UNIT 6 Heme catabolism Heme Catabolism: Heme catabolism is the biochemical process through which heme is broken down into its degradation products, primarily bilirubin, carbon monoxide (CO), and iron (Fe²⁺). This process occurs predominantly in the reticuloendothelial system (RES), including the liver, spleen, and bone marrow. The breakdown of heme is essential for maintaining iron homeostasis and preventing oxidative damage caused by free heme. 1. Sources of Heme Heme is