Coagulation Cascade

Question 1

Initiation

Answer 1

Tissue injury.
Cells reveal TF which combines with VII to form a complex (TF:VIIa)
TF:VIIa complex activates factor X (X->Xa)
Xa converts prothrombin (II) to thrombin (IIa)

Question 2

Amplification

Answer 2

IIa continues to activate other platelets.
This releases factor V and activates it (Va)
IIa free’s VIII from vWF and activates it (VIIIa) at the platelet membrane.

Question 3

Propagation

Answer 3

Va and Xa converts prothrombin to thrombin (II->IIa)
Thrombin cleaves fibrinogen which forms fragments.
The fragments join to form fibrin