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🩸Hema🎀 > 3.2: Platelet Activation And Microplatelets > Flashcards

3.2: Platelet Activation And Microplatelets Flashcards

1
Q

Sequence of events of adhesion:

A
  1. Collagen
  2. Vwf
  3. GP lb/IX/V
  4. ADAMTS-13
  5. GP VI
  6. TXA2 and ADP
  7. TPa and TPb
  8. P2Y1 and P2Y12
  9. A2B1
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2
Q

Sequence of events of aggregation:

A
  1. Tissue factor
  2. Thrombin
  3. PAR1 and PAR4
  4. COAT platelets
  5. TXA2 and ADP
  6. GP IIb/IIIa receptor
  7. P-selectin
  8. Phosphatidylserine
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3
Q

The combination that triggers secondary hemostasis

A
  1. Polar phospholipid exposure on activated platelets
  2. Platelet fragmentation with cellular microparticle release
  3. Secretion of the platelet’s alpha grange and dense granule contents
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4
Q

Sequence of events of secretion

A
  1. STRs
  2. GP VI
  3. Intermediate filaments
  4. Actin microfilament
  5. Alpha granules
  6. Lysosomes
  7. Dense granules
  8. Phosphatidylserine
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5
Q

Is disrupted and exposed during blood vessel injury

A

Collagen

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6
Q

Is released when endothelial cells become
damaged, then adheres to the site of injury;
Under shear stress, it becomes thread-like
as it unrolls and exposes sites that weakly
bind the GPIbα portion of the GP Ib/IX/V
receptor

A

vWF

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7
Q

Platelet membrane receptor in adhesion

A

GP Ib/IX/V

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8
Q

A liver-secreted plasma enzyme which
digests larger vWF multimers into smaller, less biologically active forms; Localizes the
platelet-vWF interaction

A

ADAMTS-13

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9
Q

Collagen binding to ______ triggers internal platelet activation pathways, releasing TXA2 and ADP, an outside-in reaction

A

GP VI

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10
Q

Are agonists that bind to the receptors TPα
and TPβ and P2Y1 and P2Y12 ,
respectively, for ADP that triggers an
inside-out reaction that raises the affinity of
integrin α2β1 for collagen

A

TXA2 and
ADP

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11
Q

STRs of adhesion

A

TPα and TPβ
P2Y1 and P2Y12

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12
Q

Increased affinity for collagen

A

α2β1

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13
Q

Blood vessel injury exposes these and are expressed on subendothelial smooth muscle cells and fibroblasts; Triggers the production of thrombin

A

Tissue factor

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14
Q

Cleaves platelet PAR1 and PAR4

A

Thrombin

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15
Q

STRs of aggregation

A

PAR1 and PAR4

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16
Q

“collagen and thrombin activated” platelets; Generated by the activation of thrombin formation

A

COAT platelet

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17
Q

Are platelet activators that is secreted from the platelet granules to the microenvironment, where they activate neighboring platelets through their respective receptors and trigger inside-out activation of integrin αIIbβ3 (GP IIb/IIIa receptor)

A

TXA2 and ADP

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18
Q

Binds to the RGD sequences of fibrinogen and vWF; Supports platelet-to-platelet binding

A

GP IIb/IIIa receptor

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19
Q

Moves from the alpha granule membrane to the surface membrane to promote binding of platelets with leukocytes

A

P-selectin

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20
Q

The more polar phospholipid molecules flip to the outer layer; Platelets change in shape from discoid to round and extend pseudopods

A

Phosphatidylserine

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21
Q

Triggers actin microfilament contraction

A

STRs
GP VI

22
Q

Also contract, moving the circumferential microtubules inward compressing the granules

A

Intermediate filaments

23
Q

Contracts due to the outside-in activation

A

Actin microfilament

24
Q

Flows through SCCS with the lysosomes; Are large molecule
coagulation proteins that participate in secondary hemostasis; Its contents (fibrinogen, factors V and VIII, and vWF) are secreted and increase the localized concentrations of the essential coagulation proteins, further supporting the action of tense and prothrombinase

A

Alpha granules

25
Q

Flows through the SCCS with alpha granules

A

Lysosomes

26
Q

Are small vasoconstrictors and platelets agonists that amplify primary hemostasis

A

Dense granules

27
Q

Is a polar phospholipid on which the factor IX/VIII (tenase) and X/V (prothrombinase) complexes assemble; Is supported by the ionic calcium secreted by the dense granules; OIs presented on the platelet membrane surface providing a localized cellular milieu that supports coagulation

A

Phosphatidylserine

28
Q

Are formed after exposure of platelets to strong agonists or shear stress

A

Platelet Microparticles

29
Q

Are membrane-derived vesicles that form in response to an activating stimulus that increases the platelet intracellular concentration of calcium

A

Platelet Microparticles

30
Q

Control cellular activation for all cells at the inner membrane surface

A

G-proteins

31
Q

αβγ heterotrimers that bind guanosine diphosphate
(GDP) when inactive

A

G-PROTEINS

32
Q

of the heterotrimer briefly dissociates,
exerts enzymatic guanosine triphosphate activity and
hydrolyzes the bound GTP to GDP, releasing a
phosphate radical

A

Gα portion

33
Q

EICOSANOID SYNTHESIS Alternatively called the

A

prostaglandin, cyclooxygenase, or thromboxane pathway

34
Q

One of the two essential platelet activation pathways
triggered by G-proteins in platelets

A

EICOSANOID SYNTHESIS

35
Q

An inner phospholipid whose number 2 carbon binds numerous types of unsaturated fatty acids, but especially 5, 8, 11, 14-eicosanoid acid (arachidonic acid)

A

Phosphatidylinositol

36
Q

a membrane enzyme that cleaves the ester bond connecting the number 2 carbon of the triglyceride backbone with arachidonic acid

A

Phospholipase A2

37
Q

is released to the cytoplasm as it is cleaved

A

Arachidonic acid

38
Q

Converts arachidonic acid to prostaglandin G2 and prostaglandin H2

A

Cyclooxygenase

39
Q

Acts on prostaglandin H2 to produce TXA2

A

Thromboxane A2

40
Q

Binds membrane receptors TPα and TPβ (inhibits adenylate cyclase activity and reducing cAMP concentrations, which mobilizes ionic calcium from the DTS)

A

TXA2

41
Q

Is incorporated in place of the thromboxane synthetase

A

Prostacyclin synthetase

42
Q

The eicosanoid pathway end point for the endothelial cells

A

Prostaglandin I2 or prostacyclin

43
Q

Binds to the IP receptor activating the IP3-DAG pathway

A

Prostaglandin I2 or prostacyclin

44
Q

Leads to the acceleration of adenylate cyclase, an increase in cAMP, and a sequestration of ionic calcium to the DTS

A

Prostaglandin I2 or prostacyclin

45
Q

Is the second G-protein-dependent platelet activation
pathway

A

IP3-DAG ACTIVATION PATHWAY

46
Q

Phospholipase C cleaves PIP2 to form

A

IP3 and DAG

47
Q

are second messengers for intracellular activation

A

IP3 and DAG

48
Q

Promotes release of ionic calcium from the DTS (triggers actin microfilament contraction)

A

IP3

49
Q

Also activates phospholipase A2

A

IP3

50
Q

Activates phosphokinase C (triggers phosphorylation of the protein pleckstrin)

A

DAG

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