metabolism 3

• insulin action

  encourages storage, supresses glucagon, stimulates glycogenesis and lipogenesis
• glucagon action

  releases stores fuels, partially suppresses insulin, stimilates glycogenolysis and glyconeogenesis
• andrenalin action

  releases fuels urgently
• 4 metabolic states

  absorptive, short term fasting, prolonged fasting, emergency
• absorptive state

  few hours after meal, high levels of nutrients, insulin stimulated
• insulin is released from the b cells of the pancreas
• short term fasting

  6-24 hours after meal, low concentrations of nutrients, glucagon secretion
• glucagon is secreted from the alpha cells of the pancreas
• glucagon acts on the liver and adipose tissue
• prolonged fasting

  over 24 hours after meal, low insulin, high glucagon, need to provide non-glucose fuels for brain
• in prolonged fasting, glucagon stimulates: TG breakdown, gluconeogenesis, and ketogenesis
• ketones can be used by the brain if there isnt enough carbs
• OAA is used in gluconeogenesis, this slows Krebs cycle
• advantages of ketone bodies

  water soluble, brain can use, enables glucose sparing, can be metabolised back to acetyl CoA
• emergency state causes

  trauma, surgery, infection, stress
• emergency state

  hypermetabolism when cells are under stress for quick ATP production, stimulates adrenalin and glucagon
• adrenaline in emergency state

  inhibits insulin, causes glycogen breakdown in muscle and liver, triglyceride breakdown in adipose tissue
• glycogen breakdown in muscle causes a buildup of ATP in muscle
• glycogen breakdown in the liver causes release of glucose into plasma for transport
• triglyceride breakdown in adipose tissue releases free fatty acids into plasma for fuel
• ketones are water soluble and can be metabolised back to acetyl CoA in extrahepatic tissues
• 2 acetyl CoA are used to form a ketone body