PROFESSOR DEPT OF PHYSIOLOGY Hematopoiesis Formation of blood cells in general is termed as Hemopoiesis or Hematopoiesis The process of differentiation from stem cells to mature erythrocyte is called Erythropoiesis ID: 1009213
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1. ERYTHROPOIESIS Dr RESHMY K.RPROFESSORDEPT. OF PHYSIOLOGY
2. HematopoiesisFormation of blood cells in general is termed as Hemopoiesis or HematopoiesisThe process of differentiation from stem cells to mature erythrocyte is called ErythropoiesisThe rate at which the blood cells are produced are regulated in healthy individuals to match the rates at which they leave the circulation.
3. Hematopoiesis
4. HEMOPOIESIS
5. Erythropoiesis-StagesProerythroblastEarly normoblastIntermediate normoblastLate normoblastReticulocyteMatured erythrocyte19-5
6. ErythropoiesisProduction of red blood cellsStem cells proerythroblasts early normoblast intermediate normoblast late normoblast reticulocytes matured RBCErythropoietin: Hormone to stimulate RBC production19-6
7. ERYTHROPOIESISThe origin , development and maturation of erythrocytesVarious control mechanisms regulate erythropoiesis, so that the red cells mass in the body remain constant.
8. Intra uterine lifeMesoblastic stageHepatic stageMyeloid stage
9. mesoblastic stage starts in the 3rd week of intrauterine life in the mesoderm of the yolk sac and continues up to the 3rd month. -intravascular erythropoiesishepatic stagefrom the 2nd month up to delivery, peak during the 5th and 6th month. spleen - between 2nd and 6th monthMyeloid stagefrom the 5th month onwards
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11. Site of Erythropoiesis
12. After birthred bone marrow is alone concerned with erythropoiesisupto 6 years all marrow is redby 6-20 years red marrow is present only in long bones and in membranous bonesafter 20 yrs, red marroe is present only at the ends of long bones like humerus, femur etc, and in the membranous bones like sternum, ribs, scapula, ilium, skull and vertebrae.
13. Relative rates of red blood cell production in the bone marrow of different bones at different ages
14. when there is increased demand of RBC the yellow marrow is capable of reverting back to active red marrow.when bone marrow is destroyed or fibrosed, extramedullary hemopoiesis occurs-in adults at times of need , liver and spleen also produce red blood cells.
15. 75% of active marrow is involved in production of WBC-MYELOID SERIES25% Produces RBC- erythroid series ----3:1(WBC to RBC)-----in peripheral blood ratio of wbc to rbc is 1: 700----the life span of RBC is far greater than of WBC
16. Changes occurring in each stage of ErythropoiesisReduction in size of the cellDisappearance of nucleoli and nucleusAppearance of hemoglobinChanges in the staining properties of the cytoplasm
17. Pronormoblast or proerythroblastRound or oval in shape15-20 micrometer in diameterLarge nucleus which occupies 80% of cell and contains 2-3 nucleoliThin rim of cytoplasm is seenNo hemoglobinFerritin molecules present
18. Basophilic normoblast/early normoblast12-17 micrometer in diameterNucleus smallerNucleoli disappearShow mitosisChromatin condensation seenCytoplasm more deeply basophilic- deep blueIncrease in ribosomes RNA Hemoglobin starts appearing
19. Polychromatophilic erythroblast/Intermediate normoblast12-15micrometer in diameterNucleus very small and assumes a cart wheel appearanceChromatin condensation moreCytoplasm shows both pink and blue areas.pink colour is due to increase in hemoglobin contentNo. of mitochondria decreasesMitosis stops in this phase due to inactivation of chromosomes
20. Orthochromatic Normoblast or late Normoblast8-12 micrometer in diameter, smallest of the nucleated precursorsCytoplasm is pink and hb synthesis is completeNucleus undergoes pyknotic degeneration and it shrinks and becomes irregularNuclear lysis and Nuclear extrusion
21. Reticulocyte8 micrometer in diameter, irregular and polylobulated due to extrusion of nucleusCytoplasm contains ribosomes, mitochondria and golgi complexSynthesize HbYoung RBCs (34% Hb)1 % of Red Cells
22. Matured ErythrocyteRBC pass from the bone marrow into the blood capillaries Dia -7.2 micrometer in diameter
23. Factors regulating ERYTHROPOIESISBPA(burst promoting activity)ErythropoietinHormonesMetalsLipids& proteinsVitaminsMaturation factors
24. FEEDBACK REGULATION OF ERYTHROPOIESIS
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