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DD/BL unit 3 > platelet function and pt approach > Flashcards

platelet function and pt approach Flashcards

1
Q

Platelets stem from

A

megakaryocytes

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2
Q

Newly formed platelets are larger in size and termed _____

A

megathrombocytes

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3
Q

Plt maturation time is ____ days and circulating life span of ____ days

A

4-5; 9-10

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4
Q

What do platelets have and do NOT have?

A

Have mitochondria and 3 functional granules (alpha, dense, lysosomal)
Canalicular system
cytoplasmic framework
DO NOT have nucleus

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5
Q

Dense Granules contains:

A

ATP, ADP, Serotonin, calcium

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6
Q

Alpha granules contain:

A

procaogulant proteins (fibrinogen, F5, vWF), plt specific factors (for activation) and growth factor

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7
Q

Lysosomal granules contain

A

acid hydrolases

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8
Q

Internal membrane tunnels in platelets are called ____ where granules can be secreted

A

canalicular system

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9
Q

What interactions occur during platelet adhesion

A

GP1b - vWF
GPIIb/IIIa (aIIbb3) - vWF (and fibrinogen)
GPVI - collagen
b1 integrin - ligands in subendothelium (collagen, laminin, fibronectin)

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10
Q

What stick to vWF during adhesion?

A

GP1B

GPIIb/IIIa

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11
Q

What sticks to collagen during adhesion?

A

GPVI

b1 integrin

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12
Q

what are soluble agents?

A

thrombin, thromboxane A2, epinephrine, ADP

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13
Q

Effects of soluble agents?

A

Increase GPIIb-IIIa to vWF

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14
Q

Soluble agents –> G protein coupled platelet membrane receptor leads to?

A

Intracellular signaling, ca mobilization

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15
Q

Calcium mobilization leads to ____?

A

activation of phospholipase A2

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16
Q

Phospholipase A2 does what?

A

releases arachidonic acid from phospholipids

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17
Q

COX 1 convert AA –>?

A

Thromboxane A2 (TXA2)

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18
Q

TxA2 with other agonist will ____?

A

further amplify platelet activation

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19
Q

Platelet activation = membrane will?

A

Switch phospholipid phosphatidylserine to outer membrane

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20
Q

Phospholipid phosphatidylserine is important to ?

A

interact with clotting factor –> generate thrombin

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21
Q

GPIIb IIIa from low to high affinity requires:

A

soluble agonists, subendothelial matrix, talin (membrane protein) to G protein

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22
Q

High affinity GPIIb IIIa can bind

A

vWF AND Fibrinogen

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23
Q

Fibrinogen and platelet interaction

A

fibrinogen acts as a bridge to lace/connect platelets together –> aggregate

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24
Q

Thrombin effect on clot

A

Fibrinogen to fibrin –> stablize clot

Factor XIII –> stablizes clot

25
Q

vWD tests to run

A

prolonged BT (abnormal plt-endothelial interactions)
PFA-100 (platelet function analyzer - should be normal)
Factor 8 level
vW Ab –> determine # of vWF
Ristocetin cofactor activity - vWF activity
vWF multimer assay - qualitative defect

26
Q

Bernard Soulier SYndrome is autosomal ____ disorder; Expression of ____ on platelet surface is reduced

A

recessive; GP1b

27
Q

Bernard soulier syndrome - platelet aggregation studies only show abnormal _____?

A

platelet aggregation with ristocetin

28
Q

Gray platelet syndrome:

A

deficiency in alpha granules

29
Q

gray platelet syndrome can be acquired _______ or rare defect in signal transduction pathway within plt

A

platelet pass across abnormal vascular surface (cardiopulmonary bypass apparatus)

30
Q

Afibrogenemia is _______ and leads to ________ hemostatis defect

A

Lack of fibrinogen (for GPIIbIIIa - for aggregation); primary (platelet plug) AND secondary (fibrin crosslinking)

31
Q

vWD presents with

A

mucosal/skin bleeding

32
Q

afibrogenemia presents with

A

mucosal and cutaneous bleeding + deep muscle hematomas

33
Q

Glanzmann thrombasthenia is a _____ bleeding disorder caused by _______

A

AR

Absent/defective GPIIbIIIa

34
Q

Glanzmann thrombasthenia - platelets can ____ but cannot ____

A

adhere

(no) aggregate

35
Q

Glanzmann thrombasthenia presents with

A

petechiae and easy brusing

36
Q

ITP = aka?

A

Immune thormbocytopenic purpura

37
Q

Etiology of ITP

A

antibody to platelet antigen –> remove by macrophage/RES

Acute (viral) or Chronic

38
Q

Acute ITP typically in ____ (pt population), presents with _____, likely caused by _____

A

children/young adults
petechiae/nosebleeds
viral infection - self resolving 2-6 weeks (can give steroids)

39
Q

Chronic ITP typically in ____ (pt population), caused by __________, typical treatments are ______

A

adults
concurrent autoimmune disorder, lymphoa, HIV, (?)
corticosteroids, IVIG, splenectomy

40
Q

ITP and steroid - how does it work

A

steroids dampen B cell proliferation = decrease antibody = less autoimmune (7-9 day lag)

41
Q

ITP and IVIS - how does it work?

A

IVIG - block FcR - prevents binding to antibody coated platelets (1-2 day lag)

42
Q

Splenectomy and ITP, why?

A

Remove site of autoanitbody induced platelet removal - 60-70% lasting responses

43
Q

Alloimmune thrombocytopenia is when _________________, typically caused by ______

A

pt develop Ab to platelet antigen not present on self plts

transfusion, neonates, drug induced, heparin induced

44
Q

TTP =?

A

thrombotic thrombocytopenic purpua

45
Q

TTP characterized by ___?

A

fever, renal insufficiency, microangiopathic hemolytic anemia, mental status changes, thrombocytopenia

46
Q

TTP occurs because

A

damage to endothelial tissue + Large vWF; antibody to ADAMTS13; large vWF = plt adhesion/aggre - plt plugs in small arterioles

47
Q

ADAMTS13

A

metalloprotease - digest vWF to smaller multimers

48
Q

TTP treatment

A

plasmapheresis - remove vWF multimer

Replace missing ADAMTS13

49
Q

HUS = ?

A

hemolytic uremic syndrome

50
Q

HUS associated/presents with

A

renal failure (children), similar to TTP

51
Q

HUS caused by

A

(bacterial toxin) damage to endothelial lining - microthrombi - self limiting

52
Q

Thrombocytopenia lab will show abnormal:

A

platelet count

53
Q

Platelet dysfunction lab will show abnormal:

A

bleeding time

54
Q

hemophilia lab will show abnormal:

A

APTT

55
Q

Factor 7 deficiency lab will show abnormal:

A

PT/INR

56
Q

Dysfibrinogenemia lab will show abnormal:

A

TCT - thrombin clotting time - fibrinogen defects/ fibrin split products, heparin effects

57
Q

Hypofibrinogenemia lab will show abnormal:

A

FIbrinogen

58
Q

PFA-100 or Bleeding time evalutes

A

primary hemostasis

59
Q

APTT screens ______ pathway, PT/INR screens ____

A

intrinsic, extrinsic

DD/BL unit 3 (16 decks)

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