The Liver

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  • The Liver
    • Liver Cells = hepatocytes
      • Carry out hundreds of metabolic processes
        • Essential it has a very good blood suppy
          • Inside the liver is arranged to create best blood supply possible
      • Has an important role in homeostasis
      • Appear to be relatively unspecialised.
        • Simple cuboid shape with many microvilli on their surface
          • Many metabloic functions including...
            • Protein synthesis
            • Transformation and storage of carbohydrates
            • Synthesis of cholesterol and bile salts
            • Detoxification
    • Blood flow to and from the liver
      • Liver is supplied with blood from two sources
        • Oxygenated Blood from heart
          • Travels from aorta via hepatic artery into liver
            • Supplies oxygen that is essential for aerobic respiration
              • Hepatocytes carry out many metabolic processes and many require ATP so ood oxygen supply is needed.
        • De-oxygenated blood from digestive sytem
          • Enters liver from hepatic portal vein
            • Blood is rich in products of digestion
              • Concentration of various compounds is uncontrolled and blood may contain toxic compounds that have been absorbed in intestine.
                • Blood leaves liver via hepatic vein.
                  • This reaches vena cava and blood returns to normal circulation.
    • Arrangement of cells inside the liver
      • Cells, blood vessels and chambers are arranged to ensure best possible contact between blood and hepatocytes
        • Liver is divided into three parts
          • Liver
            • Lobes
              • Cylindrical lobes
      • As hepatic artery and hepatic portal vein enter liver they split into smaller vessels
        • Vessels run between and parallel to lobules
          • Inter-lobular vessels
          • At intervals branches from hepatic artery and hepatic portal vein enter lobules.
            • Blood from two vessels is mixed and passes along a special chamber called a sinusoid
              • Sinusoid is lined by liver cells.
              • Sinusoids empty into inter-lobular vessels
                • Branches of hepatic vein from different lobules join together to form the hepatic vein, which drains the blood from the liver.
    • Functions of liver cells
      • Producing bile
        • This is released into bile canaliculi (small canals)
          • These join together to form bile duct which transports bile to gall bladder.
    • Kupffer Cells
      • Specialised Macrophages
        • Move about within sinusoids and are involved in breakdown of recycling old red blood cells.
          • One of the products of haemoglabin breakdown is billrubin
            • Excreted as part of faesces
              • Brown pigment in faeces


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