Fibrinolysis - wikipedia Fibrinolysis Fibrinolysis is a process that prevents blood clots from growing and becoming problematic. This process has two types : primary fibrinolysis and secondary fibrinolysis. The primary type is a normal body process, whereas secondary fibrinolysis is the breakdown of clots due to a medicine, a medical disorder, or some other cause. In fibrinolysis, a fibrin clot, the product of coagulation, is broken down. Its main enzyme plasmin cuts the fibrin mesh at various places, leading to the production of circulating fragments that are cleared by other proteases or by the kidney and liver. Contents 1 Physiology 2 Measurement 3 Role in disease 4 Pharmacology 5 Fibrinolytic enzymes 6 References 7 External links Physiology Fibrinolysis ( simplified ). Blue arrows denote stimulation, and red arrows inhibition. Plasmin is produced in an inactive form, plasminogen, in the liver. Although plasminogen can not cleave fibrin, it still has an affinity for it, and is incorporated into the clot when it is formed. Tissue plasminogen activator ( t - PA ) and urokinase are the agents that convert plasminogen to the active plasmin, thus allowing fibrinolysis to occur. t - PA is released into the blood very slowly by the damaged endothelium of the blood vessels, such that, after several days ( when the bleeding has stopped ), the clot is broken down. This occurs because plasminogen became entrapped within the clot when it formed ; as it is slowly activated, it breaks down the fibrin mesh. t - PA and urokinase are themselves inhibited by plasminogen activator inhibitor - 1 and plasminogen activator inhibitor - 2 ( PAI - 1 and PAI - 2 ). In contrast, plasmin further stimulates plasmin generation by producing more active forms of both tissue plasminogen activator ( tPA ) and urokinase. Alpha 2 - antiplasmin and alpha 2 - macroglobulin inactivate plasmin. Plasmin activity is also reduced by thrombin - activatable fibrinolysis inhibitor ( TAFI ), which modifies fibrin to make it more resistant to the tPA - mediated plasminogen. Measurement When plasmin breaks down fibrin, a number of soluble parts are produced. These are called fibrin degradation products ( FDPs ). FDPs compete with thrombin, and thus slow down clot formation by preventing the conversion of fibrinogen to fibrin. This effect can be seen in the thrombin clotting time ( TCT ) test, which is prolonged in a person that has active fibrinolysis. FDPs, and a specific FDP, the D - dimer, can be measured using antibody - antigen technology. This is more specific than the TCT, and confirms that fibrinolysis has occurred. It is therefore used to indicate deep - vein thrombosis, pulmonary embolism, DIC and efficacy of treatment in acute myocardial infarction. Alternatively, a more rapid detection of fibrinolytic activity, especially hyperfibrinolysis, is possible with thromboelastometry ( TEM ) in whole blood, even in patients on heparin. In this assay, increased fibrinolysis is assessed by comparing the TEM profile in the absence or presence of the fibrinolysis inhibitor aprotinin. Clinically, the TEM is useful for near real - time measurement of activated fibrinolysis for at - risk patients, such as those experiencing significant blood loss during surgery. Testing of overall fibrinolysis can be measured by a euglobulin lysis time ( ELT ) assay. The ELT measures fibrinolysis by clotting the euglobulin fraction ( primarily the important fibrinolytic factors fibrinogen, PAI - 1, tPA, alpha 2 - antiplasmin, and plasminogen ) from plasma and then observing