Ministry of Higher Education, Kingdom of Saudi Arabia
Majmaah University
College of Applied Medical Sciences
MDL 241- Haematology
Blood - Introduction
Prepared by
Dr. R.K. Choudhary PhD
1436-37
Haematology
It is the branch of Medical Science concerned
with the nature, function and disease of blood.
It covers the cellular and Plasma composition of
blood, the coagulation process, blood cell
formation, haemoglobin synthesis and
disorder of these all.
Blood
Definition:
Blood described as a specialized connective
tissue in which there is liquid substance
known as plasma and cellular elements are
the red blood cells, the white blood cells and
the platelets.
The specific gravity of whole blood varies from
1.055 to 1.060. When freshly shed, blood is a
red, thick, opaque and slightly alkaline.
Composition
Function:
1. Transport of respiratory gases. It carries oxygen from the lungs to
the tissues and CO2 from the tissues to the lungs.
2. Transport of nutrition. It carries digested food material absorbed
from the intestine to the tissue cells for utilization. It also carries
nutritive material from one place of the body to the other. For
instance, from the storage depots to the tissue cells.
3. It acts as a vehicle through which the hormones, the vitamins and
other essential chemicals are brought to their places of activity.
4. Drainage of waste products. It carries the waste products of
cellular activity and brings them to the organ of excretion, e.g.
kidney, lungs, intestine etc.
5. Maintenance of water balance.
6. Maintenance of acid-base equilibrium.
7. Maintenance of ion balance between the cells and the
surrounding fluid.
8. Regulation of body temperature
9. Defensive action. Blood acts as a great defensive mechanism in
two ways. (a) The white cells due to their phagocytic properties
engulf bacteria and foreign particles. (b) It develops antibodies
which combat toxic agents.
10. By the property of coagulation it guards against haemorrhage.
11. The plasma proteins of blood have various functions.
12. Regulation of blood pressure, by changes in volume and
viscosity (haematocrit value) of blood.
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