Anatomy of the Gallbladder and Gallstones
The gallbladder is a small, pear-shaped organ that is located beneath the liver in the human body. It stores a digestive fluid called bile that is secreted by the liver. This digestive fluid aids in the process of digestion by emulsifying fats and neutralizing acids.
How Does the Gallbladder Make Concentrated Bile
The wall of the gallbladder is lined with a mucous membrane tissue, similar to the one that lines the small intestine. The cells of this mucous membrane have several tiny projections that are known as microvilli. These projections assist in increasing the areas of fluid absorption by the gallbladder. The cells of the mucous membrane absorb the inorganic salts and water from the bile and this results in the concentration of the bile stored in the gallbladder.
Path of the Flow of Bile From the Gallbladder to the Small Intestine
The bile from the gallbladder is discharged through the bile duct and it flows through this duct to reach the upper portion of the small intestine, also called duodenum.
The bile duct is made of three branches. It is shaped like the letter ‘Y’ . The three branches include:
- hepatic duct, the upper right branch of the common bile duct, is connected to the liver where the bile is produced
- cystic duct, the upper left branch of the common bile duct, passes through the gallbladder where the bile is stored
- the lower segment or the common bile duct that ends in the duodenal wall of the small intestine. Sphincter of Oddi is a constriction at the end of the common bile duct. The Sphincter of Oddi is responsible for regulating the flow of bile into the duodenum.
Bile or gall is produced by the two lobes of the liver. It flows from the liver to the hepatic duct and the common bile duct. The bile will flow and accumulate in the cystic duct (the upper left branch of the common bile duct). It is stored in the gallbladder and it become concentrated. It is stored here until it is needed to act on the food.
When the small intestine is empty, the Sphincter of Oddi remains closed, forcing the bile back into the common bile duct, leading to the open cystic duct. When the small intestine has food, the Sphincter of Oddi opens and allows the bile to flow to the duodenum of the small intestine. Here, the bile acts on the food and emulsifies fats and neutralizes acids. When the Sphincter of Oddi opens, the gallbladder constricts and facilitates the flow of bile to the small intestine.
Gallstones / Cholelithiasis
The proper functioning of the gallbladder is sometimes disrupted due to the formation of gallstones or cholelithiasis. These are small, pebble-like concretions that are formed due to the crystallization of certain components of the bile.
Composition of Gallstones
Gallstones could be made up of calcium salts, cholesterol or bile pigments. These crystalline substances are usually embedded in a small amount of protein material that is usually produced by the gallbladder.
The gallstones composed of cholesterol are the most commonly produced type of gallstones. These gallstones are saturated with cholesterol that contain very low level phospholipid lecithin and bile salts. When these elements are present in the bile, they manage to keep the level of cholesterol in the bile in control. The presence of gallstones cannot be deduced by any obvious symptoms excep for pain experienced by the patient due to an inflammation of the gallbladder. This condition is referred to as cholecystitis. When the gallstones block the passage of the bile duct, it exercises pressure above the blockage and causes pain that is often referred to as biliary colic.
Gallstones can be removed by giving the patient bile salts in order to dissolve the gallstones and reduce the level of cholesterol in the bile. The other option is to surgically remove the gallbladder to prevent the formation of gallstones.
