Brainscape's Knowledge GenomeTM

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


See full index

Y1 - PP > Lecture 9 - Intro To Haemostasis > Flashcards

Lecture 9 - Intro To Haemostasis Flashcards

1
Q

What is haemostasis?

A

Maintenance of fluid status in normal vessels whilst permitting rapid formation of a haemostatic clot at a sit of vascular injury

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

What are the 3 components of haemostasis?

A

Vascular wall

Platelets

Coagulation cascade:
-Coagulation factors
-Anticoagulant factors

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

What is the basic aim of normal haemostasis?

A

Stopping bleeding following trauma to blood vessel

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

What are the 3 general processes of stopping normal bleeding?

A

Vessel wall contracts
Platelet plug forms
Fibrin clot forms to stabilise

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

How does vessel size relate to bleeding from the vessel?

A

larger vessel = more bleeding

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

What cells are platelets made from?

A

Megakaryocytes

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

Where are megakaryocytes/platelets made?

A

In the bone marrow

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

What is the normal platelet count?

A

150 - 400 x 10^9/L

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

What 3 stages do platelets go through when a vessel is injured?

A

Adhesion
Activation
Aggregation (Forms platelet clot)

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

How do platelets adhere to blood vessels?

A

Collagen from tunica adventitia exposed

Von Willebrand factor produced by vascular endothelial cells binds to platelets binding the platelets to the collagen fibres adhering them

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

When platelets are activated what do they secrete?

A

Granules containg:
-Fibrinogen
-ADP
-Thromboxane
-Some coagulation factors
And more substances to activate other platelets

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

What is platelet aggregation?

A

When platelets cross link to form a platelet plug

Platelet plug adds some stability but is quite weak

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

What is the role of collagen in platelets action?

A

Binds platelets to vessel wall

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

What is the role of Von Willebrand factor?

A

To get platelets to adhere to the collagen

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

What is the role of ADP and Thromboxane?

A

Cause platelets to interact and form a platelet plug

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

What is the role of Thrombin?

A

Converts fibrinogen to fibrin

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

Why is formation of fibrin important?

A

It is insoluble so is what forms the stable clot

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

What is a zymogen?

A

A proenzyme (enzyme that is not active)

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

What is the clotting cascade aiming to produce?

What is the point of producing this?

A

Thrombin

Thrombin needed to convert fibrinogen into fibrin

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

Why does fibrinogen need to be converted into fibrin?

A

Fibrinogen is soluble
Fibrin is insoluble

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

Why do natural anticoagulants exist?

A

To carefully balanced the clotting cascade to prevent over clotting

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

What are the 2 pathways of the clotting cascade that lead to the common pathway?

A

Intrinsic pathway (contact activation pathway

Extrinsic pathway (tissue factor pathway)

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

What do both the intrinsic pathway and the extrinsic pathway produce which is the common insertion point into the common pathway?

A

Factor X (10)

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

What does Factor X (10) do in the common pathway?

A

Convert prothrombin to thrombin

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

Where are most the coagulation factors made?

A

The Liver

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

What are the 3 coagulation tests for clotting defects?

A

APTT (Activated partial Thromboplastin time)
PT (Prothromin time)
TT (Thrombin time)

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

What pathways does PT (prothrombin time) measure?

A

Extrinsic pathway

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

The function of what clotting factor is assed by PT (extrinsic pathway)?

A

Factor VII

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

What pathway is the (Activated partial thromboplastin time) APTT measuring the functioning of?

A

Intrinsic pathway

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

What does increased/abnormal APTT and PT indicate?

A

Problem in common pathway
(From factor X downwards)

Usually deficient Factor V, X, thrombin an fibrinogen

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

What does Thrombin clotting time measure?

A

Conversion of fibrinogen to fibrin via action of thrombin

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

If somebody has Haemophilia A or B what anticoagulation test is abnormal?

A

APTT (activated partial thromboplastin)

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

What happens to the vessel wall when damaged?

