The liver

Detoxification

  • converts toxic substances into less harmful compounds that cells can excrete

  • Breaking down amino acids

    • Amine groups are removed from amino acids by deamination

      • Produces toxic ammonia and organic acids

    • Organic acids are either used for ATP production or stored as glycogen

    • Ammonia combines with CO2 to form urea via the ornithine cycle

    • Urea is then excreted from liver cells

      • Enters blood stream

      • Filtered out of the body via kidneys as a part of urine

  • Other detoxified substances

    • Alcohol

      • Alcohol dehydrogenase breaks down ethanol to ethanal which is then converted to ethanoate to prevent cell damage

    • Hydrogen peroxide

      • The enzyme catalase splits hydrogen peroxide into oxygen and water to prevent cell damage

    • Paracetamol

      • Broken down to prevent toxicity to the liver and kidneys

    • Insulin

      • Metabolised to help regulate blood glucose concentration

Glucose regulation

  • converts excess glucose into glycogen

  • Stores glycogen granules within its cells

  • Releasing glucose into the bloodstream by breaking down glycogen when blood glucose levels fall

Breaking down RBC

  • haemoglobin from old red blood cells is broken down in hepatocytes into bile pigments

  • These are then excreted from liver cells and transported by the bile duct to the gall bladder where they are stored before their removal from the body

Structure of the liver

  • Hepatic artery

    • Supplies oxygenated blood

  • Hepatic vein

    • Carries away deoxygenated blood towards the heart

  • Hepatic portal vein

    • Brings nutrient rich blood from the intestines

  • Bile duct

    • Transports bile to the gall bladder

Structure of liver lobules

  • hepatocytes are arranged along channels called sinusoids

  • The sinusoids are where oxygen rich blood from the hepatic artery mixes with blood rich in the products of digestion from the hepatic portal vein

  • A branch of the hepatic vein is located in the centre of each lobule to remove deoxygenated blood

  • kupffer cells ingesting pathogens and other foreign particles

    • Helps to protect against disease

  • Bile canaliculus

    • Separate channel to sinusoids

    • Links to a branch of the bile duct