Bile is a fluid secreted by the liver. Bile helps the body digest and absorb fatty foods. It also rids the body of certain waste products. The liver secretes bile continuously, producing about 1 quart (0.95 liter) daily. Bile flows from the liver into a tube called the hepatic duct. This tube connects with the common bile duct, which leads to the small intestine. Except after meals, however, most of the bile does not proceed directly to the intestine. Instead, it enters the gallbladder, a pouch attached to the common bile duct. There, the bile is stored and concentrated until needed. After fatty foods enter the small intestine, the gallbladder contracts, sending bile through the common bile duct and into the intestine.
Bile’s digestive properties result from bile salts, which are manufactured by the liver from a fatty substance called cholesterol. Bile salts break up globs of fat into tiny particles that digestive enzymes in the small intestine can attack. Bile salts then temporarily link to the digested fats to speed up the absorption of fats through the intestinal wall. They also help the body absorb the fat-soluble vitamins–vitamins A, D, E, and K. Most of the bile salts return to the liver through the bloodstream.
Bile contains various waste products that eventually become part of the feces (solid body wastes). One of these waste products, bilirubin, is formed from the breakdown of red blood cells. It is joined with fat-soluble chemicals in the liver to form a product that is discharged in the bile. Bilirubin gives bile its color, which ranges from brown to greenish-yellow. Other waste matter in the bile includes excess cholesterol and certain medicines and poisons that the liver removes from the blood.
See also Gallbladder.
