1304 Somerville Rd.
Decatur, AL 35601
© 2011. Riverside Gastroenterology
1304 Somerville Rd., Decatur, AL 35601
How the Gallbladder Works
The gallbladder is a 4-inch sac with a muscular wall that is located under the liver. Here, most of the bile fluid (about 2 - 5 cups a day) is removed, leaving a few tablespoons of concentrated bile.
•The gallbladder serves as a reservoir until bile is needed in the small intestine to digest fats. This need is signaled by a hormone called cholecystokinin, which is released when food enters the small intestine.
•Cholecystokinin causes the gallbladder to contract and deliver bile into the intestine. The force of the contraction propels the bile down the common bile duct and into the small intestine, where it emulsifies (breaks down) fatty molecules.
•This part of the digestive process enables the emulsified fat, along with important fat-absorbable nutrients (such as vitamins A, D, E, and K), to pass through the intestinal lining and enter the bloodstream.
How do Gallbladder Stones Form?
The process of gallstone formation is referred to as cholelithiasis. It is generally a slow process, and usually causes no pain or other symptoms. The majority of gallstones are either the cholesterol or mixed type. Gallstones can range in size from a few millimeters to several centimeters in diameter.
Most gallstones are formed from cholesterol. Pigment stones are also very common; they are formed from a brown-colored substance called calcium bilirubinate. Patients can have a mixture of the two gallstone types.
Although cholesterol makes up only 5% of bile, about three-fourths of the gallstones found in the US population are formed from cholesterol.
Types of Gallstones
Gallstones can occur as a result of various abnormalities, although the cause is not entirely clear. There are many events that may promote their formation:
•The liver secretes too much cholesterol into the bile.
•The gallbladder may not be able to empty normally, so bile becomes stagnant.
•The cells lining the gallbladder may not be able to efficiently absorb cholesterol and fat from bile.
•There are high levels of bilirubin. Bilirubin is a substance normally formed by the breakdown of hemoglobin in the blood. It is removed from the body in bile. Some experts believe bilirubin may play an important role in the formation of cholesterol gallstones.
The other type of stones that are formed at Pigment Stones. They can be brown or black. Pigment stones are composed of calcium bilirubinate, or calcified bilirubin. Pigment stones can be black or brown.
•Black stones form in the gallbladder and are the more common type. They represent 20% of all gallstones in the U.S. They are more likely to develop in people with hemolytic anemia (a relatively rare anemia in which red blood cells are destroyed) or cirrhosis (scarred liver).
•Brown pigment stones are more common in Asian populations. They contain more cholesterol and calcium than black pigment stones and are more likely to occur in the bile ducts. Infection plays a role in the development of these stones.
Mixed stones. Mixed stones are a mixture of cholesterol and pigment stones.