Erythropoiesis and Factors Affecting Erythropoiesis

Erythropoiesis is the scientific term for the production of the red blood cells (erythrocytes) from the bone marrow called stem cells. Erythrocytes are vital for your health. They carry almost all the oxygen in your body which is used to make almost half of your blood. 8 out of 10 cells in your body are red blood cells. The marrow of certain bones constantly produces red blood cells. As noted previously, the marrow spaces of the vertebrae, ribs, breastbone, and pelvis are the primary sites of red cell generation, or erythropoiesis, in adults. The erythroblast, a nucleated cell that lacks hemoglobin, is the fundamental precursor from which the red blood cell is produced in the bone marrow. Bone marrow is the tissue in your bones that functions as the factory for producing blood cells. For starters, the bone marrow creates stem cells and then these stem cells will then develop into more specialized cells called Common myeloid progenitors (CMP) and has the ability to mature into all of the different blood cell types which includes the red blood cells (erythrocytes), the white blood cells(leukocytes) and also platelets.

(Normal RBC Physiology (Including erythropoiesis). (n.d.). Www.youtube.com. https://youtu.be/bbUlaTApuuI)

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The life cycle of a healthy erythrocyte takes about 3 to 4 months. Firstly, the stem cell commits to become a red blood cell and turns into a cell called an erythroblast. The erythroblast will then become a more developed blood cell called a reticulocyte and enter the bloodstream. It takes about a week for a healthy reticulocyte to become a mature red blood cell (erythrocyte). It then stays in your bloodstream until it naturally wears out and the body recycles them. The bone marrow will constantly replace the supply of erythrocytes and other blood cells.The development of a healthy and functioning red blood cell depends on healthy stem cells in your bone marrow. If the bone marrow is not healthy it will produce defective stem cells and may not be able to develop normally into blood cells. Hence, they will die in the bone marrow by apoptosis or programmed cell death. Apoptosis is one of our  body’s ways of removing defective cells.

Development and maturation of erythrocytes require mostly three types of factors which are the general factors, maturation factors and also factors that are necessary for hemoglobin formation. The general factors that are necessary for erythropoiesis are erythropoietin, thyroxine hemopoietic growth factor and also vitamins. The most crucial general factor for erythropoiesis is the usage of erythropoietin hormone. It is also called hemopoietin or erythrocyte stimulating factor. Major quantity of erythropoietin is secreted by peritubular capillaries of the kidney. A small quantity is also secreted from the liver and brain. Hypoxia is the stimulant for the secretion of erythropoietin. Erythropoietin also promotes processes such as the generation of proerythroblasts from bone marrow CFU-E. 

Other than that, early normoblast, intermediate normoblast, late normoblast, and reticulocyte are also several phases that proerythroblasts go through to mature into RBCs.The release of mature erythrocytes into blood, along with mature RBCs, some reticulocytes (immature erythrocytes) are also discharged. Erythropoietin levels in the blood rise with anemia.Thyroxine is a general-purpose metabolic hormone that speeds up erythropoiesis on a variety of levels. As a result, polycythemia and hyperthyroidism are widespread. There are also a few hemopoietic growth which include interleukin-3(IL-3) secreted by T-cells, Interleukin-6 (IL-6) secreted by T-cells,endothelial cells and macrophages and Interleukin-11 (IL-11) secreted by osteoblast. Vitamins are also very necessary for erythropoiesis. For instance, vitamin B, Vitamin C, vitamin D and vitamin E. The deficiency of vitamins as mentioned can cause anemia, scurvy, rickets and malnutrition. However for the maturation factors, Vitamin B12 which is also known as Cyanocobalamin is essential for the DNA synthesis in RBCs. This vitamin deficiency can cause the failure in cell maturation and the reduction in the cell division. 

Next factor is the Intrinsic factor of the castle. It is produced by gastric in mucosa by the parietal cells of gastric glands. It is important for the absorption of vitamin B12 from the intestine. If the vitamin B12 is not properly absorbed from the intestine it will lead to pernicious anemia.  The deficiency of intrinsic factor occurs in severe gastritis, ulcer and gastrectomy. Apart from that, folic acid is also crucial in maturation of RBCs. It is needed for the synthesis of DNA. If folic acid fails to present the synthesis of DNA will decrease causing the failure in maturation. This leads to anemia called megaloblastic anemia in which the cells are larger.

Next for the factors necessary for hemoglobin formation. A variety of materials are essential for the formation of hemoglobin in the RBCs. The deficiency of the substances decreases the production of hemoglobin that leads to anemia.  The first one is, first class proteins and amino acids. These Proteins contain high biological value which are essential for the formation of hemoglobin. Amino acids derived from these proteins are required for the synthesis of the protein part of hemoglobin. Next is the Iron. It is necessary for the formation of the heme part of the hemoglobin while Copper is necessary for the absorption of iron from the gastrointestinal tract. Besides, Cobalt and nickel metals are essential for the utilization of iron during hemoglobin production. Lastly vitamins such as vitamin C, riboflavin, nicotinic acid and pyridoxine are also essential for the formation of hemoglobin during hemoglobin formation. Lastly, for the Vitamins such as Vitamin C, riboflavin, nicotinic acid and pyridoxine are also essential for the formation of hemoglobin.

BY: NURUL FATIN ATHIRAH BINTI ENDRAH