Final answer:
When macrophages consume old RBCs, the iron from the heme portion of hemoglobin is stored in the liver or spleen as ferritin or hemosiderin, or carried to the red bone marrow by transferrin for recycling into new RBCs. Some iron can also be stored by mucosal cells as ferritin.
Step-by-step explanation:
When macrophages consume old and damaged red blood cells (RBCs), the iron from the heme portion of hemoglobin is processed and utilized in various ways. First, the iron can be stored in the liver or spleen as ferritin or hemosiderin.
Alternatively, it can be carried through the bloodstream by transferrin to the red bone marrow for recycling into new RBCs. Additionally, some iron can be taken up by mucosal cells and stored as ferritin, while the heme enters the mucosal cells and is broken down, with iron appearing in the plasma transferrin.