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2=Haematology > 5. Intro to haemostasis > Flashcards

5. Intro to haemostasis Flashcards

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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
coagulation factor number for fibrinogen?
I
26
coagulation factor number for prothrombin?
II
27
some CF are serine proteases. what are these?
circulating proeznymes known as zymogens
28
which 2 CF are co-factors?
V and VIII
29
what is vWF produced by?
platelets and vascular endothelial cells
30
3 main stages of haemostasis?
1. primary H 2. secondary H 3. fibrinolysis
31
how do normal platelets in healthy tissue travel in the blood?
inactive
32
what causes platelet activation?
damage in BV endothelium causes release of collagen
33
what effects does the attachment of collagen to platelts cause?
1. changes shape of platelet 2. activates platelets's alpha and dense granules to release chemicals 3. release thrombaxane A2
34
role of thromboxane a2 ?
1. promotes platelet aggregation 2. activates other platelets 3. vasocontriction
35
2 ways which platelets attach to endothelium
1. integrin membrane receptor | 2. leucine rich motif receptors
36
complex on platelet memrbane which binds vWF
GP1b-1X-V complex
37
how do platelets form linkages between each other?
fibrinogen (FI) to activated Gp11b11a on adjacent platelets
38
what is PAF?
platelet activating factor
39
what CF activates platelet aggregation/activation?
thorombin
40
what is formed at the end of primary haemostasis?
platelet plug
41
3 steps of secondary haemostasis
1. initiation 2. amplification 3. propagation
42
how to remember secondary haemostasis - step 1 initiation?
79102
43
what does FIIa activate at the end of initiation?
activates coenzymes FV and FVIII, FXI and platelets
44
where do all amplication steps take place?
platelet surface
45
4 functions of thrombin in amplification?
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
how to remember amplification?
8511
47
in propagation, what activates FX?
FIXa and FVIII
48
what is the result of propagation?
larger amounts of prothrombin into thrombin
49
what does thrombin do?
converts soluble fibrinogen (FI) into insoluble fibrin (FIa)
50
2 descriptions of coagulation cascade?
1. physiological | 2. coagulation testing/classical
51
what does coagulation testing entail?
PT and PTT
52
what is PT? what does it measure?
prothrombin time - extrinsic pathway
53
what is PTT? what does it measure?
Partial thromboplastin time - instrinsic pathway
54
what CF are part of the common pathway
1, 2, 5, 10
55
what CF are only part of the extrinsic pathway?
7
56
what CF are only part of the instrinsic pathway?
8, 9, 11, 12
57
what is the tenase comples?
Factors 5, 8 and 9, Ca2+ and phospholipids
58
what other test (other than PTT and PT) can be used to measure haemostasis?
factor assay
59
2 reasons why fibrinolysis occurs
1. to prevent excess fibrin formation | 2. removes fibrin as new tissue replaces it
60
main component involved in fibrinolysis
plasmin
61
3 natural anticoagulants in the body
1. antithrombin 2. Protein S 3. protein C
62
what factors does anti-thrombin inhibit?
2, 7, 10, 11, TF
63
what factors does protein S and C inhibit
co-factors V and VIII
64
what can deficiency of anti-thrombin cause
venous thromboembolism

2=Haematology (9 decks)

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