The first is the physiological coagulation cascade, which is used to describe a very complex step-by-step process that occurs in the body (in vivo) when a blood vessel is injured. Several special proteins known as coagulation factors are activated one after the other in a "cascade" effect. The end result is a blood clot that creates a barrier over the injury site, protecting it until it heals. This process also involves a feedback system that regulates clot formation in the body so that clots are removed when the injury site is healed.