What processes take place in the large intestine. Causes of diseases of the colon. Be careful with colon cancer

Usually cleansing begins with the large intestine.

The large intestine is the end digestive system, through which the main and powerful metabolism of the body with the external environment takes place, this process is constant and continuous.

Substances introduced into the body, having passed through the digestive system in the body, must be promptly excreted back into the environment.

If excretion does not occur in a timely manner, there is an accumulation of waste substances in the body and clogging connective tissue(through it nutrition, respiration, protection of all cells of the body are carried out), violation of its normal operation and the occurrence of many diseases.

The total length of the human colon is about 2 m. In the large intestine, two parts are distinguished: the colon and the rectum. Wall colon four-layer. From the inside, the intestine is lined with a mucous membrane that produces and secretes mucus, which protects the intestinal wall and facilitates the passage of contents. Under the mucosa are adipose tissue and muscle layer. Due to these muscle layers, alteration and promotion of intestinal contents towards the exit occurs.

The main functions of the large intestine are: suction, evacuation, excretory.

suction function.

In the colon, reabsorption processes predominate. Here is the absorption of glucose, vitamins and amino acids, up to 95% of water and electrolytes. About 2000 g of food gruel (chyme) moves daily from the small intestine to the large intestine, and after absorption, 200-300 g of feces remain.

evacuation function.

are stored in the large intestine and retained stool before taking them out. They move slowly through the large intestine. If the intestinal contents pass through the small intestine (5 m) in 4-5 hours, then in the large intestine (2 m) - in 12-18 hours. The absence of stool for 24-32 hours is considered constipation. When constipation is noted the following symptoms: coated tongue, bad breath from the mouth, heaviness in the lower abdomen and its swelling, pain and rumbling in the abdomen.

The most common causes of constipation are the consumption of high-calorie foods of small volume, dry eating. As a result malnutrition- eating starchy and boiled foods (potatoes, products made from fine flour, richly flavored with butter, sugar) mixed with protein foods (meat, sausage, cheese, eggs, milk) - a film of feces forms on the walls of the large intestine - "scale" , from which, during dehydration (after all, up to 95% of water is absorbed there), fecal stones are formed.

If evacuation is disturbed, the processes of putrefaction and fermentation take place in the large intestine. Toxic products that appear as a result of these processes, along with water, enter the bloodstream and cause intestinal autointoxication.

Autointoxication can be caused sedentary image life, refined food, mainly meat food with a lack of vegetables, herbs and fruits, neuro-emotional overload, frequent stress. Toxic effusions easily penetrate into the abdominal cavity through the thin walls of the large intestine, poisoning the liver, kidneys, genitals, etc. At chronic constipation feces become dehydrated because the large intestine absorbs excess water, which normal conditions removed along with feces.

With age colon gets clogged fecal stones. It can stretch, deform, squeeze and displace other organs from their places in abdominal cavity, which are immersed in a fecal sac. Normal operation these organs are disrupted.

As a result, there are various diseases: with damage to the mucous wall - various types of colitis; with squeezing and stagnation of blood in the wall of the large intestine - hemorrhoids and varicose veins veins; with prolonged exposure to toxins in one part of the intestine - polyps and cancer. Constant poisoning with poisons through the intestines creates a certain concentration of toxins in the blood. Slags are the result not only of intoxication, but also of wrong, unbalanced diet with a predominance of meat, flour products, sugar.

Constipation is also facilitated by ignoring the urge to defecate. As a result of anti-peristaltic movement, feces are pushed back into iliac region and accumulate there.

excretory function.

The large intestine has the ability to secrete digestive juices with a small amount of enzymes into the intestinal lumen. Alcohol, salts and other substances can be released from the blood, which can cause irritation of the mucous membrane and the development of related diseases. Salt and spicy food. As a rule, hemorrhoids worsen after eating smoked meats, dishes with vinegar.

More than 400-500 live in the large intestine various kinds bacteria. The normal microflora in the large intestine not only takes part in the final link of the digestive processes and performs protective function, but also produces from dietary fibers (cellulose, pectin, lignin) a number of important vitamins, amino acids, enzymes, hormones and others nutrients(for example, vitamins B1; B2, B6, biotin, pantothenic, nicotinic, folic acid, B12 and vitamin K).

