Paramedic National Registry Practice 2025 - Free Paramedic Practice Questions and Exam Preparation Guide

The third stage of the clotting process is called coagulation. In this stage, a series of complex biological events occur in which blood changes from a liquid to a gel, forming a stable clot. Coagulation is primarily initiated by the activation of clotting factors, which work in cascade to convert fibrinogen, a soluble plasma protein, into fibrin strands that weave through the platelet plug formed in earlier stages and solidifies the clot.

This stage is critical as it establishes a definitive barrier to prevent further blood loss and begins the healing process of the damaged blood vessel. The understanding of coagulation emphasizes the importance of the interaction between various components of the blood, including plasma proteins and platelets.

The other options, while related to the overall clotting process, refer to different aspects. Hemostasis is the overall process that includes all stages of clotting, vasoconstriction is the initial response where blood vessels narrow to reduce blood flow, and platelet aggregation refers to the clumping of platelets at the injury site but occurs before the coagulation stage.