Bile is secreted by the liver cells and collected by a system of tubes that mirrors the blood supply to the organ. This network of bile-drainage channels carries the bile out of the liver by way of the hepatic ducts, which join together to form a common duct that opens into the duodenum at a controlled orifice called the ampulla of Vater. Bile does not pass directly into the duodenum but is first concentrated and then stored until needed in the gall bladder, a pear-shaped reservoir lying in a hollow under the liver, to which it gains access by way of the cystic duct.
When food is eaten, the presence of fat in the duodenum causes the secretion of a hormone, which opens the ampulla of Vater and causes the gall bladder to contract, squeezing stored bile via the cystic and common bile ducts into the duodenum. In the duodenum, bile salts emulsify the fat, breaking it down to a kind of milk of microscopic globules.
Related category• ANATOMY AND PHYSIOLOGY
Source: British Medical Association
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