American Board of Dental Examiners (ADEX) Dental Hygiene Licensing Examination 2025 - Free Dental Hygiene Practice Questions and Study Guide

Heparin is an anticoagulant that primarily functions to inactivate thrombin, which is a key enzyme in the blood coagulation process. By inhibiting thrombin, heparin prevents the conversion of fibrinogen to fibrin, a crucial step in the formation of blood clots. This action leads to a decreased ability for blood to clot, which is important in preventing and treating thromboembolic disorders.

The other options do not accurately describe the primary role of heparin. For instance, activating thrombin would promote clot formation, which is contrary to heparin's purpose as an anticoagulant. Increasing clotting factor production does not relate to the immediate action of heparin, as heparin does not stimulate the synthesis of coagulation factors. Preventing blood vessel dilation focuses on vascular response rather than the mechanism of action of heparin, which specifically targets coagulation pathways. Thus, the primary action of heparin is indeed the inactivation of thrombin, making it a critical agent in the management of conditions requiring blood thinning.