Bile Duct

Within the liver lobules, there are many fine "bile canals" that receive secretions from the hepatic cells. The canals of neighboring lobules unite to form larger ducts, and these converge to become the "hepatic ducts." They merge, in turn, to form the "common hepatic duct." The "common bile duct" is formed by the union of the common hepatic and the cystic ducts. It leads to the duodenum, where its exit is guarded by a sphincter muscle. This sphincter normally remains contracted until the bile is needed, so that bile collects in the common bile duct and backs up to the cystic duct. When this happens, the bile flows into the gallbladder and is stored there.