BLOOD CLOTTING

There is a complicated process for sealing off holes or ends of blood vessels after a cut or rupture. 

By this process, called coagulation or clotting, the blood forms a solid mass to seal the opening where the blood is escaping.

The mass is called a blood clot. 

After many intermediate steps, the protein fibrinogen of the blood is converted into sticky strands of fibrin. 

These sticky strands adhere to the wall of the opening and form a meshwork in the opening, which traps RBCs and plasma. Thus, the opening is sealed.