Brainscape's Knowledge GenomeTM

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


See full index

Sympsoiums yr2 > 9- Haemostasis > Flashcards

9- Haemostasis Flashcards

1
Q

What is haemostasis?

A

The body’s response to injury/bleeding by stopping blood flow?

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

What are the 5 main stages of haemostasis

A
  1. Vasoconstriction
  2. Platelet plug formation
  3. Coagulation pathways
  4. Coagulation inhibitors
  5. Fibrinolysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is exposed when you have a vessel injury?

A

Collagen

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

What is the first haemostatic line of defence?

A

vasoconstriction of the blood vessels

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

Name some chemical vasoconstrictors

A

Serotonin, Thromboxane A2

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

What is the second haemostatic line of defence?

A

Platelet plug formation

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

What is another name for platelets?

A

Thrombocytes

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

What stimulates the production of platelets?

A

Thrombopoietin

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

Where is thrombopoietin produced?

A

In the liver

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

Where are platelets produced?

A

In the bone marrow

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

What stem line do platelets (thrombocytes) come from?

A

Myeloid stem line

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

What is the precursor of thrombocytes?

A

Megokaryocytes

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

What is the precursor of megakaryocyte?

A

Megakaryoblasts

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

How many platelets is one megakaryocyte equal to?

A

1 megakaryocyte = 4000 platelets

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

What is the diameter of a platelet/thrombocyte?

A

2-4um

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

What is the lifespan of circulating platelets?

A

9-10 days

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

What is the normal platelet count?

A

150 - 400x10^9

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

What does a platelet contain?

A

No nucleus, mainly contains granules needed for haemostatic process (e.g- calcium, ADP, Serotonin (vasoconstictor), and clotting factors such as vWF, factor V, factor VIII)

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

What is the ratio of red blood cell to platelet to white blood cell?

A

700:40:1

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

What are the 3 main stages of platelet plug formation?

A
  1. Adhesion
  2. Release of granular contents
  3. Aggregation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does exposed collagen do?

A

attracts platelets, which stick to the damage surface thus activating the platelet

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

What does the activated platelet then do?

A

Release its granular contents (e.g, calcium, ADP, Serotonin, vWF, factor V, factor VIII)

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

What is aggregation?

A

granular contents which begin to clump together to form a haemostatic platelet plug

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

How does the platelet adhere to exposed collagen on blood vessel?

A

adheres via glycoproteins and vWF

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

What does adhesion activate?

A

Activates prostoglandin synthesis

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

What does prostoglandin stimulate?

A

prostoglandin stimulates ADP release from dense bodies, causing the platelets to swell promoting adhesion

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

What does ADP stimulated by prostoglandin cause?

A

Causes platelets to swell and adhere better

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

What kind of feedback mechanism does ADP release lead to?

A

positive feedback, more ADP and TXA2 released, further adhesion, more platelet aggregation

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

What does further platelet aggregation around blood vessels lead to?

A

formation of the platelet plug plug

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What induced platelet aggregation?

A

ADP, Thromoboxane A2 and phospholipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the next step once the platelet has been activated?

A

Coagulation Pathways

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How does an activated platelet appear on an electron microscope?

A

Green, psuedophilia like extentions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How does a non-activated platelet appear on an electron microscope?

A

Blue, round disc shaped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the third haemostatic line of defence?

A

Coagulation factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Name some coagulation factors

A
  • tissue factor (FIII)
    -pro thrombin (FII)
  • thrombin (FIIA)
    others are known by factor number:
  • factor 8 (VIII)
  • factor 9 (IX)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Where are coagulation factors produced?

A

in the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What 2 things do coagulation factors need to be produced?

A
  • vitamin k

- calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

How do you show a factor is activated?

A

a = activated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

How many coagulation pathways are there?

A

3 pathways

  1. extrinsic pathway
  2. intrinsic pathway
  3. common pathway
40
Q

What is the main initiator of the coagulation process?

A

‘tissue factor” which is exposed on the damaged blood vessle

41
Q

What is the first clotting factor which binds to tissue factor

A

clotting factor VII, activates and binds to the tissue factor forming “factor VII-Tissue factor complex”

42
Q

What does tissue factor VIIa complex activate?

A

factor X

43
Q

What does factor X activate in the extrinsic pathway?

A

Small amount of prothrombin to be converted to thrombin

44
Q

How is the activation of prothrombin regulated?

A

tissue factor pathway inhibitor

45
Q

How is the intrinsic pathway different to the extrinsic?

A

it is slower than extrinsic but more efficient

46
Q

What 2 factors does the intrinsic pathway utilise?

A
  • factor IX (9)

- Cofactor VIII (8)

47
Q

Briefly describe the intrinsic pathway

A

factor XII bingd to clotting factors VIII and IX and platelet factors to form factor X activator complex. This activated FX to FXa

48
Q

What does factor X activate in the intrinsic pathway?

A
  • small amounts of prothrombin to thrombin

- thrombin activates co-factor 8 from factor 9 helping to activate factor X to factor Xa

49
Q

What is the main outcome of the common pathway?

A

Fibrin production

50
Q

What are the 2 co-factors of prothrombinase?

