Physiology

Question 1

Vasoconstriction is caused by several regulatory molecules, which include:

a) fibrinogen and vWF
b) ADP and EPI
c) thromboxane A2 and serotonin
d) collagen and actomyosin

Answer 1

c)
Thromboxane A2 promotes platelet aggregation and vasoconstriction. Serotonin released from the dense bodies of platelets is a vasoconstrictor that binds endothelial cells and platelet membranes.

Question 2

Warfarin is classified as a vitamin K antagonist. The factors that are impacted by warfarin therapy are:

a) VII, IX, and X
b) I, II, V, and VII
c) II, VII, IX, and X
d) II, V and VII

Answer 2

c. II, VII, IX, and X

Question 3

When a patient is placed on warfarin therapy , the first factors that will be decreased is:

a) factor I
b) factor V
c) factor VII
d) factor VIII

Answer 3

c.
Factor VII (proconvertin) has the shortest half life of 6 hours and will therefore be decreased first.

Question 4

A patient with a positive family history of bleeding presents to the ED with the results below.
Test Result Reference range
aPTT 29.5s 25-35 s
PT 19.2 s 10.5-12.5 s

The patient is not on any medication and so is likely to be deficient in factor:

a) II
b) V
c) VII
d) VIII

Answer 4

c. VII
Factor VII is the only factor found in the extrinsic pathway and is the most likeley.

Question 5

Hageman factor (XII) is involved in each of the following reactions except:

a) activation of C1 to C1 esterase
b) activation of plasminogen
c) activation of factor XI
d) transformation of fibrinogen to fibrin

Answer 5

d.
Fibrinogen is converted to fibrin by the action of thrombin.

Question 6

The most potent plasminogen activator in the contact phase of coagulation in:

a) kallikrein
b) streptokinase
c) HMWK
d) fibrinogen

Answer 6

a) kallikrein

Question 7

The activation of plasminogen to plasmin resulting in the degradation of fibrin occurs by:

a) PAI-1
b) alpha-2 antiplasmin
c) tPA
d) alpha-2 macroglobulin

Answer 7

c)
tPA converts plasminogen to plasmin. tPA is released as a result of the activity of endothelial damage and the production of thrombin.

Question 8

How does tissue factor pathway inhibitor inhibit coagulation?

Answer 8

inhibition of tissue factor-factor VIIa-factor Xa complex

Question 9

An inhibitor of plasmin activity is:

a) tPA
b) PAI-1
c) alpha-2 antiplasmin
d) plasminogen

Answer 9

c.
alpha-2 antiplasmin is synthesized in the liver and is the primary inhibitor of free plasmin.

Question 10

Anti-thrombin inhibits factors:

a) IIa and Xa
b) Va and VIIIa
c) VIIa and XIIa
d) IXa and Va

Answer 10

a)
IIa and Xa

Question 11

The propagation phase of the in vivo coagulation model includes:

a) a final burst of thrombin
b) activation of platelets
c) feedback mechanism to thrombin
d) activation of factor Va and factor VIIIa

Answer 11

a)

Question 12

In the cell-based model of coagulation the intrinsic pathway operates on the:

a) activated platelet surface to produce the burst of thrombin
b) tissue factor bearing cell to initiate and amplify coagulation
c) proteolytic digestion of fibrinogen
d) activation of the contact pathway

Answer 12

a)
model states that the intrinsic pathway is said to occur on the platelet surface.

Question 13

A new oral anticoagulant apixaban has been given to a patient who was previously on warfarin. This drug directly inhibits:

a) vitamin-k-dependent factors
b) factor IIa
c) Xa
d) both factor IIa and Xa

Answer 13

c) Xa

Note:
Apixaban is an oral direct anti-FXa inhibitor used to prevent VTE.

