Blood physiology
BLOOD
1. ERYTHROPOIESIS
* Refers to the process of production
and maturation of Red Blood
Cells (erythrocytes)
* Site of production – Red bone marrow of all the bones upto
20
years of life. After 20 years, only flat bones produce RBCs.
Stages of Erythropoiesis :
1.
Hemocytoblast
2.
BFU
–E, Blast Forming Unit – E
3.
CFU-E,
Colony Forming Unit – E
4.
Proerythroblast
5.
Early
normoblast
6.
Intermediate
normoblast
7.
Late
normoblast
8.
Recticulocyte
9.
Mature
erythrocyte
1. Hemocytoblast:
- 18 – 23 um in diameter
- Large Nucleus
- Thin rim of basophilic cytoplasm
- Pleuripotent stem cells
2. Blast Forming Unit – E:
- Unipotent progenitor cell.
- Less Sensitive to Erythropoietin
3. CFU (E) – Colony Forming Unit
- Matured unipotent progenitor cell
- Highly sensitive to erythropoietin
4. Proerythroblast:
- 14-19 µm in diameter.
- Large nucleus with distinct nucleoli
- Basophilic cytoplasm.
- Vit B12 & Folic acid are required
for the conversion of this stage into next stage.
5. Early normoblast;
- 11-17 µm in diameter.
- Dense nucleus
- Basophilic cytoplasm.
6. Intermediate normoblast:
- 10-12 µm in diameter
- more condensed nucleus
- Hb (Hemoglobin) is formed
- Polychromatophilic cytoplasm.
7. Late normoblast:
- 8-12 µm in diameter.
- Dense nucleus (Pyknotic)
- Nucleus extrudes after this stage
& disintegrates
- Acidophilic cytoplasm.
8. Reticulocyte:
- Almost of the same size of matured
RBC
- A small reticulum is seen in the
cytoplasm.
10. Mature Erythrocyte:
- About 7.2 um in diameter.
- No nucleus
- Acidophilic cytoplasm
Regulation of Erythropoiesis
1. Erythropoietin a hormone secreted by kidneys
- Stimulates the bone marrow tissue
to produce more RBCs.
2. Hypoxia: Lack of O2 is the main condition which
stimulates erythropoietin secretion.
Lack of O2 (Hypoxia)
 |
Kidneys
 |
Erythropoietin
|
Red Bone marrow
 |
|||
 |
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RBC Production
 |
Restoration of O2 Suppl
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