CHAPTER 2: PHYSIOLOGY OF THE BLOOD
CONTENTS
1. Functions of the blood
2. Features of the blood
3. Blood composition
4. Blood clotting
5. Blood types
6. Immunity
1. Functions of the blood
-
Transportation: O2 and CO2,
nutrients, wastes, hormones.
-
Regulation: temperature,
homeostasis, organ activities.
-
Protection: viruses, bacteria,
tocxin.
2. Features of the blood
Student’s task 1
(1) Briefly show the main features of the blood
(2) When is the stored blood used? Explain why losing
blood slowly is not as easy to die as losing blood fast.
(3) Why is the blood osmolality needed to be
constant? When losing blood, should we supply
water? Why? What is the concentration of NaCl in a
physiological solution?
(4) Why is the blood pH needed to be constant? How
to maintan the blood pH?
- Blood viscocity (viscidity): 4-5 times higher than water
- Blood density: 1.05 – 1.06
* In man: Total 4 – 5L, accounting
for 7 – 9% body weight.
* ½ total blood circulating in
vessels, ½ storing in liver, spleen
and skin.
* Blood buffers:
- Bicarbonate buffer:
H2CO3/BHCO3 (B: Na or K)
- Phosphate buffer:
BH2PO4/B2HPO4 (B: Na or K)
- Protein buffer:
HHb/BHb (Hb: Hemoglobin, B:
Na or K)
- Organs regulate the blood pH:
Lungs, Kidneys, Liver.
3. Blood composition
Plasma
Formed
elements
Questions
(1) What is the change in numbers of red blood cells
when a man living in a low altitude place moves to a
high altitude place? Explain the mechanism of this
change.
(2) How do the partial pressure of CO2 and O2, pH
value and body temperature affect the concentration
of HbO2 in the blood? Explain the roles of those
effects?
(3) What happens in the blood of a baby in the first 2
weeks after being born? How to treat this problem?
3.1. Plasma (55%)
3.2. Cellular elements (45% - Hematocrit)
3.2.1. Erythrocytes – Red blood cells
- Living period: 90 – 120 days
- Death: In liver and spleen (globin and iron
reabsorbed, Hb changed into bile pigments).
Hemoglobin (Hb)
- Hb includes: 1 molecule
of globin (2 polypeptide α
+ 2 polypeptide β) + 4
hem (4 pyrol rings + 1
Fe2+).
Functions of red blood
cells:
- Taking part to blood
buffer (protein bufferHHb/BHb).
- Transporting oxygen
and carbondioxide
Hb + O2
Lungs
Tissues
HbO 2
Tissues
Hb + CO2
Lungs
HbCO 2
The production of red blood cells is related to oxygen
- The dissociation of oxyhemoglobin depends on CO2,
pH and temperature.
- Bohr effect: CO2 increased, pH decreased, temerature increased 
the curve shifts to right and in a reverse way In tissue, high CO2 
increase O2 released; In lungs, low CO2  increase O2 uptaken.
3.2.2. Leukocytes – White blood cells
3.2.3. Thrombocytes – Platelets
3.2.4. Differentiation of blood cells
Summary
4. Blood clotting
When bleeding, the body has some changes to reduce
blood to flow out of vessels: vessels contraction +
endothelial cells sticking together  a smaller broken
hole + platelet cells sticking together to form a plug at
the broken hole.
Blood clotting (forming a clot) includes 3 steps:
- Step 1: Formation and release of thromboplastin
(from damaged tissues and platelets)
- Step 2: Formation of thrombin from prothrombin
(from plasma)
- Step 3: Formation of fibrin from fibrinogen
(from plasma)
Vessel broken
and bleeding
Fibrin clot
5. ABO blood type
Student’s task 2
(1) Briefly show the principle of the ABO blood types
formation and the diagram of blood transfusion.
(2) Type O has antibodies α and β, type AB has
antigens A and B. Why can the type O blood be
transfused to a person with type AB blood?
No agglutination and agglutination
Blood type
Antigen
Antibody
A
A
β
B
B
α
AB
A and B
None
O
None
β and α
- Vietnamese people: A (19,8%), B (28,6%), AB (4,2%)
and O (47,3%).
- Diagram of blood transfusion:
α,β
6. Rh blood type
- Vietnamese people: Rh+ group accounting for more
than 99.9%; Rh- group accounting for less than 0.1%.
Diagram of blood transfusion related to Rh blood type
A mother with Rh- and her child with Rh+
7. Immunity

Inflammatory response:

Fever: Increase body temperature  inhibiting
viruses and bacteria growth and reproduction.

Protective proteins:
- Interferon: inhibiting viruses production.
- Complement system: forming holes in bacreria.
REVIEWS
1. Functions of the blood
2. Features of the blood
3. Blood composition
4. Blood clotting
5. Blood types
6. Immunity