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27 Cards in this Set
- Front
- Back
Which factors are unique to the extrinsic pathway?
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VII and Tissue Factor
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What is main function of the extrinsic pathway?
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Creates the immediate clot in response to vascular injury (and subsequent release of Tissue Factor)
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What inhibitor inhibits the TF/VIIa/Xa complex?
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Tissue Factor Pathway Inhibitor (TFPI)
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What is main function of the intrinsic pathway?
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Allows for clot remodeling after extrinsic pathway has been blocked by TFPI (which blocks the TF/VIIa/X complex)
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What are the 3 components of the Ten-ase complex?
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1. VIIIa
2. Phospholipds (on platets) 3. Ca++ |
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What does the Ten-ase complex do?
What pathway is it a part of? |
Cleaves X ---> Xa
Part of intrinsic pathway |
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What is the prothrombinase complex composed of?
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1. Xa
2. Va 3. Phospholipids 4. Ca++ |
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What is the function of the prothrombinase complex?
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Cleave prothrombin ---> thrombin
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Draw out clotting cascade
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(see notes)
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What are 5 functions of Thrombin?
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1. Cleave Fibronigen ---> Fibrin
2. Stimulate production of TF & Protein C 3. Create VIIIa 4. Create Va 5. Stimulate XI --> XIa |
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What are the 6 serine protease clotting factors?
Why important? |
1. XIIa
2. XIa 3. IXa 4. Xa 5. VIIa 6. Thrombin Important because prime targets for regulators and anticoagulant drugs |
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What is the only factor, that if missing, doesn't results in bleeding problem?
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XII - because XI can be activated by Thrombin, as well as XII
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What does defect in IX cause?
What does defect in VIII cause? |
IX = Hemophilia B
VIII = Hemophilia A |
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What factors does a Prothrombin Time (PT) test?
What pathway does it test? |
VII, V, X, Thrombin (II), Fibrinogen
Tests extrinsic pathway |
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What factors does the activated Partial Thromboplastin Time (aPTT) test?
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XII, HMWK, PK, XI, IX, VIII, X, V, Thrombin (II), Fibrinogen
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What are the 2 main categories of items that can cause a prolonged aPTT?
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1. Deficiencies (either acquired or inherited)
2. Inhibitors (always acquired). Either antibodies or drugs |
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What are 2 examples of acquired clotting deficiency that cause prolonged aPTT?
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1. Vit K deficiency
2. Liver Defect |
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What step is taken after a prolonged aPPT to see whether problem is a deficiency or inhibitor?
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Mix with normal blood.
If becomes normal, must be deficiency. If not, must be inhibitor. |
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What 4 clotting factors depend on Vitamin K?
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Thrombin (II), VII, IX, X
Note: Vit. K required for post-translational modification, not synthesis |
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What are the 3 primary regulators of coagulation?
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1. Tissue Factor Pathway Inhibitor (TFPI)
2. Anti-Thrombin 3. Protein C |
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Heparin increases the activity of what endogenous regulator of clotting?
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Anti-Thrombin
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What is the function of protein C/S?
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Cleaves and inactivates factors Va and VIIIa, slowing thrombin production
Note: Protein S is a cofactor of Protein C |
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What activates the production of protein C?
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Thrombin (negative feedback loop)
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What enzyme degrades clots when they are no longer needed?
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Plasmin
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Draw out fibrolytic pathway
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(see notes)
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What are D-Dimers?
What are the useful for? |
XIII-crosslinked fragments of polymerized fibrin
useful as a marker for clot production |
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What is thrombosis?
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Over-clotting in vasculature
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