How does the gallbladder work?
The gallbladder is a thin-walled, pear-shaped pouch. It is about 7 to 10 centimeters (about 2.7 to 3.9 inches) long, up to 5 centimeters (about 2 inches) across at its widest point, and is located in an indentation under the liver. The gallbladder stores and concentrates bile from the liver. The bile then helps to digest and absorb fats from food in the duodenum, the first section of the small intestine.
Every day the cells of the liver produce about 800 to 1,000 milliliters (about 27 to 34 fluid ounces) of yellow, brownish or olive-green bile. The liver cells then pass the bile on through small canals to the bile duct, which leads from the lower surface of the liver into the duodenum. After about 4 to 6 centimeters (about 1.6 to 2.4 inches), a small duct leading to the gallbladder branches off of the larger bile duct before it connects to the intestine.
The bile produced by the liver flows directly into the small intestine during a meal. Between meals, when there is no fat that needs to be digested, most of the bile flows into the gallbladder instead, where it is concentrated and stored. The gallbladder usually holds about 30 to 80 milliliters (about 1 to 2.7 fluid ounces) of fluid. When we eat fatty foods, the gallbladder contracts and squeezes bile through the bile duct bit by bit. The bile is mixed into the semi-digested food in the duodenum.
Bile is mainly made up of water, but also has bile salts, cholesterol, certain fats (lecithin) and bile pigments in it. The most important bile pigment, bilirubin, is made when old red blood cells are broken down in the liver. It is bilirubin that makes urine yellow and stool brown.
Bile salts break down larger fat globules in food into small droplets of fat. Smaller fat droplets are easier for the digestive enzymes from the pancreas to process and break down. Bile salts also help the cells of the intestine to absorb these broken-down fats.
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Pschyrembel W. Klinisches Wörterbuch. Berlin: De Gruyter; 2014.
Schmidt R, Lang F, Heckmann M. Physiologie des Menschen: mit Pathophysiologie. Heidelberg: Springer; 2011.
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