What is the mechanism of hemostasis

Hemostasis and coagulation: the blood as a repair system

Blood clotting: seals the injury

The platelet plug cannot permanently close the injured blood vessel. This is where blood coagulation (secondary hemostasis) comes into play: The blood coagulation causes long fibers of fibrin to form in the liquid part of the blood. This protein surrounds the platelets and red blood cells in a mesh within five to seven minutes - a blood clot forms.

To prevent blood clots from forming in the flowing blood, fibrin is usually present as a soluble precursor, as fibrinogen. Humans have a complicated system of enzymes or coagulation factors whose inactive precursors are first converted into the active form, the so-called coagulation cascade. At the end of this cascade is the active enzyme thrombin, which arises from an inactive precursor (prothrombin) and converts fibrinogen into active fibrin.

A distinction is made between two ways of activating blood coagulation, which are set in motion in the event of major external tissue injuries or damage or changes to the vascular lining.

Fibrinolysis: antagonist of blood clotting

Once a wound has healed, the blood clot in the fibrin fibers is dissolved (plasminogen). This process can be activated in two different ways: by tissue and by blood activators. Such activators can be produced by genetic engineering and are used in medicine, for example, for the treatment of myocardial infarction and thrombosis.