hemopoiesis-I.ppt
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Hematopoiesis is the process of formation of blood cells
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hemopoiesis-I.ppt
- 1. HEMOPOIESIS
- 2. Hemopoiesis is process of origin, development & maturation of all the blood cells 1. Erythropoiesis 2. Leucopoiesis 3. Thrombopoiesis
- 3. Erythropoiesis: Process of origin, development and maturation of erythrocytes (RBC) SITE OF ERYTHROPOIESIS: In fetal life: 1. Mesoblastic Stage: During first two months of intrauterine life, RBCs are produced from mesenchyme 2. Hepatic Stage: From third month of intrauterine life, liver is the main organ that produces RBCs 3. Myeloid Stage: During last three months of intrauterine life, the RBCs are produced from red bone marrow and liver
- 4. SITE OF ERYTHROPOIESIS: In newborn babies, children and adults: RBCs are produced from the red bone marrow 1. Up to age of 20 years: RBCs are produced from red bone marrow of all bones (long bones & all flat bones) 2. After age of 20 years: RBCs are produced from membranous bones like vertebra, sternum, ribs, scapula, iliac bones & skull bones and from ends of long bones
- 6. 20 mm STAGES OF ERYTHROPOIESIS 18 mm 15 mm 10–12 mm 8–10 mm 8 mm 7.2 mm
- 7. Stages Cell Size Nucleus Cytoplasm Staining Hb Hemocytobl ast 19-23 mm Very big – occupies almost whole cell Open chromatin Containing 4-5 nucleoli Deep basophilic Rim all around the nucleus Deep basophilic Absent Proerythrob last 15-20 mm Occupies 3/4 of cell volume 2-3 nucleoli Chromatin open Slightly more in amount Deep basophilic Do Early normoblast 14-16 mm Size decreases No nucleoli Chromatin condenses Further increase in amount Less basophilic Do
- 8. Stages Cell Size Nucleus Cytoplasm Staining Hb Intermediate normoblast 10-14 mm Nucleus size further decreases Chromatin further condenses Marked cytoplasm Polychromatophil ic staining Starts appearing Early late normoblast 8-10 mm Nucleus very small with chromatin dot Cart wheel appearance Increases markedly Further increase in amount Late late normoblast 7-8 mm Nucleus degenerates becomes uniformly deeply stained stained pyknotic Further increases More acidic, less basophilic Do
- 9. Stages Cell Size Nucleus Cytoplasm Staining Hb Reticulocyte 7-8 mm No nucleus; Remnants of RNA present Acidophilic Further increase in amount Erythrocyte 7.2-7.4 mm Nil Do Do
- 10. FACTORS NECESSARY FOR ERYTHROPOIESIS 1. General factors 2. Maturation factors 3. Factors necessary for hemoglobin formation 1. General factors i. Erythropoietin ii. Thyroxine iii. Hemopoietic growth factors iv. Vitamins
- 11. i. Erythropoietin: • Production of proerythroblasts from CFU-E of bone marrow • Development of proerythroblasts into matured RBCs through several stages – early normoblast, intermediate normoblast, late normoblast and reticulocyte • Release of matured erythrocytes into blood
- 12. ii. Thyroxine: Being a general metabolic hormone, thyroxine accelerates the process of erythropoiesis at many levels. So, hyperthyroidism & polycythemia are common iii. Hemopoietic growth factors: Interleukins (IL) induce the proliferation of HSCs a. IL-3 secreted by T-cells b. IL-6 secreted by T-cells, endothelial cells and macrophages c. IL-11secreted by osteoblast
- 13. iv. Vitamins: Vitamins are necessary for the process of erythropoiesis. Deficiency of these vitamins cause anemia associated with other disorders Vitamin B, C, D, E 2. Maturation factors: • Vitamin B12 (Deficiency causes pernicious anemia) • Intrinsic factor (Deficiency causes pernicious anemia) • Folic acid (Deficiency causes megaloblastic anemia)
- 14. 3. Factors necessary for hemoglobin formation • First class proteins: Globin synthesis • Iron: Heme synthesis • Copper: Iron absorption • Cobalt and nickel: Iron utilization
- 15. • Diameter 7.2 mm (6.9 - 7.4 mm) • Thickness in periphery 2 mm & center 1 mm • Surface area is about 120 – 140 mm2 • Volume is about 80 mm3 Normal counts of RBC Adult males, 5 – 6.6 million / mm3 (5.5 million / mm3 ) Adult females, 4.5 – 5.5 million / mm3 (4.8 million / mm3) Normal size of RBC
