Blood Clotting

Question 1

What are the three main stages of blood clotting?

Answer 1

Vascular spasm, platelet plug formation, and coagulation.

Question 2

Which factor initiates the extrinsic pathway of coagulation?

Answer 2

Tissue factor (factor III).

Question 3

Name the enzyme responsible for converting fibrinogen to fibrin.

Answer 3

Thrombin.

Question 4

Which vitamin is essential for the synthesis of clotting factors II, VII, IX, and X?

Answer 4

Vitamin K.

Question 5

What is the primary function of thrombin in the clotting cascade?

Answer 5

Converts fibrinogen to fibrin and activates factors V, VIII, XI, and XIII.

Question 6

Which anticoagulant inhibits thrombin and factor Xa?

Answer 6

Heparin.

Question 7

What is the role of platelets in the clotting process?

Answer 7

They adhere to the site of injury, aggregate to form a temporary plug, and release chemicals that activate other platelets.

Question 8

Name the pathway that involves tissue factor and factor VII.

Answer 8

The extrinsic pathway.

Question 9

Which factor cross-links fibrin to stabilize the blood clot?

Answer 9

Factor XIII.

Question 10

What is the function of plasmin in the fibrinolytic system?

Answer 10

Breaks down fibrin into fibrin degradation products.

Question 11

Name the intrinsic pathway initiator.

Answer 11

Factor XII (Hageman factor).

Question 12

Which test measures the extrinsic pathway of coagulation?

Answer 12

Prothrombin time (PT).

Question 13

What is the role of calcium ions (Ca2+) in coagulation?

Answer 13

Acts as a cofactor in multiple steps of the coagulation cascade.

Question 14

Name the complex that activates factor X in the extrinsic pathway.

Answer 14

The tissue factor–factor VIIa complex.

Question 15

Which factor is known as Christmas factor?

Answer 15

Factor IX.

Question 16

What activates protein C?

Answer 16

Thrombin-thrombomodulin complex.

Question 17

Which test is used to measure the intrinsic pathway of coagulation?

Answer 17

Activated partial thromboplastin time (aPTT).

Question 18

What is the role of von Willebrand factor in coagulation?

Answer 18

Mediates the adhesion of platelets to damaged blood vessel walls and stabilizes factor VIII.

Question 19

Name the factor that is deficient in hemophilia A.

Answer 19

Factor VIII.

Question 20

What is the final product of the coagulation cascade that forms the clot?

Answer 20

Fibrin.

Question 21

Which protein acts as a cofactor for the activation of protein C?

Answer 21

Protein S.

Question 22

Name the enzyme that degrades fibrin clots.

Answer 22

Plasmin.

Question 23

What is the role of tissue plasminogen activator (tPA)?

Answer 23

Converts plasminogen to plasmin.

Question 24

Which factor is known as the Stuart-Prower factor?

Answer 24

Factor X.

Question 25

Name the anticoagulant that works by activating antithrombin.

Answer 25

Heparin.

Question 26

What is the significance of the INR (International Normalized Ratio)?

Answer 26

It standardizes prothrombin time results to monitor warfarin therapy.

Question 27

Which pathway is initiated by contact with negatively charged surfaces?

Answer 27

The intrinsic pathway.

Question 28

What is the role of factor XIII in coagulation?

Answer 28

Cross-links fibrin to form a stable clot.

Question 29

Name the factor that combines with factor VIII to activate factor X.

Answer 29

Factor IXa.

Question 30

Which laboratory test assesses the function of the common pathway of coagulation?

Answer 30

Thrombin time (TT).