What is the function of thrombocytes?

Thrombocytes, or platelets, are the smallest cellular component of blood. They circulate inactivated, about 250,000 per cubic mm of blood, until they come into contact with a damaged blood vessel.
At this point, the platelets form a clump, adhering to each other and to the blood vessel wall.
They secrete chemicals that alter a blood-borne protein, fibrinogen, so that it forms a mesh of fibers at the damage site. A clot forms when platelets and red and white blood cells become trapped in the fibers.
Blood clotting begins within seconds of injury.