Bile acids

Acids made by the liver that work with bile to break down fats.


Substances produced by the gallbladder that aid in the digestion of fats, bile.


An acid found in the bile, e.g. cholic acid.


Cholic and chenodeoxycholic acid are synthesized by the liver from cholesterol. These acids are present as anions and are referred to as bile salts. At pH values above 7.4, bile salts form aggregates with fats at concentrations above 2-5 mM. These aggregates are called micelles. The primary bile acids are secreted into the intestine, and the intestinal flora convert these acids to their conjugated forms by dehydroxylating carbon 7. Further metabolism occurs at the far end of the intestinal tract where lithocholate is sulfated. The dehydroxylated acids can be reabsorbed and sent back to the liver via the portal blood, whereas the sulfated lithocholate is not and appears in the feces. All four of the bile acids, the primary and dehydroxylated forms, are recirculated via the enterohepatic system such that very little of the bile acids is lost. It has been estimated that the bile acid lost in the feces (-0.8 g/day) equals that newly synthesized by the liver such that the total pool remains between 3-5 g. The amount secreted per day is in the order of 16-70 g. Since the pool size is only 3-5 g, this means that these acids are recirculated as much as 14 times a day. The function of the bile acids is thus quite similar to that of enzymes. Neither are “used up” by the processes they participate in and facilitate. In fat absorption, the bile acids facilitate the formation of micelles, which in turn facilitate the uptake of the dietary fatty acids, monoglycerides, sterols, phospholipids, and other fat-soluble nutrients by the enterocyte of the small intestine.


Bile acids are synthesized from cholesterol in the liver. At physiological pH levels, bile acids are present as anions and are referred to as bile salts. The primary functions of bile acids are to aid in the digestion and absorption of fats.


The organic acids in bile, mostly occurring as bile salts (sodium glycocholate and sodium taurocholate). They are cholic acid, deoxycholic acid, glycocholic acid, and taurocholic acid.


Any one of the complex acids that occur as salts in bile (e.g., cholic, glycocholic, and taurocholic acids). They give bile its foamy character, are important in the digestion of fats in the intestine, and are reabsorbed from the intestine to be used again by the liver. The circulation of bile acids is called enterohepatic circulation.


Acids liberated by the gall bladder which play a role in the digestion of fats.


A cleansing agent produced within the liver and expelled into the intestine to facilitate the assimilation of fats.


 


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