5. Advantages
Red cells quite flexible so that they can pass
through the capillaries.
• The biconcavity provides greater surface area
• Thus, the RBC can withstand considerable
changes of osmotic pressure.
• RBCs can resist hemolysis to certain extent
when placed in the hypotonic solution.
• Greater surface area allows easy exchange of O2
and CO2 and rapid diffusion of other substances.
6. Functions
• Gas transport
• Acid base balance
• Formation of bilirubin
• 50% of viscosity of blood
• Identification of blood group
7. Hemopoiesis
• . Hemopoiesis or hematopoiesis is the process
of origin, development and maturation of all
the blood cells.
10. SITE OF ERYTHROPOIESIS
3 stages:
1. Mesoblastic Stage-
• During the first two months of intrauterine
life, the RBCs are produced from
mesenchyme of yolk sac.
2. Hepatic Stage
• 3rd month of intrauterine life - liver
• Spleen and lymphoid organs
11. 3. Myeloid Stage
• During the last three months of intrauterine
life, the RBCs are produced from red bone
marrow and liver.
12. • „IN NEWBORN BABIES, CHILDREN AND ADULTS -
red bone marrow.
• 1. Up to the age of 20 years: red bone marrow of
all bones (long bones and all the flat bones)
• . 2. After the age of 20 yr - membranous bones like
vertebra, sternum, ribs, scapula, iliac bones and
skull bones and from the ends of long bones.
• After 20 years of age, the shaft of the long bones
becomes yellow bone marrow because of fat
deposition and looses the erythropoietic function.
13.
14. Hemocytoblast (stem cell)
• 18-20μm
• Nucleus- Very large (almost occupying whole
of the cell),
• deep basophilic containing 4–5 nucleoli
• Proliferate and give rise to committed stem
cell.
15. Commited stem cell
• Two types – myelod and lymphoid
• Erythrocytes, platelets,monocyte.
• Myelod series giv rise to all types of cells
except lymphocytes.
25. Function
Acts from the stage committed stem cell
Differentiation of erythropoietin sensitive
stem cell.
Prevents apoptosis of red cell
↑ synthesis of RNA, DNA ,globin ,ferritin
↑ the release of reticulocyte from bone
marrow.
28. HEMOPOETIC GROWTH FACTORS
• Interleukins
• Stem cell factor
• Function – proliferation of pluripotent stem
cells
29. Maturation factors
• Vitamin B 12 and folic acid – extrinsic factors
• Function – DNA synthesis
• Iron – Hb synthesis
• Castle intrinsic factor – absorption of vit B12
• Dietary factor –
Protein – globin formation
Fe , Mn, Cu, Co – heme formation
Vit c & Ca - ↑ iron absorption from gut
