1. Erythrocytes (RBCs)
Figure 17.3

2. Haemoglobin

3. Haemoglobin Definition:
- It is the principal constitute (33% ) of RBCs
- It is a red pigment which gives the blood its red colour
Normal levels:
- Infant at birth 20 gm/dl
- Infant after one week 15.5gm/dl
- Children (3-12 years) =11-14 gm/dl
- Adult male gm/dl
- Adult female gm/dl

4. Structure:
1) Globin: 2 pairs of polypeptide chains (2  and 2 )
2) 4 Haem:
each is an iron-protoporphyrin :
- 4 pyrrole rings  protoporphyrin
- protoporphyrin + Fe++  haem

5. Structure of Hemoglobin
Figure 17.4

6. Functions - Carriage of O2 & CO2 - Strong buffer system
Reactions of Hb
- Oxyhemoglobin:
O2 bind with iron in ferrous state . It is called oxygenation not oxidation
- Met Hb:
strong oxidation by certain drugs or oxidizing agents  ferric state which can not carry O2. Dusky coluoration of skin like cyanosis

7. Carboxy Hb:
carbon monoxide is a toxic gas and attached to Fe++ instead of O2. It has high affinity to Fe++ (210 times as O2).
Carbamino Hb:
normally CO2 attached to the amino group of globin part of Hb.

8. Types of Hb 1-Adult (HbA):
2  chain (each is consisted of 141 amino acids) and 2 chain (146 amino acids).(97.5% of adult Hb.)
2-HbA2:
2 chains and 2 delta (146 amino acids) chains which differ from -chains in the terminal 10 amino acids.
3-Fetal Hb (HbF):
It is the type of Hb in the human fetus. It is usually replaced by adult Hb after birth . It contain 2 and 2 gamma (146 amino acids) chains which differ from -chains in 37 amino acids.

9. 4-Glycosylated Hb:
(3-7% of Hb) glucose is attached to terminal valine amino acid in -chain. This value increases in cases of uncontrolled diabetes mellitus.
5-HbS::
It is abnormal type of Hb due to congenital abnormality of -globin in which the amino acid No. 6 (glutamic acid ) is substituted by valine amino acid in the -chain  hemoglobin -S (sickle cell anemia).

10. Destruction of RBCs
- The life span of RBCs is 120 days
- Old RBCs are destroyed in narrow capillaries and spleen  Hb released and splits by the cells of the reticuloendothelial system into globin & haem.
- Globin is used in protein metabolism
- Haem losses its iron to be stored as ferritin.
- The protoporphyrin part of haem  bile pigments

13. RBCs laboratory tests (A) RBCs count: By Haemocytometer Normally
- In newly borns = millions/mm3
- In children = 4 – 5 million/mm3
- In adult male = million/mm3
- Female = million/mm3
Increase in: hypoxia & polycythaemia
Decrease in: anaemia

14. (B) RBCs volume (Haematocrit value) (packed cell volume)
It is the volume of RBCs contained in 100 ml of blood.
Normally
- In adult male = 47% (42-54%)
- In adult female = 42% (37-47%
- In children = %
- In newly borns = %

15. Plasma (55% of whole blood)
Buffy coat: leukocyctes and
platelets (<1% of whole blood)
Formed elements
Erythrocytes (45% of whole blood) 1 2
Centrifuge
Withdraw blood and place in tube
Figure 17.1

16. Importance of Haematocrit value:
Increases by:
- increased RBCs (polycythaemia)
- decreased plasma :(dehydration or hemo-concentration as after burn)
Decreases by:
- decreased RBCs (anaemia)
- increased plasma (overhydration)

17. physiologically hematocrit value is increased in:
venous blood than in arterial blood
as RBCs volume is larger in venous blood (due to chloride shift phenomenon )
large vessels due to skimming phenomenon as RBCs prefer to pass in large vessels than in small blood vessels
- newborn as he contains more RBCs due to relative ischemia during intrauterine life.

18. (C) Hemoglobin content
By Sahli-Adam’s hemometer.
Normally
- in Male = gm/100 ml blood
- in Female = gm/100 ml blood
Decreased
in anemia
Increased
in polycythymia

19. (D) Saline fragility test (Osmotic fragility test)
- If the RBCs are put in hypotonic solution, H2O pass inside RBCs  the cells swell and rupture (hemolysed).
- Normal RBCs show partial hemolysis at 0.45% NaCl and complete hemolysis at 0.35%.
More fragility occurs in:
- Infant RBCs, old RBCs, venous RBCs (have big size),  CO2 and acidity, Spherocytosis
Less fragility
occurs in sickle cell anaemia and iron deficiency anaemia.

21. (E) Erythrocytic sedimentation rate (ESR)
It is the rate of RBCs sedimentation in a vertical blood column at end of one and two hours.
RBCs sediment because:
-Their density is more than plasma.
-They tend to form rouleaux shapes, in which ratio of mass to surface area is increased causing sedimentation
Normal value At 1st hour nd hour
- Male mm mm
- Female mm mm

22. Factors affecting E.S.R
1- Plasma fibrinogen and globulin  rouleaux formation by reduction –ve charges on RBCs  less repellent forces  sedementation rate
2- RBCs count. It decreases in polycythemia and increased in anemia.
Increases in:
Physiological:
during menstruation, pregnancy & exercise.
Pathological :
Tissue destruction and inflammation due to increased fibrinogen and globulins as in:
*- Acute and chronic infections *- Severe trauma
*- Malignant tumors *- Rheumatic conditions
*- Myocardial infarction
(3) Anaemia
ESR is important as prognostic test not diagnostic test