Which of the following is not a phase of hemostasis? A platelet plug formation. B vascular spasm. C fibrinolysis. D coagulation. A include thrombus formation, a clot in a broken blood vessel.
The correct answer and explanation is:
The correct answer is C) fibrinolysis.
Hemostasis is the process that prevents and stops bleeding, or hemorrhage. It involves a series of steps to form a clot at the site of a vascular injury. The main phases of hemostasis include:
- Vascular spasm (B): This is the first response to blood vessel injury. When blood vessels are damaged, their walls constrict to minimize blood loss. This spasm is a temporary measure that reduces blood flow and limits the size of the wound.
- Platelet plug formation (A): Following vascular spasm, platelets are activated and adhere to the exposed collagen in the damaged vessel wall. These platelets then release substances that attract even more platelets to the area, forming a plug that temporarily seals the wound.
- Coagulation (D): In this phase, a series of complex chemical reactions occur involving clotting factors, which lead to the conversion of fibrinogen into fibrin. Fibrin threads form a mesh over the platelet plug, stabilizing and solidifying the clot.
Fibrinolysis (C), on the other hand, is the process that occurs after the clot has formed and the vessel is healed. It involves the breakdown of the fibrin clot to remove it once it is no longer needed. This is not a phase of hemostasis but rather a separate process to ensure the clot does not persist longer than necessary.
In summary, while the first three options are directly involved in stopping bleeding, fibrinolysis occurs later to resolve the clot. Therefore, it is not a phase of hemostasis, but part of the clot removal process.