The waste products of microbes have a regulatory effect on the autonomic nervous system, create a protective barrier against pathogenic microbes.

For the normal functioning of microorganisms, a certain environment is necessary - a slightly acidic environment and alimentary fiber. Rotting feces determine alkaline environment promoting the growth of pathogenic microflora.

The mold formed during the decay of food contributes to the development of a serious pathology in the body. external sign mold formation in the body and damage to the mucous membranes of the large intestine, as well as vitamin A deficiency is the formation of black plaque on the teeth. With vitamin A deficiency, there is a degeneration of the mucous membrane of the large intestine, the processes of its recovery are confused. This is one of the reasons for the development of colitis, polyps, etc. in the large intestine.

Body and colon cleansing system

It contains the retention of unnecessary and neutralization harmful substances that brought blood from the digestive system and large intestine. The kidneys play an important role in cleansing the body, excreting metabolic products. The work of the kidneys is closely related to the work of the liver.

The kidneys remove nitrogenous compounds and salts from the body, synthesize biologically active substances, affect the level blood pressure, blood clotting, protective properties of the body. If the toxins in the liver are not neutralized, the kidneys begin to suffer, break down, various kidney disease develops renal failure.

When the large intestine does not remove food waste, the liver and kidneys are overloaded, conditions are created for the general slagging of the body. The body is forced to connect other systems for excreting substances that are not normally adapted for this purpose. The excretory work includes lungs, skin, mucous membranes that have an outlet to the outside (nasopharynx, urinary canal, vagina, ears, mucous membrane of the eye).

In a person, 85% of his entire body consists of connective tissue, which absorbs substances that are not excreted in the normal way, toxins, toxins. Sooner or later, this process leads to the fact that the connective tissue ceases to perform its functions normally - to nourish and protect the working cells of the body normally.

On this basis, there is an abundance of various diseases (immune, metabolic, vascular, tumor), which indicate a lack of connective tissue. Its source is an abnormally functioning large intestine. It is for this reason that the cleansing of the body must begin with the large intestine, with the normalization of its evacuation and other functions, because the main thing for a person is to have a healthy and clean intestine.

B.Yu. Lamikhov, S.V. Glushchenko, D.A. Nikulin, V.A. Podkolzina, M.V. Bigeeva, E.A. Matykin

Food enters the large intestine almost completely digested, with the exception of plant fiber. In this section of the digestive tract, intensive absorption of water from the intestinal cavity occurs. Remains of food are compacted, stick together with mucus and form feces. In an adult, an average of 150-250 g of feces is formed and excreted from the body per day. The glands of the large intestine produce a large number of alkaline secretion, poor in enzymes, but containing a lot of mucus.

For colonic motility the following types of movements are characteristic:

· pendulum- provide mixing of chyme, which accelerates the absorption of water;

· peristaltic- contribute to the promotion of chyme in the distal direction;

· antiperistaltic- move the contents of the intestine in a retrograde direction, which also accelerates the absorption of water;

· propulsive- provide the promotion of chyme over a long distance - from the transverse colon to the sigmoid and rectum; food intake accelerates the occurrence of propulsive contractions;

· tonic- other abbreviations are superimposed on them.

Movements are made very slowly, which leads to a long stay of food in this department. gastrointestinal tract.

Motility is mainly regulated by local reflexes carried out by the neurons of the intestinal wall. Mechanical irritation of the intestinal mucosa with food masses causes an increase in peristalsis. Eating plant foods containing fiber not only increases the amount of feces formed due to undigested plant fibers, but also accelerates the movement of food masses through the intestines, providing irritant effect on the mucosa.

The role of the microflora of the colon

The human large intestine, unlike other parts of the digestive tract, is abundantly populated by microorganisms. The content of microbes in the colon is 10 11 -10 12 per 1 ml of content. About 90% of the microflora of the colon is obligate anaerobic bifidobacteria and bacteroids. Found in lesser numbers lactic acid bacteria, coli , streptococci.

Colon microorganisms perform a number of important functions.:

· Enzymes produced by bacteria can partially break down plant fibers undigested in the overlying sections of the digestive tract - cellulose, pectins, lignins.

