2.4 and 2.5 Platelets Flashcards

1
Q

Platelets adhere to _______________, which is mediated by ____________

A

subendothelial collagen; vWF

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2
Q

Platelet dense granules contain

A

ADP

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3
Q

Platelet alpha granules contain (5)

A

β-thromboglobulin; platelet factor 4; PDGF; fibrinogen; factor V

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4
Q

Platelet lysozymes contain

A

hydrolase

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5
Q

To quantify platelets, you should collect blood into what type of tube

A

purple top (EDTA)

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6
Q

When it comes to MPV, there is an inverse relationship between ______ and _______

A

size and number (more platelets but smaller size vs less platelets but larger size)

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7
Q

what can artifacturally lower platelet counts in an analyzer

A

platelet clumping

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8
Q

shift platelets indicate

A

increased thrombopoiesis

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9
Q

small platelets can be a sign of

A

iron deficiency; ITP

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10
Q

platelet concentration changes due to (3)

A

decreased thrombopoiesis; increased destruction of platelets; increased consumption of platelets

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11
Q

what can be used to assess platelet function/number

A

BMBT

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12
Q

when would you NOT do a BMBT test

A

if the patient has thrombocytopenia

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13
Q

BMBT is _____________ with coagulation factor deficiencies

A

unaltered

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14
Q

if you wanted to assess the entire clotting mechanism, what test would you use

A

thromboelastography

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15
Q

T/F petechial hemorrhages are characteristic of Von Willebrands Disease

A

F

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16
Q

what are the clinical signs of von willebrands disease

A

1) bleeding from mucous membranes
2) prolonged bleeding after trauma, surgery, venipuncture

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17
Q

vWF allows platelet adhesion to_____________, _________________ and stabilizes

A

subendothelium, platelet-platelet adhesion, FVIII

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18
Q

_______ is an example of thrombocytopenia due to destruction and causes (marked/moderate) thrombocytopenia

A

ITP; marked

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19
Q

______ is an example of thrombocytopenia due to consumption and causes (marked/moderate) thrombocytopenia

A

DIC; moderate

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20
Q

most of the pro-coagulation factors are made in the _________ and are ________

A

liver; enzymes

21
Q

what are the vitamin K dependent factors

A

2, 7, 9, 10

22
Q

what are the contact factors

A

11, 12, 13, prekallikrein

23
Q

what are the non-enzymatic factors

A

5, 8, fibrinogen

24
Q

what are the three anti-coagulant factors

A

antithrombin III; protein C; tissue factor pathway inhibitor

25
Q

the main protein responsible for degrading fibrin is

A

plasmin

26
Q

the intrinsic pathway is also called the

A

contact pathway

27
Q

the extrinsic pathway is also called the

A

tissue factor pathway

28
Q

in vivo, which pathway is activated first

A

extrinsic

29
Q

activation of coagulation occurs on the surface of _________, which have a ________ charge

A

platelets; negative

30
Q

what is the role of calcium in the coagulation cascade

A

provides the positive charge between the negatively charged platelet membrane and negatively charged coagulation factors

31
Q

which tests require citrated tubes

A

APTT, OSPT, fibrinogen

32
Q

ACT tests which pathways

A

intrinsic and common

33
Q

what is an important consideration before running ACT

A

need to do a CBC first to make sure patient does not have thrombocytopenia, because the test relies on the patients own platelets

34
Q

what is an advantage of ACT

A

inexpensive and easy to do in practice

35
Q

APTT (PTT) tests which pathways

A

common and intrinsic

36
Q

what is an advantage of APTT

A

is not affected by thrombocytopenia

37
Q

with clotting factor disorders, we tend to see ________, whereas with platelet disorders, we tend to see __________

A

hematomas; petechiae

38
Q

hemophilia A is a deficiency of

A

Factor VIII

39
Q

OSPT tests which pathways

A

extrinsic and common

40
Q

APTT tests which 5 diseases

A

hemophilias; DIC; hereditary factor XII or XI deficiency; vitamin K deficiency; therapeautic anticoagulation

41
Q

OSPT tests which 3 diseases

A

factor VII deficiency; DIC; vitamin K deficiency

42
Q

what is an advantage of OSPT

A

not affected by thrombocytopenia

43
Q

which test is inversely proportional to TCT

A

fibrinogen

44
Q

fibrinogen tests for what 3 disorders

A

hereditary hypo or dysfibrinogenemia; DIC; therapeutic anticoagulation

45
Q

elevated FDPs can indicate which diseases (3)

A

DIC; renal disease; internal hemorrhage

46
Q

DIC is diagnosed by _____ OSPT and APTT; _____ FDPs; ____ fibrinogen; _______ platelets and ____________________

A

increased; increased; decreased; decreased; RBC fragmentation

47
Q

what is an RBC abnormality seen in DIC

A

shistocytes

48
Q

what are some causes of hypercoagulability

A

DIC
hypoalbuminemia
loss of antithrombin III
polycythemia
hyperviscosity, proteins/cells
shock
drugs, platelet agonists
snake bites, other toxins

49
Q

what can cause thrombocytosis

A

1) splenic contraction
2) iron deficiency
3) hemorrhage
4) paraneoplasia
5) myeloproliferative disease
6) FelV associated disease (non-neoplasia)
7) inflammatory disease