Bilirubin is the predominant pigment in what?

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Bilirubin is the pigment produced from heme breakdown and becomes the main pigment that bile carries. After red blood cells are recycled, heme is converted first to biliverdin and then to bilirubin. In the blood, bilirubin binds to albumin and travels to the liver, where it is conjugated to glucuronic acid to become water-soluble. This conjugated bilirubin is then secreted into bile and travels with it into the intestine. Because bilirubin is the primary pigment in bile, it determines bile’s yellow-brown color. Other options don’t serve as the main bile pigment; for example, urine’s color comes from urobilinogen/urobilin after intestinal processing, while blood plasma and lymph contain bilirubin but are not the pigment-dense medium that bile is.