Gastric juice: what it consists of and why it is needed. The role of pancreatic juice in digestion Intestinal juice is produced in

intestinal juice- It is a colorless liquid, slightly alkaline, containing about 3% dry matter.

Secretion of intestinal juice

Throughout the intestine, starting from the pyloric opening, there are many small glands of various types that secrete intestinal juice. Some of them of the alveolar structure - Brunner's glands - are located only in the duodenum, others - tubular Lieberkün - throughout the intestine.

During starvation, intestinal juice is secreted a little, while eating, the secretion of juice increases. Particularly increases the separation of juice with mechanical irritation of the intestinal walls with food. Intestinal juice secretion also increases under the influence of certain chemicals: products of food digestion, extracts from certain organs.

Composition of intestinal juice

In the intestinal juice there are enzymes that decompose all nutrients: into carbohydrates - amylase, invertase, lactase, maltase, phosphatase; on proteins - erepsin; for fats - lipase.

Erepsin

The protein enzyme erepsin turned out to be a complex of various peptidases. It quickly and completely decomposes protein products formed under the action of pepsin and trypsin.

Lipase

Intestinal juice lipase breaks down fats in a general way.

carbohydrate enzymes

The amount of carbohydrate enzymes in the intestinal juice depends on the type of food. This indicates that the composition of food affects the activity of cells that produce enzymes. So, for example, with food devoid of milk, there is no lactase in the intestinal juice, but it appears in it when fed with milk. In sucklings, lactase is a constant component of the intestinal juice, gradually disappearing when the animal passes to another kind of food. The same was noted for the enzyme invertase, which decomposes cane sugar. Intestinal amylase and maltase are always present in the intestinal juice. material from the site

Intestinal juice can be obtained from a Tiri Vell fistula. For its formation, a segment of the intestine is isolated, which maintains a vascular and nervous connection with the rest of the intestine through the mesentery. Both ends of this segment are sutured into the skin wound, and the integrity of the intestine is restored by suturing (Fig. 26). However, only the sap of the Lieberkühn glands can be obtained from the Tiri-Vell fistula, since the Brunner glands take up so little space (in the dog) that it is impossible to make a separate fistula to obtain pure Brunner sap.

Gastric juice- a complex chemical substance designed to digest food. It is produced by cells mucous membrane of the stomach and is an acidic, odorless, transparent substance. Color changes to green and yellow are indicative of content impurities duodenum or bile, a brown or red tint may be the result of blood impurities, a putrid odor indicates problems with the transport of stomach contents to the intestines.

The rate of secretion of gastric juice, its neutralization by mucus, as well as the state of health of the digestive system organs determine the acidity of gastric juice. Normally, the secretion of gastric juice into the cavity is almost not released, this should only happen when food enters. Although it is considered normal even to secrete juice when smelling food, seeing it, and sometimes when talking and thinking about it. Unpleasant sight or smell of food can significantly or completely stop the production of juice.

Among the main components of gastric juice are:

• hydrochloric acid , which is one of the most important substances that make up gastric juice. Its functions are to maintain the necessary acid balance in the stomach, promotes the formation of a special substance that protects the body from the penetration of pathogenic substances from the gastrointestinal tract - pepsin , prepares food for hydrolysis, activates, provides swelling of food proteins.

• Bicarbonates protect the duodenum and gastric mucosa by neutralizing hydrochloric acid in these areas. Superficial accessory cells produce this substance, its concentration is 45 mmol/l in gastric juice.

• Slime - one of the main defenders of the gastric mucosa. It creates a layer of gel with a thickness of about half a millimeter, which concentrates bicarbonates, thus protecting the necessary areas from the damaging effects of pepsin and hydrochloric acid. Mucus is also produced by accessory surface cells. Only a small amount of mucus in the gastric juice is the norm, its high concentration indicates inflammatory processes in the gastric mucosa.

• Pepsin is the main enzyme responsible for the breakdown of proteins. Its different isoforms interact with different proteins. They are formed from pepsinogens , which are produced endocrine system of the body .

Other components of gastric juice include water, ammonia, phosphates, sulfates, chlorides, bicarbonates of calcium, potassium, magnesium, sodium and other substances.

During the day, the human stomach normally produces about 2 liters of this substance. Not stimulated by food, at rest in men, secretion is:

• Gastric juice - about 90 ml / hour
• Hydrochloric acid - 3-4 mmol / hour
• Pepsin - about 22-30 mg / hour

The secretion of these substances in the body of a woman is 20-30% less.

