Final answer:
Bacteria in the intestines convert conjugated bilirubin into stercobilin, a brown pigment that gives stool its characteristic color and allows for bilirubin excretion.
Step-by-step explanation:
Conjugated bilirubin is further broken down by bacteria in the intestines into stercobilin, which is then excreted as part of the feces, providing the brown color we associate with stool. This degradation process is essential for the excretion of bilirubin, a byproduct of the breakdown of red blood cells.
In the process of bile pigment excretion, bilirubin is first bound to albumin in the blood and then transported to the liver. Here, bilirubin is conjugated with glucuronic acid to form bilirubin diglucuronide, which is water-soluble. This soluble form is excreted into the intestine through the bile duct. Once in the large intestine, bacteria convert most of the bilirubin into stercobilinogen, and subsequently into stercobilin, which is then eliminated from the body in feces. It's noteworthy that broad-spectrum antibiotics may disrupt the populations of these bacteria, potentially altering feces color.