LG2.14 Introduction to Coagulation Part 1 Flashcards

1
Q

What are the 4 major events that occur in hemostasis?

A

1) Vasoconstriction
2) Platelet Actions: Adhesion, Activation, Release or Secretion, Aggregation
3) Fibrin Clot formation/coagulation
4) Fibrinolysis

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2
Q

What is hemostasis?

A

Hemostasis is the process of normal blood clotting, the subsequent dissolution of the clot, and subsequent repair of the injured tissue.

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3
Q

What are the major components of the hemostatic system?

A

a. Vascular endothelium
b. Platelets
c. Coagulation system
d. Fibrinolytic system

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4
Q

What does Nitric Oxide do?

A

Inhibits platelet adhesion and aggregation by elevating levels of cGMP

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5
Q

What does Prostacyclin do?

A

Inhibits platelet aggregation by increasing levels of cAMP

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6
Q

What does Thrombomodulin do?

A

Binds thrombin which then cleaves protein C to yield activated protein C

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7
Q

What substances does the Endothelial cells produce that are potent vasodilators and inhibitors of platelet functions?

A
  • prostacyclin (prostaglandin I2, PGI2)

- nitric oxide (NO).

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8
Q

What does Tissue Plasminogen activator (TPA) do?

A

Activates fibrinolysis

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9
Q

What is Primary Hemostasis?

A

Formation of a Platelet Plug

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10
Q

What is the steps of Primary hemostasis?

A

i. Platelet Adhesion
ii. Shape change
iii. Granule release (ADP,TXA2)
iv. Recruitment
v. Aggregation (hemostatic plug)

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11
Q

What is secondary hemostasis?

A

Formation of a fibrin Clot

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12
Q

What is the steps of secondary hemostasis?

A

i. Tissue factor
ii. Phospholipid complex expression
iii. Thrombin generation
iv. Fibrin polymerization

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13
Q

What is Prothrombin converted to?

A

Thrombin

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14
Q

What is thrombin covert?

A

Fibrinogen to Fibrin

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15
Q

What is the function of vWF?

A

function is binding to other proteins, in particular factor VIII, and it is important in platelet adhesion to wound sites.[1]

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16
Q

What does vWF stand for?

A

von Willebrand Factor

17
Q

What is the function of ADP?

A

A mediator of further platelet activation, leads to a conformational change in platelet gpIIb/IIIa receptors that induces binding to fibrinogen

18
Q

What does TXA2 stand for?

A

Thromboxane A-2

19
Q

What is the function of TXA2?

A

A prostaglandin, Vasoconstriction

20
Q

What is Gp IIB/IIa?

A
  • Is an integrin complex found on platelets. It is a receptor for fibrinogen[1] and von Willebrand factor and aids in platelet activation.
  • The complex is formed via calcium-dependent association of gpIIb and gpIIIa, a required step in normal platelet aggregation and endothelial adherence.
  • Platelet activation by ADP leads to a conformational change in platelet gpIIb/IIIa receptors that induces binding to fibrinogen.
21
Q

What is Fibrinogen?

A

Form bridges between platelets, by binding to their GpIIb/IIIa surface membrane proteins; however, its major function is as the precursor to fibrin

22
Q

What is PAI stand for?

A

Plasminogen activator inhibitor

23
Q

What is FDP stand for?

A

Fibrin degradation products

24
Q

What does t-PA stand for?

A

tissue plasminogen activator

25
Q

How is Plasminogen involved in clotting?

A

Plasminogen is a zymogen of plasmin. It is manufactured in the liver and circulates in the blood in a form that is activation-resistant. Upon binding to fibrin, it can readily be converted to plasmin by plasminogen activators

26
Q

What does activated GpIIb/IIa receptors provide?

A

The GpIIb/IIIa receptors on activated platelets form bridging crosslinks with fibrinogen, leading to platelet aggregation.

27
Q

What do alpha granules contain?

A

• α granules contain fibrinogen, clotting factors V and VIII

28
Q

What do dense bodies contain?

A

ADP, ionized calcium and serotonin

29
Q

How are platelets involved in clotting?

A
  • Platelets are anucleate cell fragments shed into the bloodstream by marrow megakaryocytic.
  • They play a critical role in normal hemostasis by forming a hemostatic plug that seals vascular defects, and by providing a surface that recruits and concentrates activated coagulation factors.
30
Q

What do platelet receptos GP1a-IIa and GP VI bind directly to?

A

Subendothelial collagen

31
Q

What do platelets bind indirectly to collagen via GPib and vWF bind indirectly to?

A

Collagen/

32
Q

What is ECM?

A

Extracellular matrix

33
Q

What happens directly after vascular injury?

A

After vascular injury, platelets encounter ECM constituents (collagen is most important) and adhesive glycoproteins such as vWF. This sets in motion a series of events that lead to (1) platelet adhesion, (2) platelet activation and (3) platelet aggregation.

34
Q

What does activation of thrombin cause?

A

Activation of thrombin promotes fibrin deposition, cementing the platelet plug in place.

35
Q

Where does the conversion of prothrombin to thrombin occur?

A

-The conversion of prothrombin to thrombin usually takes place on anionic phospholipid membranes that are exposed on the activated platelet membrane.