Fibrinolysis Flashcards
- Final stage of hemostatic activation
- Fibrin degradation; restoring normal blood flow during vascular repair
Fibrinolysis
Systematic, accelerating hydrolysis of fibrin by
Plasmin
Inactived form of plasmin present in circulating blood
Plasminogen
If plasmin breaks the fibrin polymer (the unstable one), the product is called
FDP or Fibrin Degradation Products (fragments X, Y, D, and E)
If plasmin breaks the crosslinked fibrin (the stable one), the product is called
Fragment D-D or D-dimer
2 activators of Fibrinolysis
Tissue Plasminogen Activator (TPA) and Urokinase Plasminogen Activator (UPA)
Tissue Plasminogen Activator (TPA) is secreted by
Endothelial cells
Urokinase Plasminogen Activator (UPA) is secreted by
Urinary tract epithelial cells, monocytes and macrophages
The central E domain with the two D domains (D-E-D), minus some peptides cleaved by plasmin
Fragment X
The E domain after cleavage of one D domain (D-E)
D-E fragments are further digested to individual D and E domains
Fragment Y
Produced by digestion of either fibrin or fibrinogen by plasmin
Fragment X, Y, D, E
Composed of two D domains from separate fibrin molecules (not fibrinogen) cross-linked by the action of factor XIIIa
Fragment D-D (D-Dimer)
Specific product of digestion of cross-linked fibrin only
Fragment D-D (D-Dimer)
Marker of thrombosis and fibrinolysis
Fragment D-D (D-Dimer)
Inhibitors of Fibrinolysis
- Plasminogen Activator Inhibitor-1 (PAI-1)
- Α2-antiplasmin
- Thrombin Activatable Fibrinolysis Inhibitor (TAFI)
Principal inhibitor of plasminogen activation, inactivating both TPA and UPA, thus preventing them from converting plasminogen to the active fibrinolytic enzyme plasmin
Plasminogen Activator Inhibitor-1 (PAI-1)
Synthesized in the liver and is the primary inhibitor of free plasmin (small amounts of plasmin is found in the blood)
Α2-antiplasmin
- Synthesized in the liver
- Activated by the thrombin-thrombomodulin complex
- Activated TAFI: Functions as an anti-fibrinolytic enzyme (this enzyme cannot dissolved blood clot)
Thrombin Activatable Fibrinolysis Inhibitor (TAFI)