Analysis

The analysis of gastric juice is an important diagnostic method, which is carried out using special probes. The analysis is carried out on an empty stomach or using special stimulants. With the help of a probe, gastric juice or the contents of the stomach are extracted.

Natural gastric juice or its artificial substitutes can be used to treat certain diseases of the stomach, which are accompanied by insufficient secretion.

Bile, its composition and significance.

Bile is the secretion and excretion of the liver cells.

Distinguish:

1. Cystic bile- has a high density due to the absorption of water (pH 6.5-5.5, density - 1.025-1.048).

2. Hepatic bile- is located in the hepatic ducts (pH 7.5-8.8, density - 1.010-1.015).

In herbivores, it is dark green in color.

Carnivores have a red-yellow color.

Bile is produced per day - in dogs - 0.2-0.3 liters, pigs - 2.5-4 liters, cattle - 7-9 liters, horses - 5-6 liters.

The composition of bile:

1. Bile pigments (0.2%):

a.) bilirubin (formed during the breakdown of red blood cells);

b.) biliverdin (during the breakdown of bilirubin, there is very little of it).

2. Bile acids (1%):

a.) glycocholic (80%);

b.) taurocholic - about 20% and less representative deoxycholic.

3. Mucin (0.3%).

4. Mineral salts (0.84%).

5. Cholesterol (0.08%), as well as neutral fats, urea, uric acid, amino acids, a small amount of enzymes (phosphatases, amylase).

The value of bile:

1. Emulsifies fats, i.e. turns them into a finely dispersed state, which contributes to their better digestion under the action of lipases.

2. Provides absorption of fatty acids. Bile acids, when combined with fatty acids, form a water-soluble complex available for absorption, after which it breaks down. Bile acids enter the liver and again go into bile, and fatty acids combine with already absorbed glycerol, forming triglycerides. One molecule of glycerol combines with three molecules of fatty acids

3. Promotes the absorption of fat-soluble vitamins.

4. Enhances the activity of amylo-, proteo- and lipolytic enzymes of pancreatic and intestinal juices.

5. Stimulates the motility of the stomach and intestines and promotes the passage of contents into the intestines.

6. Participates in the neutralization of hydrochloric acid, which enters the intestine with the contents from the stomach, thereby stopping the action of pepsin and creating conditions for the action of trypsin.

7. Stimulates the secretion of pancreatic and intestinal juices.

8. It acts bactericidal on the putrefactive microflora of the gastrointestinal tract and inhibits the development of many pathogens.

9. Many medicinal substances and products of the breakdown of hormones are excreted in the bile.

Bile is secreted continuously, and the intake of food enhances its secretion. Nervus vagus causes increased contraction of the bladder wall and the opening of the sphincter. Sympathetic nerves act in reverse, causing the sphincter to close. Stimulates the secretion of bile fatty foods, the hormone - cholecystokinin, which acts similarly to the vagus nerve, gastrin, secretin.

Methods for obtaining intestinal juice:

1. The Tiri method is based on the formation of an isolated segment of the intestine, one end of which is sutured tightly, and the other is brought to the surface of the skin and sewn to its edges.

2. The Tiry-Vell method is a modification of the 1st method. In this case, both ends of the segment are brought to the surface. The disadvantage of this method is that the holes shrink rapidly, so a glass tube is inserted into them, while this area did not take part in digestion and it atrophied.

3. The method of external enteroanastomoses (according to Sineshchekov) - this method allows you to obtain objective data.

There are 2 types of glands in the small intestine:

1. Brunner's (they are only in the 12. p. intestine).

2. Lieberkyunova (there is in the mucous membrane of the entire small intestine).

These glands produce intestinal juice- it is a colorless, cloudy liquid with a specific odor (pH 8.2-8.7), containing 97.6% water and 2.4% solids, which are represented by carbonic salts, NaCl, cholesterol crystals and enzymes.

Intestinal juice consists of 2 parts:

1. Dense - consists of cells of desquamated epithelium.

2. Liquid part.

The bulk of the enzymes (there are more than 20 of them) is located in the dense part and most of all in the upper sections of the small intestine, as well as in the upper layers of the mucous membrane.

