Osmosis video - Bile secretion and enterohepatic circulation

Bile is a greenish liquid secreted by the liver cells and stored in the gallbladder. Its purpose is the excretion of various compounds, digestion, and absorption of fats. Bile consists mainly of bile salts, phospholipids, cholesterol, conjugated bilirubin, electrolytes, and water. From the liver cells, bile moves through a series of ducts and exits through the common hepatic duct to get stored and concentrated in the gallbladder.

When the gallbladder is stimulated by cholecystokinin (CCK) hormone, it contracts and pushes bile through the cystic duct and into the common bile duct. The sphincter of Oddi relaxes, allowing bile to enter the intestinal (duodenal) lumen to fulfill its functions. Enterohepatic circulation refers to the substances metabolized in the liver, excreted through this bile to get into the intestinal lumen, and then reabsorbed and returned to the liver through the portal circulation.