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The balance of bleeding of clotting is commonly called coagulation or hemostasis. Hemostasis is a complex process, which keeps blood fluid and running through vessels (arteries and veins) under normal circumstances, but stops blood flow and forms thrombi or blood clots when injury occurs. Disturbance of this delicate system leads either to abnormal bleeding (bleeding disorders), or to abnormal formation of thrombi and blood clots in the arterial or venous system ( thrombotic disorders).
The most important components of this system are blood platelets, clotting factors, von Willebrand factor, fibrin, the vessel wall and the organs which produce those factors. For example, platelets are produced in the bone marrow, and clotting factors in the liver. Therefore, bleeding and thrombotic disorders cannot only be inherited, they can also be acquired during periods of other illnesses. Therefore, liver failure or diseases involving the bone marrow can lead to abnormal coagulation.
After vessel injury (for example, a cut), our body wants to prevent blood loss by constricting the injured vessels and by forming a platelet plug with a fibrin meshwork around the wound. Von Willebrand factor acts as a glue to hold the components together. This process is called thrombus, or clot formation, and is a part of normal blood clotting or coagulation. As long as the wound is healing, this process is maintained. New platelets, fibrin and von Willebrand factor are deposited at the site of injury every day. Once wound healing is completed, the body signals to stop thrombus formation, and remnants of the clot are dissolved, the crust falls off.
You now can imagine how delicate and intricate this process is, and how catastrophic it can be if it happens at the wrong time (without obvious injury to your vessel) or the wrong place (like in a vessel of your brain), or not at all when required to stop bleeding from a wound.
Bleeding disorders can include:
Thrombotic disorders can include:
Conditions that can predispose to thrombosis:
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