The Complement and Coagulation pathways are central to host defense. The Complement pathway, which is part of innate immune system, eradicates invasive pathogens. It can be activated by three different pathways depending on the initiating stimulus: the classical pathway, the lectin pathway, and the alternative pathway.
The Coagulation pathway is essential for clot formation and the prevention of excessive bleeding. The coagulation cascade is initiated by two different routes, the intrinsic or contact factor pathway and the extrinsic or tissue factor pathway. There are many additional factors involved in the regulation of the coagulation cascade.
In addition, the Kallikrein Kinin System is involved in inflammation, blood pressure control, coagulation and pain. The Kallikrein Kinin System is dependent on the generation of Bradykinin, a potent vasodilator and Plasmin, which degrades blood clots during fibrinolysis.