24.1 General characteristic of digestion
24.2 Regulation of digestion
24.3 Digestive functions of digestive system
24.4 Non-digestive functions of digestive system
24.5 Methods of research of digestion
24.6 Digestion in the oral cavity
24.7 Swallowing
Profile materials Control questions Situational tasks
24.1. General characteristic of digestion
Digestion is a physiological system providing for entry of food into the body, its mechanical and chemical processing into monomers, and their absorption into the internal environment of the body. ?Precise knowledge of what happens to the food entering the body must be the subject of ideal physiology, physiology of the future.? (From the I. Pavlov?s Nobel speech, 1904). The digestive system eliminates allergic and toxic ''aggression' of nutrients, primarily proteins (Fig. 24.1).
Digestion types are distinguished according to the site of action and sources of enzymes.
According to the site of enzymatic effect: 1) abdominal (extracellular); 2) membrane (parietal); 3) intracellular (lysosomal).
According to the source of enzymes: 1) own (enzymes of the body); 2) symbiotic (microflora enzymes); 3) au-tolytic (food enzymes).
The digestive conveyor includes the following steps: oral - mechanical processing of food, moistening it with saliva, preparation for dosed transport into the stomach, esophageal - dosed transport of food into the stomach, gastric - deposition of food, moistening it with gastric juice, hydrolysis of food products and conversion of food to chymus, dosed transport of chymus into the duodenum, small intestine - movement, hydrolysis, absorption of chymus products and its dosed transport into the colon, colon - deposition of chymus, absorption of water and other substances, conversion of chymus to feces and its portioned release into the external environment. During these stages, digestive functions are performed at varying degrees of expression: secretion, motility, chemical hydrolysis, absorption.