Physiology of intestines

The intestines performs two main functions: digestive and motor. Along with this, duodenum is involved in regulation of a number of nearby bodies of digestion. Suffice it to say that at present we know of six hormones secreted by mucous membrane duodenal ulcer. Interrogation (Ewald, Boas, 1886), an inhibitory effect of the vagus nerve, and gastrina on secretory and motor function of stomach. Secretin (Bayliss, Starling, 1902) stimulates the secretion of pancreatic juice, rich in bicarbonates, as well as activities brunnerova glands and separation of liquid watery bile. Cholecystokinin (Ivy, Oldberg, 1928) causes contraction of the gallbladder and some increases biliary excretory function of liver. Pancreozymin (Harper, Raper, 1943) stimulates the secretion of pancreatic juice, rich in enzymes: cancinogens, lipase, and amylase. Willikins (Kokas, Ludany, 1933) causes the contraction of the intestinal villi. Anteroinen (Greengard, 1948) enhances the secretory activity of the mucous membrane of the small intestine. The existence of the latter hormone is not yet fully justified (Koelsch, Giilzow, 1969). It should be emphasized that the allocation of these hormones influence on the mucous membrane duodenal ulcer hydrochloric acid, bile, bile acids and certain food ingredients: sugar, fat, protein products. Said is consistent with the opinion of K. A. Treskunova (1968), according to which duodenum - hormonal centre of digestion. In patients who underwent resection of the stomach by Billroth II, one of the major reasons of the digestive system is the lack of allocation of hormones duodenum. Contents end of the resected stomach directly into the small intestine, bypassing the duodenum, and therefore there is no impact on the last natural stimuli, stimulating the secretion of hormones. There is a basis to assume that the duodenum of the stomach secretes the hormones and General actions (A. M. Ugolev, 1962; K. A. Treskunov, 1968). In their absence, there is a pathological state, which is accompanied by a number of common symptoms of the disease duodenal failure.
Digestive function occurs primarily in the small intestine, and power is more important in the activities of the colon. In this regard, the clinical manifestations associated with digestive disorders, are more common with predominant lesion of the small intestine, and changing motor functions symptoms most commonly observed side of the colon.
Movements that occur in the small intestine, mix the contents of the intestine and thereby contribute to the process of digestion (pendulum-like or oscillatory motion) and promote the contents of the small intestine towards colon (peristalsis). Violation of motor function of the small intestine, leading to more rapid passage of chyme, may cause abnormalities of the digestive process in connection with reduction of time of contact of the substrate digesting enzyme. It is observed both in functional diseases of the small intestine and organic her defeats.
The colon is all the time in the status of a particular muscle tension - tone. In addition, it is capable of a variety of active movements. As a result of their mixing content and slow progress toward the rectum. But, in addition, in motor activity of the colon there are two types of specific movements, not typical of other intestine (antiperistaltic and defecation). The first type of movement there is in the area of the caecum and ascending part of the colon, and the sigmoid colon.
In the result of antiperistaltic the contents of the intestine is returned in a retrograde direction, and thus the conditions for better absorption of nutrients. The defecation is a complex, subtly adjustable motor process of the distal colon.
From the positions of modern physiology should, in addition to the motor, to distinguish a number of functions ulcer, providing the absorption of nutrients. Secretory function of the small intestine consists in allocation of intestinal juice (about 3 litres a day) with the contents of several enzymes (fermentopathia function of the small intestine). Outstanding intestinal juice brunnerova glands libertylove glands and epithelial cells. The maximum allocation of intestinal juice is observed in about 4-5 hours after ingestion. The gastric juice is enhanced when entering the duodenum of hydrochloric acid, as well as under the influence of the hormone enterokinase. Digestive function of the small intestine is done through processes fermentative digestion of nutrients. They occur in the cavity of the small intestine (abdominal digestion), and directly on the surface of mucous membranes in the field of the brush border (microvilli). This wall or membrane digestion. It is the enzymes as pancreatic and intestinal juice, fixed (adsorbed) on the cell membrane (A. M. Ugolev, 1967). Adsorption enzyme on the surface of cells with the proper orientation of their active centers increases their concentration in this area, and greatly increases the intensification of the process of enzymatic degradation. Thanks enzymatic processes nutrients are decomposed to the point, at which they are suitable for suction. Absorption function is villi due to the presence of an extensive network of blood and lymphatic vessels as through active transport (the cost of appropriate energy)and by diffusion. Water, soluble salts and sugars are absorbed very quickly (within minutes) in the duodenum and jejunum. A few more slowly absorbed products from the breakdown of proteins (amino acids) and fat (in the form of glycerol and fatty acids). In cases of pathological changes in these areas of the small intestine absorption of products of fission can occur in the ileum. Only in the last there is an intake of vitamin b and bile salts (Berndt et al., 1969). The vacuum function is closely connected with parietal digestion - both process depends on the state structures and cells ultrastructure of the surface epithelium of intestinal mucosa. According to A. M. Ugolev (1967), the cell membrane separating the two environment (intracellular and extracellular), is not only transport (absorption) surface, but digestive, and there is effective communication between processes, hydrolysis and transport.


