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10 Cards in this Set
- Front
- Back
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Define haemostasis |
functions to limit blood loss (haemorrhage) following vascular damage, yet without compromising the fluidity of the blood. |
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Define thombosis |
occlusion of a blood vessel (venous or arterial) by an intravascular blood clot or platelet clump. |
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How is intravascular blood coagulation and platelet activation normally suppressed? |
•non thrombogenic surface of endothelium •production by endothelium of prostacyclin (PGI2)and nitric oxide which inhibit platelet aggregation; nitric oxide also inhibits adhesion of platelets to vascular wall •presence in plasma of natural anticoagulants, e.g. antithrombin III |
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Describe what happens during the activation of platelets and the coagulation cascade |
•platelets adhere to exposed sub-endothelial collagenand become activated •coagulation is initiated by exposure of blood to tissue factor (Factor III) and facilitated by exposure of pro-coagulant phospholipid on platelet surface •platelets release agents which promote vasoconstriction and platelet aggregation, i.e. thromboxane A2, 5-HT and ADP •fibrin strands enmesh the platelet aggregate to consolidate the haemostatic plug •the haemostatic plug is dissolved by the fibrinolytic systemto allow tissue repair |
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Draw the coagulation cascade |
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Give an example of 4 blood clotting deficiencies and state what part of the coagulation cascade is affected |
•Von Willebrand disease(most common) –deficiency of von Willebrand factor –binds to and stabilises factor VIII and binds platelets to collagen •haemophilia A–deficiency of factor VIII •haemophilia B–deficiency of factor IX •haemophilia C–deficiency of factor XI |
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What system removes clots? Describe how it is done (draw) |
- fibrinolytic system |
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Describe the differences between a venous and arterial thrombus |
VENOUS THROMBOSIS: intravascular blood clot (red) ARTERIAL THROMBOSIS: platelet aggregate (white) encapsulated by clot (red) |
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Give two examples of common sites of arterial thrombi and what is most likely to occur |
-coronary artery: myocardial infarction -cerebral artery: thrombotic stroke |
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Describe the differences in treatment for a venous and arterial thromubus |
arterial: anticoagulants venous: fibronolytics (clot dissolvers) and anthrombotics (anti-platelt drugs) |
