Hemopoiesis B.pharmacy 2 semester

Hematopoiesis is the production of all of the cellular components of blood and blood plasma.
It occurs within the hematopoietic system, which includes organs and tissues such as the bone marrow, liver, and spleen.
Simply, hematopoiesis is the process through which the body manufactures/produces the blood cells.

1. HEMOPOIESIS/HEMATOPOIESIS Hematopoiesis  is the production of all of the cellular components of blood and blood plasma. It occurs within the  hematopoietic  system, which includes organs and tissues such as the bone marrow, liver, and spleen. Simply,  hematopoiesis  is the  process  through which the body manufactures/produces the blood cells.

2. EARLY HAEMATOPOIESIS: Before birth the production of blood cells begins in the  embryonic yolk sac around 14-19 days.  The predominant sites of haematopoiesis in the foetus during the second trimester are liver, spleen, thymus and lymph nodes. From seven months , the bone marrow takes over and continues to be the predominant site in adults.  In the first four years of life , almost all marrow cavities contain haematopoietic tissue, termed red bone marrow . As we age, the quantity of this haematopoietic tissue decreases and is replaced by fat (yellow marrow). In adults red marrow is limited to the axial skeleton and long bones.

3. ADULT HAEMATOPOIESIS: Normal adult haematopoiesis occurs within the   red bone marrow .  The increase in yellow marrow during ageing restricts sites of haematopoiesis to the axial skeleton and proximal ends of long bones (e.g. femur and humerus). In the presence of defective or insufficient haematopoiesis in the bone marrow, expansion of the red marrow may occur. Haematopoiesis can occur in organs such as the liver and spleen , termed extra- medullary haematopoiesis.  All blood cells are derived from the most primitive haematopoietic cell which is located in bone marrow, referred to as a multipotent/ pluripotent haemopoietic stem cell. From these cells, all cell lineages can be formed . In order to form blood cells, pluripotent/multipotent stem cells in red bone marrow produce to further types of stem cells, called myeloid stem cells and lymphoid stem cells. In next generation, these cells are divided into precursor cells, also known as blasts. Over several cell divisions they develop into actual formed elements of blood. Successful hemopoiesis is dependent on both cell proliferation and cellular maturation. (e.g. development of structural and functional characteristics) Several hormones called hemopoietic growth factors regulate the differentiation and proliferation of particular cells. e.g. ERYTHROPOIETIN(EPO) - Red Blood Cells (PRODUCE FROM KIDNEY) THROMBOPOIETIN(TPO) – Platelets (PRODUCE FROM LIVER)

4. DIFFERENT TERMS: 1.Erythropoiesis  is the process which produces red blood cells (erythrocytes), which is the development from  erythropoietic  stem cell to mature red blood cell. 2 . Leukopoiesis is a form of hematopoiesis in which white blood cells (WBC, or leukocytes) are formed in bone marrow located in bones in adults and hematopoietic organs in the fetus. 3.Thrombopoiesis is the formation of platelets in the Bone marrow. 

5. S. NO Red Bone Marrow Yellow Bone Marrow 1 Also called medulla osium rubra Also called medulla osium flava 2 Mainly located in the shoulder blades, skull, and long bones and flat bones Mainly located in the hollow cavity of long bones 3 Level slowly decreases with age Level slowly increases with age 4 Rich in hematopoietic cells Rich in adipocytes (fats) 5 Color: red Color: Yellowish 6 Responsible in the production of platelets, red blood cells, and white blood cells Responsible for the storage of fats and the release of blood cells during emergency situations 7 Comprised of active cells that continuously divide and multiply to develop and release blood cells Comprised of inactive cells that release blood cells in emergency situations