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Respiratory and Cardio > Platelets > Flashcards

Platelets Flashcards

1
Q

what is thrombosis?

A

the formation of clots.

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2
Q

Describe the steps of atherogenesis and atherothrombosis?

A
  1. fatty acid build up
  2. driven by LDL cholesterol
  3. fibrous tissue forms a plaque
  4. inflammatory process
  5. when inflammed plaque ruptures forming a thrombus
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3
Q

name 4 methods of platelet activation?

A
  • thrombin (from coagulation)
  • thromboxane (blocked by aspirin)
  • collagen
  • ADP
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4
Q

what receptor is involved in thrombin activation of platelets?

A

PAR1 or PAR4

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5
Q

what receptor is involved in thromboxane activation of platelets?

A

TPalpha

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6
Q

what receptor is involved in collagen activation of platelets?

A

GP VI

releases thromboxane

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7
Q

what receptor is involved in ADP activation of platelets?

A

P2Y1

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8
Q

what organ synthesis coagulation factors and fibrinogen?

A

the liver

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9
Q

what is the precursor for an enzyme that lyses clots?

A

plasminogen.

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10
Q

which clotting factors are involved in the extrinsic factors?

A

collagen

- factors 12, 11, 8, 9

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11
Q

which clotting factors are involved in the intrinsic pathway?

A

tissue factors

- factor 7

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12
Q

describe the platelet shape change process?

A
  • activation causes a shape change
  • smooth discoid –> spiculated + pseudopia
  • increases surface area
  • increases possibility of cell to cell interactions
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13
Q

what glycoproteins are on the surface of the platelets?

A

glycoprotein IIB/IIIa receptors

50,000 to 100,000

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14
Q

what G protein is coupled to P2Y1 - present in ADP activation of platelets?

A

G protein g

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15
Q

what G protein is coupled to P2Y12 - present in ADP activation of platelets?

A

G protein j

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16
Q

what does P2Y1 cause?

A

aggregation and shape change of platelets

17
Q

what does P2Y12 cause?

A

sustains platelet activation, aggregation and granule release.

18
Q

what releases ADP from a platelet causing further activation when shunted to outer surface receptors?

A

Dense granules

they amplify the process of platelet activation by ADP

19
Q

what else causes platelet activation amplification?

A

when platelets bind together.

20
Q

what other G protein coupled receptor amplifies the process of platelet activation?

A

PAR-1

which amplifies it via ADP

21
Q

name 2 coenzymes in the fibrinolytic system?

A

tPA (tissue plasminogen activator)

PAI-1 ( plasminogen activator inhibitor-1)

22
Q

what is fibrinolysis?

A

break down of fibrin/dissolving of clots

23
Q

what enzyme cleaves fibrinogen to form fibrin?

A

thrombin

24
Q

what breaks down fibrin into fibrin degradation products?

A

plasmin

25
Q

what blocks tPA activation?

A

PAI-1 blocks tPA activation

26
Q

describe the fibrinolytic system?

A

plasminogen –> plasmin via tPA

plasmin –> breaks fibring into fibrin degradation products.

27
Q

what do platelet alpha granules do?

A

they mediate expression of surface P-selectin and release of inflammatory mediators.

28
Q

what response and factor is driven by platelet alpha granules?

A

inflammatory response and coagulation factors.

29
Q

what are cyclooxygenase 1&2 (COX-1 & COX-2)?

A

phospholipids form arachidonic acid - using enzyme phospholipase A2.
forms 2 pathways (prostaglanin and leukotrienes)

30
Q

what does prostaglanin H2 do in platelets?

A

uses COX-1 to form prostaglandin H2.
forms thromboxane A2 (TXA2)
vasoconstriction and platelet aggregation

31
Q

what does prostaglandin H2 do in endothelial cells?

A

uses COX-1/2 to form prostaglandin H2.
forms prostacyclin (PGI2)
anti-coagulant

32
Q

what do platelets do in inflammation?

A

they interact with leukocytes through P-selectin from alpha granules.

P-selectin presented on surface allows bonding with monocytes (PSGL-1 receptors)

Respiratory and Cardio (5 decks)

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