Biochemistry

organic acids (acetic, butyric, etc.). Some of these products are absorbed by the intestinal wall and used as an energetic material, while some are consumed as a nutrient medium for microorganisms and for the biosynthesis of certain vitamins (for example, K, B| 2 , folic acid). The degree of splitting of cellulose by enzymes of microorganisms largely depends on the fetal maturity. Fiber of unripe and ripe fruits, vegetables and fruits is digested better than overripe ones. The nutritional value of fermentation products for human is very small and is not taken into account when calculating the diet. However, fiber is an indispensable irritant of the secretory and motor functions of the intestine. Excess fiber increases peristalsis of the human intestine, which accelerates the movement of food through the gastrointestinal tract. This leads to insufficient digestion and absorption of food, in connection with which many unused nutrients are absorbed into the feces. Their losses increase also because fiber delays the access of enzymes to digestible carbohydrates and, therefore, make it difficult to digest food. Previous culinary processing of food and chewing thoroughly contribute to the destruction of fiber. With a large amount of it, fermentation processes in the intestine are enhanced, which leads to the occurrence of meteorism. It causes discomfort and a number of complications in diseases of the intestines, as well as in people leading a sedentary lifestyle. The bulk of the pulp in unchanged form is excreted from the body with feces. Carbohydrate absorption in the small intestine is a complex biochemical process. Simple sugars are absorbed by transmembrane transport using carrier proteins. On the outer surface of the membranes of cells of the small intestine, they combine with a specific carbohydrate (glucose or galactose), forming a mobile complex "carrier - carbohydrate". In the form of such a complex, carbohydrate is transported through the membrane into the cell. Here the complex breaks down, the carbohydrate is used or transported further by the blood, and the carrier protein returns and re-enters the reaction of the transport. An important role here belongs to Na + ions, i.e. this process is Na +- dependent. The process occurs with the expenditure of ATP energy, it is catalyzed by the enzyme hexokinase. This increases the oxidative reactions in the intestinal wall, providing resynthesis of ЛТР consumed for the absorption of monosaccharides. The absorption of various monosaccharides into the blood from the intestine iscarried outat different speeds. If the rate of glucose absorption is taken as 100%, then the absorption of galactose will be 110, fructose - 43, mannose - 19, xylose - 15, arabinose - 9. The absorbed monosaccharides through the portal vein enter the liver, where they undergo various transformations, in particular, there is a mutual 212