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Hematology > Platelets > Flashcards

Platelets Flashcards

1
Q

Platelets are produced directly from…

A

Megakaryocyte cytoplasm

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2
Q

Hormone responsible for megakaryopoiesis

A

Thrombopoietin

70,000 daltons

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3
Q

Thombopoietin is produced by which organ

A

Liver

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4
Q

Refers to the form of mitosis that lacks telophase and cytokinesis

A

Endomitosis

formation of giant multinucleated or polyploidy cells

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5
Q

Megakaryopoiesis: Least mature specific progenitor

A

Burst forming unit-Meg / BFU-Meg

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6
Q

Megakaryopoiesis: most mature specific progenitor

A

Light density colony forming unit - Meg / LD-CFU-Meg

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7
Q

Megakaryopoiesis: Least mature precursor

A

MK-I / Megakaryoblast

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8
Q

Megakaryopoiesis: Most mature precursor

A

MK-III / Megakaryocyte

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9
Q

Endomitosis starts at_________________ (specific progenitor)

A

LD-CFU-Meg

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10
Q

Endomitosis end at ________________ (precursor)

A

MK-II / Promegakaryocyte

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11
Q

Thrombopoietin (TPO) is also known as…

A

MPL ligand

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12
Q

Stimulating hormonal factors that controls the production and release of platelets

A

TPO/MPL ligand and IL-11

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13
Q

Each megakaryocyte produces ________ (#) platelets

A

2,000-4,000 (Rodaks)
1,000-4,000 (Steinenger)

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14
Q

Thrombocytes’ lifespan

A

8-11 days or 9-12 days

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15
Q

Platelets are phagocytized by the…

A

Liver
Spleen
Other mononuclear phagocytic system

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16
Q

Major source of energy of platelets

A

Glucose / dextrose

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17
Q

Platelet composition

A

60% protein
30% lipid
8% carbohydrates
Mineral
Water
Nucleotides

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18
Q

Platelet’s maturation time:

A

5 days

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19
Q

Platelet structure that is responsible for adhesion and aggregation

A

Peripheral zone

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20
Q

Coagulation factors composed in Glycocalyx

A

Factor V, Factor VIII, Fibrinogen

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21
Q

Platelet structure responsible for change in shape, extension of pseudopods, and secretion of granules

A

Sol-gel zone

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22
Q

Which among the Sol-gel components is majorly responsible for the platelet disc shape

A

Microtubules

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23
Q

Microtubules disassemble when treated with…

A

Colchicine

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24
Q

Rope-like polymers

A

Intermediate filaments of the Sol-gel zone

connect the actin to tubules = maintain shape

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25
Q

Alpha granules

A

Platelet factor IV, platelet derived growth factor, thrombospondin, VWF, fibrinogen, fibrinectin, Factor V

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26
Q

Dense / Delta granules

A

CAPASM
Calcium, ADP, Pyrophosphate, ATP, Serotonin, Magnesium

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27
Q

Lysosomes / Lysosomal type granules

A

Acid hydrolases, ACP, hydrolytic enzymes

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28
Q

Which composition in organelle zone has “clearing” responsibilities

A

Lysosomes

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29
Q

Membranous system that is derived from Rough ER

A

Dense tubular system / DTS

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30
Q

DTS sequesters/hold _________ for _______________ and ________________

A

Calcium
Platelet activation process
Prostaglandin synthesis

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31
Q

Control center for platelet activation

A

DTS system

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32
Q

System that acts as a canal for the release of alpha-granules

A

Surface connecting canalicular system (SCCS) or Open canalicular system (OCS)

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33
Q

Sponge like portion of the cell

A

SCCS / OCS

provides an expanded reactive surface to which plasma clotting factors are selectively adsorbed

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34
Q

Route for endocytosis

A

SCCS / OCS

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35
Q

Type of platelet that is associated with increased risk of cardiovascular disease

A

Reticulated platelets

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36
Q

Platelets become round when in ____________ and cylindrical and beaded when in ___________

A

EDTA
Citrated blood

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37
Q

Pro platelet process occur in MK- ______

A

III

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38
Q

Megakaryocyte progenitors arise from _______ under the influence of transcription gene product: ___________, regulated by: _____________.

A

CMP
GATA-1
Cofactor FOG1

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39
Q

Megakaryocyte differentiation is suppressed by ________

A

transcription gene product: MYB

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40
Q

Which transcription factor mediates the switch from mitosis to endomitosis?

