22. Clotting Cascade

Question 1

What are the steps from tissue injury to the common pathway for the extrinsic pathway?

Answer 1

Tissue Injury

Factor III (Tissue Factor) released

Tisue factor turns Factor VII into Factor VIIa

Factor VIIa turns Factor X into Factor Xa

Question 2

Which factors are vitamin K dependent?

Answer 2

Factors II, VII, IX, X

Question 3

What all makes up prothrombinase?

Answer 3

Factor Va

Factor Xa

Ca²⁺

Question 4

What is the role of thrombin in the polymerization of fibrin?

Answer 4

It activates Factor XIII, which crosslinks fibrin polymers to form “stable fibrin.”

Question 5

Thrombin catalyzes the activation of which two factors?

Answer 5

Factor V and Factor VIII

Question 6

What lab test primarily tests the extrinsic and common pathway?

What factors of the extrinsic pathway are tested?

Answer 6

Prothrombin time

Just VII

Question 7

What lab test primarily tests the intrinsic and common pathway?

Answer 7

Activated partial thromboplastin time

(Remember that kaolin is used for the negative surface in activated partial thromboplastin time tests.)

Question 8

What test measures the activity of Heparin?

Answer 8

Activated partial thromboplastin time

Question 9

Which factors are inhibited by heparin?

Answer 9

II, IX, and Xa

Question 10

Which factors are inhibited by coumadin?

Answer 10

The ones that use Vitamin K

II, VII, IX, X