Platelets are the smallest blood particles. When a
capillary is cut, the platelets collect at the site of the injury. There they
break into smaller fragments and initiate the complicated chemical process of
blood clotting in which more than 15 factors, including thromboplastin, calcium
(Ca27), and fibrinogen, are involved in the formation of a clot containing
wblood cells in a fibrin meshwork.
