in turn are incorporated in the plasma lipoproteins Phospholipids to some extent are ant cholesterol agents. Thus, normally the cholesterol .

there should not be hypercholesteremia While this may be partly, correct, it is not fully correct Desprte satisfactory control of The blood sugar, serum (plasma) cholesterol values remain high in some diabetics This means, we still do not know, all the aspects of the pathogenesis of hypercholesteremia in diabetics. Incidenlly, In modern health conscious world diabetics usually do not die of diabetic ketosis or coma, but of atherosclerotic diseases Serum (plasma) cholesterol lowering measures are 1 Avoidance of saturated fats m ihe food. The subject should take more polyunsaturated fatty acids. Polyunsaturated fatty acids probably reduce The synthesis of cholesterol Reduction of obesity. Certain plasma cholesterol lowering agents are available in the market.They may lower the serum cholesterol Thyroxine in the midfifties became a popular drug for hy-percholesteremia This drug is no longer used for this purpose Clofibrate, In the mid 60s and early 1970s, this drug was very popular . Many other measures are available, for details, see, 'atherosclerosis of coronary artery' (CHD), in chap 5.10. SUMMARY & HIGHLIGHTS oxidation occurs for even numbered C atom containing fatty acid chains and most Tatty acids (FA) of our body thus suffers B oxidation Site mainly liver Five major steps, only 1st step extramitochondrinal, others intramitochondrial Camitine acts as a carrier and in diabetic ketosis, carntine activity is, enhanced. End products of P oxidation is2C Cholesterol has exogenous and endogenous source Biosynthesis occurs mostly in the liver. Steps discussed Dangers of hypefcholsteremia as well as measures to reduce it also have been discussed Finally, although our body can synthesize the CPP ring from the active acetate. the human body cannot degrade the CPP ring structure once formed in the body All it can do is to after/remove the side chain. A major avenue for removal of cholesterol is via bile salts. METABOLISM OF PHOSPHOLPIDS Introduction Utility of phospholipids Synthesis and degradation IntroductionThe lipids of the body are sometimes divided into two groups, (i) element constant and: (ii) element variable. Element variable is that fraction of lipids which are reduced in quantity during starvation, because they undergo catabolism to provide energy. Conversely, by overfeeding, the element variable's amount in Ihe body can be increased Triglycerides in the depot fat are, thus, element variable Element constant of the lipid is made up of that fraction of The body lipid which are required principally for formation of the cell membrane of the animal cell This fraction is not sharply altered in amount by starvation or overfeeding Phospholipids fall in this category. The general chemistry of the phosphohpids have been discussed earlier (chap.7.7) in short, phospholipids are compounds containing fatty acids, phosphoric acid, nitrogenous base and a higher alcohol. Most commonly, the higher alcohol is glycerol and phospholipids containing glycerols are often called glycerophospholipids (for example, lecithin, cephalins, plasmalogens etc.). Commonly occurring nitrogenous bases are chorine, ethanol amine. serine etc. Utility (1) Lecithin and other phaspholipids take part In the formation of the cell membrane (fig.1.1.7) (2). Sphingomyelin forms the myelin sheath Presence of myelin sheath makes the nerve fiber a faster conducting nerve (see 'saltatory conduction' fig. 10A 3.3). Most of the nerve fibers of man and higher animals are myelinated where as in the non vertebrates they are mostly non myelniated This gives a superior mobility to the mammals Each molecule of a phospholipids. can carry fatty acids (e.g. lecithin in its molecule can incorporate two molecules of fatty acids) Thus, phospholipids are vehicles of fatty acid transport in the blood Phospholipids, in turn are incorporated in the plasma lipoproteins Phospholipids to some extent are ant cholesterol agents. Thus, normally the cholesterol . phospholipid ratio is around 0.8 If the ratio exceeds 1, then, [particularly in the past), it was regarded as a sign of disorder of cholesterol metabolism and an indication of development of atherosclerosis. Thus, more than the actual value of plasma cholesterol. C P ratio used be regarded as a better index (Owing to the introduction of better parameters, determination of C P ratio is no longer very popular) Phospholipid opposes the development of fatty liver Synthesis and degradation Synthesis of phospholipds occur in all tissues, excepting the skin and blood. Discussion of the actual chemical steps of the phosphclipid synthesis, is however, outside the scope of this book Degradation of phospholipids The phospholipids are degraded by the enzyme phos-pholipase Actually there are several phospholipases in our body Success entercus and spleen contain rich amount and varieties of phosphalipases. Phospholipids removes one of Ihe fatty acids from the phosphohpid molecule resulting in lysophosphatid, for example, from lecithin, lysorecithin is obtained by the action of phospholipase. A phospholipase is presant in the venoms of some types of common Indian snakes (vipers e.g. Chandraborta) which converts lecithin into lysolecithin Lysophosphahds (e.g. lysolecithin) are poisonous because they rupture the cell membrane.Thus. they can lyses the RBC membrane and cause hemolysis Indeed the phospholipase present in snake venom, as mentioned above, causes massive hemolysis Normally the lysophosphatids formed by the phospholipase are immediately removed, so that no harm can be