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3.4.1.4 Lipid metabolism
3.4.1.4.Lipid metabolism
Lipid metabolism is concerned mainly with fatty acids and cholesterol.The source of long-chain fatty acids is either dietary lipid or de novo synthesis from acetyl-CoA derived from carbohydrate. In the tissues, fatty acids may be oxidized to acetyl-CoA (β-oxidation) or esterified to acylglycerols, where, as triacylglycerol (fat) they constitute the body’s main caloric reserve. Acetyl-CoA fromed by β-oxidation has several important fate. (1)As in the case of acetyl-CoA derived from carbohydrate, it is oxidized completely to CO2 + H2O via the citric acid cycle. Fatty acids yield considerable energy both in β-oxidation and in the citric acid cycle and are therefore very effective tissue fuels. (2) It is a source of the carbon atoms in cholesterol and other steroids. (3) In the liver, it forms ketone bodies, alternative water-soluble tissue fuels that become important sources of energy under certain conditions (eg, starvation)
Fig. 4.1.3Fatty acid metabolism |