Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

Which component of blood is crucial to clotting?

1. Red blood cells

2. White blood cells

3. Plasma

4. Platelets

The correct answer is: Platelets

Platelets are a crucial component of blood when it comes to the clotting process. They are small, disc-shaped cell fragments that originate from megakaryocytes in the bone marrow. When an injury occurs, platelets quickly gather at the site, adhering to the exposed endothelium of the injured blood vessel. They release chemical signals that attract more platelets to the area and promote the formation of a "platelet plug." This action is an essential first step in the complex cascade of events that leads to blood coagulation. The clotting process is carried out through a series of steps involving the activation of various clotting factors in the plasma, ultimately leading to the conversion of fibrinogen into fibrin, which stabilizes the platelet plug and forms a more durable clot. While red blood cells transport oxygen and white blood cells play key roles in immune response, it is the platelets that are primarily responsible for initiating and regulating the clotting process in response to vascular injury.