The microflora of the large intestine synthesizes vitamins K and group B(B 1 , B 6 , B 12), which are in a small amount can be absorbed in the large intestine.

Microorganisms are also involved in enzyme inactivation digestive juices.

· The most important function the microflora of the colon is ability to protect the body from pathogenic bacteria falling into digestive tract. Normal microflora prevents the reproduction of pathogenic microorganisms in the intestine and their entry into internal environment organism. Violation of the normal composition of the microflora of the large intestine with long-term use antibacterial drugs accompanied by active reproduction pathogenic microbes and leads to a decrease immune protection organism.

The act of defecation

defecation- liberation of the colon from feces due to the contraction of its smooth muscles and relaxation internal and external sphincters. internal sphincter formed by smooth involuntary muscles. external sphincter formed by the striated muscles of the perineum. Its activity is regulated arbitrarily due to the influence of the cortex on motor neurons. spinal cord that innervates the external sphincter.

The urge to defecate occurs when the walls of the colon are stretched and the mechanoreceptors located in them are excited. Defecation is promoted by an increase intra-abdominal pressure that occurs during muscle contraction abdominals, lowering the diaphragm and pelvic floor. The regulation of the act of defecation occurs due to local reflexes, the action of the ANS and motor neurons of the sacral spinal cord, when damaged, the sphincters relax, and arbitrary removal of feces becomes impossible. If the spinal cord is damaged above the sacral regions, the involuntary component of the reflex is preserved, but the ability to perform a voluntary act of defecation is lost.

The small intestine almost completely digests and absorbs food. Digestion in the large intestine begins after the arrival of fragments that the small intestine has not digested. The work of the large intestine is that here the remnants of chyme (a lump of partially digested food and gastric juice) acquire a more solid state by releasing water. Here there is a splitting of molecules, for example, fiber (its small intestine is not able to split), with the help of digestive juice and bacterial flora. The main function of the colon is to convert food fragments into a semi-solid state for further excretion from the body.

Important processes of digestion occur in the large intestine, and their failure is fraught with a significant complication of human health.

The role of microflora

In this part of the gastrointestinal tract, there is a considerable proportion of microbes that form a "microbial community". Flora is divided into 3 classes:

• the first group (main) - bacteroids and bifidobacteria (approximately 90%);
• the second group (accompanying) - enterococci, lactobacilli and escherichia (approximately 10%);
• the third group (residual) - yeast, staphylococci, clostridia and others (about 1%).

The standard human flora performs a number of functions:

• colonization resistance - activation immune system, intermicrobial confrontation;
• detoxification - splitting the results of the process of metabolism of proteins, fats, carbohydrates;
• synthetic function - obtaining vitamins, hormones and other elements;
• digestive function - increased activity of the gastrointestinal tract.

The functions of natural stabilizers of the intestinal flora are performed by antimicrobial elements produced by the mucosa (lysozyme, lactoferrin). normal contraction, pushing the chyme, has an effect on the degree of filling with microorganisms of a particular section of the gastrointestinal tract, keeping their distribution in the proximal direction. Violations at work motor activity intestines contribute to the appearance of dysbacteriosis (a change in the composition of microorganisms, when pathogenic bacteria increase due to the disappearance of beneficial ones).

The imbalance of microflora can be associated with the following factors:

• frequent SARS, allergies;
• reception hormonal drugs, anti-inflammatory drugs ("Paracetamol", "Ibuprofen", "Aspirin") or narcotic drugs;
• oncological diseases, HIV, AIDS;
• age-related physiological changes;
• infectious diseases of the intestine;
• work in heavy industry.

Involvement of plant fiber

The way the colon works depends on the substances that enter the body. Among the substances that ensure the process of multiplication of the microflora of the large intestine, it is worth highlighting vegetable fiber. The body is not able to digest it, but it is broken down by enzymes into acetic acid and glucose, which then pass into the blood. Excitation of motor activity is due to the release of methane, carbon dioxide and hydrogen. Fatty acids (acetic, butyric, propionic acids) give the body up to 10% of the total energy, and the final stage products that feed the walls of the mucous membrane are produced by the flora.

The microflora of the colon is involved in the formation of a number of useful substances necessary for the human body.

