The biliary tract is derived from the branches of the bile ducts. A gallstone is a stone formed within the gallbladder out of bile components. Cholesterol is oxidized by the liver into a variety of bile acids. Metabolites are excreted in the bile and urine. Tizoxanide is excreted in the urine, bile and feces. Preferably, the toxins are conjugated to avail excretion in bile or urine. The liver is the sole site of bile salts formation. Colestyramine is commonly used to treat diarrhea resulting from bile acid malabsorption. Elimination is by excretion in the bile and then feces. These glucuronides are then eliminated mainly through excretion into bile. Bilirubin may rise when there is obstruction of the flow of bile. The Human body contains blood, phlegm, yellow bile and black bile. Medical imaging such as ultrasound is useful for detecting bile duct blockage. Cholangiocytes are the epithelial lining cells of the bile ducts. It has high concentrations in bile and urine.