Introduction to Biochemistry - Quiz 2.3.4.2

This whole quiz is about blood coagulation, this diagram on Wikipedia helped me a lot.

Here are the problems:

This question confused me a bit, thrombin is not cleaved? It is used in both the activation and the regulation of the coagulation cascade. It looks like the question is asking which protein "activates" thrombin (or the cleaving of prothrombin), that should be factor X, and that's the correct answer.

This is easy by looking at the diagram:

Factor XII is intrinsic
Factor VII is extrinsic
Tissue Factor is extrinsic

I was confused the factor VII with von Willebrand factor, they are not the same thing, so it does not require physical force to stretch it. It also got activated when exposed to tissue factor, not air.

Therefore the correct answer is:

The endothelium forms a barrier between tissue factor and blood so that it cannot bind to its ligand, factor VII.

The platelets found in the core of a blood clot contains the protein fibrin and are thrombin-dependent while those in the shell have little or none of this protein.

I generally hate memorizing, but I remembered this one.

Initiation - at initiation vWF binds collagen and unfold by the force to start attracting platelets.

TFPI inhibits tissue factor activity. The remaining plays a role in the stopping on the coagulation cascade but does not inhibit tissue factor itself.

Factor X is supposed to interacts with thrombin, but there is to fibrin forms, so it is most likely that thrombin lost its capability to cleave fibrinogen to form fibrin.

If fibrin cannot be formed, blood clot cannot be formed, so it is causing hemophilla.