Explain Lipid Metabolism I ?
You learnt earlier in Unit 5 that the lipids are absorbed through the intestine. As these molecules are oils, solubilization (emulsification) of dietary lipids is accomplished via bile salts that are synthesized in the liver and secreted from the gall bladder. The emulsified fats are then degraded by pancreatic lipases. These enzymes, secreted into the intestine from the pancreas, generate free fatty acids and a mixture of monoand diacylglycerols from dietary triacylglycerols.
Following absorption of the products of pancreatic lipase by the intestinal mucosal cells, the resynthesis of triacylglycerols occurs. The triacylglycerols are then solubilized in lipoprotein complexes (complexes of lipid and protein) called chylomicrons.
Triacylglycerols synthesized in the liver are packaged into VLDLs and released into the blood directly. Chylomicrons from the intestine are then released into the blood via the lymphatic system for delivery to the various tissues for storage or production of energy through oxidation. The triacylglycerol components of VLDLs and chylomicrons are hydrolyzed to free fatty acids and glycerol in the capillaries of adipose tissue and skeletal muscle.