Formation of RBC

Formation of RBC

The process of RBC formation is called Erythropoiesis. Blood cell formation also called Hematopoiesis or Hemopoiesis.  RBC main function is to transport oxygen around our body. Blood cell are divided into 3 groups. The red blood cells (Erythrocytes), white blood cells (Leukocytes) and blood platelets (thrombocytes).

It takes place at Hematopoietic stem cell in Red bone marrow of Humerus, Femur, Sternum, Rib, Vertebra and Pelvis. This stem cell divided by mitosis and some of the daughter cell get matured into erythrocyte when other remain as stem cell. The entire maturation phase take around 4 days and proceed step by step.  As a matter of fact all the blood cell are divided from these stem cell. RBC are formed and destroyed at breathtaking rate. 200 billion RBC are destroyed and replace.

Area of the body that produce RBC

In early weeks of embryonic life, primitive , nucleated red blood cell are produced in yolk sac. During the middle trimester of gestation, the liver is the main organ for production of RBC, but reasonable number are also produced in the spleen and lymph nodes. Then, during the last month or so of gestation and after birth, RBC are produced exclusively in bone marrow.

All bone marrow Is red initially but after certain age, some bone marrow like humerus, femur become fatty (yellow).

In adult, 2.4 million RBC are produced each second.  In normal adult, the red cell of about half a liter (almost one point) of blood is produced by the bone marrow every week. RBC have a life span of approximately 100-120 days. After they have completed their life span, they are removed from the blood stream by the spleen.

Regulation of erythropoiesis:

Kidney main function to monitor blood volume and oxygen content of blood. As necessary kidney release Erythropoietin (EPO). When oxygen concentration in the blood are low erythropoietin is released from the kidney. Erythropoietin operate in a negative feedback mechanism to maintain RBC homeostasis.

There are few hormone that secret kidney ie, Thyroxin . The main job of thyroxin is to increase the ATP  production of cells. That means that cell need more oxygen to make more ATP then they need more RBC. So Thyroxin stimulate the release of EPO from the kidney.

   Man have more Thyroxin then female because Testosterone stimulate Thyroxin. So man have more RBC in their blood than women because Testosterone stimulated Thyroxin which stimulate EPO. 


Presented by: Manoj karki (BVSC&AH)