Intestinal juice enzymes act on the intermediate products of nutrient hydrolysis and complete their hydrolysis.

Among the enzymes are:

Peptidases (break down proteins), of which enteropeptidase converts trypsinogen into the active form trypsin.

Lipase - acts on fats.

Amylase, maltase, sucrase - act on carbohydrates.

Nucleases, phospholipase.

Alkaline phosphatase (in alkaline gray it hydrolyzes esters of phosphoric acid, participates in the processes of absorption and transport of substances).

Acid phosphatase - it is abundant in young animals.

Intestinal juice is formed by a morphonecrotic type of secretion associated with rejection of the intestinal epithelium.

Intestinal juice is secreted continuously into the intestinal cavity, mixed with feed and forms chyme - a homogeneous liquid mass (cattle - up to 150 liters, pigs - up to 50 liters, sheep - up to 20 liters). For 1 kg of dry food, 14-15 liters of chyme are formed.

The secretion of intestinal juice also occurs in 2 phases:

1. Complex reflex.

2. Neurochemical.

Enhance the secretion nervus vagus, mechanical irritation, acetylcholine, mucosal hormone enterocrinin, duocrenin. Inhibit secretion - with impatic nerves, epinephrine, norepinephrine.

4. Intestinal digestion proceeds in 3 stages:

1. Cavitary.

2. Parietal digestion.

3. Suction.

cavity digestion - (that is, in the cavity of the digestive canal, enzymatic processing occurs first of the eaten (in the oral cavity), then the food coma, gruel (in the stomach), and finally - chyme (in the intestines). Cavitary hydrolysis is carried out due to the enzymes of pancreatic, intestinal juices and bile, which enters the intestinal cavity.In this case, mainly large molecular compounds are hydrolyzed and oligomers (peptides, disaccharides, diglyceride) are formed.

Parietal (membrane digestion) – Academician A.M. Ugolev (1958). This type of digestion takes place actively in the small intestine. There are villi and microvilli that form a brush border, which is covered with mucus forming a mucopolysaccharide network - or glycocalyx.

The resulting monomers are transferred into the cell due to the enzymes structurally associated with cell membranes adsorbed on the surface of the villi.

With parietal digestion, the final stage is the hydrolysis of nutrients (monomers) already subjected to abdominal digestion.

Parietal (membrane) digestion is a highly economical mechanism that proceeds under sterile conditions, since the distance between the villi is less than the size of the microorganism.

This is the initial stage of nutrient absorption.

Pure gastric juice is a colorless liquid, sometimes slightly opalescent, with lumps of mucus. It contains hydrochloric acid, enzymes, minerals, the hormone gastrin, mucus, traces of organic compounds. Gastric juice is acidic.

Hydrochloric acid - the main component of gastric juice

The most important component of gastric juice, which is produced by the parietal cells of the fundic glands of the stomach, is hydrochloric acid.

It maintains a certain level of acidity in the stomach, prevents the penetration of pathogens into the body and prepares food for efficient hydrolysis. Hydrochloric acid has a constant and unchanged concentration - 160 mmol / l.

Digestion begins in the mouth. Saliva enzymes - maltase and amylase - are involved in the breakdown of polysaccharides. The food bolus enters the stomach, where approximately 30-40% of carbohydrates are digested with the help of gastric juice, as a result of exposure to hydrochloric acid, the alkaline environment changes to acidic, maltase and amylase are inactivated.

Bicarbonates

Bicarbonates in gastric juice serve to neutralize hydrochloric acid at the surface of the gastric and duodenal mucosa and protect the mucosa from acid.

The concentration of bicarbonates in gastric juice is 45 mmol/l.

Slime

Mucus contains bicarbonates and protects the mucous membrane from hydrochloric acid and pepsin. Produced in the stomach by additional surface cells.

Pepsin

The main enzyme contained in the gastric juice, with the help of which the breakdown of proteins occurs. Medicine is familiar with several isoforms of pepsin, each of which is involved in the breakdown of a particular type of protein.

Lipase

An enzyme that is found in gastric juice in small quantities. It performs the function of the initial hydrolysis of fats, splitting them into fatty acids and glycerol. Lipase is a surface-active catalyst, like the rest of the enzymes of gastric juice.

