stomach is the most expanded part of the digestive tube, which is laid on the most early stages development of the embryo. In humans and many omnivores, the capacity of this organ varies within three liters. By the way, the shape of the stomach is extremely variable and largely depends on its capacity. Most often there is a hook-shaped or horn-shaped form.

The stomach is responsible for the digestion of proteins and fats (to a very small extent). After about 12 hours, the semi-digested food gruel is sent to the small intestine due to the contractions of the muscle wall. What are the parts of the stomach? It's simple, since there are not many of them. Let's list them:

  • Fundal (bottom).
  • Cardiac.
  • Body.
  • Pylorus, the place of transition to the duodenum.

These are the sections of the stomach.

Understanding the mucous membrane

Unlike all of the above organs, in this case, the structure of the mucous membrane that lines interior stomach is very difficult. This is due to the differentiation of the functions performed by the cells: some of them secrete protective mucus, and some are engaged in the production of digestive secretions directly.

So, hydrochloric acid is secreted by parietal cells. They are the largest. Slightly smaller are the main cells that are responsible for the production of pepsinogen (the precursor of pepsin). All these cells are distinguished by the presence of a tubule through which the secretion they produce enters the organ cavity.

It should be remembered that hydrochloric acid is a powerful antimicrobial agent. In addition, it is a fairly strong oxidizing agent (even if its concentration in gastric juice is weak). The walls of the stomach are protected from the destructive action of acid by a thick layer of mucus (which we have already written about). If this layer is damaged, inflammation begins, fraught with the formation of an ulcer and even perforation of the organ wall.

The cells of the gastric mucosa completely regenerate every three days (and even more often in adolescents). In general, the digestive organs in children are distinguished by a rare ability to heal themselves, but in adulthood this function almost completely fades away.

The muscular layer of this organ consists of three layers. There is a special, oblique layer of striated muscle fibers, which is found throughout the digestive tract only in the stomach and nowhere else. The peristaltic contractions, which we already wrote about above, begin in the region of the body of the stomach, gradually spreading to its pyloric section (the place of transition to the small intestine).

In this case, the half-digested, homogeneous food mass flows into the duodenum, and the larger pieces again pass into the human stomach, the structure of which we have just described.

Small intestine

In this section, a deeper enzymatic decomposition begins with the formation of soluble compounds that can already enter the portal vein. After cleaning in the liver, ready-made nutrients are carried to all organs and tissues. In addition, the peristaltic role is also important. thin department intestines, since food is actively mixed in it and moves towards the thick section.

Finally, some hormones are formed here. The most important of these are the following compounds:

  • Serotonin.
  • Histamine.
  • Gastrin.
  • Cholecystokinin.
  • Secretin.

In humans, the length of the small intestine can reach about five meters. It consists of three sections: the duodenum, the jejunum and the ileum. The first is the shortest, its length does not exceed 25 - 30 cm. At least 2/5 of the length falls on the jejunum, and the remaining part is occupied by the ileum.

Duodenum

The duodenum has a horseshoe shape. It is in the bend of this part of the intestine that the head of the pancreas, the most important enzymatic organ, is located. Its excretory duct, together with a similar duct of the gallbladder, opens inside the organ on a special tubercle, which anatomists call the greater papilla.

In many people, at a distance of about two centimeters from it, there is also a small papilla, at the top of which an accessory pancreatic duct opens. With the help of the mesenteric ligaments, the duodenum is connected to the liver, kidneys, and also some parts of the large intestine.

The jejunum and ileum

The jejunum and ileum are tightly covered by the serous membrane (abdominal) on all sides. These areas are collected in complex loops, which, thanks to constant peristaltic contractions, constantly change their position. This ensures high-quality mixing of the chyme (half-digested food mass) and its movement into the large intestine.

There is no clearly defined anatomical boundary between these two intestines. The distinction is made only when cytological examination, since the characteristics of the epithelium that lines inner surface organ on these two sites are different.

The blood supply is carried out through the mesenteric and hepatic arteries. Innervation is the vagus nerve and the autonomic nervous system (ANS). In this, the human digestive system is no different from the analogous organs of animals.

