Bile is a green-yellow fluid made by the liver to help digest fat. The gallbladder, a small pear-shaped sac under the liver, stores and concentrates it between meals.
What bile contains
Bile contains water, bile salts, cholesterol, phospholipids and bilirubin. Bile salts break fat into tiny droplets (emulsification) so lipase can digest it.
The bile ducts
The right and left hepatic ducts join as the common hepatic duct, which meets the cystic duct to form the common bile duct. This duct joins the pancreatic duct and opens into the duodenum at the ampulla of Vater.
Release after a meal
Fat in the duodenum releases the hormone cholecystokinin (CCK). CCK makes the gallbladder contract and the sphincter of Oddi relax so bile flows into the gut.
Recycling bile salts
About 95 percent of bile salts are reabsorbed in the ileum and return to the liver through the portal vein. This loop is called the enterohepatic circulation.
At the bedside
A gallstone blocking the cystic duct causes right upper quadrant pain after fatty meals and a positive Murphy sign. A stone in the common bile duct can cause jaundice, dark urine and pale stools.
Related guides
Written by Making Synapses. Topic reference: OpenStax, Anatomy and Physiology 2e (no text adapted).