The clotting process must eventually be slowed (and then stopped) otherwise the process would eventually cause all circulation to cease – which is not a good thing.
How does the body do this?
To prevent unwarranted and excessive clotting, blood contains several anticoagulant factors. At the site of an injury the body litterally sends as many coagulation factors into the wound site to cause clotting. Once these coagulation factors reach a critical level, the natural, anticoagulant factors become unable to stop a clot from forming. As the clotting factors travel outside of the wound area, there are many more anticoagulant factors than coagulant factors, and it is this dilution of coagulant factors, that stop blood clots from continuing forever until circulation ceases altogether.
These are some common anticoagulation factors:
1. Antithrombin (which is produced in the liver and stimulates the activation of thrombin).
2. Haparin (which is found both in the basophils and endothelial cells.
3. Prostacyclin – which acts to counteract the effects of thrombin by causing vasodilation.