Coagulation Cascade Quiz
Questions: 16 · 10 minutes
1. During amplification of coagulation, thrombin helps generate a larger thrombin burst by activating which two cofactors?
Factors VII and XII
Factors V and VIII
Factors IX and XI
Factors X and XIII
2. Which reaction marks the point at which the classical intrinsic and extrinsic pathways enter the common pathway?
Conversion of factor XII to XIIa
Activation of factor VII by tissue factor
Cross-linking of fibrin by factor XIIIa
Conversion of factor X to Xa
3. A direct factor Xa inhibitor is present at a therapeutic concentration. Which step of the cascade is most directly reduced?
Cleavage of fibrin by plasmin
Expression of tissue factor on injured tissue
Conversion of prothrombin to thrombin by the prothrombinase complex
Cross-linking of fibrin by factor XIIIa
4. At an injured vessel wall, which interaction initiates the tissue factor pathway?
Factor VIII binds fibrinogen and releases factor XIII
Factor XII binds tissue factor and directly converts prothrombin to thrombin
Tissue factor binds factor VII or VIIa, forming a complex that activates factors IX and X
Platelet factor 4 binds factor XI and directly produces fibrin
5. Unfractionated heparin produces its immediate anticoagulant effect mainly by enhancing the activity of which protein?
Antithrombin
Protein C
Tissue factor
Plasminogen
6. A laboratory sample has a prolonged prothrombin time (PT) but a normal activated partial thromboplastin time (aPTT). An isolated deficiency of which factor best fits this pattern?
Factor XII
Factor VIII
Factor X
Factor VII
7. A person forms fibrin, but the clot is unusually unstable and delayed bleeding occurs because fibrin is not properly cross-linked. Which factor is most directly implicated?
Factor XIII
Factor X
Factor VII
Factor XII
8. Which natural anticoagulant directly neutralizes several activated serine proteases, especially thrombin and factor Xa?
Antithrombin
Protein S
Thrombomodulin
Tissue plasminogen activator
9. In the classical laboratory model of the intrinsic pathway, which factor is activated first during contact activation?
Factor VII
Factor X
Factor XII
Factor XIII
10. Why can widespread systemic activation of coagulation produce both small-vessel thrombosis and bleeding?
Fibrinogen is converted entirely into plasminogen
Ongoing coagulation can consume platelets and clotting factors while fibrinolysis is activated
Factor XII selectively suppresses every natural anticoagulant
Platelets stop adhering because von Willebrand factor is overproduced
11. Hemophilia A is caused by a deficiency or dysfunction of which coagulation factor?
Factor VII
Factor VIII
Factor IX
Factor XI
12. After tissue factor initiates coagulation, which natural regulator limits the tissue factor-factor VIIa complex and factor Xa?
Von Willebrand factor
Activated protein C
Alpha-2 antiplasmin
Tissue factor pathway inhibitor
13. Which group contains the four vitamin K-dependent procoagulant factors?
II, VII, IX, and X
I, V, VIII, and XIII
II, V, XI, and XII
VII, VIII, X, and XIII
14. A blood collection tube contains citrate to prevent the sample from clotting before testing. How does citrate achieve this effect?
It directly breaks down fibrin strands
It permanently inactivates thrombin
It binds calcium needed for multiple coagulation reactions
It blocks platelet receptors for fibrinogen
15. A patient's prolonged aPTT returns to the reference range after the plasma is mixed with normal plasma. What does this correction most strongly suggest?
A direct anticoagulant effect that remains active after mixing
A persistent phospholipid-dependent inhibitor such as a lupus anticoagulant
A strong specific inhibitor against a supplied coagulation factor
A deficiency of one or more coagulation factors measured by the aPTT
16. Which enzyme directly cleaves soluble fibrinogen to form fibrin monomers?
Factor Xa
Thrombin
Factor XIIIa
Plasmin