Final answer:
Bilirubin is a waste product resulting from the breakdown of hemoglobin from old or damaged RBCs. It is processed by the liver and excreted in bile, with excess levels leading to jaundice. This understanding is crucial for diagnosing liver and blood disorders.
Step-by-step explanation:
Hemoglobin Breakdown and Bilirubin Formation:
The breakdown of hemoglobin (Hgb) into bilirubin involves several steps. Old or damaged red blood cells (RBCs) are removed from circulation by the spleen. These cells contain hemoglobin, which is then decomposed into its component parts: the protein globin and the heme group. The globin portion breaks down into amino acids to be reused, while the heme group undergoes further degradation.
Bilirubin then binds to albumin and is carried to the liver. Here, it's processed and secreted into bile, with some of it ending up in the intestines. Intestinal bacteria convert bilirubin into urobilinogen and stercobilin, substances that ultimately leave the body in feces, imparting the characteristic brown color. Excess bilirubin may lead to a yellowish discoloration of the skin and eyes, a condition known as jaundice.