Question

Lysis of a fibrin clot A. is in equilibrium with formation of the clot. B. begins when plasmin binds to the clot. C. requires the hydrolysis of plasminogen into heavy and light chains. D. is regulated by the action of protein inhibitors on plasminogen. E. requires the conversion of plasminogen to plasmin by t-PA.

Short answer

Short Answer: The lysis of a fibrin clot begins when the enzyme plasmin binds to the clot. This leads to the breakdown of the clot, thereby restoring blood flow and initiating tissue repair. Therefore, Option B is the correct answer.

Step-by-step solution

Understanding Fibrin Clot Formation and Lysis

Fibrin clots are formed during the process of blood coagulation (clotting) to prevent excessive bleeding. Lysis of a fibrin clot is the breakdown of the clot, allowing the restoration of blood flow and the initiation of tissue repair.

Analyzing Option A

Option A states that the lysis of a fibrin clot is in equilibrium with the formation of the clot. In reality, these are two separate processes: clot formation occurs to prevent excessive bleeding, and clot lysis occurs to restore blood flow and initiate tissue repair. Therefore, Option A is incorrect.

Analyzing Option B

Option B states that the lysis of a fibrin clot begins when plasmin binds to the clot. Plasmin is an enzyme that breaks down fibrin clots. So, when plasmin binds to the fibrin clot, the clot starts to break down. Therefore, Option B is correct.

Analyzing Option C

Option C states that the lysis of a fibrin clot requires the hydrolysis of plasminogen into heavy and light chains. This statement seems to confuse the process of lysis with the activation of plasminogen into plasmin. Therefore, Option C is incorrect.

Analyzing Option D

Option D states that the lysis of a fibrin clot is regulated by the action of protein inhibitors on plasminogen. While protein inhibitors do play a role in regulating plasminogen, they do not directly regulate fibrin clot lysis. Therefore, Option D is incorrect.

Analyzing Option E

Option E states that the lysis of a fibrin clot requires the conversion of plasminogen to plasmin by tissue plasminogen activator (t-PA). This statement is correct, as the conversion of plasminogen to plasmin is an essential process for the lysis of fibrin clots. However, it does not fully describe when the lysis process begins, so this option is also not entirely correct.

Conclusion and Correct Answer

Based on the analysis of each option, the correct answer is Option B: the lysis of a fibrin clot begins when plasmin binds to the clot.