Gallbladder

 The gallbladder (or cholecyst, sometimes gall bladder''') is a pear-shaped organ that stores about 50 ml of bile (or "gall") until the body needs it for digestion.

Anatomy
The gallbladder is about 100 to 120 mm long in humans and appears dark green because of its contents (bile), rather than its tissue. It is connected to the liver and the duodenum by the biliary tract.


 * The cystic duct connects the gallbladder to the common hepatic duct to form the common bile duct.


 * The common bile duct then joins the pancreatic duct, and enters through the hepatopancreatic ampulla at the major duodenal papilla.


 * The fundus of the gallbladder is the part farthest from the duct, located by the lower border of the liver . It's at the same level as the transpyloric plane.

Microscopic anatomy
The different layers of the gallbladder are as follows:
 * The gallbladder has a simple columnar epithelial lining characterized by recesses called Aschoff's recesses, which are pouches inside the lining.
 * Under the epithelium there is a layer of connective tissue (lamina propria).
 * Beneath the connective tissue is a wall of smooth muscle (muscularis externa) that contracts in response to cholecystokinin, a peptide hormone secreted by the duodenum.
 * There is essentially no submucosa separating the connective tissue from serosa and adventitia.

Section References

Function
The gallbladder stores about 50 ml (1.7 US fluid ounces / 1.8 Imperial fluid ounces) of bile, which is released when food containing fat enters the digestive tract, stimulating the secretion of cholecystokinin (CCK). The bile, produced in the liver, emulsifies fats and neutralizes acids in partly digested food.

After being stored in the gallbladder the bile becomes more concentrated than when it left the liver, increasing its potency and intensifying its effect on fats. Most digestion occurs in the duodenum.