A

RUNX1

suppress Rho/ROCK signaling pathway = suppresses the assembly of actin cytoskeleton

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41
Q

Morphological vague clue of megakaryoblast

A

Plasma membrane blebs

Blunt projections from the margin that resemble platelets

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42
Q

Procoagulant-laden alpha-granules, dense granules (bodies), and demarcation system (DMS) begin to develop during the ___________ stage

A

Megakaryoblast / MK-I

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43
Q

Nuclear lobularity first becomes apparent during the _______________ stage.

A

MK-II / Promegakaryocyre

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44
Q

Most abundant precursor stage

A

MK-III / Megakaryocyte

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45
Q

Megakaryocyte characteristics/features

A

30-50um
Intensely indented and lobulated nucleus
Degree of lobulation is imprecisely proportional to ploidy
Chromatin is variably condensed w/ light and dark patches
Azurophilic cytoplasm, granular

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46
Q

Ploidy levels are measured using

A

Mepacrine

a nucleic acid dye in megakaryocyte flow cytometry

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47
Q

MRNA for TPO is found in….

A

Liver
Kidney
Stromal cells
Smooth muscle cells

Liver - has the most copies = main site

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48
Q

Cytokines act in synergy with TPO to induce early differentiation of stem cells

A

IL-3

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49
Q

Cytokine that enhance endomitosis, megakaryocyte maturation, and thrombocytopeiesis

A

IL-6 and IL-11

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50
Q

Normal peripheral blood platelet count

A

150-400x10^9/L

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51
Q

Excess hemostasis = ___________________
Inadequate hemostasis = __________________

A

Clot extension, thrombosis
Poor wound healing and prone to bleeding

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52
Q

Key component in intravascular hemostasis

A

Platelets and biochemical (procoagulants)

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53
Q

Primary or Secondary hemostasis: Involves vascular intima

A

Primary hemostasis

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54
Q

Primary or secondary hemostasis: activated by large injuries to blood vessels and surrounding tissues

A

Secondary hemostasis

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55
Q

Primary or secondary hemostasis: Rapid, short lived

A

Primary hemostasis

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56
Q

Primary hemostasis is initiated by…

A

Exposure of platelets to the subendothelial connective tissue components blood vessels

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57
Q

Factors essential for vascular integrity or resistance to vessel disruption

A

CFP-3As:

Circulating functional platelets
Adrenocorticosteroids
Ascorbic acid

58
Q

Anticoagulant used for collection tubes for hemostasis testing

A

Buffered sodium citrate

59
Q

Example of drug to avoid prior hemostasis testing

A

Aspirin

60
Q

Needle gauge:
Adult w/ good veins: ______
Child/adult w/ small/fragile/hardened veins: ________
Transfer from syringe to tube:______

A

20-21
23
19

61
Q

Tourniquet application of >1min

A

Activate endothelial cells
Elevate conc. Of vWF and fibrinogen
Falsely shortening clot-based tests

62
Q

Specimen storage at 1-6deg C causes

A

Precipitation of VWF multimers
Activation of coagulation factor 7/11
Activation of plts
Destruction of plt integrity

63
Q

Specimen storage at >25deg C causes

A

Coagulation of factor 5/8 to deteriorate

64
Q

Ratio if blood to anticoagulant

A

9:1

65
Q

Specimen processing for hemostasis should be done at _________ (*temp *)

A

37deg C

66
Q

Drugs like aspirin and other NSAIDS INHIBIT __________________

A

Cyclooxygenase pathway

Plt Func Test: 1 week abstinence
Bleeding time test: 24hrs prior to test

67
Q

Specimen processing validity:
PT: _______
APTT: ______

A

24hrs
4hrs

68
Q

Platelet rich plasma obtained by centrifuging ______________ from 3.2% sodium citrate at ___________________________

A

Whole blood
50g x for 30mins

69
Q

Platelet poor plasma obtained by centrifuging ______________ from 3.2% sodium citrate at ___________________________

A

Whole blood
1500g x for 15mins

70
Q

PRP samples are used for __________________ (type of tests)

A

Platelet aggregometry or platelet function test

PPP is for clot-based coagulation tests (PT/APTT)

71
Q

Blood collection volume is less than specified minimum

A

PT falsely prolonged
Recollect

72
Q

Visible hemolysis PT is….