the time required for clot dissolution. A shortened lysis time indicates a hyperfibrinolytic state and bleeding risk. Such results can be seen in peoples with liver disease, PAI - 1 deficiency or alpha 2 - antiplasmin deficiency. Similar results are also seen after administration of DDAVP or after severe stress. Role in disease Few congenital disorders of the fibrinolytic system have been documented. Nevertheless, excess levels of PAI and alpha 2 - antiplasmin have been implicated in the metabolic syndrome and various other disease states. However, acquired disturbance of fibrinolysis ( Hyperfibrinolysis ), is not uncommon. Many trauma patients suffer from an overwhelming activation of tissue factor and thus massive hyperfibrinolysis. Also in other disease states hyperfibrinolysis may occur. It could lead to massive bleeding if not diagnosed and treated early enough. The fibrinolytic system is closely linked to control of inflammation, and plays a role in disease states associated with inflammation. Plasmin, in addition to lysing fibrin clots, also cleaves the complement system component C3, and fibrin degradation products have some vascular permeability inducing effects. Pharmacology In a process called thrombolysis ( the breakdown of a thrombus ), fibrinolytic drugs are used. They are given following a heart attack to dissolve the thrombus blocking the coronary artery ; experimentally after a stroke to allow blood flow back to the affected part of the brain ; and in the event of a massive pulmonary embolism. Thrombolysis refers to the dissolution of the thrombus due to various agents while fibrinolysis refers specifically to the agents causing fibrin breakdown in the clot. Antifibrinolytics, such as aminocaproic acid ( ε - aminocaproic acid ) and tranexamic acid are used as inhibitors of fibrinolysis. Their application may be beneficial in patients with hyperfibrinolysis because they arrest bleeding rapidly if the other components of the haemostatic system are not severely affected. This may help to avoid the use of blood products such as fresh frozen plasma with its associated risks of infections or anaphylactic reactions. The antifibrinolytic drug aprotinin was abandoned after identification of major side effects, especially on kidney. Fibrinolytic enzymes Nattokinase Serrapeptase Papain DNase Bromelain Honokiol References ^ Jump up to : Dugdale, David et al. `` Primary or secondary fibrinolysis '', Medline Plus. Retrieved 7 August 2011. Jump up ^ Cesarman - Maus G, Hajjar KA ( May 2005 ). `` Molecular mechanisms of fibrinolysis ''. British Journal of Haematology. 129 ( 3 ) : 307 -- 21. doi : 10.1111 / j. 1365 - 2141.2005. 05444. x. PMID 15842654. Jump up ^ Cotran, Ramzi S. ; Kumar, Vinay ; Fausto, Nelson ; Nelso Fausto ; Robbins, Stanley L. ; Abbas, Abul K. ( 2005 ). Robbins and Cotran pathologic basis of disease. St. Louis, Mo : Elsevier Saunders. p. 125. ISBN 0 - 7216 - 0187 - 1. Jump up ^ Levrat et al. Evaluation of rotation thrombelastography for the diagnosis of hyperfibrinolysis in trauma patients. Br J Anaesthesia 2008 ; 100 : 792 - 7 Jump up ^ Goodnight, Jr., Scott H. ; Hathaway, William E. ( 2001 ). Disorders of Hemostasis and Thrombosis ( 2nd ed. ). New York : McGraw - Hill. ISBN 0 - 07 - 134834 - 4. Jump up ^ Tieu BH, Holcomb JB, Schreiber MA. Coagulopathy : Its pathophysiology and treatment in the injured patient. World J Surg 2007 ; 31 : 1055 - 64 External links Graphical representation of the fibrinolytic pathway ( site not available ) Proteins involved in coagulation Coagulation factors