What is the role of blood coagulation and anticoagulation systems in the human body?

The blood tends to coagulate due to its special shaped structures. They are called platelets. These are very important structures, as they allow the body to survive some injuries. When a person or any animal is injured with skin damage, blood loss begins. The platelets form blood clots at the wound site and blood loss stops. Without this property, even a small cut would have a great chance of dying from blood loss. But blood does not coagulate in the vessels, since platelets cannot activate on their own without the need and without the presence of air.