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1. Theme 2 > T2 L2: Haemostasis > Flashcards

T2 L2: Haemostasis Flashcards

1
Q

What is extravasation?

A

Movement of fluid and molecules out of vessels

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2
Q

What is the first stage of wound healing?

A

Haemostasis

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3
Q

What does the endothelium secrete when it’s injured?

A

It stops secreting inhibitors and starts secreting von Willebrand factor

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4
Q

What does von Willebrand factor (vWF) do?

A

A multi-subunit protein that serves both to anchor the platelets to the subendothelial collagen and as a carrier protein for Factor VIII in plasma

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5
Q

What is the 3 step platelet-based pathways for repair of blood vessels?

A
  1. Platelets form a haemostatic plug by adhesion, activation and aggregation.
  2. Coagulation using the enzyme cascade
  3. Vasoconstriction by release of vasoconstrictors and pro-thrombotic agents `
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6
Q

Give 3 examples of molecules used for vasoconstriction

A

Serotonin, ADP, and Thomboxane A2

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7
Q

What are the 3 points of Virchow’s triad?

A

Venous stasis, activation of blood coagulation, and vein damage.

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8
Q

What white blood cells develop from the common lymphoid progenitor?

A

NK cells, T-cells, and B-cells

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9
Q

What do plasma cells develop from?

A

B-cells

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10
Q

What common progenitor do megakaryocytes develop from?

A

The common myeloid progenitor

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11
Q

What cell do thrombocytes develop from?

A

A megakaryocyte

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12
Q

What is thrombocytopaenia?

A

Low platelet count

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13
Q

How many platelets can 1 megakaryocyte produce?

A

About 4000

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14
Q

What does exocytose mean?

A

Excrete

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15
Q

What 3 changes occur to platelets once they’re activated?

A

They start to exocytose, they change shape and their respiratory rate increases

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16
Q

Describe the shape of an activated platelet

A

Irregular shape with many protruding pseudopodia

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17
Q

What do platelets adhere to during the first step of activation?

A

To exposed collagen

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18
Q

What do platelets exocytose once they’re activated?

A

Dense granules like serotonin, ADP, calcium, and Thromboxane A2 (TXA2)

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19
Q

What molecule stimulates platelet aggregation?

A

ADP

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20
Q

Which drug blocks platelet aggregation?

A

Prasugrel via fibrinogen

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21
Q

What happens during platelet activation in detail?

A

Extracellular ADP activates P2Y12 receptors and cause a cation flow

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22
Q

Which 2 clotting factors are not enzymes?

A

Factor V and factor VIII (they’re co-factors)

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23
Q

Where are tissue factors in terms of the endothelium?

A

Behind the endothelium, it’s revealed when the endothelium is damaged which causes coagulation

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24
Q

Where are clotting factor precursors found?

A

In the blood

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25
Q

What is the difference between the intrinsic and extrinsic coagulation pathway?

A

Extrinsic begins with trauma, intrinsic begins with a damaged surface within

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26
Q

What factor does factor 5 develop from?

A

Factor 10

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27
Q

How does Prothrombin (II) turn into fibrin?

A

Prothrombin (II) turns into Thrombin (IIa) by factor 5. Thrombin (IIa) then turns Fibrinogen (I) into Fibrin (Ia). This is the common pathway of the coagulation cascade

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28
Q

What do labs use to stop clotting?

A

Citrate, heparin or EDTA

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29
Q

What is the difference between plasma and serum?

A

Plasma in blood without the white or red cells. Serum is the fluid after clotting has occurred

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30
Q

What is thrombosis?

A

Abnormal formation of a clot locally

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31
Q

What 2 molecules are needed to make fibrin cross-linked?

A

cross-linked fibrin is made with the interaction of factor XIII (fibrin stabilising factor) and Ca2+

32
Q

What is Factor Xa co-factor and why is it needed to activate thrombin?

A

Va is needed because factor Xa activated thrombin poorly

33
Q

What are the 3 ways to activate factor X into factor Xa?

A

Extrinsic Xase, Intrinsic Xase, and thrombin by positive feedback

34
Q

What factors are involved in Extrinsic Xase?

A

Tissue factor and factor VIIa

35
Q

What factors are involved in intrinsic Xase?

A

Factor VIIIa and Factor IXa

36
Q

Describe an example of positive feedback in the coagulation cascade

A

Thrombin. I activates factor V and Factor XIII that activate thrombin later on in the cascade.

