Blood is a fluid. It is a connective tissue.
Composition: Blood contains the following components:
(i) Plasma: It is a fluid matrix. It is colourless and contains a lot of water, many proteins and salts.
(ii) Red blood corpuscles (RBC): Blood looks red because of the red coloured pigment haemoglobin present in Red blood cells. RBCs are circular in shape and do not contain nuclei.
Fig. 6.28. Blood cells
(iii) White blood corpuscles (WBC): These are lesser in number than the red blood cells. They are white or colourless cells. They protect from infection.
(iv) Blood platelets: Blood platelets are fragments of cells and they do not possess nuclei. They help in clotting of blood.
