Lipid 3

• What inhibits pyruvate dehydrogenase during fasting?

  Elevated hepatic fatty acids
• What does pyruvate carboxylase form from pyruvate?

  Oxaloacetate
• How is oxaloacetate used in the liver during fasting?

  For gluconeogenesis instead of TCA cycle
• When does ketogenesis occur?

  During prolonged starvation
• What happens to the TCA cycle during prolonged starvation?

  It shuts down or slows down
• Why do some tissues not utilize fatty acids?

  They need an alternative fuel source
• What are the three types of ketone bodies?

  Acetoacetate, β-hydroxybutyrate, acetone
• How are ketone bodies transported in the body?

  Soluble in aqueous solution without albumin
• When are ketone bodies produced in the liver?

  When acetyl CoA exceeds liver capacity
• Where does ketogenesis occur?

  In the liver
• What is the first step in ketogenesis?

  Formation of acetoacetate
• What does the liver do during ketogenesis?

  Breaks down TAG into FFA
• What is the process of converting acetyl CoA to ketone bodies?

  Acetyl CoA is converted to acetoacetate
• What happens to ketone bodies after they are formed?

  They are transferred to peripheral tissue
• What is the relationship between acetyl CoA and acetoacetate?

  Acetyl CoA is converted to acetoacetate
• What is the role of ketone bodies in extrahepatic tissue?

  They are broken down into acetyl-CoA
• How do ketone bodies affect the TCA cycle in tissues?

  They resupply OAA to resume TCA cycle
• What are the three mechanisms regulating ketogenesis?

  Lower FA mobilization, inhibit CPT1, raise OAA
• What is a medical significance of ketone body metabolism?

  Ketoacidosis
• What is acetone breath?

  Smell like decaying apple or nail polish
• What causes ketoacidosis?

  Ketone bodies cause acidic blood
• What is ketosis?

  Presence of ketone bodies in blood
• What is the threshold for normal blood ketone levels?

  Less than 0.6 mmol/L
• What is a ketogenic diet?

  Low carbohydrate diet without fat restriction
• What are the short-term effects of a ketogenic diet?

  Weight loss, lower blood pressure, lower glucose
• What are potential risks of a ketogenic diet?

  Increased VLDL and LDL, stressed kidney
• What does "fat burns in the fire of carbohydrate" mean?

  Acetyl CoA needs to enter TCA cycle
• What is the product of β-oxidation of fatty acids?

  Acetyl CoA
• What is the role of isomerase in fatty acid metabolism?

  Convert double bonds in unsaturated FA
• What is the final product of odd-chain fatty acid metabolism?

  Succinyl CoA
• What is the relationship between TCA cycle and fatty acid metabolism?

  Fatty acids enter TCA cycle as acetyl CoA
• How does the presence of double bonds affect fatty acid metabolism?

  Requires isomerase for proper metabolism
• What is the role of hydratase in fatty acid metabolism?

  Hydrates double bonds in fatty acids
• What is the role of reductase in fatty acid metabolism?

  Reduces double bonds in fatty acids
• What is the function of acyl-CoA in fatty acid metabolism?

  Activates fatty acids for β-oxidation
• What is the significance of propionyl CoA in fatty acid metabolism?

  It is a product of odd-chain fatty acid oxidation
• How does the TCA cycle relate to energy production?

  It is essential for complete energy breakdown
• What is the role of succinyl CoA in metabolism?

  It is involved in TCA cycle and energy production
• What happens to fatty acids during β-oxidation?

  They are broken down into acetyl CoA
• What is the significance of the TCA cycle in metabolism?

  It is crucial for energy production from nutrients