The gallbladder is a pear-shaped, hollow structure located under the liver and on the right side of the abdomen. Its primary function is to store and concentrate bile, a yellow-brown digestive enzyme produced by the liver. The gallbladder is part of the biliary tract.
The gallbladder serves as a reservoir for bile while it’s not being used for digestion. 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. A person with gallstones will rarely feel any symptoms until the gallstones reach a certain size, or if the gallstone obstructs the bile ducts. Surgical removal of the gallbladder (cholecystectomy) is the most common way to treat gallstones.