The main function of the gallbladder is to concentrate and store bile. When bile leaves the liver, a portion of it is sent directly to the large intestine. The other portion is redirected from the common bile duct to the cystic duct where it is then stored in the gallbladder. The gallbladder can store around 100 ml of bile.
The gallbladder’s absorbent lining concentrates the stored bile. When food enters the small intestine, a hormone called cholecystokinin is released, signaling the gallbladder to contract and secrete bile into the small intestine through the common bile duct.
The bile helps the digestive process by breaking up fats. It also drains waste products from the liver into the duodenum, a part of the small intestine. An excess of cholesterol, bilirubin, or bile salts can cause gallstones to form. Gallstones are generally small, hard deposits inside the gallbladder that are formed when stored bile crystallizes.