Explanation:

• After about 100-120 days, RBCs are removed from circulation through a process called eryptosis.
• Erythropoiesis is the process by which human erythrocytes are produced. It is triggered by erythropoietin, a kidney hormone produced during hypoxia.
• Erythropoiesis takes place in the bone marrow, where hemopoietic stem cells differentiate and eventually shed their nuclei to become reticulocytes. Iron, vitamin B12, and folic acid are required for hemoglobin synthesis and normal RBC maturation.
• Reticulocytes mature into normal, functional RBCs after 24 hours in the bloodstream.
• Following eryptosis, the liver breaks down old hemoglobin into biliverdin and iron. The iron is taken back to the bone marrow for reuse by transferrins, while biliverdin is broken down into bilirubin and excreted through digestive system bile.