Question

What is the function of $Ca^{2+}$ ions in blood clotting?

Answer 1

Blood coagulation, or coagulation, is a crucial process that forestalls excessive bleeding when a vessel is injured. Platelets (a type of blood cell) and proteins in your plasma (the liquid part of blood) work together to prevent the bleeding by forming a clot over the injury.

Complete answer:
In the presence of calcium ions and other clotting factors, prothrombinase activates an enzyme called prothrombin activator. This enzyme then converts the protein prothrombin into thrombin. Thrombin is an enzyme that, in turn, converts fibrinogen to fibrin which causes the blood to clot.
Thrombin converts fibrinogen, a blood coagulation 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.

1. Constriction of the vessel.
2. Formation of a short lived “platelet plug”.
3. Activation of the coagulation cascade.
4. Formation of “fibrin plug” or the ultimate clot.
   Coagulation factors are proteins within the blood that help control bleeding. you've got several different coagulation factors in your blood. Once you get a cut or other injury that causes bleeding, your coagulation factors work together to make a grume. The clot stops you from losing an excessive amount of blood.

Note:
Clotting times measure the time required to make a clot. In most tests, an activator is employed to initiate coagulation and test the response of some or portions of the cascade model of coagulation.