There are four components of blood:

(i) Plasma is a liquid part of blood which is yellowish in colour and contain 90% water. It contains food, enzymes, wastes and proteins etc.

(ii) Red blood cells are disc shaped cells containing red coloured pigment called haemoglobin in it. Haemoglobin helps in transportation of oxygen.

(iii) White blood cells are the fighting cells which protect us against bacteria and foreign materials causing infections.

(iv) Platelets help in clotting of the blood.