A

Factor Xa and Factor Va

51
Q

What does prothrombinase do?

A

Activates prothrombin to thrombin

52
Q

What does thrombin do?

A

Thrombin converts fibrinogen to fibrin

53
Q

What does activated FXa and Thrombin activate?

A

Factor Va

54
Q

what does FXa and FVa make up

A

prothrombinase

55
Q

Which pathway produces enough thrombin to convert fibrinogen to fibrin?

A

the common pathway

56
Q

What is thrombin?

A

An enzyme in blood plasma that causes the clotting of blood by converting fibrinogen to fibrin

57
Q

What factor stabilises the fibrin clot?

A

FACTOR 13 XIII, produces a stable haemostatic plug

58
Q

What does a stable haemostatic plug allow?

A

no more blood loss, prevents damage and allows wound to start healing

59
Q

What helps regulate the coagulation pathway ?

A

coagulation inhibitors

60
Q

Name 3 coagulation inhibitors

A
  1. Tissue factor pathway inhibitor
  2. Antithrombin
  3. Heparin co-factor
61
Q

How does tissue factor pathway inhibitor work?

A

Acts on factor VIIa and Xa, used in extrinsic pathway

62
Q

Which coagulation inhibitor works in the extrinsic pathway?

A

Tissue factor pathway inhibitor

63
Q

How does antithrombin work?

A

Works on factor Xa and thrombin, used in common pathwy to help regulate coagulation process and thrombin feedback

64
Q

Which coagulation inhibitor works in the common pathway?

A

Antithrombin

65
Q

What does heparin cofactor act on?

A

Thrombin

66
Q

What is the final stage of haemostasis?

A

Fibrinolysis

67
Q

What is fibrin broken down by into?

A

Fibrin is degraded by plasmin into fibrin degredation products (FDP)

68
Q

Why are FDPs (fibrin degredation products) helpful

A

they tell us the amount of clotting going on in the body. i.e. lots of FDP = excessive production therefore a clot may be present

69
Q

Name some laboratory tests for haemostatisis?

A
  1. Bleeding test
  2. Prothromin time
  3. Activated partial thromboplastin time
70
Q

Which test can you do that looks at platelet numbers/functions

A

A bleeding test

71
Q

What does a bleeding test look for?

A
  1. tests for abnormal platelet function

2. tests platelet count

72
Q

Normal platelet count?

A

150 - 400 x 10^9/L

73
Q

What does prothrombin time look at?

A

How blood clots, the coagulation process

measures factors in the extrinsic pathway : VII, X, V, prothrombin, Fibrinogen

74
Q

What is normal prothrombin time?

A

10-14 seconds

75
Q

In which patients would prothrombin time be prolonged?

A
  • patients with liver disease as alot of the clotting factors are produced n the liver
  • patients on oral anticoagulants (e.g- warfarin)
76
Q

What is prothrombin time standardised as?

A

INR (International Normalised Ratio)

77
Q

Name some oral anticoagulants

A

Warfarin

78
Q

What is warfarin

A

An oral anticoagulant which decreases vitamin k dependant factors II, V, VII, IX and X
only prevents new factors being produced, doesn’t affect pre-formed factors

79
Q

What is warfarin prescribed for?

A
  • atrial fibrillation
  • deep vein thrombosis
  • heart valve replacement
80
Q

What is the INR range in patients on warfarin?

A

2.0 to 3.0

81
Q

What does activated partial thrombinase time (APTT) measure?

A

measures factors in the intrinsic pathway: VIII, IX, XI, XII and also X, V, prothrombin and fibrinogen

82
Q

What is normal APTT (activated partial thrombinase time )

A

3-40 seconds

83
Q

When is APTT prolonged?

A

in haemophillia, heparin therapy

84
Q

What does heparin do?

A

Increases the action of antithrombin on thrombin and FXa, acts immediately to prevent clots

85
Q

Explain Low Molecular Weight Heparin?

A

Has high bioavailabltiy (93%), injected into abdomen subcutaneously

86
Q

Why is heparin given in pregnancy instead if warfarin?

A

Warfarin can cross the placenta and cause harm to the baby

87
Q

What do direct oral anticoagulants do?

A

Target Thrombin and Factor Xa directly (common to both pathways)

88
Q

Thrombin’s action in anticoagulants?

A

final effector of blood coagulation and most potent platelet agonist

89
Q

FXa’s action in anticoagulants?

A

Shown to activate clotting over wider concentration than thrombin

90
Q

Name a thrombin inhibiting drug?

A

Dabigatran : PRADAXA

91
Q

Name a Factir Xa inhibiting drug?

A

Rivaroxaban : XARELTO

92
Q

Name some antiplatelet drugs

A

Aspirin
Clopidogrel
Ticlopidine

93
Q

How does aspirin work as an antiplatelet drug?

A

inhibits COX enzyme required for platelet production of Thromboxane A2

94
Q

How does clopidogrel work as an antiplatelet drug?

A

irreversibly blocks ADP receptor on platelet membrane (blocks IIb/IIa complex)

95
Q

why do dentist need to know about haemostasis?

A

possibilty of bleeding prevention is key

Sympsoiums yr2 (27 decks)

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