The Mechanisim of Blood Coagulation

More than 50 important substances have been found in blood and tissue that affect blood coagulation. Some of these provide coagulation, these are called procoagulants; others inhibit coagulation, these are called anticoagulants. Whether the blood coagulates or not depends on the balance between these two groups of substances. Normally, anticoagulants predominate and blood does not clot; but when a vessel is damaged, the procoagulants in the damaged area are "activated" and overpower the antioagulants and a clot forms.

Coagulation consists of three basic steps:

1. 1. With the rupture of the vessel or in response to damage to the blood itself, a complex of chemical reactions occurs in the blood in which more than a dozen coagulation factors play a role. The net result is that all activated substances form a complex called prombin activator.
2. 2. Prothrombin activator catalyzes the conversion of prothrombin to thrombin.
3. 3. Thrombin acts as an enzyme and converts fibrinogen into fibrin filaments, then the fibrin filaments take in platelets, blood cells and plasma and form a clot.