Overview 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