Red blood cells (RBCs) are the most common type of blood cell in the human body and are created through a process known as erythropoiesis. Red blood cells are created in the red bone marrow and, after a life cycle of approximately 120 days, they are recycled in the liver, bones (red bone marrow), or spleen. Red blood cells undergo their recycling and destruction process by macrophages, which phagocytize the red blood cells. Macrophages are white blood cells that essentially clean and protect the body at a cellular level.
“The rate of RBC formation by red bone marrow equals the rate of RBC destruction by macrophages” (Tortora, 2014). With red blood cells, it is important for macrophages to perform their phagocytic process because red blood cells age over time. During their life cycles, since red blood cells lack nuclei and are unable to repair themselves, red blood cells can rupture, burst, and can become very fragile with age. Therefore, for healthy circulation, it is very important to recycle and destruct unhealthy or damaged red blood cells.
Red blood cells are formed from pro-erythroblast cells. These cells divide several times and one of the side products of these divisions are red blood cells. The red blood cells then depart from the red bone marrow in which they were formed and enter “the bloodstream by squeezing between the endothelial cells of blood capillaries” (Tortora). After entering the bloodstream, red blood cells circulate, aiding the body in various ways before being recycled and destructed after 120 days.
Macrophages then break the red blood cycles down through metabolic processes. The left over products of red blood cells can be used or turned into hemoglobin, which is split into heme and globin, which is then turned into amino acid that can be used towards protein synthesis. Iron is another byproduct of the breakdown of hemoglobin.
- Tortora, G. J., & Derrickson, B. H. (2014). Principles of anatomy and physiology. John Wiley & Sons.