As red blood cells disintegrate, which organ is primarily responsible for bilirubin production from hemoglobin?

As red blood cells disintegrate, which organ is primarily responsible for bilirubin production from hemoglobin?

• A. Spleen
• B. Kidneys
• C. Intestines
• D. Liver

Answer: (A)

When red blood cells are aged or damaged, they are engulfed by macrophages in the spleen, part of the reticuloendothelial system. In these splenic macrophages, heme from hemoglobin is broken down by heme oxygenase to biliverdin and free iron, and biliverdin is reduced to bilirubin. This bilirubin, in its unconjugated form, is then released into the bloodstream to travel to the liver for conjugation. The spleen is the primary site where bilirubin is produced from hemoglobin because that is where most RBC breakdown occurs. The liver’s role is to conjugate bilirubin for excretion, while the kidneys and intestines handle processing after bilirubin is formed, not its initial production.

When red blood cells are aged or damaged, they are engulfed by macrophages in the spleen, part of the reticuloendothelial system. In these splenic macrophages, heme from hemoglobin is broken down by heme oxygenase to biliverdin and free iron, and biliverdin is reduced to bilirubin. This bilirubin, in its unconjugated form, is then released into the bloodstream to travel to the liver for conjugation. The spleen is the primary site where bilirubin is produced from hemoglobin because that is where most RBC breakdown occurs. The liver’s role is to conjugate bilirubin for excretion, while the kidneys and intestines handle processing after bilirubin is formed, not its initial production.