The endogenous system (intrinsic system)
- Blood gets in touch with anionic (negatively charged) surfaces (collagen). Factor XII is activated.
- Through the activation of factor XII the activation of the related factors XI is induced, and thereby the activation of the factors IX and VIII, which build a complex, is induced.
- The complex of IX and VIII activates for itself the building of a complex of the factors V and X.
- Advantaged by the factors V and X prothrombin turns into thrombin (factor II). Thereby a separation of the fibrinogen, factor I of the clotting cascade, is induced. Fibrinomers are formed, which finally turn to fibrinpolymers (under induction of the activated factor XIII) and build a firm mesh network, to which blood cells can conjoin for building a red separation thrombus.
- The edges of the injury now retracts.The yellowish serum is over the red cruor and can be flushed away by the bloodstream. Through the retraction and supported by the PDGF (platelet-derived growth factor) the permeation of tissue cells which conduce to the wound healing is stimulated and the solidness of the plug is enforced. The decomposition of the fibrin thrombus is effected by the fibrinolysis.