Castle's intrinsic factor

The enzyme, which is part of the gastric juice, converts the inactive form of vitamin B12, which enters the stomach with food, into the active form. It is produced by the parietal cells of the glands of the stomach.

intestinal juice

intestinal juice- a complex digestive juice produced by the cells of the mucous membrane of the small intestine.

It is secreted by the Lieberkün glands and released by them into the lumen of the small intestine. It contains up to 2.5% solids, heat curdling proteins, enzymes and salts, among which soda is especially prevalent, giving the whole juice a sharply alkaline reaction. When acids are added to the intestinal juice, it boils, due to the release of carbon dioxide bubbles. This alkaline reaction is apparently of high physiological significance, since it neutralizes the free hydrochloric acid of gastric juice, which could have a harmful effect on the body not only from the disturbance of the digestive processes occurring in the intestinal canal and usually requiring an alkaline reaction, but and, once in the tissues, could disrupt the normal course of metabolism in the body. Previously, intestinal juice was credited with very diverse digestive functions - the digestion of both proteins and carbohydrates, even fats; but these conclusions were more and more limited, as the methods of obtaining pure intestinal juice, without admixture of gastric juice, pancreatic and bile, were improved. The observations made by many authors on occasional intestinal fistulas in humans are therefore full of contradictions; only since the introduction of the intestinal fistula of Tiri, in which K. juice is extracted only from its loop isolated from the rest of the intestinal canal (and the patency of the rest of the channel is restored by an appropriate operation), the functions of K. juice have become clearer: it contains mainly an enzyme that converts cane sugar into grape, the so-called inverting enzyme (Claude Bernard), an amylolytic enzyme, that is, converting starch into grape sugar (Claude Bernard). The role of the inverting enzyme is explained by the fact that grape sugar, according to Claude Bernard, is incomparably more easily metabolized in the body than cane sugar. The effect not only on all proteins, but even on fibrin alone is doubtful. Now there are even indications that deny these functions to the intestinal juice and assert that the intestinal walls, either by themselves or with the help of microorganisms, secrete only such masses that, enveloping the contents of K., contribute to the adoption of more and more of the character of fecal masses (Herman, Tsybulsky). The mechanism of secretion of intestinal juice is little known. Apparently, direct irritation of the intestinal mucosa causes an increase in the separation of juice. Transection of the mesenteric nerves leading to a certain part of the intestines, although it causes the accumulation of fluid in it, but is this latter a true K. juice or just blood transudate - remains unresolved (Moro, Radzievsky). The digestive functions of this fluid are questionable. Colon juice has no chemical effect on food substances; it is doubtful whether the statement of some authors about the saccharifying effect of this juice on starch is true. According to Paladino, the juice of the caecum, however, has this effect in large herbivores, and in particular on barley starch. The juice of the Brunner glands seems to contain pepsin (Grützner), which, when hydrochloric acid is added, is able to digest proteins and convert them into peptones, like the juice of the pylorus of the stomach, but this fact is applicable to a dog and a pig, but not to the Brunner glands of a rabbit. . From what has been said, it clearly follows that the digestive action of K. juice, like all other digestive juices, depends on the type of animal, on the food it takes, and on the varieties of those organic substances on which the digestive power of the juice is tested. Many dark sides and contradictions in the physiology of digestion will be eliminated as soon as the conditions mentioned above are taken into account. In addition, when clarifying the special digestive purpose of this or that juice, one should not lose sight of the fact that such enzymes as diastatic, peptonic, in small quantities are very widely distributed throughout the body and are found even in almost all secretions (both in urine and in sweat) and, therefore, a weak peptonic or diastatic effect of one or another digestive juice does not at all prove that it is a special carrier of the corresponding enzymes. In addition, it should not be overlooked that among the microorganisms that inhabit the soil, air and water and easily penetrate everywhere, there are a lot of peptonic, saccharifying elements that act as organized enzymes, and therefore experiments aimed at determining the digestive power of a particular juice must be guaranteed against microbial interference. Failure to comply with all these conditions has more than once served as a pretext for erroneous conclusions.

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• Intestines

intestinal juice- digestive juice produced by the intestinal glands; colorless or yellowish liquid, having an alkaline reaction, with lumps of mucus and desquamated epithelial cells. Contains enzymes that complete the breakdown of proteins, fats and carbohydrates in food. encyclopedic Dictionary

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intestinal juice- digestive juice, which is the secret of the glands of the intestinal mucosa ... Big Medical Dictionary

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