1. E rythropoiesis Dr. Wasif Haq

2. Introduction Red blood cells also called as “Erythrocytes”. R.B.C. required for transportation of respiratory gases. Biconcave disc shaped. Mean diameter 7.5.-7.8 micrometer. Initially nucleated, later anucleated. Flexible cell membrane. Significance?

3. Count & Levels Most numerous amongst all blood cell types. In males: 5,200,000 (+ 300,000) Million cells/cubic millimeter. In females: 4,700,000 (+ 300,000) Million cells/cubic millimeter. Why the count in males is greater?

4. Hemoglobin Levels Maximum concentrating ability of R.B.C.’s for Hemoglobin is 34 g/dl. Every deciliter of blood in men carry 16 grams of Hemoglobin, while in females; 14 grams. 1 single gram of Hemoglobin is capable of combining with 1.39 milliliters of Oxygen.

5. Functions of R.B.C.’s Transportation of Oxygen bound with Hemoglobin: 97% Hemoglobin. Carbonic anhydrase enzyme: Transportation of CO 2 from tissues back to lungs in form of ‘bicarbonate’ ions. Acid-base buffering.

6. R.B.C.’s Production Also known as “Erythropoiesis” or “Erythrogenesis”. Intra-embryonic/ Intra-uterine life Postnatal life

7. Intra-Embryonic Life Initially: Yolk sac. Second trimester: Mainly liver along with Spleen & lymph nodes. Third trimester and after birth : Only in bone marrow.

8. Post-natal Life Bone marrow of all the bones till 5 years of life. Relation between age & R.B.C.’s production? Vertebrae, sternum, ribs and ilia produce R.B.C.’s throughout life.

10. Erythropoiesis Pluripotent Hematopoetic stem cells in bone marrow (also called as Hemocytoblast) are source for R.B.C.’s. Any type of blood cell type can be formed by Hemocytoblasts. Certain number of Pluripotent Hematopoetic stem cells will become committed to form only R.B.C.’s, hence called “Committed stem cells”. Commitment occurs before any structural differences observed. Growth & differentiation inducers.

11. Haematopoetic stem cell Proerythroblasts Basophil erythroblasts Polychromatophil erythroblasts Orthochromatic erythroblasts Reticulocytes Erythrocyte

13. Nutrients Required Vitamin B12, Folic Acid & Iron. Deficiency of Vitamin B 12 & Folic Acid- Maturation failure. Larger than normal size R.B.C.’s are produced called Macrocytes. Macrocytes can carry O2 but are extremely fragile. B12 deficiency takes 3-4 years to develop. Folic acid destroyed by cooking vegetables, meat & fruits.

14. Nutrients Required Sprue= Small intestinal disease, difficulty in absorbing Folic acid & Vitamin B 12 due to deficiency of Intrinsic factor. Iron: Stored in body in form of “Ferritin”. Hemoglobin: 65% Iron, Myoglobin 4%, Reticulo- endothelial cells in bone marrow and liver 15- 30%.

15. Erythropoietin Concentration of R.B.C.’s is not important but functional ability to transport respiratory gases. Protein hormone stimulates R.B.C.’s production. Released from Kidneys (90%) & Liver (10%). Epinephrine, Nor-epinephrine & Prostaglandins stimulate Erythropoietin release. Production starts within minutes, new cells appear after 4-5 days. Action: Stimulates Proerythroblast formation from hematopoietic stem cell and accelerates progression & maturity of cell through different stages of Erythropoiesis.

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