Platelet Function Flashcards

1
Q

What are the 3 steps for the formation of a platelet plug?

A
  1. Platelet Adhesion
  2. Platelet Activation
  3. Platelet Aggregation
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2
Q

Describe the process of platelet adhesion.

A

endothelial damage–release of:
PGI2, tpA, vWF, thromboplastin (tissue factor)
vWF binds exposed collagen.
platelets bind vWF via Gp1b receptor

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3
Q

Describe the process of platelet activation?

A

after platelets adhere, they change conformation and form pseudopods that help them bind tightly to site of injury
secrete substances: fibrinogen, thrombin, thromboxane A2, ADP, PDGF, serotonin, lysosomal enzymes, vWF

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4
Q

Describe the process of platelet aggregation.

A

released ADP from platelets that are activated is attached to platelet receptor. Then Gp2b3a receptor pops up on platelet. This binds the fibrinogen that was released.
A bunch of platelets start aggregating by binding fibrinogen

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5
Q

vWF is linked by _____ bonds. IT is released from 2 things and has 2 functions and increases 2 lab values. What are they?

A

disulfide bonds

  • *Endothelial cells (weibel palade bodies)
  • *platelets alpha granules
  • **stabilizes Factor 8
  • *causes platelet adhesion
  • *increases PTT
  • *increases bleeding time IF DEFICIENCY
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6
Q

Describe the contents of the 2 types of granules of platelets.

A

dense granules: ADP, Ca++ (important for coag)

alpha granules: vWF, fibrinogen

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7
Q

What is the MOA of aspirin?

A

irreversibly inhibits COX1,2
decreases thromboxane A2 production
No effect on PT or PTT
but b/c it is anti-platelet, increases bleeding time

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8
Q

What are the SE of aspirin?

A
gastric ulcers (COX1)
Reye syndrome in kids w/ viral infections: hepatoencephalopathy. Don't give to kids except Kawasaki
tinnitus
respiratory alkalosis via hyperventilation-->metabolic acidosis
interstitial nephritis
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9
Q

What are the ADP receptor inhibitors?

A

clopidogrel
ticlodipine
ticagrelor
prasugrel

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10
Q

What are the GP2b3a inhibitors?

A

Abciximab: monoclonal antibody fab fragment
eptiFIBatide
tiroFIBan

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11
Q

What would you use to treat a STEMI? NSTEMI? If PCI was unavailable.

A

NSTEMI: anti-platelet therapy like GP2b3a inhibitor
STEMI: tpa

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12
Q

What’s the deal with cilostazol and dipyridamole?

A

phosphodiesterase III inhibitors, increase cAMP in platelets to prevent aggregation

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