Microorganisms, absorbing waste, produce vitamins of several groups, biotin, amino acids, acids (folic, pantothenic), and other enzymes. With a positive flora, many useful biologically active elements are broken down and synthesized here, and the processes responsible for generating energy and warming the body are activated. Through beneficial flora, pathogens are suppressed, and positive activity of the immune system and body systems is ensured. Deactivation of enzymes from the small intestine occurs due to microorganisms.

food with high content carbohydrates contributes to the development of fermentation of proteins with decay, which leads to the formation of toxic substances and gases. The components during the decomposition of the protein are absorbed into the blood and reach the liver, where they are destroyed with the participation of sulfuric and glucuronic acids. A diet that harmoniously contains carbohydrates and proteins balances fermentation and putrefaction. If there are discrepancies in these processes, there are digestive disorders and problems in other body systems. Digestion in the large intestine comes to the final stage by absorption, the contents accumulate here and fecal masses are formed. Varieties of contraction of the large intestine and its regulation occur in much the same way that the small intestine works.

When moving chyme (significantly digested food products) in the small intestine, under the influence of intestinal juice, the intermediate compounds of the breakdown of proteins, fats and carbohydrates are digested to final products.

intestinal juice is a cloudy, rather viscous liquid, a product of the activity of the entire mucous membrane of the small intestine.

In the mucous membrane of the upper part duodenum a large number of duodenal glands are laid. In structure and function, they are similar to the glands of the pyloric part of the stomach. The juice of the duodenal glands is a thick, colorless liquid of slightly alkaline reaction, has a small enzymatic activity.

Intestinal glands are embedded in the mucosa of the duodenum and the entire small intestine.

AT intestinal juice more than 20 different ones involved in digestion: enterokinase, several peptidases, alkaline phosphatase, nuclease, lipase, amylase, lactase and sucrase, etc. B vivo they are fixed in the zone of the brush border and carry out parietal digestion.

The secretion of the intestinal glands increases during meals, with local mechanical and chemical irritation of the intestine and under the influence of certain intestinal hormones.

The leading role belongs to local mechanisms. Mechanical irritation of the mucous membrane of the small intestine dramatically increases the release of the liquid part of the juice. Chemical stimulants of the small intestine are products of digestion of protein, fat, pancreatic juice, hydrochloric acid(and other acids).

Motor function of the small intestine

The motility of the small intestine provides mixing of its contents (chyme) with digestive secretions, the promotion of chyme through the intestine, the change of its layer near the mucous membrane, an increase in intra-intestinal pressure, which contributes to the filtration of solutions from the intestinal cavity into the blood and lymph. Therefore, small bowel motility promotes hydrolysis and absorption of nutrients.

Hydrolysis - the process of sequential depolymerization of proteins, fats, carbohydrates and other food components under the action of appropriate enzymes that ensure the splitting of their specific intramolecular bonds.

The movement of the small intestine occurs as a result of coordinated contractions of the longitudinal and circular layers of smooth muscles. It is customary to distinguish between several types of contractions of the small intestine:

• rhythmic segmentation;
• pendulum;
• peristaltic (very slow, slow, fast, rapid);
• antiperistaltic;
• tonic.
• The first two types are rhythmic or segmental contractions.

Rhythmic segmentation It is provided mainly by contractions of the circular layer of the muscular membrane, while the contents of the intestine are divided into two parts. The next contraction forms a new segment of the intestine, the contents of which consist of the chyme of the two halves of the former segments. These contractions achieve mixing of the chyme and increasing the pressure in each segment.

pendulum contractions provided by the longitudinal muscles and participation in the contraction of the circular muscles. When this happens, the chyme moves back and forth and its weak forward movement in the caudal direction. AT upper divisions human small intestine frequency of rhythmic contractions is 9-12, in the lower - 6-8 per minute.

peristaltic wave, consisting of the interception and expansion of the small intestine, pushes the chyme in the caudal direction. At the same time, several peristaltic waves move along the intestine. The peristaltic wave moves along the intestine at a speed of 0.1-0.3 cm / s, in the proximal sections it is greater than in the distal ones. The speed of the rapid (propulsive) wave is 7-21 cm/s.

