In vertebrates the gallbladder (cholecyst, gall bladder or biliary vesicle) 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 main purpose of the gallbladder is to store bile, also called gall. 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 to 60 cubic millimetres (0.0010 to 0.0020 US fl oz) 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 cholecystokinin, the gallbladder rhythmically contracts and releases its contents into thecommon 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.
The bile that is secreted by the liver and stored in the gallbladder is not the same as the bile that is secreted by the gallbladder. During gallbladder storage of bile, it is concentrated by removal of some water and electrolytes. This is through the active transport of sodium ions across the epithelia of the gallbladder, which creates an osmotic pressure that also causes water and other electrolytes such as chlorine to be reabsorbed.
Gallstones are the most common problem to affect the gallbladder. Gallstones generally form because the bile is saturatedwith either cholesterol or bilirubin. Only the minority of gallstones cause symptoms, and the majority of stones are passed along the biliary tree. When symptoms occur, a person may feel severe pain in the upper right part of their abdomen. If the stone blocks the gallbladder, cholecystitis may occur. If the stone lodges in the biliary tree, jaundice may occur; and if the stone blocks the pancreatic duct, then pancreatitis may occur. Gallstones are often managed by waiting for them to be naturally passed. In people with recurrent gallstones, surgery to remove the gallbladder may be considered. Some medication, such as UDCA, andultrasound to break down the stones may also be used.
Inflammation of the gallbladder is known as cholecystitis. Inflammation is most commonly because of obstruction of the duct with gallstones, known as cholelithiasis. Blocked bile accumulates, and pressure on the gallbladder wall may lead to the release of substances that cause inflammation, such as phospholipase. There is also the risk of bacterial infection. An inflamed gallbladder is likely to cause pain and fever, and tenderness in the upper, right corner of the abdomen, and may have a positive Murphy’s sign. Cholecystitis is often managed with rest and antibiotics, particularly cephalosporins and, in severe cases, metronidazole.
Cholecystitis may also occur chronically, particularly when a person is prone to getting gallstones.