Question

Compare and contrast ways which hemostasis is controlled -- be sure to discuss the coagulation cascade and/or fibrinolytic system.

Answer 1

Steps in hemoptysis:- Constriction of blood vessel followed by formation of temporary platelet plug. This is followed by activation of coagulation cascade and then formation of fibrin plug that is final clot.

Coagulation cascade:-

Intrinsic pathway :- Injury to blood vessels which activates factor XII which in turn activates factor XI and XI(activated) activates factor IX.

Extrinsic pathway :- Tissue factors activate factor VII.

Now both the pathway follow common path:- Activated factors IX, VII and VIII activates factor X in presence of Calcium ion. Activated factors X and V converts prothrombin to thrombin. Thrombin converts fibrinogen to fibrin. Fibrin along with activated factor XIII forms cross linking fibrin and thus results in clot formation.