Overview
![image 2022 09 10T142805.893](https://usmlestrike.b-cdn.net/wp-content/uploads/2022/09/image-2022-09-10T142805.893.jpg)
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
- space of Disse lies between basal surfaces of hepatocytes and basal surfaces of endothelial cells and Kupffer cells that line sinusoids
- sinusoids are lined by Kupffer cells and fenestrated endothelial cells (pores 100-200 nm in diameter)
- 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
- zone I