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Section XI: Special Topics (C)

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Which one of the following statements regarding the blood coagulation pathways is NOT CORRECT?

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A. The components of the extrinsic Xase (tenase) complex are factor VIIa, tissue factor, Ca2+, and factor X.

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B. The components of the intrinsic Xase (tenase) complex are factor IXa, factor VIIIa, Ca2+, and factor X.

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C. The components of the prothrombinase complex are factor Xa, factor Va, Ca2+, and factor II (prothrombin).

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D. The extrinsic and intrinsic Xase complexes and prothrombinase complex require anionic procoagulant phosphatidylserine on LDL (low-density lipoprotein) for their assembly.

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E. Fibrin formed by cleavage of fibrinogen by thrombin is covalently cross-linked by the action of factor XIIIa, which itself is formed by the action of thrombin on factor XIII.

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On which one of the following coagulation factors does a patient taking warfarin for his thrombotic disorder have decreased Gla (γ-carboxyglutamate) residues?

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A. Tissue factor

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B. Factor XI

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C. Factor V

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D. Factor II (prothrombin)

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E. Fibrinogen

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D. Of the listed proteins, only factor II is a vitamin K-dependent coagulation factor.

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A 65-year-old mansuffers a myocardial infarction and is given tissue plasminogen activator within 6 hours of onset of the thrombosis to achieve which one of the following?

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A. Prevent activation of the extrinsic pathway of coagulation

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B. Inhibit thrombin

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C. Enhance degradation of factors VIIIa and Va

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D. Enhance fibrinolysis

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E. Inhibit platelet aggregation

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Which one of the following statements regarding platelet activation in hemostasis and thrombosis is NOT CORRECT?

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A. Platelets adhere directly to subendothelial collagen via GPIa-IIa and GPVI, while binding of GPIb-IX-V is mediated via von Willebrand factor.

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B. The aggregating agent thromboxane A2 is formed from arachidonic acid liberated from platelet membrane phospholipids by the action of phospholipase A2.

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C. The aggregating agent ADP is released from the dense granules of activated platelets.

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D. The aggregating agent thrombin activates intracellular phospholipase Cβ, which forms the internal effector molecules 1,2-diacylglycerol and 1,4,5-inositol trisphosphate ...

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