The digestion of Lipids

Saliva doesn’t contain lipases. There is a gastric lipase which has got optimal pH near 3-5. Such pH is characteristicall for children therefore gastric lipase is acitive in childhood. Firstly lipids undergo the emulagation.This process occurs in lumen of small intestine. There are emulagators – compounds which decrease superficial tension of lipid’s drops (proteins, phospholipids, bile acids and soap). Under influence of peristalsis of intestine the lipid’s drop breaks up to smallest droplets. On these droplets bile acids and salts are absorbed and droplets acquire negative charge. Hence they repulse from each other. Some of droplets (30%) are absorbed into lymphatic vessels. But majority of them (70%) undergoes the digestion.

Lipase of pancreas is secreted in inactive form and it is activated under influence of salts of bile acids. Lipase acts on TAG and DAG. Lipase of intestinal juice is secreted in active form and acts on beta-MAG.

However, lipase of intestinal juice is not enough secreted therefore beta-MAG are main products of digestion of TAG.

Phospholipids are hydrolyzed under influence of phospholipase.

Cholesterolesterase is secreted by pancreas in inactive form. It is activated under influence of bile acids. This enzyme hydrolyzes esters of cholesterol.

The absorption of products of Lipids digestion

Glycerol, H3PO4, nitrogen-containing substances, FFA with quantity of carbon atoms less than 10 are absorbed passively in portal vein. Other products of lipids digestion form micelle.

Micelles enter the intestianal wall by pinocytosis.

The role of intestinal wall, lungs, liver and adipose tissue in Lipid Metabolism

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Cholesterol and its esters (Sterides)	\|	The role of intestinal wall:

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