The Cascade System (PART 2)

Question 1

Which pathway is being tested by Prothrombin Time (PT)

Answer 1

Extrinsic Pathway

Question 2

Which pathway is being tested by Activated Partial Thromboplastin Time (APTT)

Answer 2

Intrinsic Pathway

Question 3

List the correct order of activation of factors for in vitro testing by the Prothrombin Time (PT)

Answer 3

• VII
• X
• V
• II
• I

Question 4

List the correct order of activation of factors for in vitro testing by the activated partial thromboplastin time (APTT)

Answer 4

• XII (plus Fletcher and Fitzgerald )
• XI
• IX
• VIII
• X
• V
• II
• I

Question 5

List the correct order of activation factors for the common pathway

Answer 5

X, V, II, I

Question 6

What is the role of prothrombinase complex in the common pathway?

Answer 6

Macromolecular complex which forms on the surface of the platelets; great amplifier of thrombin activation
- (made up of Xa, Va, PL, and calcium)

Question 7

How is the unstable, soluble fibrin monomer formed in the common pathway?

Answer 7

• Fibrinogen is composed of three pairs of polypeptide chains (alpha, beta, and gamma)
• Thrombin cleaves a portion of the alpha and beta to form fibrinopeptides A and B
• After the cleavage, the fibrinogen molecule is called a fibrin monomer
• fibrin monomer quickly polymerizes (line up side by side) to form fibrin (unstable w/ loose hydrogen bonds)

Question 8

What factor is responsible for forming the stable, insoluble fibrin clot

Answer 8

Factor XIII and calcium convert loose hydrogen bonds to stronger covalent (cross-linked) bonds

Question 9

List four hemostatic actions of thrombin

Answer 9

1. converts fibrinogen to fibrin
2. activates factors XI, V, VIII, and XIII
3. Induces platelet aggregation
4. Binds the endothelial cell membrane protein, thrombomodulin, to activate the protein C pathway

Question 10

Nomenclature of the two portions of the Factor VIII complex

Answer 10

von Willebrand Factor and Factor VIII:c

Question 11

Site of synthesis of the two portions of the Factor VIII complex

Answer 11

vWF: endothelial cells and megakaryocytes
VIII: Liver

Question 12

Principle biologic activity of the two portions of the Factor VIII complex

Answer 12

vWF: carrier for factor VIII
VIII: corfactor for X to Xa

Question 13

Clinical disorder due to deficiency of the two portions of the Factor VIII complex

Answer 13

vWF: von Willebrand’s Disease
VIII: Hemophilia A

Question 14

Which Factor VIII complex is responsible for normal bleeding time?

Answer 14

• vWF

Question 15

Which Factor VIII complex is responsible for normal platelet adhesion

Answer 15

*vWF

Question 16

Which Factor VIII complex is responsible for ristocetin co-factor activity

Answer 16

*vWF

Question 17

List the coagulation factors present in the fibrinogen group

Answer 17

• I
• V
• VIII
• XIII

Question 18

List the coagulation factors present in the prothrombin group

Answer 18

• II
• VII
• IX
• X

Question 19

List the coagulation factors present in the contact group

Answer 19

• XI
• XII
• PK
• HMWK

Question 20

Which coagulation factors are consumed or destroyed during clotting?

Answer 20

I, V, VIII (VII:C/vWF), XIII, II

(fibrinogen group AND II)

Question 21

Which coagulation factors are dependent upon vitamin K for synthesis

Answer 21

II, VII, IX, X (prothrombin group)

Question 22

Which coagulation factors are destroyed by plasmin

Answer 22

I, V, VIII, XIII (fibrinogen group)

Question 23

Which coagulation factors are heat labile

Answer 23

I, V, VIII, XIII (fibrinogen group)