Primary hemostasis vWF platelet membrane glycoproteins : Ib ( A IX ) IIb / IIIa ( IIb IIIa ) VI Intrinsic pathway HMWK / Bradykinin Prekallikrein / Kallikrein XII `` Hageman '' XI IX VIII Extrinsic pathway III `` Tissue factor '' VII Common pathway X V II `` ( Pro ) thrombin '' I `` Fibrin '' Fibrinogen ( FGA, FGG ) XIII Coagulation inhibitors Antithrombin ( inhibits II, IX, X, XI, XII ) Protein C ( inhibits V, VIII ) / Protein S ( cofactor for protein C ) Protein Z ( inhibits X ) ZPI ( inhibits X, XI ) TFPI ( inhibits III ) Thrombolysis / fibrinolysis Plasmin tPA / urokinase PAI - 1 / 2 α2 - AP α2 - macroglobulin TAFI Antithrombotics ( thrombolytics, anticoagulants and antiplatelet drugs ) ( B01 ) Antiplatelet drugs Glycoprotein IIb / IIIa inhibitors Abciximab Eptifibatide Orbofiban Roxifiban Sibrafiban Tirofiban ADP receptor / P2Y inhibitors Thienopyridines Clopidogrel Prasugrel Ticlopidine Nucleotide / nucleoside analogs Cangrelor Elinogrel Ticagrelor Prostaglandin analogue ( PGI2 ) Beraprost Iloprost Prostacyclin Treprostinil COX inhibitors Acetylsalicylic acid / Aspirin Aloxiprin Carbasalate calcium Indobufen Triflusal Thromboxane inhibitors Thromboxane synthase inhibitors Dipyridamole ( + aspirin ) Picotamide Terbogrel Receptor antagonists Terbogrel Terutroban Phosphodiesterase inhibitors Cilostazol Dipyridamole Triflusal Other Cloricromen Ditazole Vorapaxar Anticoagulants Vitamin K antagonists ( inhibit II, VII, IX, X ) Coumarins : Acenocoumarol Coumatetralyl Dicoumarol Ethyl biscoumacetate Phenprocoumon Warfarin 1, 3 - Indandiones : Clorindione Diphenadione Phenindione Other : Tioclomarol Factor Xa inhibitors ( with some II inhibition ) Heparin group / glycosaminoglycans / ( bind antithrombin ) Low molecular weight heparin Bemiparin Certoparin Dalteparin Enoxaparin Nadroparin Parnaparin Reviparin Tinzaparin Oligosaccharides Fondaparinux Idraparinux Heparinoids Danaparoid Dermatan sulfate Sulodexide Direct Xa inhibitors ( `` xabans '' ) Apixaban Betrixaban Darexaban Edoxaban Otamixaban Rivaroxaban Direct thrombin ( IIa ) inhibitors Bivalent : Hirudin Bivalirudin Desirudin Lepirudin Univalent : Argatroban Dabigatran Efegatran Inogatran Melagatran Ximelagatran Other Antithrombin III Defibrotide Protein C Drotrecogin alfa Ramatroban REG1 Thrombolytic drugs / fibrinolytics Plasminogen activators : r - tPA Alteplase Reteplase Tenecteplase Desmoteplase UPA Saruplase Urokinase Anistreplase Monteplase Streptokinase Other serine endopeptidases : Ancrod Brinase Fibrinolysin Non-medicinal Citrate EDTA Oxalate WHO - EM Withdrawn from market Clinical trials : Phase III Never to phase III Myeloid physiology Hematopoiesis Myelopoiesis ( CFU - GEMM ) CFU - GM Granulopoiesis Myeloblast Promyelocyte Myelocyte Metamyelocyte Band cell Monocytopoiesis Monoblast Promonocyte MEP Thrombopoiesis Megakaryoblast Promegakaryocyte Erythropoiesis Proerythroblast Normoblast Reticulocyte General Extramedullary hematopoiesis Hemostasis Coagulation Fibrinolysis Clot retraction Platelet adhesiveness Other Erythrocyte aggregation Retrieved from `` https://en.wikipedia.org/w/index.php?title=Fibrinolysis&oldid=831606520 '' Categories : Fibrinolytic system Talk Contents About Wikipedia Azərbaycanca Deutsch Español Euskara Français Bahasa Indonesia Italiano Қазақша Nederlands Plattdüütsch Polski Português Русский தமிழ் 6 more Edit links This page was last edited on 21 March 2018, at 11 : 54 ( UTC ). 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Question: which protein is responsible for the breakdown of a fibrin clot
Answer: plasmin