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2=Haematology > 5. Intro to haemostasis > Flashcards

5. Intro to haemostasis Flashcards

1
Q

what is homeostasis?

A

process which changes blood from a fluid to a solid state

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2
Q

haemostasis is a homeostatic mechanism which does the following; (3)

A
  1. minimises blood loss during injury
  2. balance between clotting and bleeding
  3. keeps blood in liquid state when there is no injury
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3
Q

where and what do platelets originate from?

A

BM - megakaryocyte

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4
Q

what is the main hormone controlling platelet production/

A

thrombopoietin

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5
Q

describe shape of plateles

A

discoid anuclear cells

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6
Q

what do platelets do after differentiation and maturation?

A

shed cytoplasm into platelet sized fragments

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7
Q

circulation life span of platelet

A

7-10 days

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8
Q

role of platelets in primary homeostasis

A

form plug at site of injury

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9
Q

2 functions of platelet membrane

A
  1. contains glycoprotein receptors for coagulation factors, endothelium and other platelets
  2. contains phospholipids
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10
Q

2 glycoprotein receptors on platelet membrane - what do each of them bind to?

A 
GP1a = collagen 
GP1b = vWF
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11
Q

what do the phospholipids on platelet membrane bind to?

A

Factors II and X

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12
Q

what is another name for Factor II?

A

thrombin

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13
Q

2 functions of open canalicular system in platelets

A
  1. increase SA - allowing molecules to reach cytoplasm

2. route of extrusion of substances after platelet activation

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14
Q

what is the dense tubular system?

A

internal membrane of platelet derived from ER of parent megakaryocyte

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15
Q

2 functions of dense tubular system of platelets?

A
  1. site of prostaglandin synthesis

2. controls P activation by removing or releasing Ca2+

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16
Q

function of platelet cytoskeleton

A

maintain discoid shape

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17
Q

what organelle in a platelet supports its discoid shape

A

microtubule coil

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18
Q

what 4 haemostasis molecules are contained in alpha granules?

A
  1. platelet factor 4
  2. FV
  3. FVIII
  4. vWF
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19
Q

which granule contains small non-protein secretions?

A

delta granules

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20
Q

what do delta granules contain?

A

ADP, serotonin, small non-proteins

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21
Q

function of lysosomes/lambda granules?

A

digest blood clots when no longer needed

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22
Q

how are activated coagulation factors denoted?

A

a after the factor

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23
Q

where are CF produced?

A

liver

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24
Q

how to coagulation factors bind to platelets?

A

glycoprotein receptors on platelet membrane

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25
Q

coagulation factor number for fibrinogen?

A

I

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26
Q

coagulation factor number for prothrombin?

A

II

27
Q

some CF are serine proteases. what are these?

A

circulating proeznymes known as zymogens

28
Q

which 2 CF are co-factors?

A

V and VIII

29
Q

what is vWF produced by?

A

platelets and vascular endothelial cells

30
Q

3 main stages of haemostasis?

A
  1. primary H
  2. secondary H
  3. fibrinolysis
31
Q

how do normal platelets in healthy tissue travel in the blood?

A

inactive

32
Q

what causes platelet activation?

A

damage in BV endothelium causes release of collagen

33
Q

what effects does the attachment of collagen to platelts cause?

A
  1. changes shape of platelet
  2. activates platelets’s alpha and dense granules to release chemicals
  3. release thrombaxane A2
34
Q

role of thromboxane a2 ?

A
  1. promotes platelet aggregation
  2. activates other platelets
  3. vasocontriction
35
Q

2 ways which platelets attach to endothelium

A
  1. integrin membrane receptor

2. leucine rich motif receptors

36
Q

complex on platelet memrbane which binds vWF

A

GP1b-1X-V complex

37
Q

how do platelets form linkages between each other?

A

fibrinogen (FI) to activated Gp11b11a on adjacent platelets

38
Q

what is PAF?

A

platelet activating factor

39
Q

what CF activates platelet aggregation/activation?

A

thorombin

40
Q

what is formed at the end of primary haemostasis?

A

platelet plug

41
Q

3 steps of secondary haemostasis

A
  1. initiation
  2. amplification
  3. propagation
42
Q

how to remember secondary haemostasis - step 1 initiation?

A

79102

43
Q

what does FIIa activate at the end of initiation?

A

activates coenzymes FV and FVIII, FXI and platelets

44
Q

where do all amplication steps take place?

A

platelet surface

45
Q

4 functions of thrombin in amplification?

A
  1. changes shape of platelets - makes it more sticky
  2. dissociates FVIII from vWF
  3. brings FVa to surface
  4. activates FXI to FXIa
46
Q

how to remember amplification?

A

8511

47
Q

in propagation, what activates FX?

A

FIXa and FVIII

48
Q

what is the result of propagation?

A

larger amounts of prothrombin into thrombin

49
Q

what does thrombin do?

A

converts soluble fibrinogen (FI) into insoluble fibrin (FIa)

50
Q

2 descriptions of coagulation cascade?

A
  1. physiological

2. coagulation testing/classical

51
Q

what does coagulation testing entail?

A

PT and PTT

52
Q

what is PT? what does it measure?

A

prothrombin time - extrinsic pathway

53
Q

what is PTT? what does it measure?

A

Partial thromboplastin time - instrinsic pathway

54
Q

what CF are part of the common pathway

A

1, 2, 5, 10

55
Q

what CF are only part of the extrinsic pathway?

A

7

56
Q

what CF are only part of the instrinsic pathway?

A

8, 9, 11, 12

57
Q

what is the tenase comples?

A

Factors 5, 8 and 9, Ca2+ and phospholipids

58
Q

what other test (other than PTT and PT) can be used to measure haemostasis?

A

factor assay

59
Q

2 reasons why fibrinolysis occurs

A
  1. to prevent excess fibrin formation

2. removes fibrin as new tissue replaces it

60
Q

main component involved in fibrinolysis

A

plasmin

61
Q

3 natural anticoagulants in the body

A
  1. antithrombin
  2. Protein S
  3. protein C
62
Q

what factors does anti-thrombin inhibit?

A

2, 7, 10, 11, TF

63
Q

what factors does protein S and C inhibit

A

co-factors V and VIII

64
Q

what can deficiency of anti-thrombin cause

A

venous thromboembolism

2=Haematology (9 decks)

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