Enterohepatic Circulation
In addition to the normal constituents of bile, a wide variety of exogenous compounds (drugs) are the liver into the bile ducts (table 18.2). The liver can thus “clear” the blood of particular compounds by removing them from the blood and excerting them into the intestine with the bile. Molecules that are cleared from the blood by secretion into the bile are eliminated in the feces; this is analogous to renal clearance of blood through excretion in analogous to renal clearance of blood through excretion in the urine
Many compounds that are released with the bile into the intestine are not eliminated with the feces,however. Some of these can be absorbed through the small intestine and enter the hepatic portal blood. These molecules are thus carried back to the liver, where they can be again secreted by hepatocytes into the bile ducts.compounds that recirculate between the liver and intestine in this way are said to have an enterohepatic circulation For example, a few grams of bile salts (discussed shortle) released into the intestine recirculate six to ten times a day , with only about 0.5 g of bile salts per day excreted in the feces.