Hemostasis and Coagulation Factors: The Cascade System

Question 1

What are clotting factors that circulate in the blood as distinct entities in an inactive form?

Answer 1

Zymogens

Question 2

When this factor becomes activated, it’s referred to as what?

Answer 2

Serine protease

Question 3

What binds to a particular serine protease to stabilize and increase reactivity?

Answer 3

Cofactors

Question 4

This factor is a substrate for thrombin and polymerizes to form fibrin

Answer 4

Factor I/Fibrinogen

Question 5

This factor is a cofactor for II → IIa and is a part of the prothrombinase complex

Answer 5

Factor V/Labile factor

Question 6

This factor is a cofactor for X → Xa

Answer 6

VIII:C

Question 7

This factor is a carrier protein for VIII:C and is needed for platelet adhesion to collagen

Answer 7

vWF

Question 8

This factor is a transglutaminase which converts loose hydrogen bonds of fibrin monomers to covalent bonds

Answer 8

XIII/Fibrin stabilizing factor

Question 9

This factor is a serine protease and a precursor to thrombin

Answer 9

Factor II/Prothrombin

Question 10

This factor is a serine protease and activates X and IX (in vivo)

Answer 10

Factor VII/Stabilizing factor

Question 11

This factor is a serine protease and w/ help of the cofactor VIIIa, it converts X → Xa

Answer 11

Factor IX/Christmas factor

Question 12

This factor is a serine protease that is a part of the prothrombinase complex which converts II → IIa

Answer 12

Factor X/Stuart-Prower factor

Question 13

This factor is a serine protease that converts IX → IXa

Answer 13

Factor XI/Plasma thromboplastin antecendant

Question 14

This factor is a serine protease (in vivo) that is activated in the presence of HMWK and PK to activate XI → XIa

Answer 14

Factor XII/Hageman factor

Question 15

This factor is a serine protease (in vivo) and w/ the help of cofactor HMWK it activates XII→ XIIa

Answer 15

Factor PK/Fletcher factor

Question 16

This factor is a cofactor that participates in the (in vitro) contact activation of XI → XIa and activates the kinin system

Answer 16

Factor HMWK/Fitzgerald factor

Question 17

Which 12 factors are synthesized in the liver?

Answer 17

Factors I, V, VIII:C, XIII, II, VII, IX, X, XI, XII, PK, and HMWK

Question 18

Which cofactors are synthesized in the endothelial cells and megakaryocytes?

Answer 18

vWF

Question 19

Which enzyme is generated from the coagulation pathway that is needed to convert fibrinogen to fibrin?

Answer 19

Thrombin

Question 20

Which site provides the surface for the coagulation cascade?

Answer 20

PF3 (PL) (assembly molecule)

Question 21

Initiation of coagulation by ____ is sufficient to initiate activation of both pathways

Answer 21

TF or Factor VII complex

Question 22

Which pathway is being tested by prothrombin time (PT)?

Answer 22

Extinsic pathway

Question 23

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

Answer 23

Intrinsic pathway

Question 24

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

Answer 24

• VII
• X
• V
• II
• I

Question 25

List the correct order of activation of factors for in vitro testing by the Activated Partial Thromboplastin Time (APTT)

Answer 25

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

Question 26

List the correct order of activation factors for the common pathway

Answer 26

X, V, II, I

Question 27

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

Answer 27

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

Question 28

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

Answer 28

- Fibrinogen is composed of three pairs of polypeptide chains (α, ß, and γ) - Thrombin cleaves a portion of the α and ß 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 29

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

Answer 29

Factor XIII and Ca2+ convert loose hydrogen bonds to stronger covalent (cross-linked) bonds

Question 30

Four hemostatic actions of thrombin

Answer 30

- Converts fibrinogen to fibrin - Activates factors XI, V, VIII, and XIII - Induces platelet aggregation - Binds the endothelial cell membrane protein, thrombomodulin, to activate the protein C pathway

Question 31

Nomenclature of the two portions of the Factor VIII complex

Answer 31

vWF and VIII:C

Question 32

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

Answer 32

- vWF: endothelial cells and megakaryocytes | - VIII: liver

Question 33

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

Answer 33

- vWF: carrier for Factor VIII | - VIII: cofactor for X → Xa

Question 34

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

Answer 34

- vWF: von Willebrand's Disease | - VIII: Hemophilia A

Question 35

Which portion of the Factor VIII complex is responsible for normal bleeding time?

Answer 35

vWF

Question 36

Which portion of the Factor VIII complex is responsible for normal platelet adhesion?

Answer 36

vWF

Question 37

Which portion of the Factor VIII complex is responsible for ristocetin cofactor activity?

Answer 37

vWF

Question 38

Which coagulation factors are present in the fibrinogen group?

Answer 38

- I - V - VIII - XIII

Question 39

Which coagulation factors are present in the prothrombin group?

Answer 39

- II - VII - IX - X

Question 40

Which coagulation factors are present in the contact group?

Answer 40

- XI - XII - PK - HMWK

Question 41

Which coagulation factors are consumed or destroyed during clotting?

Answer 41

I, V, VIII (VII:C/vWF), XIII, II | fibrinogen group AND II

Question 42

Which coagulation factors are dependent upon vitamin K for synthesis?

Answer 42

II, VII, IX, X (prothrombin group)

Question 43

Which coagulation factors are destroyed by plasmin?

Answer 43

I, V, VIII, XIII (fibrinogen group)

Question 44

Which coagulation factors are heat labile?

Answer 44

I, V, VIII, XIII (fibrinogen group)

Question 45

What is another name for coagulation/clotting factors?

Answer 45

Procoagulant

Question 46

What are plasma GPs that serve as inhibtors to coagulation?

Answer 46

Anticoagulants

Question 47

Describe what happens in contact activation?

Answer 47

Contact w/ a negatively charged surface is one means to activate the intrinsic coagulation pathway - Examples: prosthetic valves, stents (in vivo); nonsiliconized glass, microsilica, elagic acid (in vitro) - Contact factors, EXCEPT IX (!), do not normally have an in vivo procoagulant function