Liver Structure

• The liver is composed of smaller histological structures called lobules, which are roughly hexagonal in shape
• Each lobule is surrounded by branches of the hepatic artery (provide oxygen) and the portal vein (provide nutrients)
• Vessels drain into capillary-like structures called sinusoids, which exchange materials directly with the hepatocytes
• The sinusoids drain into a central vein, which feeds deoxygenated blood into the hepatic vein
• Hepatocytes in the liver produce bile, which is transported by vessels called canaliculi to bile ducts surrounding the lobule
• Sinusoids in the liver are small blood vessels with increased permeability, allowing larger molecules like plasma proteins to enter and leave the bloodstream
• Structural features of sinusoids that contribute to their increased permeability include:

  • The surrounding diaphragm (basement membrane) is incomplete or discontinuous
  • The endothelial layer contains large intercellular gaps and fewer tight junctions, allowing for the passage of larger molecules