VII7 - thrombin stimulates: fibrinogen -> fibrin...

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VII. Coagulation (blood clotting) A. General Events in Clotting platelet cells activated by damage-> PF3 and/or Tissue Factor produced by platelet cells-> Factor X activated-> prothrombin activator (enzyme) produced-> prothrombin conversion -> thrombin (another enzyme) thrombin stimulates: fibrinogen----> fibrin mesh 1. anticoagulant - chemical that inhibits clotting 2. procoagulant - chemical that promotes clotting 3. intrinsic pathway - within the damaged vessel a. more procoagulants needed (I-XIII) toward PF3 and Factor X b. allows more "scrutiny" before clotting occurs 4. extrinsic pathway - in outer tissues around vessel a. tissue thromboplastin (Tissue Factor) - skips intrinsic steps straight to PF3 and Fac X b. allows rapid response to bleeding out of vessel (clot can form in 10 to 15 seconds) 5. After activation of Factor X, common pathway: Factor X, PF3 (thromboplastin), Factor V, Ca ++ --> prothrombin activator -> prothrombin converted -> thrombin (active enzyme)
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Unformatted text preview: thrombin stimulates: fibrinogen -> fibrin (meshwork) Ca ++ & thrombin -> Factor XIII (fibrin stabilizer) B. Clot Retraction (shrinking of clot) 1. actomyosin - causes contraction of platelets 2. blood serum - plasma WITHOUT clotting Factors 3. platelet-derived growth factor (PDGF) - stimulates fibroblast migration and endothelial growth C. Clot Eradication (Fibrinolysis) 1. healing occurs over 2 - 10 days 2. tissue plasminogen activator (TPA) - causes the activation of plasminogen 3. plasminogen--> plasmin 4. plasmin degrades proteins within the clot D. Factors Limiting Growth and Formation of Clots 1. Limiting Normal Clot Growth a. blood moves too fast to allow procoagulants b. factors interfere with normal clotting i. prothrombin III - deactivates thrombin ii. protein C - inhibits clotting Factors iii. heparin - inhibits thrombin; prevents adherence of platelets to injured site...
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VII7 - thrombin stimulates: fibrinogen -> fibrin...

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