Question

Bile pigments are:

a. formed in the degradation of heme.
b. generated by oxidation of sterols.
c. responsible for light reception in the vertebrate eye.
d. secreted from the pancreas
e. the products of purine degradation.

Answer 1

Bile pigments such as bilirubin and biliverdin are byproducts of heme degradation from red blood cells, with bilirubin being the primary pigment excreted in bile and transformed by bacteria into stercobilin, which colors feces.

Step-by-step explanation:

Bile pigments such as bilirubin and biliverdin are formed in the degradation of heme, which is a component of hemoglobin in red blood cells. The process starts when the spleen removes old or damaged red blood cells from the circulation. The breakdown products include proteins, iron, and the toxic pigment bilirubin, which is transported to the liver via the splenic vein of the hepatic portal system. In the liver, bilirubin is conjugated and excreted into the bile, contributing to its green color.

The bilirubin is ultimately converted by intestinal bacteria into stercobilin, a brown pigment that gives feces their characteristic color. Additionally, bilirubin can be seen contributing to the color of bruises and, when not properly excreted due to liver issues, can lead to jaundice, which causes a yellowish tinge to the body's tissues.