The main function of platelet is the
formation of mechanical plugs during the normal haemostatic response to vascular
injury. In the absence of platelets spontaneous leakage of blood through small
vessels may occur. The immobilization of platelets at the sites of vascular
injury requires specific platelet-
vessel wall (adhension) and platelet –platelet (aggregation interactions) (Hoffbrand
et al, 2006).
Platelets have been documented to play a vital role in blood coagulation (Guyton and Hall, 1996). They
act as plugs around the opening of a
wound and release contain factors that are necessary for formation of a blood
clot to prevent loss. The platelets also maintain the integrity of the blood vessels by
plugging the gaps in the endothelial lining (Ochei and Kolhatkar, 2008)
Clotting takes
place in 3 essential steps:
1.
In response to rupture of the vessel or damage
to the blood itself, a complex cascade
of chemical reactions occurs in the blood involving more than a dozen blood coagulation
factors. The net result is formation of a complex of activated substances collectively
called protheombin activator.
2.
The
prothrombin activator catalyzes conversion of prothrombin into thrombin.
3.
The
thrombin acts as an enzymes to convert fibrinogen into fibrin
fibers that enmesh platelets, blood cells and plasma to form the clot (Guyton and Hall;
1996)