Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Heme > Hemostasis > Flashcards

Hemostasis Flashcards

1
Q

What is the major process in primary hemostasis?

A

FIRST vessel reflexively constricts

platelets form a plug to minimize blood loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the major process in secondary hemostasis?

A

Clotting cascade forms a fibrin clot that anchors and stabilizes the platelet plug

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

______ is central to the hemostatic response because i tis a potent platelet activator and it converts soluble fibrinogen to an insoluble fibrin clot

A

thrombin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The _________ surface is an important site for assembly and localization of the membrane bound enzyme complexes of coagulation

A

Activated platelet surfac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Gradual transition to ______ facilitates removal of a clot and wound healing

A

fibrinolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

List three pro-thrombotic components

A
  1. Platelets/ vWF: formation of hemostatic plug
  2. Coagulation cascade: thrombin–> fibrin clot formation
  3. Fibrinolysis inhibitors: soluble protease inhibitors that down regulate fibrinolysis and prevent degradation of the clot
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

List three anti-thrombotic components

A
  1. Intact endothelium
  2. Fibrinolysis: second enzyme cascade converts plasminiogen to plasmin which lyses the fibrin clot
  3. Coagulation inhibitors: soluble protease inhibitors that down-regulate the coagulation cascade and remove activated coagulation factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

List three classes of drugs that can be used to prevent hemostasis and their major targets

A
  1. antiplatelet drugs: target formation of primary platelet plug
  2. anticoagulants: prevent formation of fibrin clot
  3. antifibrinolytics: prevent breakdown of fibrin clot
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

List the steps in primary hemostasis

A
  1. Platelet adhesion: interaction of platelet Gp-Ib with vWF
  2. Platelet activation: by thrombin, collagen, ADP
  3. Platelet aggregation: cross linking of activated platelets by fibrinogen binding to Gp IIb/IIIa
  4. Secretion of platelet granules
  5. Retraction of the newly formed thrombus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Platelet ______ results in conformational change and activation of Gp IIb/IIIa, granule release, and thrombus contraction

A

activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Megakaryocyte differentiation is characterized by _____ in which DNA replication occurs but the nucleus does not divide

A

endomitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The production of platelets is controlled by the cytokine _____

A

TPO, thrombonpoietin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

About 30% of platelets are stored in the spleen and can be released in response to _____

A

epinephrine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

There is usually an ____ relationship between platelet number and mean platelet volume

A

inverse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the relationship between platelet sequestration, platelet desttruction, and megakaryocyte hyperplasia

A

As platelets are sequestered, but not destroyed, in a large spleen, there is no compensatory megakaryocyte hyperplasia in the marrow in patients with thrombocytopenia due to hypersplenism. In contrast, when the platelet count is reduced due to rapid destruction, there is megakaryocytic hyperplasia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Large circulating platelets on the blood smear in a patient with thrombocytopenia suggests:

A

peripheral destruction of platelets

Rapid platelet production leads to increased size of circulating platelets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

List the two hemostatic functions of vWF

A
  • major carrier of VIII, prolongs half life of VIII

- mediates platelet tethering and adhesion to exposed subendothelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Where is vWF found/ stored

A

endothelial cells, megakaryocytes, subendothelial connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

wVW is released by endothelial cells in the blood, which can be enhanced by ________

A

DDAVP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

If there is inherited or acquired deficiency of________, large VWF-platelet aggregates can form
in the circulation and occlude small blood vessels causing tissue injury.

A

ADAMTS13

This causes the disease thrombotic thrombocytopenic purpura (TTP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

_______ promotes vWF unfolding

A

high shear stress- as in arterial circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

List platelet agonists that trigger platelet activation

A 
collagen (in ECM)
thrombin (generated by TF)
epinephrine
ADP
serotonin
TXA2 produced by COX1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the contents of a granules and dense granules

A

a granules: proteins such as fibrinogen, vWF and factor V that promote clot formation as well as chemokines that recruit inflammatory cells

Dense granules: ADP/ATP and serotonin which activates additional platelets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

______ is normally sequestered on the inner membrane of a platelet but is exposed after platelet activation. It enhances the assembly of membrane bound coagulation enzyme complexes

A

phosphatidylserine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Describe the terms intrinsic pathway and extrinsic pathway

A

Extrinsic pathway: plasma clotting in response to addition of tissue homogenates- factors “extrinsic to the blood”. Measured by PT

Intrinsic pathway: clotting of plasma in a glass tube using only factors intrinsic to the blood. Measured by aPTT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the initiation phase of the clotting cascade?

A

formation of TF-VIIa complex, must exceed a specific threshold in order to trigger clotting mechanism

27
Q

What occurs in the propagation phase of the clotting casdcade

A

Amplifies clotting response through factor IXa-VIIIa complex

28
Q

Which components of the coagulation cascade are vitamin K dependent?

A

II, VII, IX, X, C and S

29
Q

Describe how the phospholipid platelet surface is involved in activation of zymogens

A

Acts as a surface to bring a protease, a cofactor/ helper protein, and a zymogen into close contact

30
Q

Describe factor XI

A

a serine protease but not vitamin K dependent

31
Q

Describe factor XIII

A

enzyme that is activated by thrombin, works by cross linking fibrin to stabilize a thrombus

32
Q

What is the function of antithrombin?

