Pathology of carbohydrate metabolism
Carbohydrate: - is an aldehyde and ketone of polynuclear alcohol (spirit). Hydrolysis of glycogen and starch starts in the mouth under the influence of alfa-amilase of saliva. Monosaccharides can be absorbed in the mouth. In the stomach there are no enzymes which hydrolyze carbohydrates. In duodenum and in the small intestine under the influence of alfa-amilase they get hydrolyzed up to dextrin and maltose (cavity digestion). Such enzymes as saccharose, maltose, lactose, isomaltose and et cetera are localized on the surface of microvillae which splinter dextrins and disaccharides up to monosaccharides. In congenital or acquired deficiency of one or more enzymes of disaccharide hydrolyze disaccharide deficiency develops. Disaccharides block the place of absorption so that absorption of monosaccharides gets disturbed. Let's see the pathology of disaccharide deficiency on the example of children with the congenital deficiency of lactose. Undigested lactose enters the large intestine and gets splinted by the bacteria up to organic acids (milky acid, acetic acid). The increase of lactose and organic acids changes osmotic pressure in the lumen of the intestine which appears with the rise of liquid secretion and the volume of fecal masses, the intestinal peristaltic increases, and osmotic diarrhea develops. In physiological conditions glucose gets absorbed very fast in the small intestine because of the existence of a passive diffusion. All other sugars like mannose, ksilose, arabinose get absorbed only by the passive diffusion. That's why glucose and galactose get absorbed faster than the other monosaccharides. The functional condition of gastrointestinal tract, the content of food products, vitamins, microelements and etc influences the absorption of carbohydrates. The absorption of glucose abruptly decreases due to disturbance of its phosphorylisation in the cells of the intestinal wall. The main reasons of the given disorder are hexokinase enzyme deficiency which develops due to inflammation of the intestinal wall, poisoning by: phloridizin, monoiodacytate. Due to malabsorption of carbohydrates hypoglycemia and loss of body weight occur. As for the synthesis of glucose by the gluconeogenesis fats and protein are expensed. In the intestine the unsplitted carbohydrates are metabolized by the bacteria which cause the osmotic diarrhea. Pathology of glucose develops more often than the other carbohydrates pathology. Упражнение 1. Изложите основное содержание текста на русском языка. Упражнение 2. Составьте письменно аннотацию текста на английском языке.
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