Question

Which enzyme is responsible for blood clotting?

Answer 1

Blood clotting, or coagulation, is an important process in the body of organisms which helps in blocking excessive bleeding when a vessel is injured. Platelets (a sort of blood cell) and proteins in your plasma (the liquid a part of blood) work together to prevent the bleeding by forming a clot over the injury. Typically, your body will naturally dissolve the grume after the injury has healed. Sometimes, however, clots form on the inside of vessels without a transparent injury or don't dissolve naturally. These situations are often dangerous and need accurate diagnosis and appropriate treatment.

Complete answer:
As soon as a vessel wall is broken, a series of reactions activates platelets in order that they stick with the injured area. The "glue" that holds platelets to the vessel wall is the Willebrand factor, an outsized protein produced by the cells of the vessel wall. At the site of injury the protein's collagen and thrombin acts, which induces platelets to stay together. At the location of injury, platelets accumulate and form a mesh like structure which seals the injury, and the shape of platelets change from round to spiny, and they release proteins and other substances that entrap more platelets and clotting proteins within the enlarging plug that becomes a grume .

Formation of a clot also involves activation of a sequence of blood coagulation factors, which are proteins produced mainly by the liver. There are over a dozen blood coagulation factors. They interact during a complicated series of chemical reactions that ultimately generate thrombin. Thrombin converts fibrinogen, a blood clotting factor that's normally dissolved in blood, into long strands of fibrin that radiate from the clumped platelets and form a net that entraps more platelets and blood cells. The fibrin strands add bulk to the developing clot and help hold it in situ to keep the vessel wall plugged.

So the enzyme thrombin is responsible for blood clotting.

Note:
The reactions that end within the formation of a grume are balanced by other reactions that stop the clotting process and dissolve clots after the vessel has healed. Without this technique, minor vessel injuries could trigger widespread clotting throughout the body—which actually happens in some diseases.