At antiperistaltic contractions the wave moves in the opposite (oral) direction. Normally, the small intestine, like the stomach, does not contract antiperistaltically (this is typical for vomiting).

tonic contractions may have a local character or move at a very low speed. Tonic contractions narrow the intestinal lumen over a large area.

Regulation of motility of the small intestine

The motility of the small intestine is regulated by nervous and humoral mechanisms; the role of myogenic mechanisms, which are based on the properties of smooth muscle automation, is quite large.

Parasympathetic nerve fibers predominantly excite, and sympathetic - inhibit the contraction of the small intestine. These fibers are conductors of the reflex regulation of the motility of the small intestine. The act of receiving write conditionally and unconditionally reflex first briefly slows down, and then enhances intestinal motility. In the future, it is determined by the physical and chemical properties chyme: rough, rich in dietary fiber and fats indigestible in the small intestine, food enhances it.

Local irritants that enhance intestinal motility are the products of digestion of nutrients, especially fats, acids, alkalis, salts (in concentrated solutions).

Bark big brain It influences intestinal motility mainly through the hypothalamus and limbic system. Important role cerebral cortex and the second signaling system in the regulation of intestinal motility is proved by the fact that when talking or even thinking about delicious food intestinal motility increases, and with a negative attitude towards food, motility is inhibited. With anger, fear and pain, it is also inhibited. Sometimes, with some strong emotions, such as fear, there is a violent intestinal motility ("nervous diarrhea").

Adequate irritation of any part of the gastrointestinal tract (GIT) causes excitation in the irritated and underlying areas and enhances the movement of the contents in the caudal direction from the site of irritation. At the same time, it inhibits motility and delays the progress of chyme in the overlying sections of the gastrointestinal tract.

Humoral substances change intestinal motility, acting directly on muscle fibers and through receptors on intramural neurons. nervous system. Strengthen the motility of the small intestine serotonin, histamine, gastrin, cholecystokinin-pancreozymin.

Digestion in the large intestine

From the small intestine, portions of chyme pass through the ileocecal sphincter - the Bauhinian damper - into the large intestine. The sphincter acts as a valve that passes the contents of the intestine in only one direction.

Outside, the ileocecal valve is closed. After 1-4 minutes after eating, every 0.5-1.0 minutes the valve opens and the chyme in small portions passes from the small intestine to the blind. The opening of the valve is carried out reflexively. The peristaltic wave of the small intestine, increasing the pressure in it, opens the valve. An increase in pressure in the colon increases the tone of the muscles of the ileocecal valve and inhibits the flow of the contents of the small intestine into the colon. In the process of digestion of food, the large intestine plays a small role, since the food is almost completely digested and absorbed in the small intestine, with the exception of some substances, such as plant fiber. A small amount of food and digestive juices undergoes hydrolysis in the large intestine under the influence of enzymes from the small intestine, as well as the juice of the large intestine itself.

Colon juice is excreted without any mechanical irritation in a very small amount. It distinguishes liquid and dense parts, the juice has alkaline reaction(pH 8.5-9.0). The dense part looks like mucous lumps and consists of sloughed epithelial cells and mucus, which is produced by goblet cells.

The main amount of enzymes is contained in the dense part of the juice. Enterokinase and sucrase are absent in the colonic juice. The concentration of alkaline phosphatase is 15-20 times less than in the small intestine. Small amounts of peptidase, lipase, amylase and nuclease are present.

Juice secretion in the large intestine is due to local mechanisms. With mechanical stimulation, secretion increases by 8-10 times.

In a person, about 400 g of chyme passes from the small intestine to the large intestine per day. In its proximal part, some substances are digested. In the colon, water and some ions (K +, Na +) are intensively absorbed, which is greatly facilitated by the motility of the colon. Chyme gradually turns into feces, which are formed and excreted per day on average 150-250 g. When eating plant food, there are more of them than when taking mixed or meat. The intake of food rich in fibers (cellulose, pectin, lignin) not only increases the amount of feces due to undigested fibers in its composition, but also accelerates the movement of chyme and forming feces through the intestines, acting like laxatives.

The value of the microflora of the large intestine

The bacterial flora of the gastrointestinal tract is necessary condition the normal existence of the organism. The number of microorganisms in the stomach is minimal, in the small intestine there are much more of them (especially in its distal section). The number of microorganisms in the large intestine is exceptionally high - up to tens of billions per 1 kg of contents.