- 16. Normal shape RBCs are circular, biconcave discs Advantages of biconcave shape 1. Helps in equal & rapid diffusion oxygen & other substances into interior of the cells 2. Large surface area is provided for absorption or removal of different substances 3. Minimum tension is offered on membrane when volume of cell alter 4. RBCs squeeze very easily through capillaries without getting damaged
- 17. STRUCTURE OF RED CELL MEMBRANE Trilaminar structure having a bimolecular lipid layer interposed between two layers of protein Lipids: Glycolipids, phospholipids, cholesterol Proteins: Outer peripheral proteins: Lecithin & sphingomyelin Integral proteins: Band 3 (Anion exchange protein) Glycophorins (Blood group antigen) Inner surface protein: Ankyrin & Actin (Shape &flexibility) Spectrin (Cytoskeleton)
- 19. Permeability: Semi-permeable membrane Impermeable: Sodium, calcium, barium, fats & sugars Slightly Impermeable: Amino acids Freely permeable: Cl-, SO4 -, HCO3 -, urea, ammonia, aldehyde, alcohol, bile salts Composition of RBC: Water: Constitutes 60% of wet weight of RBC Hb: Forms 90% dry weight of RBC Lipids: cephalin, lecithin & cholesterol Proteins: Glutathiones, albumin-like insoluble protein Enzymes: Glycolytic enzymes, catalase, CA Glucose & amino acids: Small amounts Ions: Cl-, SO4-, HCO3- K+ (Large); Na+, Ca2+ (Small)
- 20. Variations in number of RBC Physiological variations A. Increase in RBC Count 1. Age At birth, the RBC count is 8 to 10 million/cu mm of blood. Count decreases within 10 days after birth due to destruction of RBCs causing physiological jaundice 2. Sex Before puberty & after menopause in females the RBC count is similar to that in males. During reproductive period of females, the count is less than that of males (4.5 million/cu mm).
- 21. 3. High altitude Inhabitants of mountains (above 10,000 feet from sea level) have an increased RBC count of more than 7 million/cu mm. High altitude Hypoxia Stimulation of JG cells of JGA Production of erythropoietin Stimulation of bone marrow Production of RBCs
- 22. 4. Increased temperature Increase in temperature increases RBC count. Generally increased temperature increases all the activities in the body including production of RBCs. 5. After meals There is a slight increase in the RBC count after taking meals. It is because of need for more oxygen for metabolic activities.
- 23. 6. Muscular exercise RBC count increases during muscular exercise Muscular exercise Increased sympathetic activity Increased secretion of adrenaline Contraction of spleen Release of RBCs
- 24. Decrease in RBC Count 1. High barometric pressures At high barometric pressures, when the oxygen tension of blood is higher, RBC count decreases 2. During sleep RBC count decreases slightly during sleep & immediately after getting up from sleep 3. Pregnancy In pregnancy, RBC count decreases. It is because of increase in ECF volume.
- 25. PATHOLOGICAL VARIATIONS Polycythemia: Red cell count increases above 7 million/ cu mm of the blood. Primary Polycythemia – Polycythemia Vera Polycythemia vera occurs in myeloproliferative disorders like malignancy of red bone marrow. • RBC count above 14 million/cu mm of blood. • WBC count above 24,000/cu mm of blood
- 26. Secondary Polycythemia This is secondary to some of the pathological conditions (diseases) such as: 1. Respiratory disorders like emphysema 2. Congenital heart disease 4. Chronic CO poisoning 5. Poisoning by phosphorus & arsenic 6. Repeated mild hemorrhages
- 27. Functions of RBC 1. Transport of O2 from lungs to tissues Hb in RBC combines with O2 to form oxyhemoglobin. About 97% O2 is transported in blood in the form of oxyhemoglobin Hb + O2 HbO2
- 28. 3. Buffering action in blood: Hemoglobin function as a good buffer. Regulate H+ ion concentration. 4. Blood group determination: RBCs carry blood group antigens like A-antigen, B-antigen & Rh factor. 2. Transport of CO2 from tissues to lungs Hb combines with CO2 and form Carbhemoglobin. About 30% CO2 is transported in this form HbNH2 + CO2 Hb- NH -COOH
Hinweis der Redaktion
- Development of blood cells i.e. rbc, wbc, and platelets called hemopoiesis. ERYTHROPOIESIS: Development of RBCs; Leucopoiesis: development of WBCs; Megakaryocytopoiesis: development of platelets.
- or hematopoiesis
- In fetal life, the erythropoiesis occurs in three stages: 2. Hepatic Stage: Spleen and lymphoid organs are also involved in erythropoiesis.
