Brainscape's Knowledge GenomeTM

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


See full index

Haematology > Coagulation > Flashcards

Coagulation Flashcards

1
Q

What is the culminative event of coagulation?

A

The generation of thrombin

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

What is Thrombin’s function?

A

Turns soluble fibrinogen to Fibrin

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

What is the function of fibrin?

A

enmeshes the platelet aggregates at the sites of vascular injury and converts the unstable primary plug to firm definitive and stable haemostatic plug

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

Of all the enzymes of coagulation which is not a serine protease?

A

Factor VIII (8)

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

What are the three enzyme complexes that thrombin generation is dependent on?

A

1.Extrinsic case (VIIa, TF, PL, Ca2+)
2.Intrinsic case (IXa, VIIIa, PL, Ca2+)
These 2 pathways both generate FXa and the prothrombinase complex (Xa,Va,PL,Ca2+) generating thrombin

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

How does the generation of thrombin occur after tissue injury?

A

In two waves.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens during the initial wave?

A

Small amount generated which prepares the coag cascade for the second larger burst.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does initiation occur?

A

Occurs by the interaction of membrane bound (TF) which is exposed and activated by an enzyme protein dislphide isomerase after vascular injury, with plasma factor VIIa.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is TF?

A

The sole initiator of thrombin generation and fibrin formation. It is expressed on fibroblasts of the adventitia and small muscle of the vessel wall, and on non vascular cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does Factor VIIa activate?

A

Activates both both Factor IX and Factor X

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

What inhibits the extrinsic pathway (extrinsic case)?

A

Tissue factor pathway inhibitor.

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

What does TFPI form?

A

A complex with VIIa, TF and Xa

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

What does this inactivation of extrinsic pathway lead to?

A

Dependence of thrombin generation on the intrinsic pathway.

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

What happens to the small amounts of Thrombin generated by the Extrinsic pathway?

A

It activates Factors VII and V to VIIIa and Va

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

How is the prothrombinase complex (Xa + Va) formed?

A

Xa is generated by IXa and VIIIa (Intrinsic Xase) in the presence of calcium Ca2+, which then combines with Va PL and Ca2+.

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

What does generation of prothrombinase yeild?

A

THROMBIN

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

What is the role of Factor XI?

A
  1. Does not seem to have a role in physiological initiation of coag.
  2. Appears to have a role in activation of Factor IX.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the role of Thrombin? How does it work?

A

Hydrolyzes fibrinogen releasing Fibrinipeptides A and B to form Fibrin monomers.

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

What Happens to The Fibrin monomers?

A

Bound spontaneously by hydrogen bonding to form loose insoluble fibrin polymer.

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

How is Factor XIII activated?

A

By Thrombin + Ca2+

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

What is a function of Xllla?

A

Stabilizes the fibrin polymers with formation of covalent cross links

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

Describe Fibrinogen

A

Heterodimer of 3 dissimilar sub units Alpha, Beta, and Gamma.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Which factors are dependent upon Vitamin K?

A

2, 7, 9, 10

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

Why is vitamin K important for these factors?

A

Carboxylates some terminal glutamic acid residues on those molecules.

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

Which 2* factors are not protease enzymes?

A

V and VIII

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

What 3 molecules produced by Endothelial cells have a inhibitory effect on platelets?

A

NO, CD39, and Prostacyclin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What 2 molecules released by platelets also have vasocontricive activity?

A

TXA2 and Fibrinopeptides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What facilitates platelet adherence to exposed connective tissue?

A

GPIa and GPIb mediated via VWF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How does platelet aggregation and release accelerate the coagulation process?

A

By providing abundant membrane phospholipid

30
Q

What molecules does TFPI inhibit?

A

Xa. VIIa, and Thrombin

31
Q

How does TFPI work?

A

Forms a quaternary complex

32
Q

What is another direct inactivator of thrombin and other serine proteases?

A

antithrombin-the most potent

33
Q

What drug potentiates the action of antithrombin?