Therefore, in the small intestine happen main stages in the complex process of breakdown and absorption of nutrients (proteins, fat and carbohydrates). This is done under the influence of combined effect of intestinal juice, bile secretion of the pancreas. But these digestive juices for normal course of the process of digestion and absorption is not enough. Need a full-fledged structure and ultrastructure of epithelial cells of the small intestine, which determines the appearance on the surface of cells phenomenon parietal digestion and transport processes. In this regard, in the development of pathological processes is particularly important damage to the structure and ultrastructure of the epithelium of the small intestine. The usefulness of the latter is closely connected with the processes of regeneration (recovery) of the mucous membrane. It is known (Bertalanfy, 1964; Creamer, 1965), the time of complete update of the mucosa of the duodenum is about 2 days, thin - 2,8, and thick - till 6 days. These data are consistent with the quantitative relation functionally complete cell surface epithelium to non-differentiated epithelial cells in the crypts of the small intestine (3 : 1). If you increase the shedding of cells and maintain the same intensity of regeneration, or the decline of the past comes the main pathological process is observed almost in all diseases of the small intestine, the atrophy of the mucous membrane with a corresponding violation of the functions of digestion. Indigestion can touch and isolated individual nutrients in connection with congenital enzyme nedostatochnosti small intestine. Of them, most frequent milk intolerance is associated with a deficiency of the enzyme that breaks down milk sugar (lactose). Partial indigestion with respect to certain food substances may occur in connection with various pathological processes that are not linked to birth defects (acquired the enzymatic deficiency of the small intestine).
In the large intestine ends absorption of digested food and mainly of water, and is the splitting of the remaining substances as under the influence of enzymes, coming from the small intestine, and bacteria. The latter are located in the terminal ileum in the caecum. The number of germs decreases towards the distal part of the intestine as the seal of feces. It is known that the microbes living in the intestines, include in its action or "rotten" (proteolytic), or to "fermentation" (splitting carbohydrates). Depending on the quantity and quality of the source material (proteins and carbohydrates) in the colon can be different according to the intensity of the process of microbial breakdown of substances with prevalence or putrid, or the fermentation process. As in normal conditions in the small intestine is almost a complete breakdown and absorption of proteins and carbohydrates, it is a very small and a roughly equal amount of these substances reaches the caecum and causes involving relevant microbes weak and equal intensity processes of rotting and fermentation. In violation of the absorption of carbohydrates in the small intestine (significant acceleration of passing the content, the defeat mucous membrane of the small intestine and its atrophy, failure of function of the pancreas) large number of them reaches the colon. As a consequence of this activates the vital activity of fermentation flora, resulting in the formation of significant amounts of carbon dioxide and organic acids, which leads to bloating and changes the way the feces with a neutral or slightly alkaline to acid (pH Cala can achieve this 5,2). Putrefaction processes with participation of microbes and with the final formation of ammonia in the colon " with increasing protein products. Food proteins in most cases, in conditions of a pathology time to be broken down and absorbed in the small intestine (M. D. Mikhaylov, 1962). Protein substances in the colon increase at the expense of increased desquamation of the epithelium as thin and large bowel, and highlight inflammatory exudate, which is often observed in pathological conditions. With the strengthening of proteolytic processes in the colon associated with microbial flora, the reaction of Cala becomes alkaline and pH his exceed 7,4.
The composition of microbes in the colon can change not only due to the prevalence of "fermentation" or "rotten". The term "dysbacteriosis (dysbiosis" - Haenel, 1964) means a decrease in the amount of anaerobic bacteria (lactobacilli) and the emergence or increase of Escherichia coli, cocks, clostridia and others In elderly and old dysbacteriosis observed significantly more often than the young. The normal ratio of separate kinds of intestinal microbes may be violated in connection with the use of antibiotics. In this respect the most effective tetracyclines and neomycin. If antibiotics are not used for a long time, then restore normal bowel flora is relatively fast days after their removal.
Recently there have been signs on the participation of the large intestine and immunological reactions. The prerequisites for this was very common in the lining of lymphocytes (in its own layer), the large surface of the bowel that deals directly with possible antigens, doubtless part of immunological reactions in a number of intestinal diseases and, finally, the effectiveness of steroid therapy for them.