Question

Erythropoiesis starts in
A. Kidney
B. Liver
C. Spleen
D. Red bone marrow

Answer 1

Hint: Erythropoiesis is the formation of erythrocytes. Erythropoietin hormones in bone marrow helps in the growth and development of erythrocytes.

Complete Answer:
- Erythropoiesis is derived from the Greek words erythron means “red” and poiesis means “to make”. The process of producing red blood cells or erythrocytes is known as erythropoiesis. A particular hormone known as erythropoietin secreted by kidneys stimulates the red blood cell precursors. It helps in the activation process of production of red blood cells in hematopoietic tissues present in the red bone marrow.
- Erythropoietin hormone triggers the growth of stem cell or proerythroblast which further grows into erythroblast. Erythroblast develops into erythrocytes.
- In the early foetal development, erythropoiesis is started in the yolk sac and after a few months it takes place in the spleen and liver. After birth, erythropoiesis is taking place in red bone marrow.

Hence, the correct answer is (D) red bone marrow.

Note:
- There are three types of blood cells found in human blood: RBC (red blood corpuscle)/ erythrocyte, WBC (white blood corpuscle)/leucocyte, platelet.
- Various factors affecting the erythropoiesis mechanism are: Amount of oxygen supply to the tissues, Hormones, Proper diet and Healthy bone marrow.
- Spleen is regarded as the graveyard of RBCs.