Platelets are small disc shaped cells that are formed in the bone marrow.
Seventy to eighty percent of platelets circulate in the bloodstream while the remainders are stored in the spleen. The average platelet lives about 10 days. Platelets play a crucial role in helping blood to clot. A defect in any one of these functions will result in an increased tendency to bleed. Platelets attach to the lining of the injured blood vessel and begin the first phase of the clotting process.