It is a small hollow organ where bile is stored and concentrated before being released into the small intestine.
In humans, the pear-shaped gallbladder is located under 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, through the common hepatic duct and releases it through the common bile duct into the duodenum, where bile helps the digestion of fats.
The gallbladder is a hollow organ in a shallow depression below the right lobe of the liver, which is blue-gray. It is pear-shaped, and its tip opens towards the cystic duct.
In adults, the gallbladder is approximately 7 to 10 centimeters (2.8 to 3.9 inches) long and 4 centimeters (1.6 inches) in diameter when fully distended. It has a capacity of approximately 50 milliliters (1.8 fluid imperial ounces).
The gallbladder is divided into three sections:
- The bottom is the rounded base at an angle to face the abdominal wall.
- The body is in a depression on the surface of the lower liver.
- The neck narrows and is continuous with the cystic duct, part of the biliary tree.
The pit of the gallbladder, against which lies the bottom and body of the gallbladder, is located below the junction of segments IVB and V.
The cystic duct joins 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 outer pocket of the gallbladder wall that forms a mucosal fold known as the ” Hartmann’s pouch. “
The main objective of the gallbladder is to store bile, also called gall, necessary for the digestion of fats in food.
Produced by the liver, bile flows through tiny vessels to the larger hepatic ducts and finally through the cystic duct (parts of the biliary tree) into the gallbladder, where it is stored. At any time, 30 to 60 milliliters (1.0 to 2.0 ounces fl oz US) of bile are held inside the gallbladder.
When food containing fat enters the digestive tract, it stimulates cholecystokinin secretion from the I cells of the duodenum and jejunum. In response to cholecystokinin, the gallbladder contracts and rhythmically releases its contents into the common bile duct, eventually draining into the duodenum.
Bile emulsifies fats in partially digested foods, which helps their absorption. Bile consists mainly of water and bile salts and acts as a means to eliminate bilirubin, a product of the metabolism of hemoglobin, from the body.
The bile secreted by the liver and stored in the gallbladder is not the same as the bile secreted by the gallbladder. The storage of bile in the gallbladder is concentrated by removing a little water and electrolytes.
This is through the active transport of sodium ions through the epithelium of the gallbladder, which creates an osmotic pressure that also causes water and other electrolytes such as chloride to be reabsorbed.
Disorders of the gallbladder
The most common problem of the gallbladder is gallstones, small stones formed from hardened bile and cholesterol.
Gallstones can block the release of bile from the gallbladder and cause:
- Severe pain, particularly after eating large, fatty, or fatty foods.
- Jaundice (yellowing of the skin and eyes).
- Inflammation and irritation of the walls of the gallbladder.
Other gallbladder problems may also occur, but these are extremely rare:
- Gallbladder cancer.
- Perforation (tear or rupture) of the gallbladder.
- Gangrene if the adequate blood flow to the gallbladder is blocked.
- Pancreatitis is caused by gallstones that migrate from the gallbladder and prevent pancreatic enzymes from traveling to the small intestine.
- Intestinal obstruction is caused by a gallstone that passes into the intestine and then blocks the intestines.