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18 Cards in this Set
- Front
- Back
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what are the basic steps after vessel injury?
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- vasoconstriction --> exposure of endothelium --> exposure of collagen/VWF --> platelet recruitment --> primary platelet plug
AT SAME TIME - Tissue factor:FVIIa complex --> generate thrombin --> form fibrin --> FXIII crosslinks --> at end want fbrinolysis do don't have huge clot left over |
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what are the 4 steps in primary platelet formation?
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1) adhesion (VWF & collagen)
2) activation (shape change) 3) secretion (granule content release) 4) aggregation (platelet-platelet interactions) |
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what factors does thrombin activate to generate more thrombin? which factor is responsible for crosslinking fibrin?
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- V, VIII, XI
- XIII |
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what do proteins C & S do?
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- inhibit clot formation
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what factors do TF:VII complex activate? why?
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- Activate FIX & FX in order to produce more thrombin from prothrombin
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what does PAI-1 do?
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- during endothelial injury plasminogen activator inhibitor inhibits breakdown of fibrin
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what clotting factors are vit K dependent? what does vit K do?
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- V, VII, IX, X, protein C & S
- vit K converts glutamic acid --> gamma carboxyglutamic acid via vit K dependent carboxylase |
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how does warfarin work?
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- inhibits vit K epoxide reductase --> cannot recycle vit K
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what factor is not reflected in the screening assays? what would happen if you had a deficiency of it?
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- FXIII b/c it is a late step
- if you had a deficiency of this you do not make a good fibrin clot so you will start bleeding 3-5 days post trauma |
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how do you breakdown the fibrin clot? what factors control it?
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- activated by tPA (tissue plasminogen activator) release from endothelium
- converts plasminogen --> plasmin --> lyses fibrin to degradation products - controlled by plasminogen activator inhibitor-1 & antiplasmin |
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what is the extrinsic pathway? intrinsic? common?
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- extrinsic: common pathway + VII
- intrinsic: common pathway + VIII, IX, XI, XII - common pathway: X, V, II (prothrombin), I (fibrinogen) |
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what is PTT testing? PT? thrombin time?
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- PTT: intrinsic system
- PT: extrinsic system - thrombin time: fibrinogen --> fibrin |
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what does it mean if PT is elevated & PTT is normal?
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- common pathway is fine, need to look at factor VII
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what does it mean if PT is normal PTT is elevated?
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- common pathway is fine, need to look at VIII, IX, XI, XII
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what does it mean if PT & PTT are normal?
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- common pathway fine
- could be VWF or XIII |
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what does it mean if PT & PTT are elevated?
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- could be vit K deficiency or DIC
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what if thrombin time is elevated?
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- could be low or abnormal fibrinogen, heparin or DIC (fibrin breakdown)
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what are hemophilia a & b?
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- hemophilia a: VIII
- hemophilia b: IX - X linked, bleeding at birth |
