Question 4#

Arterial thrombosis after plaque rupture is initiated by:

a. Tissue plasminogen activator
b. Factor XIII
c. Protein C
d. Activated protein C
e. Tissue factor

Correct Answer is E


Tissue factor. Tissue factor binding to factor VII is the initiating event for the extrinsic blood coagulation cascade. The complex can also cleave factor IX and contribute to activation of the intrinsic cascade as well. Tissue factor is normally not expressed in the vasculature, but, in atherosclerotic vessels, tissue factor is expressed by macrophages and smooth muscle cells. Tissue factor expression is increased in the lesions of patients who present with unstable angina. On plaque rupture, the exposure of tissue factor to bloodborne coagulation factors leads to thrombus formation.