A

Heparin

34
Q

What are some other thrombin and serine protease inhibitor

A

Heparin cofactor II (only thrombin), Alpha 2 macroglobulins, Alpha2-antiplasmin, C1 esterase inhibitor and a1-antitrypsin (only serine proteases)

35
Q

What are proteins C & S?

A

These are inhibitors of Factors V and VIII

36
Q

How is Protein C activated?

A

Thrombin binds to the endothelial cell surface receptor thrombomodulin

37
Q

What other Vitamin K dependent protein enhances the activity of protein C?

A

Protein S.
It binds protein C to the platelet surface, and endothelial protein C receptor localizes protein C to the endothelial cell surface.

38
Q

What else does activated protein C enhance?

A

Fibrinolysis

39
Q

What else does Protein C inhibit?

A

TFPI and thus increases fibrinolysis

40
Q

What is plasminogen?

A

A B-blobulin proenzyme in blood and tissue fluid that is converted to a serine protease plasmin by activating factors of both intrinsic and extrinsic pthwy

41
Q

What is TPA?

A

A serine protease that binds to fibrin, enhancing its capacity to convert thrumbus bound plasminogen to into plasmin

42
Q

How does Protein C affect TPA levels?

A

Protein C destroys plasma inhibitors of TPA

43
Q

How does thrombin inhibit fibrinolysis?

A

By activating TAFI

44
Q

What is the function of Plasmin?

A

Generation of plasmin at the site of injury limits the extent of the evolving thrombus

45
Q

What is one of the functions of the split fibrin products?

A

Competitive inhibitors of thrombin and Fibrin polymerization

46
Q

What inhibits most local free plasmin?

A

Alpha2-antiplasmin

47
Q

What are two well known and characterized fibrin degradation products (used to test for DIC)?

A

Fragments D and E

48
Q

What are the molecules that Plasmin is capable of digesting?

A

Fibrinogen, fibrin, Factors V and VII

49
Q

What inhibits TPA?

A

PAI

50
Q

What inactivates circulating plasmin?

A

Alpha2-antiplasmin and Alpha2-Macroglobulin

51
Q

What does PT measure?

A

Factors VII, X, V, Prothrombin and Fibrinogen

52
Q

PTT measures what?

A

VIII, IX, XI, XII, X, V, Prothrombin and Fibrinogen

53
Q

How is defect of a factor checked?

A

By adding normal plasma to test plasma 50:50

54
Q

If the test fails what is indicated?

A

The presence of an inhibitor of coagulation

55
Q

What interaction intiates the platelets to degranulate?

A

Binding to Collagen

56
Q

What is released on degranulation?

A

ADP TXA2

57
Q

Deficiency of factor XIII leads to?

A

Normal clotting but clots are not stabilized and break down and bleeding continues

58
Q

How does Factor XIII work?

A

It is a transaminase that covalently links fibrin polymers

59
Q

What do haemophilia A patients lack?

A

Factor VIII

60
Q

What do Haemophilia B patients lack?

A

Factor IX

61
Q

What is the difference between serum and plasma?

A

Plasma contains unactivated clotting factors, serum contains used up clotting factors.

62
Q

Factor XII deficiency causes?

A

Long PTT but patients won’t bleed out

63
Q

Cannot fix clotting factor deficiency with?

A

Fresh frozen plasma.

64
Q

Normal PT and PTT but still bleeding suggests?

A

Deficiency of factor XIII

65
Q

What is the ratio of prothrombin 1.2 : thrombin after the cleavage by prothrombinase?

A

1:1

66
Q

How does factor VIII exist in the circulation?

A

Bound to VWF

67
Q

What is Anti-thrombin III?

A

An anti-serine protease, neutralizes the active site on a serine protease

68
Q

How does heparin affect anti-thrombin III?

A

It binds at an allosteric site and makes it a much more effective anti serine protease.

69
Q

What is a naturally occuring analogue of heparin that has the same effect on anti-thrombin III?

A

Haparan sulphate

70
Q

What are D dimers specific for?

A

Cross-linked fibrin.

Haematology (16 decks)

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