Fibrinolysis

Scheme for fibrinolysis

Fibrinolysis is a minor, but no less important, event in hemostasis. It is necessary to remove the fibrin (hemostatic) plug. In fibrinolysis, fibrin is split by plasmin. The whole system has four components: plasminogen , plasmin , plasminogen activators, plasminogen inhibitors.  Plasmin is produced from plasminogen by proteolytic cleavage.

Activators and inhibitors

Plasminogen activators are:

  • tissue activator (t-PA);
  • activator isolated from urine (urokinase type; u-PA).

Plasminogen inhibitors are:

  • from α-granules of blood platelets – protects the primary hemostatic plug;
  • inhibitors of already formed plasmin;
    • α 2 -antiplasmin;
    • α 2 -macroglobulin.

They are produced by the cells of the vascular endothelium and the placenta.

Fibrinolysis products

Plasminogen is activated to plasmin, which then cleaves fibrin into fragments of different sizes, the so-called fibrin degradation products (FDP). The final cleavage product is D-dimers.


References

  1. TROJAN, Stanislav, et al. Medical Physiology. 4., revision and edit the release. Prague: Grada Publishing, as, 2003. 772 pp.  ISBN 80-247-0512-5 .[1]
  1. ↑ TROJAN, Stanislav, et al. Medical Physiology. 4., revision and edit the release. Prague: Grada Publishing, as, 2003. 772 pp.  ISBN 80-247-0512-5 .