A

Falsely shortened
Recollect

73
Q

If sample undergo heparin therapy, solution:

A

Use rgt known to be in to heparin sensitive
Or w heparin neutralizer such as polybrene

74
Q

Electromechanical detection fibrin clot formation uses ________________

Instrument: _______________

A

Wire loop/hook
Fibrometer

75
Q

Detection of fibrin clot formation through Photo-optical detection depends on the _________________________

A

Increase in light scattering

76
Q

Semi automated photo-optical detection instruments

A

Electra 750 and 750A
Fibrintimer series
FP 910 Coagulation analyzer

Other semi automated instruments:

Fibrometer
-Start 4
-Cascade M and M-4 -BFT-II
-KC1 -KC4

77
Q

Automated photo-optical detection instruments

A

Ortho Koagulab 16s and 40A,
Coag-A-Mate X2 and XC,
MLA Electra 700

Other Automated instruments:
ACL TOP,
STA-R Evolution,
STA Compact, and Compact CT
Sysmex CA-530, CA-560, CA-620, CA-660, CA1500, CA-7000, BCS XP, CoaLAB

78
Q

Clotted samples will cause results to be _______________

A

Falsely shortened clotting times

Due to premature activation of coagulation factors and plts that generate Factor VIIa and thrombin

(same with Hemolyzed samples)

79
Q

Samples that are expected to have liver dysfunction

A

Icterus/Bilirubinemia and abnormal clot formation

Prolonged clotting times because of inadequate factor production

80
Q

Measurement that measures the uniformity of platelet size

A

Platelet distribution width

Serve as validity chech and monitor false results

81
Q

PdW normal value

A

<20%

82
Q

Conditions w/ INC PDW

A

Aplastic and megaloblastic anemia
CML
Antileukemic chemotherapy

83
Q

Measurement that measures the average volume of platelets

A

Mean Platelet Volume

Analogous to erythrocytic MCV

84
Q

MPV should be based on EDTA specimens that are between _______________ hours old

A

1-4

85
Q

Healthy patients have inverse relationship between ________________ and ___________

A

Count
Size

INC count = DEC MPV (vice versa)

86
Q

Conditions w/ INC MPV

A

ITP
After splenectomy
Sickle cell anemia

87
Q

Prostacyclin’s action:

A

Inhibit PLT activation
Vasodilator (synthesized through eicosanoid pathway)

88
Q

ATP’s action in intact endothelial cells:

A

Stimulates vasodilation

89
Q

Endothelial surface receptor of thrombin

A

Thrombomodulin

Binds and inactivates thrombin, enhances anticoagulant and fibrinolytic action of protein c in plasma

90
Q

Heparan sulfate’s action in endothelial cells:

A

Coats the surface and weakly enhances anti-thrombim III

91
Q

Converts plasminogen to plasmin

A

Tissue plasminogem activator (tPA)

92
Q

Storage site of vwf in:
- endothelium:
- PLTs or Megakaryocyte:

A

Wiebel palade
Alpha granules

93
Q

“Carpet” on which activated platelets assemble

A

VWF

94
Q

Teh vasculau “relaxing” factor

A

Nitric oxide

95
Q

Heparan sulfate is a…..

A

Blood plasma serine protease that enhances the activity of antithrombin

96
Q

The alteration in cellular shape is triggered by an ____________^^^^^

A

Increase level of cytoplasmic calcium

97
Q

During platelet (adhesion, activation, aggregation) occurs the morphological and functional change in platelets

A

Activation

98
Q

During platelet (activation, aggregation, secretion):

Cyclooxygenase metabolizes _______________ to form _______________ that is then converted to _______________ which is a ____________ and a ____________ that causes _________ and __________

A

Arachidonic acid
Prostagalndin endoperoxidase
Thromboxane A2
Vasoconstrictor
Platelelet stimulator
Platelet Aggregation
Secretion

99
Q

Necessary cofactor for platelet aggregation

A

Fibrinogen

100
Q

(Adhesion, aggregation, secretion) seals the endothelial gaps

A

Adhesion

Requires VWF

101
Q

(Adhesion, aggregation, adhesion) essential to coagulation

A

Secretion

102
Q

Proteins that controls the cellular activation for all cells in the inner membrane surface

A

G proteins

103
Q

Three stages of coagulation mechanism

A

Generation of prothrombinase complex
Conversion of prothrombin to thrombin
Conversion of fibrinogen to fibrin

104
Q

Extrinsic pathway is initiated by the entry of ______________________

A

Tissue thromboplastin (tissue factor)

105
Q

Fibrinogen is mainly synthesized in ______________

A

Liver

106
Q

Largest and most concentrated clotting factor

A

Fibrinogen

107
Q

Fibrinogen is the primary substrate of __________

A

Thrombon

108
Q

Prothrombin half life

A

3 days

70% consumption during clotting

109
Q

In the presence of ______________, prothrombin is converted to ____________ by the enzymatic action of _________________ from both extrinsic and intrinsic sources

