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Human physiology > haemostasis > Flashcards

haemostasis Flashcards

1
Q

define haemostasis

A

cessation of bleeding

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2
Q

define a harmorrhage

A

excessive flow of blood

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3
Q

what happens in normal haemostasis?

A

when collagen is exposed during injury of the vessels, platelets clump together stopping blood flow

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4
Q

what are te five steps of haemostasis

A 
vessel spasm
platelet plug formation
coagulation
clot retraction
fibrinolysis
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5
Q

what happens in the vessel spasm step?

A

vasoconstriction
triggers pain receptors and reflex of constriction
slows the amount of blood
very ra[id response

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6
Q

what happens to platelets during activation

A

send out protrusions called pseudopodia

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7
Q

what are the types of protrusions made by platelets during activation

A

filopodia: stringy tenticles to establish platelet contact
lamellipodia: flat thin membrane giving coverage

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8
Q

what happens during platelet plug formation?

A

platelets detect actiating molecules using proteins o their surface
activatory molecules bind to the receptor signal causing a cascade
signal transmitted intocells activating platelet

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9
Q

what are strong activators of platelets

A

collagen and thrombin

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10
Q

what is a weak activator of platelets

A

ADP, adrenaline
platelet activating facyor
vasopressin
serotonin

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11
Q

4 steps of platelet plug formation

A

adhesion to site of damage
activation
secretion
aggregation

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12
Q

what are found inside platelets

A

vesicles/granules

alpha and dense graules

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13
Q

what causes platelets to stick to collagen?

A

vWF

transient tethering

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14
Q

what is vWF?

A

plasma protein which sticks to collagen and platelets

weak interaction so just slows patelet down so it can make other interactions

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15
Q

what does vWF allow to bind to the platelet

A

GP6 which triggers the signal cascasde

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16
Q

what effects does GP6 have?

A

shape change
alpha 2B 3 receptor changes shape
secretion

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17
Q

what happens during activation in plug formation

A

the signal cascase: changes shape of the platelet and trggers secreton

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18
Q

what is a dense graule

A

ADP and seronin

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19
Q

what is an alpha granule

A

fibrinogen

vWF

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20
Q

what happens during secretion?

A

graunules inside the platelet released
contense spilled
these activate other platelets and act back on the same platelet
positive feedback

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21
Q

what is the aggregation step of plug formation?

A

receptor alpha2B3 changes to be open

fibrinogen binds clumping the platelets together

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22
Q

what is fibrinogen used for?

A

to bind platelets together

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23
Q

what regulates platelets in health?

A

endothelium produced chemicals to keep platlets calm
PGI2
NO

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24
Q

what does loss of health endotheliam causee>

A

chemical inhibitors to be lost and thus the platelets become activated

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25
Q

what is coagulation?

A

process in which the fluid blood is converted into a gelatinous clot

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26
Q

what happens during coagulation

A

platelet plug covered to make it more stable
red and white cells trapped and stringy strands/ filaments made and fibrin accumulates
jelly clot now

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27
Q

what is fibrin?

A

protein polymer with lots of subunits

monomer is fibrinogen

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28
Q

what makes fibrin?

A

monomers of fibrinogen stick together to make fibron

29
Q

what converts fibrin to fibrinogen?

A

thrombin

30
Q

what is thrombin?

A

converts monomer fibrinogen to polymer fibrin
poretease
not present all the time

31
Q

what is fibrinogen?

A

sticks to fibrin and activated platelets receptors to form the plug

32
Q

what is fibrinogen?

A

sticks to fibrin and activated platelets receptors to form the plug

33
Q

what can lead to th conversion of prothromin to thrombin?

A

intrinsic and extrinsic

34
Q

how does the intrinsic pathway for thrombin work>

A

everything is already int he blood
stimulated in the contact of blood on collagen/charged surfaces
platets activated on exposure to colalgen and release phopholipids

35
Q

what is prothrombin

A

present in the blood all the time

version of throbin thats safer

36
Q

how does the extrinsic pathway for thrombin work?

A

cellular element needed
stimulated by tisseu factor called thromboplastin
damaged tissues release this

37
Q

what is factor 10 xa

A

converts prothrombin to thrombin

38
Q

what does X and XA mean for clotting factors

A

X means inactive

Xa means active

39
Q

what causes haemoaphillia?

A

missing factor 8

40
Q

what is the common pathway of clotting?

A

where the extrinsic and intrinsic pathways come together and are the same from then onwards

41
Q

how does positive feddback control clotting?

A

strong factos

cross talk between the pathways

42
Q

how does negative feedback control clotting?

A

antithrombin 3 inhibtiing thrombin

plasminogen breaking clots down again

43
Q

what is clot retraction

A

clot shrinkage about 20-30 mins after injury

pushes liquid out and pulls wound together for healing

44
Q

`why is fibrinolysis needed?

A

blood flow must be established for permanent tissue repiar to take place
the clot is disolved

45
Q

what enzyme breaks down fibrin and the clot

A

plasmin

46
Q

what converts plasminogen to plasmin?

A

enzymes called plasminogen actvators

47
Q

example of a plasminogen actvator?

A

TPAL

tissue-type plasminogen activator which comes from healthy endothelium to break down the clots

48
Q

wat strops blood in circulation from clotting?

A
  • healthy endothelium
  • clotting factors inactive form
  • flow carries clotting factors away
  • inhibition of clotting factors
  • fibrinolysis
49
Q

what are the patholies of platelet plug formation?

A

arterial thrombosis
mycardial infarction
ischaemic stroke
PAD

50
Q

patholigies of coagulation

A

venous thromobisis

DVT

51
Q

what causes arteial thrombosis?

A

inappropraite activation of platelets in artiers

eg rupture of altherloscloris

52
Q

how can althersclorisi cause arterial thrombosis?

A

fat is depositied into arties and this can break and leak out
this activates the platelets and a clot is formed in the vessel

53
Q

what causes venousthrombosis

A

inappropriate activation of coaulation in the veins

54
Q

wat causes inappropriate activation of coagulation in the veins?

A

virchows traid:
stasis
endothelium damage
hypercoaguability

55
Q

why is venous thromboisis bad?

A

a bit of the DVT can break off in an embolism and travel to somewhere more dangerous such as lungs or heart

56
Q

how is venous thrombosis treated?

A

anticoagulant drugs

57
Q

how is arterial thrombosis treated?

A

anti-platelet drugs

58
Q

what is a fibrinoytic drug used for?

A

disolving clots

59
Q

exa,mple of an antiplatelet drug

A

asprin

60
Q

what does asprin do

A

inhibits platele function and artial thrombosis

inhibits COX making thromboxane A2

61
Q

what does \COX do?

A

converts tothromxane A2

62
Q

example of an anticoagulant drug? e

A

warfrainhat does warfaein do?

63
Q

what does warfrain do?

A

clotting factor made in the liver

inhibits cycling of vitK which is needed to make more clotting factors

64
Q

example of a fibrinolytic drug?

A

tPA

65
Q

what is tPA

A

synthetic enyme to convert plasminogen to plasmin to break down the clot

66
Q

how is arterial thrombosis treated/prevented

A

antiplatelet drugs of asprin

67
Q

how si venous thromosis treated/prevetned

A

antiocoagulant drugs of warfarin

68
Q

how are clots dealt with and treated?

A

fibrinolytic drugs auch as tPA

Human physiology (21 decks)

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