These tiny vessels coalesce and eventually form the hepatic vein, which carries all efferent blood into the inferior vena cava. A rich supply of lymphatic vessels also drains the liver. These polygonal cells lie next to the blood-filled sinusoids and are arranged in sheets or plates that radiate from each portal triad toward adjacent central veins. Hepatocytes are responsible for the liver's central role in metabolism. In most liver diseases, hepatocellular dysfunction occurs to some degree and produces various clinical and laboratory abnormalities.
Biliary passages begin as tiny bile canaliculi formed by adjacent hepatocytes.
These microvilli-lined structures progressively coalesce into ductules, interlobular bile ducts, and larger hepatic ducts. Outside the porta hepatis, the main hepatic duct joins the cystic duct from the gallbladder to form the common bile duct, which drains into the duodenum. Endothelial cells also endocytose various molecules and particles, synthesize proteins that influence the extracellular matrix, and play a role in lipoprotein metabolism. Major functions include phagocytosis of foreign particles, removal of endotoxin and other noxious substances, and modulation of the immune response. Because of its Kupffer cells and rich blood supply, the liver is often secondarily involved in infections and other systemic disorders.