Question 14

The anticoagulant that directly inhibits thrombin is:

a) LMWH
b) argatroban
c) warfarin
d) rivorxaban

Answer 14

b)
argatroban

Question 15

A patient who presents with renal impairment is being started on oral anticoagulant therapy. The DOAC that should be avoided would be:

a) dabigatran
b) apixaban
c) rivaroxaban
d) warfarin

Answer 15

a) dabigatran

Question 16

In secondary hemostasis, coagulation proteins become activated to form a fibrin clot. Prior to these proteins being activated, their inactive proenzymes are known as:

a) serine proteases
b) cofactors
c) zymogens
d) substrates

Answer 16

c) zymogens

Question 17

Alpha granules are found on the platelet in the:

a) peripheral zone
b) sol gel zone
c) organelle zone
d) membranes

Answer 17

c)
Organelle zone contains alpha, dense and lysosome granules.

Question 18

Which of the following best represents the 3 steps of normal hemostasis (in order)?

a) decreased heart rate, adhesion of platelets, plug formation
b) platelet aggregation, formation of FXII, fibrin plug
c) vasoconstriction, platelet aggregation, fibrin formation
d) vascular damage, stasis, endothelial injury

Answer 18

c)
vasoconstriction, platelet aggregation, fibrin formation

Question 19

Which of the following platelet antigens is the receptor for collagen?

a) GPIb/V/IX complex
b) GPIIb/IIIa complex
c) GPIa/IIa complex
d) GPIc/IIa complex

Answer 19

c)
GPIa/IIa complex

Question 20

Which platelet surface antigen acts as the receptor for fibrinogen?

a) GPIb/V/IX
b) GPIIb/IIIa
c) GPIa/IIa
d) GPIc/IIa

Answer 20

b)
GPIIb/IIIa

Question 21

How does GPIb become activated in vivo and in vitro, respectively?

a) shear force, ristocetin
b) ristocetin, compression
c) activation of ADP receptor, ristocetin
d) binding vWF, epinephrine

Answer 21

a)
shear force, ristocetin

Question 22

A patient is on aspirin 100 mg/day to prevent the formation of clots caused by platelets. The mechanism in which aspirin impairs platelet function is by:

a) inactivating cyclooxygenase which blocks thromboxane A2
b) impairs vWF by via GPIb/IX/V receptor
c) decreased amounts of arachidonic acid
d) inactivation of ADP and phospholipase A2

Answer 22

a)
inactivating cyclooxygenase which blocks thromboxane A2

Question 23

A patient is diagnosed with factor V Leiden mutation. The factor V activity level should be:

a) shortened
b) prolonged
c) undetectable
d) within reference range

Answer 23

d)
within reference range

Question 24

The International Sensitivity Index (ISI) is determined by comparing the PT results of the manufacturer’s reagent against:
a) rabbit thromboplastin
b) micronized silica
c) tissue factor
d) human brain thromboplastin

Answer 24

d)
human brain thromboplastin

Question 25

A coagulation reagent should be sensitive to factor deficiencies. A reagent is considered sensitive to a factor when the level of factor activity is approximately:
a) 30%
b) 40%
c) 50%
d) 60%

Answer 25

a)
30%

Question 26

What factors are considered heat labile?

a) II and IX
b) V and VIII
c) VII and XI
d) X and XII

Answer 26

b)
V and VIII

Question 27

What factor serves as a carrier for factor VIII?
a) factor V
b) factor IX
c) tissue factor
d) von Willebrand factor

Answer 27

d)
von Willebrand factor

Question 28

Patients may present with either a bleeding or a thrombotic event in:

a) dysfibrinogenemia
b) hypofibrinogenemia
c) afibrinogenemia
d) hyperfibrinogenemia

Answer 28

a)
dysfibrinogenemia

Question 29

The key enzyme of the fibrinolytic system is:

a) Plasmin
b) thrombin
c) urokinase
d) streptokinase

Answer 29

a)
Plasmin

Question 30

The major serine protease responsible for clot breakdown is:

a) TPA
b) alpha 2 antiplasmin
c) streptokinase
d) PAI-1

Answer 30

a)
Tissue plasminogen activator

Question 31

What subendothelial structural protein triggers coagulation through activation of FVII?

a) thrombomodulin
b) nitric oxide
c) tissue factor
d) silica

Answer 31

c)
tissue factor

Question 32

Protein C and its cofactor protein S proteolytically inactivate factors:

a) IIa and Xa
b) Va and VIIIa
c) VIIIa and IXa
d) XIa and XIIa

Answer 32

b)
Va and VIIIa