A

Ionized calcium
Thrombin
Thromboplastin

110
Q

In the presence of ___________, prothrombin is converted to ___________ by the enzymatic action of ________________ from both extrinsic and intrinsic sources

A

Ionized calcium
Thrombin
Thromboplastin

111
Q

Thrombin is consumed during ___________________

A

The conversion of fibrinogen to fibrin

112
Q

Main enzyme of coagulation pathway

A

Thrombin (Factor IIa)

113
Q

Thrombin bound to __________ activate ___________ to suppress _________

A

Thrombomodulin
Protein C pathway
Coagulation

114
Q

Tjrombin activates ________ to suppress ___________

A

TAFI
Fibrinolysis

115
Q

Factor V half life

A

16hrs

116
Q

Action of Factor VII

A

Activation of thromboplastin
Acceleration of conversion of prothrombin to thrombin

117
Q

Vitamin K deficiency and Vitamin K antagonists reduce Factor _____

A

VII

118
Q

Factor ______ falsely decreased in presence of Lupus anticoagulant (LA)

A

VIII

119
Q

Factor VIII is produced by __________ and _______________ in lungs

A

Hepatocytes
Microvascular endothelial cells

120
Q

Alpha subunit of Factor XIII is produced by ___________, beta subunit by ___________

A

Megakaryocyte and monocyte
Liver

121
Q

Factors that are acute phase reactants

A

Fibrinogen
Prothrombin
Factor VIII

INC during inflammation (trauma, pregnancy, infection, stress)

122
Q

Fibrinogen group factors (Thrombin sensitive group)

A

Factor I, V, VIII, XIII

123
Q

Prothrombin group factors (Vit. k dependent group)

A

Factor VII IX X II

124
Q

Contact group factors

A

Factor XII XI HMWK PK

125
Q

Major inhibitor of blood coagulation

A

Protein C

126
Q

Protein C stimulates fibrinolysis by……

A

Inactivating plasminogen activator inhibitors

127
Q

Cofactor of protein C

A

Protein S

40% is free and active
60% is bound to complement c4 binding protein and is inactive

128
Q

Major inhibitor of thrombin

A

Antithrombin C

Enhanced by heparin = Heparin cofactor II

129
Q

Also called as lipoprotein associated coagulation inhibitor (LACI) , inhibits the VIIa-tissue factor complex

A

Extrinsic pathway inhibitor (EPI)

130
Q

Principle inactivator of factor XIIa and plasma kallekrein

A

C1-inhibitor

131
Q

Weak inhibitor of thrombin and factor Xa and XIa

A

Alpha 1 antitrypsin

132
Q

Primary purpose of fibrinolysis

A

Digest fibrin clots

133
Q

Fibrinolysis occurs when _________ is converted to ____________

A

Plasminogen
Plasmin

dissolved fibrin or fibrinogen into smaller fragments = (FDP) Fibrin Degradation product or (FSP) Fibrin split product

134
Q

Plasminogen is produced by the ______

A

Liver

135
Q

It is a single-chain protein possessing 5 glycosylated loops termed “kringles”

A

Plasmimogen

136
Q

Fibrin-bound plasminogen is converted to __________________ when cleaved between _____________ and ___________

A

Two-chain active plasmin
Arginin at position 561
Valine at position 562

137
Q

Primary or Secondary Fibrinolysis: excessive amount of plasminogen activator from damaged cells or malignant cells

A

Primary fibrinolysis

Ex. Surgery, trauma, malignancy

138
Q

Primary or secondary fibrinolysis: DEC fibrinogen and DEC plt count

A

Secondary hemostasis

Primary hemostasis has Normal PLT count

139
Q

Marker of thrombosis and fibrinolysis

A

D-dimer

Disseminated intravascular coagulation, rule out venous thromboembolism, and pulmonary embolism

140
Q

Primary inhibitor of plasmin

A

Alpha 2 antiplasmin

141
Q

Urokinase
- secreted by: ________
- circulates in ___________ at a ______ng/mL
- converts _________ to plasmin
- therapeutically used to: _________

A

Urinary tract epithelial cells, monocytes and macrophages
Plasma
2-4ng/mL
Dissolve thrombi

142
Q

Playelet stimulating agents

A

Adp
Collagen
Thrombin
Epinephrine

Hematology (6 decks)

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