- In newborn babies, growing children and adults, RBCs are produced only from the red bone marrow. 1. Up to the age of 20 years: RBCs are produced from red bone marrow of all bones (long bones and all the flat bones). 2. After 20 years of age, the shaft of the long bones ( shaft means midsection i.e. diaphysis) becomes yellow bone marrow because of fat deposition and looses the erythropoietic function.
- The process by which nucleus disappears is called pyknosis. Reticulocyte: The cytoplasm contains the reticular network or reticulum, which is formed by remnants of disintegrated organelles. Pluripotent hemopoietic stem cells (PHSC). PHSC is defined as a cell that can give rise to all types of blood cells. Stem cells are the primary cells capable of self-renewal and differentiating into specialized cells (Chapter 1). Hemopoietic stem cells are the primitive cells in the bone marrow, which give rise to the blood cells.
- Polychromatophilic Red Blood Cells: Slightly immature, non-nucleated red cells (reticulocyte stage) appear blue-gray on Wright-stained smears due to the presence of residual ribonucleic acid (RNA). These cells are referred to as polychromatophilic cells. Polychromatophilic cells are frequently larger in size than mature red cells and can be distinguished from macrocytes by their distinctive blue-gray color
- Development and maturation of erythrocytes require variety of factors, which are classified into three categories: General factors necessary for erythropoiesis are:
- Stimulant for secretion: Hypoxia is the stimulant for the secretion of erythropoietin. Development of proerythroblasts into matured RBCs through the several stages – early normoblast, intermediate normoblast, late normoblast and reticulocyte
- Hemopoietic growth factors or growth inducers are the interleukins, Generally these factors induce the proliferation of PHSCs. Interleukins (IL) are glycoproteins, which belong to the cytokines family. Pluripotent hemopoietic stem cells (PHSC). PHSC is defined as a cell that can give rise to all types of blood cells. Stem cells are the primary cells capable of self-renewal and differentiating into specialized cells (Chapter 1). Hemopoietic stem cells are the primitive cells in the bone marrow, which give rise to the blood cells.
- Vitamin D: Its deficiency causes anemia and rickets 2. Maturation factors: Vitamin B12, intrinsic factor and folic acid are necessary for the maturation of RBCs. Deficiency of vitamin B12 causes pernicious anemia. (Macrocytic normocromic/ hypochromic; MCV – Large, MCHC – Normal or less) So, vitamin B12 is called antipernicious factor. Deficiency of folic acid causes megaloblastic anemia. (Macrocytic hypochromic; MCV – Large, MCHC –less)
- Various materials are essential for the formation of hemoglobin in the RBCs. Deficiency of these substances decreases the production of hemoglobin leading to anemia. Iron: Necessary for the formation of heme part of the hemoglobin. Copper: Necessary for the absorption of iron from the gastrointestinal tract.
- Each red blood cell like any other cell in the body …
- Through out the central lopid layer there are some pores. Some proteins molecules are invaginated into these pores from either surface of cell membrane.
- Age: However, in infants and growing children, the cell count is more than the value in adults.
- It is due to hypoxia (decreased oxygen supply to tissues) in high altitude. Hypoxia stimulates kidney to secrete a hormone called erythropoietin. erythropoietin in turn stimulates the bone marrow to produce more RBCs
- Muscular exercise: It is because of mild hypoxia and contraction of spleen. Spleen stores RBCs (Chapter 25). Hypoxia increases the sympathetic activity resulting in secretion of adrenaline from adrenal medulla. Adrenaline contracts spleen and RBCs are released into blood Emotional conditions: RBC count increases during the emotional conditions such as anxiety. It is because of increase in the sympathetic activity as in the case of muscular exercise
- Decrease in RBC count occurs in the following physiological conditions: Sleep: Generally all the activities of the body are decreased during sleep including production of RBCs. Pregnemcy: Increase in ECF volume, increases the plasma volume also resulting in hemodilution. So, there is a relative reduction in the RBC count.
- Polycythemia is of two types, the primary polycythemia and secondary polycythemia. Primary: It is a disease characterized by persistent increase in RBC count above 14 million/cu mm of blood. This is always associated with increased white blood cell count above 24,000/cu mm of blood.
- This is secondary to some of the pathological conditions (diseases) such as:
- O2 from the lungs diffuses into circulation. Blood reaches the tissue. Tissue have low concentration of O2, hemoglobin separate. O2 is released into tissues.
- CO2 from tissues is transported by combining with aa and not in combination with Fe like O2.