tailieunhanh - Ebook Marks’ basic medical biochemistry: A clinical approach - Part 2

(BQ) Part 2 book "Marks’ basic medical biochemistry: A clinical approach" presents the following contents: Oxidation of fatty acids and ketone bodies, oxygen toxicity and free radical injury, metabolism of ethanol, basic concepts in the regulation of fuel metabolism by insulin, glucagon, and other hormones, digestion, absorption and transport of carbohydrates,. Invite you to consult. | 23 Oxidation of Fatty Acids and Ketone Bodies Fatty acids are a major fuel for humans and supply our energy needs between meals and during periods of increased demand such as exercise. During overnight fasting fatty acids become the major fuel for cardiac muscle skeletal muscle and liver. The liver converts fatty acids to ketone bodies acetoacetate and p-hydroxybutyrate which also serve as major fuels for tissues . the gut . The brain which does not have a significant capacity for fatty acid oxidation can use ketone bodies as a fuel during prolonged fasting. The route of metabolism for a fatty acid depends somewhat on its chain length. Fatty acids are generally classified as very-long-chain length fatty acids greater than C20 long-chain fatty acids C12-C20 medium-chain fatty acids C6-C12 and short-chain fatty acids C4 . ATP is generated from oxidation of fatty acids in the pathway of fi-oxidation. Between meals and during overnight fasting long-chain fatty acids are released from adipose tissue triacylglycerols. They circulate through blood bound to albumin Fig. . In cells they are converted to fatty acyl CoA derivatives by acyl CoA synthetases. The activated acyl group is transported into the mitochondrial matrix bound to carnitine where fatty acyl CoA is regenerated. In the pathway of fi-oxidation the fatty acyl group is sequentially oxidized to yield FAD 2H NADH and acetyl CoA. Subsequent oxidation of NADH and FAD 2H in the electron transport chain and oxidation of acetyl CoA to CO2 in the TCA cycle generates ATP from oxidative phosphorylation. Many fatty acids have structures that require variations of this basic pattern. Long-chain fatty acids that are unsaturated fatty acids generally require additional isomerization and oxidation-reduction reactions to rearrange their double bonds during p-oxidation. Metabolism of water-soluble medium-chain-length fatty acids does not require carnitine and occurs only in liver. Odd-chain-length fatty acids undergo .