A

Inhibits thrombin (IIa), Xa, IXa, XIa

33
Q

Describe the function of Protein C and Protein S

A

Protein C: proteolytic inactivation of V and VIII

Protein S: supports inactivation of V and VIII

34
Q

What is the function of tissue factor pathway inhibitor?

A

Forms a complex with factor Xa that inactivates the TF-VIIa complex

35
Q

List the components of the coagulation cascade that are considered cofactors

A

tissue factor: membrane protein that binds VIIa to form a complex that activates X, does not require proteolytic activation for cofactor activity

Factors V and VIII: require activation by thrombin to function.
VIII binds IXa to form a complex that activates X
Va binds to Xa to form a complex that activates prothrombin

Protein S: vitamin K dependent cofactor for protein C

36
Q

How does TF initiate coagulation?

A

After vascular injury, TF is exposed to the blood and binds circulating VIIa. TF-VIIa generates additional VII and small amounts of IX and X before being inhibited by tissue factor pathway inhibitor

A small amount of thrombin is generated by Xa which in turn activates V, VIII, and IX

37
Q

Activation of factors of VIII and V in the initiation phase allows for the formation of _____ and ______ complexes

A

IXa/VIIIa and Xa/Va

–> explosive generation of thrombin in the propagation phase

38
Q

In the propagation phase, thrombin also cleaves/ activates factor ____ which activates additional factor IX and contributes to the final rate of thrombin generation

A

XI

39
Q

______ is an abundant plasma protein that is cleaved by thrombin to form an insoluble clot

A

fibrinogen (cleaved to fibrin)

40
Q

What is the role of factor XIII in the coagulation cascade?

A

Cross links fibrin strands to stabilize the fibrin clot

41
Q

List all of the pro-coagulant functions of thrombin

A

activation of factors V, VIII, XI and XIII,activation of platelets, and cleavage of fibrinogen to fibrin

42
Q

At very low concentrations, thrombin is bound to _______ on endothelial surfaces, which acts as an anti-coagulant by accelerating activation of protein C

A

thrombomodulin

43
Q

Describe the role of the contact factors in the coagulation cascade

A

Factor XII, HMWK, prekallikrein

Deficiency does not lead to a bleeding phenotype but does show up as a prolonged aPTT
These factors are not necessary for normal hemostasis

44
Q

What is the role of factor XI? What happens in factor XI deficiency?

A

XI is activated by thrombin and activates factor IX

Deficiency causes a mild to moderate bleeding phenotype

45
Q

List three circulating coagulation inhibitors

A
  • tissue factor pathway inhibitor: inhibits TF-VIIa complex so inhibits initiation phase
  • antithrombin III: markedly reduces rate of thrombin generation in the propagation phase by inhibiting thrombin
  • activated protein C: helps terminate propagation by inactivating Va and VIIIa
46
Q

______ inhibits IXa, Xa, and thrombin, acting as a scavenger of free proteases

A

AT3

47
Q

The activity of AT3 is markedly accelerated by the drug _____

A

heparin

48
Q

How is protein C activated?

A

Thrombin bound to thrombomodulin

49
Q

The _____ response predominates on the arterial side and the _____ response is more critical on the venous side

A

platelets on arterial side

clotting cascade on venous side

50
Q

List platelet inhibitory substances produced by normal endothelium

A

PGI2
Nitric oxide synthase- NO generated from arginine by eNOS
CD39 aka ectoDAPase, degrades ADP and ATP

51
Q

List anticoagulant substances produced by normal endothelium

A

Heparin sulfate: binds AT3 to accelerate protease inhibition

Thrombomodulin: enhances generation of activated protein C

52
Q

How does intact endothelium act as a profibrinolytic surface?

A

Produces enzymes that activate plasminogen

53
Q

______ is a zymogen produced in the liver that is converted to activated protease then works to digest cross linked fibrin

A

plasminogen

54
Q

Endothelial cells secrete _____ which activates plasminogen to plasmin and binds specifically to fibrin

A

tPA

55
Q

Describe two fibrinolysis inhibitors

A
  • a-antiplasmin: circulates in blood, inhibits circulating plasmin but is less effective at inhibiting plasmin bound to a fibrin clot- helps keep plasmin activity local to a fibrin clot and not systemic
  • plasminogen activator inhibitor-1: released by endothelial cells, helps stabilize blood clots by delaying the onset of fibrinolysis
56
Q

The PT measures factors:

A

VII, X, V, II, and fibrinogen

57
Q

Prolonged PT with normal aPTT occurs in factor ____ deficiency

A

VII

58
Q

The aPTT measures factors:

A

IX, XI, VIII, X, V, II, and fibrinogen

59
Q

The aPTT is sensitive to changes in the ______ which prolong aPTT but do not cause bleeding

A

contact factors

60
Q

The aPTT is commonly used to monitor the anticoagulant effects of ______

A

heparin

61
Q

Describe how to interpret the findings of a mixing test

A

if a single coagulation factor deficiency is present, the mixing test will completely correct prolongation of the clotting
time. If a coagulation inhibitor is present, mixing will usually not correct the clotting time.

62
Q

A _____ test can be used to assess vWF activity because it causes conformational changes in vWF triggering binding to GpIb

A

Ristocetin

63
Q

The thrombin time test is very sensitive to the presence of _____

A

heparin

Heme (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions