Blood coagulation is a very complicated chemical change process. At present, it is considered that the coagulation process includes at least three basic biochemical reactions: ① the formation of prothrombin activator; ② Prothrombin); Activator can transform prothrombin into active thrombin with the participation of calcium ions; ③ Soluble fibrinogen is converted into insoluble fibrin under the action of thrombin. Fibrin is like a filament, criss-crossing, intercepting a large number of blood cells and forming a jelly-like blood clot. Protein degeneration is an irreversible process.
The study of coagulation mechanism promotes the understanding of many hemorrhagic diseases, such as hemophilia (the patient's coagulation process is very slow, even minor injuries can not stop bleeding), mainly due to the lack of coagulation factor VIII in plasma. Another example is that coagulation factors Ⅱ, ⅶ, ⅸ and ⅹ are all synthesized by the liver, and their formation requires vitamin K.. Lack of vitamin K will lead to bleeding tendency; The application of vitamin K can improve coagulation symptoms. In addition, in laboratory or clinical work, different measures can be taken according to each May Day in the process of coagulation, so as to achieve the purpose of delaying coagulation or effectively stopping bleeding. For example, in order to prevent postoperative bleeding, coagulation substances such as thrombin and fibrin can be applied to the surgical site, or warm gauze, cotton or gelatin sponge can be used to press the wound to promote coagulation and hemostasis.
Both mosquito straws and leech mouths can secrete anticoagulant factors, which is convenient for blood sucking. Or the experimenter adds a little acetic acid before blood coagulation to prevent blood coagulation. So generally speaking, it can only prevent blood from clotting, but can't make the coagulated blood return to liquid state.