Explanation

Process of formation of blood clot is also known as blood coagulation. This process can be described under four major stages. Damaged platelets or tissue cells release thromboplastin. Prothrombin $\overset{Ca^{2 +} \downarrow}{\rightarrow}$ Thrombin Fibrinogen $\overset{Ca^{2 +}}{\rightarrow}\$Fibrin Fibrin + cells $\rightarrow$ Clot Thrombocytes help in blood coagulation.