Composition of blood

define

red blood cells

carry oxygen to all living tissue, containing haemoglobin giving blood its red colour, which when combined with oxygen forms oxyhaemoglobin. They are round flattened discs with and intended shape giving them a large surface area and allowing them to flow easily within plasma.

Plasma

Liquid component of blood, carries nutrients for the body

white blood cells

fighstbagsints infections, they destroy and remove bacteria and viruses from the body pathogens. 

Platelets 

disc-shaped cell fragments produced in bone marrow, their function is clotting to prevent blood loss by sticking to the damaged area to form a temporary plug.