27.26 : Gallbladder

The gallbladder is a small, pear-shaped organ that plays a crucial role in our digestive system. Measuring about 10 cm in length, it is comparable in size to a kiwi fruit and is located in a hollow area on the lower surface of the liver. The gallbladder's primary function is to store and concentrate bile, a fluid produced by the liver that aids in digestion.

The gallbladder's anatomy consists of three regions: the fundus, body, and neck. Extending from the neck, the cystic duct joins the common hepatic duct to form the common bile duct. When filled, the gallbladder holds approximately 40 to 70 mL of bile. As bile remains in the gallbladder, its composition changes as water is absorbed, increasing the concentration of bile salts and other components.

When empty, the gallbladder's mucosa forms honeycomb-like folds, similar to the rugae in the stomach. These folds allow the gallbladder to expand as it fills. Its muscular wall contracts to force bile into the cystic duct, from where it flows into the common bile duct.

However, if bile becomes excessively concentrated, insoluble minerals and salts may crystallize, leading to the formation of gallstones.