HNF 461 1st Edition Lecture 19 Outline of Last Lecture I Major Events of Digestion II Cholesterol Esters and Phospholipid Digestion III Micelles IV Bile V In the Cell VI Chylomicron VII Therapeutic Inhibition of Fat Absorption a Olestra sucrose Polyester b Orlistat lipase Inhibitor Outline of Current Lecture I General Structure of a Lipoprotein II Functions of Apolipoproteins III Major Lipoproteins in Circulation IV Major Apolipoproteins in Circulation V Transport of Chylomicrons VI Metabolism of Chylomicrons VII LPL Km VIII Lipid Metabolism in Adipocyte IX Lipid Metabolism in Hepatocyte Current Lecture Dietary Fat Transport and Clearance 1 General Structure of a Lipoprotein a Integral apoprotein ex apoB 48 b Peripheral apoprotein ex apoC 2 c Phospholipid outer layer with free cholesterol These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute d Core consists of cholesterol esters and triacylglycerol 2 Functions of Apolipoproteins a Recognition sites for cell surface receptors b Activator or coenzymes for enzymes c Some are essential structural components ex for chylomicrons and VLDL d Some can be transferred between lipoproteins e Functions of some are not yet clear 3 Major Lipoproteins in Circulation a Chylomicrons contains the most lipids b VLDL c LDL d HDL contains highest amount of triglycerides and the highest portion of proteins 4 Major Apolipoproteins in Circulation a apoA 1 Mostly important for HDL function b apoB 100 LDL and VLDL c apoB 48 chylomicron d apoC 2 VLDL HDL and chylomicrons activates lipoprotein lipase e apoE VLDL HDL and chylomicrons allows liver recognition of chylomicron remnants for reabsorption 5 Transport of Chylomicrons a Produced in the intestine b Transported to lymphatic system blood 6 Metabolism of Chylomicrons a In blood encounter lipoprotein lipase which metabolizes chylomicron into cholesterol and free fatty acids i Fatty acids are absorbed by cells and re estrified for various purposes depending on the cell type b Rapid clearance by heart muscle and adipose tissue c Chylomicron Remnant What remains of chylomicron after broken down by lipase smaller and more condensed Is absorbed by the liver when binded to apoE 7 LPL Km a Fatty Acids very important for heart muscle i Heart LPL Km is low b Fat tissue LPL Km is high because not essential for survival 8 Lipid Metabolism in Adipocyte a Chylomicron broken down to LPL and triglycerides i Triglycerides glycerol which is transported back to liver b Free fatty acids enter the fatty acid pool in adipocyte which will be converted to TAGs and then enter the TAG pool c Glucose absorbed by adipocytes become Acetyl CoA which is converted to fatty acids 9 Lipid Metabolism in Hepatocyte a Chylomicron remnants CR go back to liver liver recognizes apoE b Liver uses components of CR to make new products or to pack phospholipids cholesterol to make VLDL and HDL
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