In case of violation of the integrity of the circulatory system, the hemostasis system provides a reduction in blood loss. Hemostasis is maintained in two ways: stopping bleeding with the help of platelets and blood clotting. This section focuses on the enzymatic reactions of blood clotting. Among the many useful and necessary substances for our body, there is a vitamin that is often forgotten. In the course of various studies, a certain substance was discovered that has the property of stopping bleeding. This substance was called vitamin K (from Koagulationsvitamin — vitamin of coagulation).