Florida Basic Recruit Training Program High Liability (First Aid) Practice Exam

Which blood component is responsible for clotting?

1. White blood cells

2. Red blood cells

3. Plasma

4. Platelets

The correct answer is: Platelets

Platelets are the blood components that play a critical role in the clotting process, known as hemostasis. When a blood vessel is injured, platelets quickly aggregate at the site of the injury, adhering to the exposed tissue and one another. This aggregation forms a platelet plug that temporarily seals the wound. Subsequently, platelets release substances that promote further clotting by attracting more platelets and activating the clotting cascade, which ultimately leads to the formation of a stable fibrin clot. Other components of the blood serve different functions. White blood cells are primarily involved in immune responses and protecting the body against infections. Red blood cells function to transport oxygen from the lungs to the body's tissues and carry carbon dioxide back to the lungs for exhalation. Plasma, the liquid portion of blood, contains water, electrolytes, proteins, hormones, and waste products, but it does not directly participate in the clotting process like platelets do. Thus, platelets are specifically identified as the key players in blood clotting.