Cystic duct

Cystic duct also known as gallbladder’s duct, is the short duct that joins the gall bladder to the common bile duct. Cystic duct usually lies next to the cystic artery. It is of variable length. Cystic duct contains a ‘spiral valve’, which does not provide much resistance to the flow of bile. During a cholecystectomy, the cystic duct is clipped two or three times and a cut is made between the clips, freeing the gallbladder to be taken out.

Figure 1. Cystic duct

Cystic duct function

The cystic duct joins the common hepatic duct from the liver to form the bile duct, which empties into the duodenum. The liver secretes bile continuously, but sphincters at the end of the bile duct and at the hepatopancreatic ampulla are closed when bile is not needed for digestion. At these times, bile backs up through the cystic duct into the gallbladder for storage. When fatty chyme from a meal enters the duodenum, the gallbladder’s muscular wall contracts in response to the hormone cholecystokinin, which is released from the enteroendocrine cells of the duodenum. The sphincters at the end of the duct system relax, and bile is expelled from the gallbladder through the cystic duct to the bile duct into the duodenum.

Bile can flow in both directions between the gallbladder and the common hepatic duct and the (common) bile duct.

In this way, bile is stored in the gallbladder in between meal times and released after a fatty meal.