A

Vasoconstriction (Reduce blood flow/bleeding)

Producing Von Willebrand factor (so platelets stick to the collagen)

Exposure of platen and tissue factor initiates activation of clotting factors

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

What is the goal of haemostasis?

A

Make a clot
Control clotting
Break down clot

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

What 3 natural anticoagulants?

A

Protein C
Proteins S
Antithrombin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What Factors does Protein C inactivate?

A

Factor VIIIa
Factor Va

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

How is protein S related to Protein C?

A

Proteins S is a cofactor for protein C

Protein S must be activated in order for Protein C to be activated

38
Q

What vitamin is the synthesis of Protein C and Protein S dependant on?

A

Vitamin K dependant

39
Q

What does Antithrombin inactivate?

A

Thrombin
Other clotting factors

40
Q

What activates Antithrombin?

A

Heparin

41
Q

What is the function of Antithrombin on the body as a whole ?

A

Prevents spread of clot (rapidly inactivates travelling clotting factors)

42
Q

Where does Tissue Factor Pathway Inhibitor act?

A

Start of Extrinsic pathway inhibiting Factor VII
Extrinsic pathway = tissue factor activation pathway

43
Q

What is Fibrinolysis?

A

Break down of the final clot

44
Q

What takes place in fibrinolysis?

A

Plasminogen converted to plasmin
Plasmin breaks down clot forming D-Dimers

45
Q

What is the clinical significance of measuring D-Dimers in the blood?

A

Indicates clotting is taking place

46
Q

What causes bleeding disorders?

A

Abnormalities in:
-Vessel wall
-Platelets
-Coagulation factors

47
Q

What is Thrombocytopenia?

A

Deficiency of platelets in the blood resulting in bleeding into the tissues, bruising and slow blood clotting after injury

48
Q

What are the signs of Thrombocytopenia?

A

Purpura
Petechiae
Mucosal bleeding
Epistaxis
Menorrhagia

49
Q

What are the signs of Thrombocytopenia?

A

Purpura
Petechiae
Mucosal bleeding
Epistaxis
Menorrhagia

50
Q

What is Purpura?

A

Haemorrhages in skin

51
Q

What is petechiae?

A

Red dots/rash on skin

52
Q

What is epistaxis?

A

Nose bleeds

53
Q

What is menorrhagia?

A

Heavy menstrual periods

54
Q

On a basic level, how does Thrombocytopenia happen?

A

Decreased production
Increased consumption

55
Q

What are some causes of decreased production of platelets?

A

Marrow aplasia
Megaloblastic anaemia
Sepsis

56
Q

What are some immun causes of thrombocytopenia?

A

Immune Thrombocytopenic Purpura

Thrombotic Thrombocytopenic Purpura

57
Q

What is Immune Thrombocytopenic Purpura?

A

Low platelet count with a normal bone marrow and any other cause of low platelets has been ruled out

58
Q

What is Thrombotic Thrombocytopenic Purpura?

A

Many small blood clots forming in small vessels are ounce the body

Leads to platelets and RBCs being used up and consumed

59
Q

What are some non immune causes of thrombocytopenia?

A

Haemolytic-uraemic syndrome (HUS)

Hypersplenism

Disseminated Intravascular Coagulation

60
Q

What’s characteristic of Haemoytic-uraemia syndrome (HUS)?

A

Low RBCs
Acute kidney injury
Low platelets

61
Q

Who often get Haemoytic-uraemia syndrome?

A

Children more than adults
Associated with E.Coli infection

62
Q

What are the symptoms of Haemoytic-uraemia syndrome?

A

Bloody diarrhoea
Fever
Vommiting
Weakness
Kidney failure
Low platelets

63
Q

How does Hypersplenism cause Thrombocytopenia?

A

Enlarged overactive spleen removes too many platelets from blood

(Bone marrow tries to proliferate more to compensate)

64
Q

What are the 3 most common congenital Coagulation factor disorders?

A

Haemophilia A
Haemophilia B
Von Willebrand’s disease

64
Q

What are the 3 most common congenital Coagulation factor disorders?

