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Section XI – Special Topics (C)

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

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

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

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

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

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.

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

A. Tissue factor

B. Factor XI

C. Factor V

D. Factor II (prothrombin)

E. Fibrinogen

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

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

A. Prevent activation of the extrinsic pathway of coagulation

B. Inhibit thrombin

C. Enhance degradation of factors VIIIa and Va

D. Enhance fibrinolysis

E. Inhibit platelet aggregation

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

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

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

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

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

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