The intestinal microflora is divided into three groups:

• the main one is bifidobacteria and bacteroids, which make up about 90% of all microbes;
• concomitant - lactobacilli, escherichia, enterococci, up to 10% of total number microorganisms;
• residual - citrobacter, enterobacter, proteus, yeast, clostridium, staphylococcus, aerobic bacilli, etc., less than 1%.

Anaerobic microflora prevails over aerobic.

The positive value of the intestinal microflora lies in the final decomposition of residues undigested food and components of digestive secrets, creation of an immune barrier, inhibition of pathogenic microbes, synthesis of certain vitamins, enzymes and other physiologically active substances participation in the body's metabolism.

Bacterial enzymes break down fiber fibers that are not digested in the small intestine. Hydrolysis products are absorbed in the large intestine and used by the body. At different people the amount of cellulose hydrolyzed by bacterial enzymes varies and averages about 40%.

Digestive secrets by doing your physiological role, are partially destroyed and absorbed in the small intestine, and part of them enters the large intestine. Here they are also exposed to microflora. With the participation of microflora enterokinase, alkaline phosphatase, trypsin, amylase are inactivated.

Normal microflora suppresses pathogenic microorganisms and prevents infection of the macroorganism. Violation normal microflora in diseases or as a result of prolonged administration of antibacterial drugs, it often leads to complications caused by rapid reproduction in the intestine of yeast, staphylococcus, proteus and other microorganisms.

The intestinal flora synthesizes vitamins To and group vitamins AT. Perhaps the microflora also synthesizes other substances that are important for the body. With the participation of the intestinal microflora in the body, the exchange of proteins, phospholipids, bile and fatty acids, bilirubin, cholesterol.

Many factors influence the intestinal microflora: the intake of microorganisms with food, dietary features; properties of digestive secrets (having to some extent pronounced bactericidal properties); intestinal motility (promoting the removal of microorganisms from it); dietary fiber in the contents of the intestine; the presence of immunoglobulins in the intestinal mucosa and intestinal juice.

Functions of the microflora of the large intestine

Mechanical protection of the mucous membrane (due to the complementary ™ glycolipids of the bacterial wall to the glycoproteins of the membranes of entsrocytes)

Inhibition of pathogenic and conditionally pathogenic microorganisms:

• competition for nutrients;
• education organic acids and polyhydric alcohols;
• production of bactericides, hydrogen peroxide;
• decrease in pH in the intestinal lumen

Synthesis of enzymes:

• glycosidases (a- and β-glycosidases, a- and β-galactosidases, β-glucuronidases, hemicellulases) that break down non-absorbable carbohydrates;
• proteases that destroy (inactivate) digestive enzymes;
• lipases that complete the hydrolysis of fats

Synthesis of vitamins K, B1, B6, B12

Detoxification of exogenous substrates through biotransformation and absorption:

• formation of biologically active substances;
• splitting of cellulose, pectins, lignins;
• fermenting carbohydrates into acidic foods

Formation immunobiological reactivity body:

• increase in phagocytic activity of macrophages and neutrophils;
• stimulation of the formation of secretory IgA;
• increase in the content of cytokines;
• production of a-, β-, γ-interferons

Participation in the metabolism of proteins, phospholipids and bile acids

Metabolism of estrogens (deconjugation of estrogens) to ensure their reabsorption

Motor function of the colon

In humans, it lasts about 1-3 days, of which longest time accounts for the movement of food debris through the large intestine. The motility of the colon provides a reservoir function: the accumulation of intestinal contents, the absorption of a number of substances from it, mainly water and ions; the formation of fecal masses from it and their removal from the intestines.

At healthy person the contrast mass begins to flow into the large intestine after 3-3.5 hours. The filling of the intestine lasts about 24 hours, and complete emptying occurs in 48-72 hours.

The large intestine has automaticity, but it is less pronounced than that of the small intestine. The motility of the large intestine is regulated in the same way as that of the small intestine.

Irritation of the mechanoreceptors of the rectum inhibits the motility of the colon. Her motility is also inhibited by serotonin, adrenaline, glucagon.

