Cholesterol and its esters (Sterides)

1) structural role – approximately 30% of membrane's lipids are cholesterol. The role of its as structural material consists in: a) amortizator of membranes, i.e. it promotes aggregate's state of membranes; b) it prevents phospholipids of membranes from lipid peroxidation; c) dielectrical role, i.e. it promotes one-directional conduction of nervous impulse and impedes its dispersion

2) structural role, i.e. cholesterol is a precursor of glucocorticoids, mineralocorticoids, sexual hormones, vitamin D3 and bile acids

3) antihemolytic action which is due to OH-group of cholesterol. Saponins are bound with cholesterol therefore hemolysis is stopped

4) antitoxic role, i.e. toxins bind with cholesterol

5) negative role of cholesterol, i.e in derangement of cholesterol metabolism the following diseases are developed: atherosclerosis, bile stone disease, cancer

Enumerated lipids can be synthesized in the body, but PUFA (essential fatty acids) need for the lipid synthesis. The majority of these acids aren't synthesized in the body and need to be supplied through the diet. Therefore they are also called as vitamin F (from fat – lipid).

Following acids belong to PUFA: linoleic acid (C17H31COOH); linolenic acid (C17H29COOH); arachidonic acid (C19H31COOH)

The importance of PUFA:

1) structural role: PUFA enter the phospholipids of membranes

2) antiatherogenic role: a) PUFA binds with cholesterol and cholesterol esters are formed. They aren't stored in vessels because cholesterol becomes more mobile (more soluble)

3) arachidonic acid is a precursor of prostanoids (PGE2, TXA2, LTRB4). These prostanoids are inflammatory mediators

4) PUFA increase the resistance to infections

5) PUFA are lipotropic factors, i.e. they prevent liver from distrophy

<== попередня сторінка	\|	наступна сторінка ==>
Elimination of final products of carbohydrates metabolism	\|	The digestion of Lipids

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