Fibrinogen is activated into fibrin strands which cluster together to form stable net. Prothrombin is activated into thrombin which the formation of fibrin net. Plasminogen is activated into plasminogen which degrade the fibrin net.
Fibrinogen binds to GP IIb-IIIa receptors on the platelets surface and play important role in platelet aggregation. GP IIb-IIIa inhibitors inhibit the binding of fibrinogen to platelets and thus interfere with platelet aggregation.