Clotting Factors Practice

Question 1

The mesh work of a wound is formed by the polymerization of which protein?

• Fibrin
• D-dimer
• Plasmin
• Vitamin K
• Protein C

Answer 1

Fibrin

Fibrin forms long polymers that bind to platelets and other fibrin molecules. this mesh form the scaffold for the secondary phase of hemostasis. Plasmin destroys clots and decreases the mesh. Vitamin K is a cofactor for GGT in the liver. D-dimer is the product of plasmin proteolysis of fibrin. Protein C is an activator of plasminogen.

Question 2

A patient on Warfarin takes aspirin for a headache and later develops signs of bleeding. What is the underlying reason for this?

Warfarin inhibits conversion of fibrinogen to fibril whereas aspirin inhibits Thromboxane A2 formation

Aspirin activates the formation of Thromboxane A2 whereas warfarin is a vitamin K antagonist both are required fro proper clotting.

Both agents bind irreversibly to factor VII.

Aspirin inhibits the formation of Thromboxane A2 whereas warfarin is a vitamin K antagonist and both decrease clotting.

Aspirin inhibits conversion of prothrombin to thrombin whereas warfarin is a vitamin K antagonist used in Thrombin.

Answer 2

Aspirin inhibits the formation of Thromboxane A2 whereas warfarin is a vitamin K antagonist and both decrease clotting.

Question 3

The conversion of plasminogen to plasmin can be accomplished by using which one of the following?

Urokinase

Urease

Ceruloplasmin

Fibrinogen kinase

Protein kinase C

Answer 3

Urokinase

Urokinase, tissue plasminogen activator, Kallikrein, Factor XIIa and Factor Xia can all act to activate plasminogen

Question 4

A 55-year-old man reports to the physician complaining that his left foot is swollen since he got off the plane after a long flight. Blood tests show that his fibrin-D dimer levels are elevated. The physician decides to administer an anticoagulant. Which of the following would be most suitable for this patient’s immediate treatment?

• Warfarin
• Aspirin
• Heparin
• Streptokinase
• Citrate

Answer 4

Heparin

Heparin binds and thereby sequesters antithrombin, preventing further clot formation. Aspirin is inhibits the production of Thromboxane A2. Streptokinase binds to prothrombin and facilitates its proteolysis to Thrombin. Warfarin is an antagonist for GGT in the liver. Citrate chelates calcium.

Question 5

Which of the following is a protease responsible for converting fibrinogen to fibrin?

• Prostacyclin
• Thrombin
• Prothrombin
• Thromboxane
• Fibrin

Answer 5

Thrombin

Question 6

Which of the following is the point where the extrinsic and intrinsic pathways converge?

• X
• IX
• Xa
• IXa
• VIIa

Answer 6

X

Both the intrinsic and extrinsic pathways act on Factor X and convert it into Factor Xa. The intrinsic path protease is the VIIIa/IXa complex and the extrinsic path protease is the VIIa/III complex.

Question 7

Which of the following initiates the extrinsic pathway of the clotting cascade?

• Factor X
• Factor VII
• Factor IX
• Factor III
• Factor VIII

Answer 7

Factor III

Question 8

The degradation of clots is essential. Which of the following is responsible for degradation of fibrin clots?

• Plasmin
• Prothrombin
• Factor XIIIa
• Thrombin
• Plasminogen

Answer 8

Plasmin

Question 9

Hemophilia A is a classic hemophilia. It is a disease referring to the inability to clot blood. Which of the following is deficient in this X-linked recessive disorder?

• Factor VIII
• Factor VII
• Factor IX
• Factor X
• Factor Xa

Answer 9

Factor VIII

Question 10

von Willebrand disease is due to an inherited deficiency in von Willebrand factor (vWF). Which of the following factors are also affected as a result of deficiency of vWF?

• Factor IX
• Factor VIII
• Factor Xa
• Factor VII
• Factor X

Answer 10

Factor VIII