AEMCA Practice Exam

What is the role of collagen fibers in hemostasis?

1. Trigger vascular spasms

2. Facilitate platelet plug formation

3. Activate clotting factors

4. Produce antibodies

The correct answer is: Facilitate platelet plug formation

Collagen fibers play a crucial role in facilitating platelet plug formation during hemostasis. When there is a vascular injury, the underlying collagen becomes exposed to the blood flowing through the damaged vessel. Platelets, which are cell fragments that help the blood clot, have receptors that specifically recognize and bind to collagen. This interaction activates the platelets, causing them to change shape, release chemical signals, and become sticky. As platelets aggregate at the site of injury, they form a temporary plug that serves to seal small breaks in the blood vessel wall, thus preventing further bleeding. This platelet plug formation is an essential preliminary step before the more complex processes of clotting, which involves activation of clotting factors and the development of a stable fibrin clot. The other options involve processes related to hemostasis but do not accurately represent the primary function of collagen fibers in this context. Vascular spasms (the contraction of blood vessels) and clotting factor activation are also critical for hemostasis but occur alongside the action of collagen and its role in platelet activation. Producing antibodies is unrelated to the hemostatic process, as antibodies are part of the immune response, not the hemostatic response.