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Overview

liver histology - larger image

Introduction
  • Blood supply to the liver    
    • liver receives majority of blood supply (75%) from the hepatic portal vein that carries venous blood that is largely depleted of oxygen
    • liver receives a lesser amount of blood supply (25%) from the hepatic artery, a branch of the celiac trunk, that carries oxygenated blood
    • in the liver, branches of the hepatic portal vein and hepatic artery supply sinusoids that bathe hepatocytes and provide for exchange of substances between the blood and liver cells
      • apical surfaces of hepatocytes face bile canaliculi
      • basolateral surfaces of hepatocytes face sinusoids
    • sinusoids empty into central veins, which empty into sublobular veins
      • sublobular veins converge to form larger hepatic veins 
      • blood leaves liver by the hepatic veins that empty into the inferior vena cava (IVC)
    • "irregular capillaries"
      • sinusoids are lined by Kupffer cells and fenestrated endothelial cells (pores 100-200 nm in diameter)
        • Kupffer cells are mononuclear phagocytic cells
      • no basement membrane between endothelium and underlying hepatocytes
      • these 2 structural modifications facilitates exchange of material in liver in perisinusoidal space (space of Disse)
        • space of Disse lies between basal surfaces of hepatocytes and basal surfaces of endothelial cells and Kupffer cells that line sinusoids
          • site of exchange of materials between blood and liver cells
  • Liver acinus
    • represents functional unit of hepatic parenchyma
    • hepatocytes in each liver acinus are described as being arranged in 3 concentric elliptical zones
      • zone I
        • periportal zone
        • cells in zone I are the first to receive oxygen, nutrients, and toxins from sinusoidal blood
        • cells are the first liver cells affected by viral hepatitis
      • zone II
        • intermediate zone
      • zone III
        • centrilobular zone
        • contains P450 system
        • cells are the first liver cells affected by ischemia and alcoholic hepatitis, and are most sensitive to toxic injury

 

 

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