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SMDEP Biochem 5
finals
| Question | Answer |
|---|---|
| Lipids...Why should I care? | Causes of Death in US-diseases of heart...Pieces of plaque can break free, travel to the brain, and block blood vessels that supply blood to the brain. |
| What are some biological roles of lipids? and Types of Lipids | Myelin sheath, Nerve, and Neuron..Types of Lipids: Triacylglyceride, Steroids, Fatty acids, Phospholipids, and Glycolipids. |
| Saturated Fats | No double bonds in tail. Solid at room temperature. Animal-based fats |
| Unsaturated Fats | One or more double bond. Plant-based fats |
| Properties of Lipids | Because lipids are polar molecules, they need to be guided through non-polar membranes and carried in aqueous environments by special proteins. (Bile salts, Chylomicrons, Lipoproteins, Albumin) |
| Lipid Sources (Exogenous lipids) | Lipids from dietary intake. 90% is TAG. 10%=cholesterol, phospholipids, & free fatty acids. |
| Lipid Sources (Endogenous lipids) | Biosynthesis, cellular degradation, stored in adipocytes. |
| TAG Structure | Triacylglycerol (TAG) Composed of glycerol and three fatty acid chain (R groups) linked together ester bonds. Polar head. Non-polar tail. |
| Lipids & Nutrition | Food labels list fat content: total fat, saturated fat, trans fat, cholesterol. What about unsaturated fat? Total fat-saturated fat-trans fat=unsaturated fat. |
| Trans Fats | Trans fats are unsaturated fats that are converted into trans configuration removing the kink that rendered them liquid at room temperature. |
| Trans Fats 2 | "Partially hydrogenated" oil. Commonly found commercial baked goods and used to fry foods in restaurants. Raise LDL and lower HDL. Increases risk for cardiac disease. If serving contains less than 0.5 grams then it's not reported. |
| Lipid Digestion | Lipids must be broken down to fatty acids, cholesterol and 2-monoacylglycerol to be absorbed by intestinal cells (enterocytes). Lipid digestion begins in the stomach and continues in the duodenum. |
| Lipid Digestion 2 | Salivary glands release lingual lipase which is activated by acidic environment in the stomach. Stomach cells secrete gastric lipase. Pancreas releases pancreatic lipase, cholesterol esterase & phospholipase A2 |
| Lipid Digestion 3 | Lipases breakdown triacylglycerides into 2-monoacyglycerol and free fatty acids. 10-15% of dietary cholesterol is in the form of cholesteryl ester which cannot be absorbed by enterocytes. |
| Lipid Digestion 4 | Cholesterol esterase hydrolyzes cholesterol esters from the diet into free cholesterol. Phospholipase A2 degrades phospholipids into fatty acids which can be absorbed and lysophospholipids. |
| Lipid Digestion 5 | Lysophospholipid is a powerful detergent that can then aid in breaking down other fat. |
| Role of Bile | Bile and bile salts are made by the liver and stored in the gallbladder. 2 jobs: Emulsify dietary fat and increase surface area for digestion. Form micelle around the products of lipid digestion. |
| Role of Bile 2 | Micelle then carry products through the aqueous layer on top of the enterocyte where they can be absorbed by the enterocyte. |
| Lipid Absorption | Digested triglycerides and phospholipids are absorbed and reassembled in the enterocyte. Then along with cholesterol they are packaged into chylomicrons. Small free fatty acids and glycerol are absorbed directly into the blood. |
| Lipid Absorption 2 | Chylomicrons are lipid transport molecules. Chylomicrons are absorbed into lymphatic system through the lacteals (lymph vessels) in the small intestine. |
| Lipid Absorption 3 | They enter the circulatory system through the thoracic duct which drains into the left subclavian vein and eventually the vena cava. They then can be transported to peripheral cells. |
| Fate of TAG | Chylomicrons deliver TAG primarily to skeletal muscle cells and adipose tissue. TAG is broken down again into free fatty acids and glycerol. Fatty acids can be converted to acetyl-CoA which can then enter the Kreb's/TCA cycle and used to make ATP. |
| Lipoproteins (VLDL & LDL) HDL picks up cholesterol from dying cells and transports it to liver. | VLDL carries mostly triglycerides and cholesterol made by the liver. Becomes IDL which is then returned to the liver where it's converted to LDL. LDL carries most cholesterol. Delivers cholesterol to cells from liver. |
| CAD Treatment: Medical Management | Statins block the enzyme HMG-CoA reductase decreasing cholesterol synthesis in the liver. Liver senses lower cholesterol level and up-regulates LDL receptors in an effort to absorb cholesterol in the circulation. Lowers LDL and create foam cells. |
Created by:
c13luong
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