Physiologic coagulation and plasma protein system

The physiologic coagulation and plasma protein system is a complex, highly regulated network of zymogens, enzymes, and cofactors that maintain vascular integrity by preventing blood loss while ensuring blood remains fluid (StatPearls, NBK470250). It involves the sequential activation of clotting factors through the intrinsic and extrinsic pathways, which converge on the common pathway to generate thrombin, the enzyme responsible for converting soluble fibrinogen into a stable fibrin clot (Merck Manual, Hemostasis Overview). This system is balanced by natural anticoagulants, such as antithrombin and the protein C/S pathway, and the fibrinolytic system, which degrades clots once tissue repair is underway. Dysregulation of these pathways leads to significant clinical conditions, including hemophilia (deficiency of factors VIII or IX) and venous thromboembolism (excessive clotting). Pharmacological management of this system is a cornerstone of cardiovascular medicine, utilizing anticoagulants to prevent thrombosis and thrombolytics to restore blood flow in acute ischemic events (NIH, Blood Coagulation). The system also interacts closely with the inflammatory and complement systems, reflecting its broad role in host defense and tissue homeostasis.

Other names

Coagulation cascadeHemostatic systemBlood clotting systemPlasma protein system

Drugs targeting this system act by inhibiting specific coagulation factors such as Factor Xa or Thrombin (e.g., direct oral anticoagulants), antagonizing Vitamin K-dependent synthesis of factors II, VII, IX, and X (e.g., warfarin), or promoting the dissolution of fibrin clots through the activation of plasminogen to plasmin (e.g., thrombolytics) (StatPearls, NBK470250; Merck Manual, Hemostasis Overview).