Blood is the body's transport system . Blood carries oxygen and other nutrients to every tissue and cell. Heart acts as a pumps and drives the blood all around the body. When you examine blood you will see RBC,WBC, Platelets, Plasma and other components. Red blood cells (RBC) carry oxygen, white blood cells (WBC) destroy the harmful organism that enter our body. Platelets are the smallest blood cells . Platelets are for sealing punctures or cuts. Whenever there is bleeding, platelets come together and form a plug or a seal. If platelets donot function, a person can bleed to death. Unwanted clumping of platelets also create a problem.