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Med 2: Cardio > Hematostasis > Flashcards

Hematostasis Flashcards

1
Q

What are the 6 steps of hemostasis?

A
  • vascular constriction
  • formation of platelet plug (primary hemostatic plug)
  • formation of a blood clot as a result of blood coagulation (secondary hemostatic plug)
  • clot retraction
  • fibrinolysis
  • growth of fibrous tissue into the blood clot
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2
Q

What are the two causes of vasoconstriction? Which vessels do each act on?

A
  • local myogenic spasm: circular smooth muscle

- local factors from traumatized tissues and blood platelets: smaller vessels

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3
Q

The first reaction contraction of circular smooth muscles is called? What is this type of contraction reducing?

A
  • Myogenic contraction

- reduce the flow of blood from a ruptured vessel

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4
Q

What are the by product vasoconstrictors from the platelet plug formation?

A

Thromboxane A 2 (TXA 2) and serotonin (5-HT)

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5
Q

What are some facts about platelets?

A
  • no nuclei
  • can’t reproduce
  • contractile protiens are: actin, myosin, thrombosthenin
  • ER and Golgi: make enzymes and store calcium
  • factor XIII
  • cell membrane have glycoprotein coat
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6
Q

What are 5 types of platelet disorders?

A
  • thrombocytosis
  • thrombocytopenia
  • platelet function defects
  • inherited
  • acquired
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7
Q

What are 3 examples of inherited platelet disorders?

A
  • von willebrand disease
  • bernard-soulier syndrome
  • glanzmann thrombasthenia
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8
Q

What are examples of aquired platelet disorders?

A
  • certain drugs like nsaids, PCN, ASA, or heparin
  • idiopathic thrombocytopenic purpura
  • chronic myeloproliferative disorders
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9
Q

Platelet plug formatiom includes what 3 A’s?

A

Adhesion, activation, aggregation

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10
Q

Where is the von willebrand factor found? What is it? What does it do?

A
  • megakaryocytes and in alpha granules
  • its a glycoprotien made by endothelial cells
  • it binds to the platelet receptor glycoprotein (Gp Ib)
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11
Q

What triggers a conformational change in the platelet receptors?

A

Adhesion

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12
Q

What 3 things promote platelet aggregation?

A

-ADP, serotonin, TXA2

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13
Q

What inhibits clotting by decreasing the release of TXA2? Its an inhibitor of what?

A
  • aspirin

- aspirin is an inhibitor of cyclooxygenase

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14
Q

What forms bridges between platelets? What step of the primary hemostatic plug does this happen?

A
  • Fibrinogen

- aggregation

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15
Q

What is a clot?

A

Semisolid mass composed of platelets and fibrin

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16
Q

When a vessel is ruptured, what is activated? What does it override when its activated?

A
  • Procoagulants

- overrides anticoagulants

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17
Q

When does a clot start to develop? Within how many minutes does the opening of the vessel get filled with a clot? When does the clot retract?

A
  • 15-20 seconds clot develops
  • 3-6 minutes
  • 20min to 1hr
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18
Q

What factor require the liver to be functioning? What vitamin is required as well?

A
  • Factor II and IIa, VII and VIIa, IX and IXa, and X and Xa

- vitamin k

19
Q

What are the names for factor I, Ia, II, IIa?

A
  • I: fibrinogen
  • Ia: fibrin
  • II: prothrombin
  • IIa: thrombin
20
Q

Warfarin is an anticoagulant drug. What is its antidote, or reverses its function?

A

-vitamin k

21
Q

What is central to the coagulationc cascade?

A

Thrombin

22
Q

What is required for clot retraction?

A

Platelets

23
Q

What two things increase the levels of circulating t-PA?

A

Catecholamines and bradykinin

24
Q

What are two paracrine factors of anti-clotting mechanisms? What do they do?

A
  • prostacyclin (PGI-2): vasodilation and inhibits platelet activation
  • nitric oxide: through cGMP inhibits platelet adhesion and aggregation
25
Q

What pathway does PT measure? Which does PTT measure? What are their functions?

A
  • PT: extrinsic, assess anticoagulant effect of warfarin

- PTT: intrinsic, ability to convert fibrinogen to fibrin clot

26
Q

What type of vitamin is vitamin k? What symptoms would you see if absorption of this is defected?

A
  • Fat soluble

- steatorrhea, greasy stools, bloating, gas

27
Q

What do platelets release when there is a wound? What action does it cause?

A
  • TXA2 and serotonin

- increase platelet aggregation and vasoconstriction

28
Q

What is the lifespan of platelets? When they die, how are they removed from the body?

A
  • 8-12 days

- by macrophages in the spleen

29
Q

What are released from endothelial cells that stimulate muscle contraction?

A

Endothelins-1 (ET-1)

30
Q

What are platelets?

A

Fragments of megakaryocytes

31
Q

What are the two types of platelet granules? What are in each?

A
  • alpha granules: procoagulant factor 5, fibrinogen, von willebrand factor, PF4, growth factors (tissue growth factor, PDGF)
  • dense granules: ADP, serotonin, calcium
32
Q

What granule and aspect of this granule plays a role in the recruitment and activation of platelets?

A
  • Dense granules

- ADP

33
Q

What glycoprotien receptor binds to collagen?

A

Glycoprotein Ia/Ib

34
Q

Which glycoprotein receptor binds to von willebrand factor? What disease is linked tothe lack of this receptor?

A
  • glycoprotien Ib/IX

- Glanzman’s thromboasthenia

35
Q

Which glycoprotien receptor binds to fibrinogen? If there is a lack of this receptor, what disease can occur?

A
  • glycoprotien receptor IIb/IIIa

- Bernand-Soulier syndrome pseudo-vWD

36
Q

What do endothelial cells release to INHIBIT platelet aggregation and relax smooth muscle? What is the process that it does this?

A
  • Prostacyclin
  • prostacyclin activates platelet adenylate cyclase, increases cAMP, decrease intracellular Ca, and inhibits platelet activation
37
Q

What is a potent inducer of platelet aggregation and vasoconstriction? Where are they released from?

A
  • TXA2

- platelets

38
Q

Injury of the endothelial exposes collagen. That exposure of collagen causes what and why?

A
  • Adhesion of platelets to the endothelium

- glycoprotien receptor Ia/IIa seeks the exposed collagen to link to

39
Q

What happens in the activation step of platelet plug creation?

A
  • adhesion causes an intracellular signalling cascade leading to exocytosis of platelets to go to the injured site
  • activates both the alpha and dense granules
40
Q

If a patient is bleeding with low platelet count, what step of coagulation will not work?

A

Second step: primary hemostatic plug

41
Q

Whats the difference between a clot and thrombus?

A
  • clot: semisolid mass composed of platelets and fibrin

- thrombus: blood clot in a vessel that has ability to move

42
Q

Between procoagulants and anticoagulants, which dominates?

A

Anticoagulant

43
Q

What factors are released in the intrinsic pathway? Extrinsic? What factor do both pathways meet at?

A
  • intrinsic: factors 12, 11, 9, 8
  • extrinisic: factor 7 and tissue factor
  • factor 10
44
Q

What type of cells clear the activated clotting factors once its no longer needed?

A

Kupffer cells of the liver

Med 2: Cardio (11 decks)

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