Gallbladder

In vertebrates the gallbladder is a small organ where bile is stored before it is released into the small intestine. Humans can live without a gallbladder. The surgical removal of the gallbladder is called a cholecystectomy.

The gallbladder is part of the biliary system and serves as a reservoir for bile, which is produced by the liver. The liver produces the bile and then it flows through the hepatic ducts into the gallbladder. At any one time, 30-60 milliliters of bile is stored within the gallbladder.

When food containing fat enters the digestive tract, it stimulates the secretion of cholecystokinin (CCK) from I cells of the duodenum and jejunum. In response to CCK, the gallbladder rhythmically contracts and releases its contents into the common bile duct, eventually draining into the duodenum. The bile, originally produced in the liver, emulsifies fats in partly digested food, thereby assisting their absorption. Bile consists primarily of water and bile salts, and also acts as a means of eliminating bilirubin, a product of hemoglobin metabolism, from the body.