In some diseases, accompanied by the appearance of severe vomiting, the contents of the large intestine can be abandoned by antiperistalsis into small intestine and from there into the stomach, esophagus and horn. There is a so-called fecal vomiting (lat. miserere- horror).

defecation, i.e. emptying of the colon, occurs as a result of irritation of the receptors of the rectum by the accumulated feces in it. The urge to defecate occurs when the pressure in the rectum rises to 40-50 cm of water. Art. Sphincters prevent fecal loss: internal sphincter anus, consisting of smooth muscles, and the external sphincter of the anus, formed by a striated muscle. Outside of defecation, the sphincters are in a state of tonic contraction. As a result of reflex relaxation of these sphincters (the exit from the rectum opens) and peristaltic contractions of the intestine, feces come out of it. Great importance at the same time, it has the so-called straining, in which the muscles contract abdominal wall and diaphragm, increasing intra-abdominal pressure.

The reflex arc of the act of defecation closes in lumbosacral section of the spinal cord. It provides an involuntary act of defecation. Arbitrary control of the act of defecation is carried out with the participation of centers medulla oblongata, hypothalamus and cerebral cortex.

Sympathetic nervous influences increase the tone of the sphincters and inhibit the motility of the rectum. Parasympathetic nerve fibers in the composition of the pelvic nerve inhibit the tone of the sphincters and increase the motility of the rectum, i.e. stimulate the act of defecation. An arbitrary component of the act of defecation consists in the descending influences of the brain on the spinal center, relaxation of the external sphincter of the anus, contraction of the diaphragm and abdominal muscles.

Differences between the right and left halves of the large intestine are also clearly manifested in functional terms, which is explained by their anatomical and physiological features.

The main processes of digestion and subsequent absorption of split substances occur in the small intestine. In the blind and partially in ascending colon enzymatic digestion of food still continues, but the intensity of these processes is insignificant.
It has been proven that about 3% of proteins and carbohydrates are digested and absorbed in the large intestine. In the caecum, water is absorbed from the small intestine during the entire process of digestion. The liquid intestinal contents in the caecum and ascending colon thicken, and already in transverse colon fecal masses become dense, turning into distal parts colon into even denser.

Under the influence of a variety of microflora, the contents of the colon undergo fermentation and decay processes, with the formation of toxic substances - indole, skatole, phenol, etc., which are partially absorbed and then neutralized in the liver. In addition, dextrose and solutions are absorbed in the large intestine. table salt. The left half of the large intestine does not take part in the processes of digestion, only a slight absorption of water and some decay products occurs here. The main role of this part of the intestine is the formation and excretion of feces.

The promotion of contents through the large intestine depends on the characteristics of its motor function. In the large intestine there are the same movements as in the small intestine, but their intensity is less pronounced. In addition to the main types of movements, pendulum and peristaltic, the colon also has antiperistaltic movements, which are most pronounced in the caecum and gradually decrease towards lower divisions intestines.
In the motor function of the large intestine, especially its right half, a significant role belongs to the ileocecal obturator apparatus, which is considered as one of the nodal sections of the intestine, affecting the function of the entire gastrointestinal tract.

Schematically, the work of the ileocecal obturator apparatus can be represented as follows: it regulates the flow of intestinal contents from ileum into the thick, opening with a peristaltic wave from the ileum and spasmodically ejecting the intestinal contents in separate portions into the caecum; when a peristaltic wave appears from the side of the caecum, it prevents the contents of the large intestine from being thrown back into the small intestine, being a kind of complex valve. The function of the ileocecal obturator apparatus is carried out by the neuroreflex pathway, which has been proven in animal experiments and clinical observations.

Violations of the function of the ileocecal obturator apparatus can lead to significant disorders of the motor function of the gastrointestinal tract. At pathological processes in the caecum and ascending colon appendix and terminal ileum inflammatory nature, as well as at malignant neoplasms this section of the intestine may develop insufficiency or narrowing of the ileocecal obturator apparatus, clinically manifested by the corresponding symptom complex.
Anatomical and physiological features largely determine the various clinical manifestations cancer of the right and left half of the colon. These circumstances not only give grounds, but urgently require consideration of the clinic, diagnosis and treatment of tumors of the colon, taking into account the anatomical and physiological characteristics of its various departments.