37
Q

Describe the prothrombin group of the coagulation cascade

A

Includes factors II, VII, IX, and X. They’re enzymes that turn prothrombin into thrombin. Vitamin K is needed for their synthesis and Ca2+ for their activation. They’re stable

38
Q

Describe the thrombin group of the coagulation cascade

A

Includes factors I, V, and VIII. They’re activated by thrombin. factor V and VIII are co-factors, and factor I is fibrinogen

39
Q

When are thrombin group factors increased?

A

Inflammation, pregnancy and oral contraceptives

40
Q

What does factor IX do?

A

Without it you get Haemophilia B

41
Q

What does factor X do?

A

It clotting factor

42
Q

Where are clotting factors produced?

A

Liver

43
Q

What is the role of vitamin K in clotting?

A

It enables gamma carboxylation of clotting enzymes

44
Q

What is factor 2 also known as?

A

Prothrombin

45
Q

What is the function of plasmin?

A

It lyses fibrin

46
Q

What does plasmin develop from and how?

A

Starts as plasminogen and is made by the liver. It then requires plasminogen activator (tPA) to mature

47
Q

Where can tPA be found?

A

On the surface of endothelial cells

48
Q

What is the function of protein C?

A

It’s a coagulation inhibitor for factor Va and VIIIa. Co-factor protein S is also needed to inactivate Va

49
Q

Where is protein C found?

A

Starts as an inactive enzyme on the surface of endothelial cells

50
Q

What is antithrombin III (ATIII)?

A

A peptide made in the liver that blocks activity of thrombin along with factors Xa and IXa

51
Q

What does Heparin do to antithrombin III?

A

It increases its activity

52
Q

How can the effects of Heparin be reversed?

A

protamine sulfate

53
Q

What does antithrombin III deficiency cause?

A

Unwanted clotting

54
Q

How is vitamin K made in the body?

A

By bacteria in the large intestine but its also found in leafy green veg

55
Q

How does Warfarin work?

A

It prevents recycling of vitamin K but takes a couple of days

56
Q

How can vitamin K deficiency occur?

A

By GI disease or no fat absorption. Liver disease can prevent bile salt production so fat won’t be absorbed

57
Q

What is Haemophillia A?

A

A clotting disorder caused by congenital lack of factor VIII. It’s X-linked so only males have symptoms

58
Q

What is the treatment for Haemophilia A?

A

Purified factor VIII injections

59
Q

What is haemophilia B?

A

A clotting disorder caused by lack of factor IX

60
Q

What was Polly the sheep meant for?

A

So scientists could derive recombinant factor IX out of her milk

61
Q

Describe the process of atherogenesis

A

Injury to the endothelium from a plaque rupture causes monocytes to enter the lesion where they become macrophages. They consume the cholesterol esters and become foam cells. When the macrophages die, they release their contents which attracts more monocytes. This results in inflammation and therefore haemostasis

62
Q

What are cholesterol esters oxidised into?

A

Into oxygen radicles which makes them immunogenic. The oxidised lipids are then consumed by macrophages

63
Q

What does immunogenic mean?

A

The ability for a foreign substance to produce an immune response

64
Q

Why can’t vessels control their dilation when damaged?

A

During injury, the endothelium is stripped away which would usually produce NO

65
Q

What do antiplatelet agents do?

A

Block platelet activation. Good for treating arterial disease especially acute coronary syndromes

66
Q

What do anticoagulants do?

A

They block the production or activity of clotting factors. Used to treat venous disease

67
Q

What are fibrinolytics used for?

A

Used to dissolve fibrin in arterial disease

68
Q

How does aspirin work?

A

It’s a cyclo-oxygenase (COX) inhibitor that blocks the formation of thromboxane A2 in platelets. It lengthens bleeding time but doesn’t increase coagulation time

69
Q

Which drug is used for prophylaxis for MI?

A

Aspirin

70
Q

What does prasugrel do?

A

It’s an antiplatelet drug that blocks ADP receptors

71
Q

What does Clopidogrel do?

A

It’s an antiplatelet drug that blocks ADP receptors

72
Q

What drug class is used for prophylaxis for deep vein thrombosis and pulmonary embolism?

A

Anticoagulants

73
Q

What do Heparins do?

A

They inhibit coagulation (with ATIII) by inhibiting factor Xa. These drugs have to be injected

74
Q

What kind of drug is Dabigatron and how does it work?

A

A novel oral anti-coagulant (NOAC) that inhibits thrombin

75
Q

What kind of drug is Rivaroxaban and how does it work?

A

A novel oral anti-coagulant (NOAC) that inhibits factor Xa

76
Q

What type of drug is streptkinase?

A

A fibrolytic

77
Q

What type of drug is Urokinase?

A

A fibrolytic

1. Theme 2 (12 decks)

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