Which of the following best describes the process of blood coagulation (clotting)? A) Blood coagulation involves the activation of a series of clotting factors that ultimately convert fibrinogen to fibrin, forming a mesh that stabilizes the blood clot. B) Blood coagulation is initiated by the aggregation of platelets that form a plug to stop bleeding. C) Blood coagulation involves the breakdown of red blood cells and the release of hemoglobin, which then forms a clot. D) Blood coagulation is the process by which white blood cells are activated to fight infection.
The correct answer and explanation is:
The correct answer is A) Blood coagulation involves the activation of a series of clotting factors that ultimately convert fibrinogen to fibrin, forming a mesh that stabilizes the blood clot.
Explanation:
Blood coagulation is a complex, multi-step process that plays a vital role in stopping bleeding when blood vessels are injured. The process is also known as hemostasis and involves a sequence of events that culminates in the formation of a stable blood clot.
- Vascular constriction: When a blood vessel is injured, it constricts to minimize blood flow at the site of injury. This initial response is followed by the activation of platelets, which adhere to the damaged vessel wall and form a temporary “platelet plug.”
- Activation of clotting factors: Simultaneously, a series of proteins known as clotting factors (numbered I to XIII) are activated in a cascade-like manner. These clotting factors work together to convert fibrinogen, a soluble plasma protein, into fibrin, which is insoluble.
- Fibrin mesh formation: The fibrin strands form a mesh that traps blood cells and platelets, creating a more stable and durable clot. This fibrin mesh seals the wound and prevents further blood loss.
- Clot retraction and wound healing: Over time, the clot contracts to reduce the wound size, while tissue repair mechanisms begin to restore the integrity of the blood vessel.
Other answer choices are incorrect because:
- B refers to the role of platelets in hemostasis but doesn’t fully describe the complex coagulation cascade.
- C incorrectly suggests that red blood cells and hemoglobin play a direct role in clot formation.
- D focuses on the role of white blood cells in immune responses, which is unrelated to the coagulation process.
The activation of clotting factors and fibrin mesh formation are essential to stabilize the clot and prevent excessive bleeding.