The gallbladder is a sac which lies on the undersurface of the liver in the right upper portion of the abdominal cavity. It is approximately the size of a pear and is connected to the liver and the intestine by a series of small tubes called bile ducts. The primary job of the gallbladder is to store bile, which is produced and secreted by the liver, until the bile is needed to aid in digestion. After a meal, the gallbladder normally contracts and bile flows into the intestine. Once the meal is digested, the gallbladder relaxes and once again begins to store bile.
Bile itself is a brown liquid, which contains bile salts, cholesterol, bilirubin and lecithin. Some of the substances in bile, such as bile salts and lecithin act like detergents and break up fat to aid in digestion. Bilirubin, however, is considered a waste product. Bilirubin is a dark brown substance, which gives the brown color to bile and stool. Approximately three cups of bile are produced by the liver every day.