Liver

• Liver


  • Breaks down harmful substances as well as toxic waste
  • Converts substances into less harmful forms, ready to be disposed of via excretion
• Liver lobules


  • Cylinders made of hepatocytes arranged in rows, connected at the centre
  • Connected to the hepatic vein, hepatic artery, hepatic portal vein, and bile duct
  • Sinusoids connect the central vein to the hepatic artery and portal vein
• Amino acid excretion


  1. Deamination (removal of amino group)

  2. Respiration of organic acids or conversion to carbohydrates

  3. Ammonia converted to urea

  4. Urea released into blood and filtered out by kidneys
• What is removed in the liver?

  C02 from respiration

  bile pigments (breakdown of rbc)

  nitrogeneous waste:

  • Urea
  • Ammonia (fish)
  • Uric acid (bird/insects)
• Define deamination


  The removal of an amine group
• Transamination 


  Converting one amino acid into another
• Detoxification


  Breaking down of harmful substances
• Examples of detoxification:


  • Ethanol with alcohol dehydrogenase --> etanal --> ethanoate
  • Hydrogen peroxide with catalase --> oxygen + water
• Ornithine cycle 


  Ammonia converted into Urea in an enzyme controlled reaction
• Ornithine cycle:


  • Amonnia + carbin dioxide --> citrulune + water
  • Citruline + Ammonia --> arginine + water
  • Arginine +water --> Urea + ornithine
• What happens to products of deamination?

  • Carbon skeletons used in respiration
  • Ammonia deaminatwd and used in ornithine cycle
• Differences between hepatic artery and hepatic portal vein

  Hepatic artery - blood delivered to liver in narrow vessels

  Hepatic portal vein - blood enters liber through branded vessel