1. Packed cell volume count (Hematocrit)
Enas Sabah
MSc. Human Physiology

2. P.C.V is the volume of the blood made only by the blood cells per 100 ml of blood.
The two main parts of blood are the plasma (which constitute on average about 55% of the blood volume) and the blood cells (which constitute about the 45% of the blood volume).

4. Red Blood Cells (Erythrocytes)
Normal RBCs, are biconcave discs, their shape of can change remarkably as they squeeze through capillaries.
In healthy men, the average number of RBCs per cubic millimeter is 5,200,000 (±300,000)
in women, its 4,700,000 (±300,000).

5. Life Span of RBCs is about 120 days.
The red blood cells are the most abundant cell in the blood and the value of the P.C.V reflects the volume of the red blood cells.

6. Production of Red Blood Cells
RBCs are derived from pluripotential hematopoietic stem cell in the bone marrow
exposure of the blood to low oxygen for along time causes growth induction & production of greatly increased numbers of erythrocytes.

7. Regulation of RBCs production.

8. Procedure: Clean the thumb with alcohol soaked cotton and puncture it.
Allow the blood to enter the capillary tube by capillary attraction leaving at least 15 mm unfilled (or fill about 80% of the tube with blood).
Seal one end of the capillary tube by sealing clay.

9. 4. Spin the capillary tube in a micro-centrifuge for 5 minutes at about 10000 RPM.
5. Read the value of the P.C.V by the Hematocrit reader.
Normal range of P.C.V for adult male is 47 ± 7% and for adult female 42 ± 5%.
Increase in the volume of P.C.V above the reference range is termed as polycythemia while decrease in the volume below normal is called anemia.

10. Hematocrit (PCV) value Increase in the following conditions:
Dehydration
Burn Injury
Polycythemia Vera 
High Altitude
Conditions associated with hypoxia

11. Hematocrit value decrease in the following conditions:
Pregnancy 
Renal failure
Bone marrow failure
Hemolytic anemia
chemotherapy

12. Anemias
Anemia means deficiency of hemoglobin in the blood, which can be caused by either too few red blood cells or too little hemoglobin in the cells.
1. Blood Loss Anemia
In chronic blood loss a person can't absorb enough iron from the intestines to form hemoglobin as rapidly as it is lost.
RBCs are smaller than normal and have too little hemoglobin inside them (microcytic hypochromic anemia).

13. 2. Aplastic Anemia
Bone marrow aplasia means lack of functioning bone marrow.
For instance, a person exposed to high-dose radiation or chemotherapy for cancer treatment can damage stem cells of the bone marrow

14. 3. Megaloblastic Anemia
Results from vitamin B12 & folic acid deficiency.
grow too large, with different shapes, and are called megaloblasts.

15. 4.Hemolytic Anemia
are hereditary disorders that make the cells fragile, so they rupture easily as they go through the capillaries, especially through the spleen.
Types include:
hereditary spherocytosis
sickle cell anemia,
glucose-6-phosphate dehydrogenase (G6PD).