Small intestine wall structure

This issue should be discussed in more detail, since there are many interesting and important nuances here. It should be noted right away that the anatomy of the digestive system (more precisely, the mucous membrane of the small intestine) in this case is almost the same throughout its entire length. There are more than 600 circular folds, as well as crypts and numerous villi.

The folds most often cover the inner diameter of the intestine by about 2/3, although it happens that they extend over the entire surface. Unlike the stomach, when the intestines are filled with food, they are not smoothed out. The closer to the large intestine, the smaller the folds themselves and the greater the distance between them. It should be remembered that they are formed not only by the mucous membrane, but also by the muscle layer (which is why the folds are not smoothed out).

Characteristic of villi

But folds are only a small part of the "relief" of the intestine. Most of it is made up of villi, which are densely located over the entire area of ​​the internal volume of the intestine. One person has more than 4 million of them. In appearance (under powerful microscope, of course) they look like small finger-like outgrowths, the thickness of which reaches about 0.1 mm, and the height is from 0.2 mm to 1.5 mm. What are the functions of the digestive organs, if we talk about the villi?

They play the most important absorptive role, due to which nutrients enter the general bloodstream of the human or animal body.

Smooth muscle cells are located along their entire surface. This is necessary for their constant reduction and reshaping, due to which the villi act like miniature pumps, sucking in nutrients already ready for assimilation. This process is most intensive in the duodenum and jejunum. In the iliac region, the semi-digested food mass is already beginning to turn into feces, so the absorption capacity of the mucous membrane is weak there. Simply put, the digestion process practically does not go there.

Characteristics of crypts

Crypts are called cavities in the mucous membrane, which, in their essence, are glands. They contain a rich set of enzymes, as well as lysozyme, which is a powerful bactericidal agent. In addition, it is the crypts that secrete a large amount of mucous secretion, which protects the walls of this tubular organ from the destructive action of the digestive juice.

Small intestine lymphoid system

In the mucous membrane of the small intestine, along its entire length, there are numerous lymphoid follicles. They can be several centimeters long and one centimeter wide. These follicles are the most important barrier to pathogenic microorganisms that can enter the digestive tract of a person or animal along with food. What other organs does the human digestive system contain?

Large intestine, general information

As you might guess, this department got its name for large diameter: in the relaxed state of the organ, it is two to three times larger than that of the thin section. In humans, the total length of the large intestine is approximately 1.3 m. The department ends with the anal opening.

What characterizes the structure of the human digestive system in the case of the large intestine? Let's list all the departments:

  • The cecum with the appendix (the same appendix).
  • Colon. It is divided into ascending, transverse, descending and sigmoid parts.
  • Rectum, rectum.

Contrary to the opinion of some "experts", the digestion process practically does not take place in this department. The colon only absorbs water and mineral salts... The fact is that fecal masses pass here, which contain a considerable amount (especially with a protein diet) of indole and skatole, putrescine and even cadaverine. The last two substances are very powerful cadaveric poisons. Of course, school anatomy (grade 8) does not study them, but you need to know about them.

As you might guess, if something other than water, salts and vitamins were absorbed in the large intestine (we will talk about them a little below), we would constantly be in a state of chronic poisoning.

A large amount of mucus is secreted into the lumen of this organ, which, unlike the case described above, does not contain any enzymes. However, one should not assume that the large intestine is a primitive reservoir of feces. If you have studied biology at all, then with the word "large intestine" you should inevitably have an association with B vitamins. Where do you think they come from? Many will say that the body itself synthesizes them, but this is far from the case.

The fact is that undigested food residues in this section are exposed to numerous microorganisms. They are the ones who synthesize essential vitamin K (without which we would die from bleeding much more often), as well as the entire group of vitamins of group B. So nutrition and digestion do not always have a direct relationship in terms of nutrients received by the body. We get some of them from bacteria.

Pancreas

One of the largest glands in our body. It has a gray-pink color and is characterized by a lobed structure. In an adult, healthy person, its weight reaches 70 - 80 grams. In length, it reaches 20 centimeters, and its width is 4 centimeters.

It is a very interesting mixed secretion gland. So, e exocrine departments produce about two liters (!) Of secretion per day. It, due to the enzymes it contains, serves to break down proteins, fats and carbohydrates. But many people around the world know much more about her. endocrine function... The reason is sad.

