How does heparin function as an anticoagulant?

Heparin functions as an anticoagulant primarily by enhancing the activity of antithrombin III, a crucial protein in regulating blood coagulation. Antithrombin III is a natural inhibitor of several enzymes in the coagulation cascade, including thrombin and factor Xa. When heparin binds to antithrombin III, it induces a conformational change that significantly increases the ability of antithrombin III to inactivate these clotting factors. This action decreases the formation of fibrin, ultimately preventing the formation of new clots and the extension of existing ones.

The effectiveness of heparin in clinical settings underscores the importance of antithrombin III in maintaining hemostatic balance and preventing pathological clot formation. By enhancing the function of this natural anticoagulant, heparin plays a key role in the management of various conditions associated with thrombosis.