Composition of blood : Blood is a fluid connective f tissue found in practically all parts of the body. It circulates in the body through vessels called arteries | and veins. The blood consists of two parts : plasma (liquid part) and corpuscles (solid parts). The blood corpuscles float in the plasma.
Plasma : Plasma is a faint yellow, slightly alkaline, somewhat viscous fluid.
Blood corpuscles : They are of three major types :
(a) Erythocytes (RBCs):
(i) These are circular disc-shaped, biconcave cells without a nucleus.
(ii) They contain a red pigment haemoglobin which has great affinity for oxygen.
(iii) They carry respiratory gases.
(iv) They are 4.5 - 5 million in healthy female while 5 - 5.5 million in a normal healthy male.
(b) Leucocytes (WBCs):
(i) They are colourless, nucleated and longer than RBC.
(ii) Their count is 6000 -1,000 per m3 of blood.
(iii) Their main function is protection against foreign particles (germs) by ingesting them, through phagocytosis.
(iv) They are of two types - agranulocytes and granulocytes.
(c) Thrombocytes (Blood platelets):
(i) These are very small, irregular bodies, without any nucleus.
(ii) Their cytoplasm contains distinct granules.
(iii) Their number is about 250,000 per cm3.
(iv) They helps in coagulation of blood