The fact is that the cells of the secretory islets secrete a number of hormones, one of the most important being insulin. It regulates fat, water metabolism, and is also responsible for the absorption of glucose. If something is wrong with these cells, diabetes, which is the most serious disease.

The function of secretory cells is regulated by the nervous and humoral pathways (with the help of other hormones in the body). It should be especially noted that some of the hormones of the pancreas are even involved in bile secretion, which makes this organ even more important for the whole organism. What other organs of the digestive system are there?

Liver

The liver is the largest gland in the human and animal body. This organ is located in the right hypochondrium, adjacent to the diaphragm. Has a characteristic dark brown color. Few people know, but in the embryonic period it is the furnace that is responsible for hematopoiesis. After birth and in adulthood, it participates in the metabolism, is one of the largest blood depots. Almost all human digestive organs are extremely important, but even against their background, this gland stands out strongly.

It is the liver that produces bile, without which the digestion of fats is impossible. In addition, the same organ synthesizes phospholipids, from which all cell membranes in the human and animal body are built. This is especially important for the nervous system. In the liver, a large part of the blood proteins is synthesized. Finally, glycogen, animal starch, is deposited in this organ. It is a valuable source of energy in critical situations when the digestive system does not receive food from the outside.

It is here that the destruction of erythrocytes that have worked out their term occurs. Liver macrophages absorb and destroy many harmful agents that enter the bloodstream from the large intestine. As for the latter, it is this gland that is responsible for the decomposition of all those rotting products and cadaveric poisons that we talked about above. Few people know, but it is in the liver that ammonia is converted into urea, which is subsequently excreted through the kidneys.

The cells of this gland perform a huge number of functions that are extremely important for the maintenance of normal metabolism. For example, in the presence of insulin, they can capture excess glucose from the blood, synthesize glycogen and store it. In addition, the liver can synthesize the same substance from proteins and polypeptides. If the body gets into unfavorable conditions, glycogen is broken down here and enters the bloodstream in the form of glucose.

Among other things, it is in the liver that lymph is produced, the importance of which for the body's immune system is difficult to overestimate.

conclusions

As you can see, the digestive organs not only supply the most valuable nutrients, without which the growth and development of the body is impossible, but also perform a number of other functions. They are involved in hematopoiesis, immunogenesis, hormone production and humoral regulation of the body.

Surely everyone knows that nutrition and digestion are closely interrelated, so do not abuse fatty, overly spicy foods and alcohol.

V oral cavity going on primary processing food, which consists in its mechanical grinding with the tongue and teeth and turning into a food lump. The salivary glands secrete saliva, which enzymes begin to break down the carbohydrates in food. Then, through the pharynx and esophagus, food enters the stomach, where it is digested under the action of gastric juice.

The stomach is a thick-walled muscle sac located under the diaphragm in the left side of the abdominal cavity. By contracting the walls of the stomach, its contents are mixed. Many glands, concentrated in the mucous wall of the stomach, secrete gastric juice containing enzymes and hydrochloric acid. After that, partially digested food enters the anterior part of the small intestine - the duodenum.

Small intestine consists of the duodenum, the jejunum and the ileum. V duodenum food is exposed to the action of pancreatic juice, bile, as well as the juices of the glands located in its wall. In skinny and ileum the final digestion of food and absorption of nutrients into the blood take place.

Undigested residues enter the large intestine. Here they accumulate and must be removed from the body. The initial part of the large intestine is called the cecum. A vermiform appendix - the appendix - departs from it.

To the digestive glands include the salivary glands, microscopic glands of the stomach and intestines, pancreas and liver. The liver is the largest gland human body... It is located on the right under the diaphragm. The liver produces bile, which flows through the ducts into the gallbladder, where it accumulates and enters the intestines as needed. The liver retains toxic substances and protects the body from poisoning.

The digestive glands, which secrete juices and convert complex nutrients into simpler and more water-soluble ones, include pancreas... It sits between the stomach and duodenum... Pancreatic juice contains enzymes that break down proteins, fats and carbohydrates. 1-1.5 liters of pancreatic juice are secreted per day.

If stale products or toxic substances (arsenic, copper compounds, natural poisons) enter the digestive system, food poisoning occurs. Acute poisoning require application emergency measures for quick removal poison even before the arrival of the doctor: gastric lavage, induction of vomiting, etc.

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