3. Learning Objectives of Todayโs Lecture
โข Sites of Erythropoiesis
โข Main features of different stages of
Erythropoiesis
โข Features of a mature RBC
โข RBC Count
4. RBC Formation before birth
โข Mesoblastic stage
โ Nucleated RBCs - Yolk sac and
Mesothelial layers of the placenta โ
3rd week
โข Hepatic stage
โข At 6 weeks - Liver form blood cells
โ Spleen + lymphoid tissues form
blood cells.
5. RBC Formation before birth
โข Myeloid stage
โข From the third month onwards - the
bone marrow gradually becomes the
principal source of the RBCs
โข Last month โ Bone marrow exclusively
6. RBC Formation after birth
โข The bone marrow - all bones - 5 years
โข Marrow of the long bones (except for the
proximal humerus and tibia)
โข Most red cells continue to be produced
in the marrow of the membranous bones,
such as
โ Vertebrae, Sternum, Ribs, and Ilium.
7. Relative rates of red blood cell production in the bone
marrow of different bones at different ages.
8. Bone marrow cells for Erythropoiesis
โข Pluripotential hematopoietic stem cell, PHSC
โข Committed stem cell that produces erythrocytes is
called
Colony-forming unitโerythrocyte, CFU-E
Factors:
โ Growth inducers
โ Differentiation inducers.
12. Basophil erythroblast
โข Early normoblast
โข Nucleoli disappear
โข Show mitosis
โข Cytoplasm deep blue
โ Increase in RNA
โข Hemoglobin starts
appearing โ Little Hb
16. Transfer of RBC to Circulation
RBC pass from the bone marrow into the
blood capillaries
By
Diapedesis
(squeezing through the pores of the
capillary membrane).
17. Erythrocytes
โข Round, biconcave, disc
shaped.
โข Smooth contours
โข Diameter 7.8 um.
โข Normally no variation in size
and shape.
โข Stain with EOSIN.
โ More stain at periphery
โข Can deform easily.
18. STRUCTURE OF RBC.
โข Negative surface charge.
โข Bag of fluid with dissolved substances and
hemoglobin
โข Membrane โ
โ Outer glycoprotein coat
โ Lipid bilayer (PL 55%,Cholesterol 45%)
โข Inner protein molecules cytoskeleton
โ Spectrin, Actin, Ankyrin etc.
โข No sub cellular particles
19. ENERGY METABOLISM
โข Less energy required
โ Na + - K + pump
โ Iron in Fe ++ form
โข Utilize Glucose by GLUT 1
โข Anaerobic respiration โ Glycolysis
โ Embden Meyerhof pathway
โข Pentose phosphate pathway.
โ Hexose monophosphate shunt
20. RBC Count
โข Remains remarkably constant although
there are some variations.
โข MALE : 5.2 ยฑ 0.3 x 106 /uL.
โข FEMALE : 4.7 ยฑ 0.3 x 106 /uL.
โข Life span : 120 ยฑ 30 Days.
21.
22. Sites of Erythropoiesis
โข Mesoblastic stage
โ Nucleated RBCs - Yolk sac and Mesothelial
layers of the placenta โ 3rd week
โข Hepatic stage
โข At 6 weeks - Liver form blood cells
โ Spleen + lymphoid tissues.
โข Myeloid stage
โข From the third month on - the bone marrow
23. Main features - stages of Erythropoiesis
โข Proerythroblast
โข Basophilic Erythroblast
โข Polychromatophil Erythroblast
โข Orthochromatic erythroblast
โข Reticulocyte
โข Erythrocyte
24. Features of a Mature RBC
โข Biconcave disc
โข Mean Diameter 7.8 um
โข Can deform easily.
โข Bag of fluid with dissolved substances
and hemoglobin
โข No sub cellular particles
โข Metabolism
โ Anaerobic respiration- Glycolysis
โ Pentose phosphate pathway.
25. RBC Count
โขMALE :
โ 5,200,000 ยฑ 300000 per mm3.
โขFEMALE :
โ 4,700,000 ยฑ 300000 per mm3.