Blood clotting, or coagulation, prevents excessive bleeding when a blood vessel is injured. Platelets stick to the wound and release clotting factors that convert fibrinogen (a plasma protein) into fibrin threads, forming a mesh that traps RBCs to seal the wound. This process is aided by calcium ions and vitamin K.

Steps to Remember

Step 1: Platelet plug formation.

Step 2: Clotting factors activate.

Step 3: Fibrin mesh seals the wound.