Adipose Tissue and Muscle Metabolism Flashcards Preview

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Flashcards in Adipose Tissue and Muscle Metabolism Deck (14)
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the majority of our energy reserve is _____ that contains __% of total energy

the majority of our energy reserve is adipose that contains 83% of total energy


describe the enzymes involved in mobilization and synthesis of lipids

  • mobilization = lipolysis
    • enzyme = hormone sensitive lipase
    • provide energy needs for the body
  • synthesis = lipogenesis (esterification)
    • enzyme = lipoprotein lipase (LPL)
    • storage of TAG in adipocyte


describe the precursor molecules for the synthesis of TAG

  • glycerol 3-P
    • in adipocyte, glycerol 3-P is obtained from glycolysis via DHAP
    • in hepatocyte, glycerol 3-P may be obtained from glycerol or from glycolysis pathway
  • fatty acids obtained from:
    • diet (chylomicrons)
    • liver (VLDL): de novo fatty acid synthesis in the liver, FA are then esterified to glycerol to form TAG


contrast the pathways in how liver vs adipose can form glycerol 3-P


describe what state causes synthesis of TAGs in adipocytes

  • occurs in the well fed state
    • absorb glucose 
    • chylmicrons
  • high insulin/glucagon ratio
    • leads to an increase in adipocyte GLUT-4 transporters
      • glucose uptake into adipocytes
  • VLDL synthesis in liver -> released into the blood


describe the mobilization of TAG in adipocytes

  • hydrolysis of stored TAG
    • catabolic; energy producing
  • catalyzed by hormone sensitive lipase (HSL)
    • active when phosphorylated
      • epinephrine 


describe the function of white adipose tissue (WAT)

  • distributed throughout body
  • WAT reclaims some of the FA that it mobilizes
    • limits the amount of FA in the blood
  • regulated energy storage


describe the function of brown adipose tissue (BAT)

  • large number of mt
    • specialized for FA oxidation and heat production
  • multiple fat droplets
  • thermogenin leads to mt uncoupling
    • ​proton gradient uncoupling leads to high activity of the ETC -> heat production


describe leptin

  • leptin secreted by adipocytes
  • leptin mediates appetite suppression
    • has receptors in the hypothalamus


does obesity cause decreased or increased leptin?

  • leptin levels are normal/HIGH in obese patients
    • not a problem of the ob gene
  • leptin induces expression of the UCP type channel


describe the link between obestiy and insulin resistance

  • altered adipokine profiles in obese patients contributes to insulin resistance
    • hyperglycemia
  • the pancreas responds with increased insulin production
    • hyperinsulinemia
  • increased HSL activity in the absence of insulin signaling
    • insulin is there BUT adipose cells don't respond to it because of insulin resistance --> hypertriacylglyceronemia 


contrast between the 3 types of sketal muscle fibers


describe the use of glycogen during anaerobic muscle contraction

  • if starting with glycogen, 3 ATP per glucose units are obtained rather than 2
  • type IIB fibers have higher levels of glycolytic enzymes to compensate
  • G6P is used 12x faster in Type IIb fibers than in Type I fibers


describe how AMP and Ca regulate gylcolysis and glycogen degradation

  • AMP stimulates PFK-1
  • AMP stimulates glycogen phosphorylase b (only in muscle)
  • Increased Ca stimulates glycogen phosphorylase kinase which leads to the full activation of glycogen phosphorylase