Gallbladder

In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although the structure and position of the gallbladder can vary significantly among animal species. It receives and stores bile, produced by the liver, via the common hepatic duct, and releases it via the common bile duct into the duodenum, where the bile helps in the digestion of fats.

The gallbladder can be affected by gallstones, formed by material that cannot be dissolved – usually cholesterol or bilirubin, a product of haemoglobin breakdown. These may cause significant pain, particularly in the upper-right corner of the abdomen, and are often treated with removal of the gallbladder (called a cholecystectomy). Cholecystitis, inflammation of the gallbladder, has a wide range of causes, including result from the impaction of gallstones, infection, and autoimmune disease.

ANATOMY

The gallbladder is a hollow organ that sits in a shallow depression below the right lobe of the liver, which is grey-blue in life.^[2] In adults, the gallbladder measures approximately 7 to 10 centimetres (2.8 to 3.9 inches) in length and 4 centimetres (1.6 in) in diameter when fully distended.^[3] The gallbladder has a capacity of about 50 millilitres (1.8 imperial fluid ounces).^[2]

The gallbladder is shaped like a pear, with its tip opening into the cystic duct.^[4] The gallbladder is divided into three sections: the fundus, body, and neck. The fundus is the rounded base, angled so that it faces the abdominal wall. The body lies in a depression in the surface of the lower liver. The neck tapers and is continuous with the cystic duct, part of the biliary tree.^[2] The gallbladder fossa, against which the fundus and body of the gallbladder lie, is found beneath the junction of hepatic segments IVB and V.^[5] The cystic duct unites with the common hepatic duct to become the common bile duct. At the junction of the neck of the gallbladder and the cystic duct, there is an out-pouching of the gallbladder wall forming a mucosal fold known as “Hartmann’s pouch”.^[2]

Lymphatic drainage of the gallbladder follows the cystic node, which is located between the cystic duct and the common hepatic duct. Lymphatics from the lower part of the organ drain into lower hepatic lymph nodes. All the lymph finally drains into celiac lymph nodes.