A

Haemophilia A
Haemophilia B
Von Willebrand’s disease

65
Q

What type of genetic inheritance are both forms of Haemophilia?

A

X linked recessive

66
Q

What Factor is lacking in Haemophilia A?

A

Factor VIII

67
Q

Why in Haemophilia A is APTT longer but PT normal?

A

Factor VIII is normally present in intrinsic pathway which is measured by APTT

PT measures the extrinsic pathway (factor VII)

68
Q

How is Haemohillia A treated?

A

Recombinant Factor VIII

69
Q

What Factor is deficient in Haemophilia B?

A

Factor IX

70
Q

Why is APTT prolonged but PT normal with Haemophilia B?

A

Factor IX involved in intrinsic pathway

71
Q

What is the only way to distinguish between Haemophilia A and B and why?

A

Presence of Factor VIII or IX

Both have same results of prolonged APTT and normal PT

72
Q

How does Haemophilia present?

A

Prolonged bleeding post dental extraction
Muscle haematomas
Life threatening post operative an post traumatic bleeding
Easy bruising
Mass haaemorrhaging

73
Q

What type of disease is Von WIllebrand disease?

A

Autosomal dominant

74
Q

What is reduced in Von Willebrand disease?

A

Reduced platelet adhesion to vessel walls
Reduced Factor VIII

75
Q

How does Von Willebrand Disease present?

A

Spontaneous nose bleeds
Excessive wound bleeding
Menorrhagia

76
Q

What do vessel wall abnormalities usually lead to?

A

Easy bruising
SPontaeous small vessel bleeds
Mainly from skin but can be mucous membranes

77
Q

What are 2 examples of vessel wall abnormalities?

A

Ehlers Danlos (connective tissue disorders)

Scurvy

78
Q

What is Disseminated Intravascular coagulation (DIC)?

A

Lots of small blood thrombi form and get broken down
Platelets and clotting factors get consumed
When actually need to form clots (Haemostasis) you can so you haemorrhage

79
Q

What would the levels of fibrinogen and D dimers be in someone with DIC and why?

A

Low fibrinogen
High D dimers

Lots of fibrinogen converted to fibrin due to overactive clotting
Lots of fibrolysis happening so high D-Dimers

80
Q

There is always a trigger to cause DIC, what are some?

A

Malignancy
Massive tissue injury (burns)
Infections (gram - sepsis)
Massive haemorrhage
Obstetric cause (amniotic fluid embolism, preeclampsia)

81
Q

What are Thrombophilias?

A

Congenital or acquired defects of haemostasis which can increase a patients risk of thrombosis

82
Q

What is a congenital cause of thrombophilia?

A

Deficient in anticoagulants

83
Q

What is more likely to happen in antiphospholipid syndrome?
Who is more likely to get this defect?

A

Clot development
A thrombophilia

Afro-Caribbean’s, Hispanics, Asians and Native Americans

84
Q

What are some Anticoagulant drugs?

A

Vitamin K inhibitors (Warfarin)
Direct oral anticoagulants
Heparin

85
Q

What are some Direct oral anticoagulants?
How do they work?

A

Dabigatran
Rivaroxaban
Apixaban

Rivaroxaban and Apixaban inhibit Factor X, this means that less prothrombin is converted to thrombin so less fibrinogen to fibrin

86
Q

Why is warfarin being moved away from as an anticoagulant?

A

Needs constant patient monitoring

87
Q

What are 2 anti platelet drugs?

A

Aspirin
Clopidogrel

88
Q

How does Aspirin act as an anti platelet drug?

A

Blocks formation of Thromboxane
Therefore preventing formation of platelet plug

89
Q

How does Clopidogrel act as an anti platelet drug?

A

Blocks ADP produced by platelets
Preventing the formation of the platelet plug

90
Q

What is the main risk of anticoagulants?

A

BLEEDING

91
Q

What is the most common Inherited Thrombophilia in Caucasians?

What type of inheritance?

A

Factor V Leiden

Autosomal dominant

Y1 - PP (20 decks)

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