Basic mechanisms of hemostasis.

Hemostasis governs two essential processes of human life in that it maintains the fluidity of blood under physiological conditions and prevents excessive blood loss after injury. Hemostasis is regulated by components of the vessel wall and blood cells and by humoral coagulation factors. Under normal conditions, these components are involved in an active equilibrium through activation, propagation, and termination of the hemostatic pathways. This equilibrium is disturbed upon vascular injury, leading to a procoagulant response when needed. Unfortunately, pathological disturbances can occur as a result of inherited or acquired coagulation factor deficiencies that may lead to bleeding or thrombotic disorders.