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What is Ketosis?

CH 3 CCH 2 COO -. . H. CH 3 CCH 2 COO -. O. O. OH. CH 3 -C-CH 3. What is Ketosis?. An excessive production of ketones in the blood 3 derivatives of acetyl-CoA. Acetoacetate.  -hydroxybutyrate. Acetone. What is the Significance of ketosis. Acidosis. Excessive acid in the blood.

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What is Ketosis?

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  1. CH3CCH2COO-  H CH3CCH2COO- O O OH CH3-C-CH3 What is Ketosis? An excessive production of ketones in the blood 3 derivatives of acetyl-CoA Acetoacetate -hydroxybutyrate Acetone

  2. What is the Significance of ketosis Acidosis Excessive acid in the blood Overflow Excessive oxidation of fatty acids Metabolic Problem Faulty Carbohydrate Metabolism

  3. Metabolic fate of Acetyl CoA Pyruvate minor Acetyl-CoA Fatty Acids Ketone Bodies major Citrate

  4. CH3C~SCoA CH3C~SCoA CH2C~SCoA O O O O O CH3CCH2C~SCoA HS-CoA CH3C + -Ketothiolase rearrangement OH Acetoacetyl-CoA

  5. HS-CoA CH3CCH2C~SCoA HO OH O O O O O O OOC-CH2-C-CH2-C~SCoA CH3CCH2C~SCoA CH2C-O- CH3C~SCoA CH3 HMG-CoA Synthase -hydroxy--methyl glutaryl-CoA (HMG-CoA)

  6. CH3-C~SCoA OH OOC-CH2-C-CH2-C~SCoA Acetoacetate CH3 OH O O O O O OOC-CH2-C-CH3 NADH + H+ OOC-CH2-C-CH2-C~SCoA CO2 NAD+ CH3 CH3-C-CH3 OOC-CH2-CH-CH3 OH HMG-CoA HMG-CoA Lyase + Acetone -hydroxybutyrate

  7. Diabetes Insufficient insulin production (Type I) Ineffective or impaired insulin function (Type II) Main Characteristics Failure to transport glucose into muscle and adipose tissue Failure to catabolize glucose at a normal rate in liver Excessive oxidation of fatty acids leading to ketosis

  8. Diabetes and Lipid Metabolism Whenever carbohydrates are not available for metabolism, fatty acid oxidation is accelerated A more rapid degradation of fatty acids augments production of acetoacetyl-CoA and acetyl CoA OAA is being used for gluconeogenesis Less carbohydrate means less pyruvate. Less pyruvate means less OAA. Less OAA means less citrate

  9. INSULIN Pancreas beta cells 5.8 kDa polypeptide Emulates the fed signal Lowers blood glucose Stimulates glycogen synthesis Stimulates glycolysis NO BACKUP Stimulates lipid synthesis Suppresses Glucagon GLUCAGON Pancreas alpha cells 3.5 kDa polypeptide Emulates the “need” signal Raises blood glucose Stimulates glycogen breakdown Stimulates gluconeogenesis GLUCORTICOIDS BACKUP Stimulates lipolysis

  10. ADIPOSE TISSUE Glucose Triacylglycerols No glucose uptake by adipose 3 fatty acids Glucagon-stimulated lipase Glycerol-PO4 DHAP Glycerol kinase 3 Fatty acids + Glycerol Missing in adipose tissue Blood Breakdown of adipose lipids grossly accelerated Liver

  11. CO2 LIVER FA Glucose Acetyl-CoA Acetyl-CoA Acetyl-CoA Acetyl-CoA Acetyl-CoA Pyruvate Ketone bodies OAA CITRATE Glucose All glucagon-stimulated activities take precedence

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