Human Biochemistry Volume 1 - Murray R. 1993

Bioenergetics and Metabolism of Carbohydrates and Lipids
Transport and Storage of Lipids
Biomedical Significance

In omnivores and humans, the anabolic phase of the nutritional cycle brings an excess of caloric intake into the body. This is followed by a period of negative caloric balance during which previously stored CARBOHYDRATES and fats are utilized. Lipoproteins serve as the connecting link in this cycle: they transport Lipids from the intestine as chylomicrons, and from the Liver as very-low-density lipoproteins (VLDL) to various Tissues where they undergo oxidation (as well as to adipose tissue for storage). From adipose tissue, lipids are mobilized as free Fatty acids that enter the bloodstream and bind to serum albumin. Disörungen of Lipid METABOLISM occur at the stages of lipoprotein formation or utilization, leading to Various Forms of hypo- and hyperlipoproteinemia. The most common condition is Diabetes Mellitus, where Insulin deficiency triggers excessive mobilization of free Fatty Acids and impairs the clearance of chylomicrons and VLDL, ultimately resulting in hypertriacylglycerolemia. Most other pathological conditions involving lipid metabolism disorders are primarily linked to hereditary defects in the Synthesis of the apoprotein moiety of lipoproteins, as well as Key Enzymes or lipoprotein receptors. Some of these genetic defects cause hypercholesterolemia and premature atherosclerosis. Excessive fat accumulation leads to obesity, one form of which arises from impaired thermogenesis in brown adipose tissue due to improper Nutrition.