Hemostasis: Blood coagulation and fibrinolysis - Part 3 Flashcards

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1
Q

What occurs, in general, in the fibrinolysis (tertiary) phase of hemostasis

A

Dissolution of the fibrin clot

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2
Q

What protein is incorporated into the developing clot which later plays a major role in degradation of the fibrin clot?

A

Plasminogen (inacitve)

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3
Q

What factors cause inactive plasminogen to become active plasmin (proteolytic)?

A
  • Tissue plasminogen activator
  • Urokinase
  • Streptokinase
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4
Q

What factors keep inactive plasminogen inhibited?

A
  • Plasminogen activator Inhibitory 1 & 2

- Antiplasmin (inhibits Active plasmin)

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5
Q

What is the role of active plasmin?

A

Breaks down fibrin clot into fibrin degradation products (FDP)

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6
Q

______ and _____ levels are raised in patients with DVT. They are estimated in clinical practice to estimate the extent and rate of _____ and in follow up patients with thrombosis.

A
  • Fibrin degradation products (FDP)
  • D-dimer
  • Firbinolysis
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7
Q

What are D-dimer levels?

A
  • An important fibrin degradation product

- Used in tests to estimate rate of fibrinolysis

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8
Q

What is the secondary hemostatic plug?

A

Plug broken down by plasmin into Fibrin degradation products

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9
Q

Chemical mediators such as ___ and ____ are released by healthy endothelium and prevent platelet aggregation.

A
  • PGI2

- Nitric Oxide

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10
Q

What is the role of PGI2 in regards to platelet aggregation?

A

PGI2 increases cAMP levels within platelets and inhibits platelet activation.
-It is a thromboxane antagonist

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11
Q

Coagulation automatically initiates what?

A

Fibrinolysis

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12
Q

What are some anti-coagulation factors?

A
  • Antithrombin III

- Protein C and S (aslo require vitamin K for gamma-carboxylation)

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13
Q

What is the role of Antithrombin III?

A
  • Binds to and inhibits factor Xa and thrombin (IIa)

- Heparin acts by activating this factor and preventing coagulation.

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14
Q

What does Heparin activated to prevent clotting?

A

Antithrombin III

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15
Q

What are the roles of Protein C and S?

A

Act together to inactivate cofactors Va and VIIIa.

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16
Q

How is Protein C, and anti-coagulant factor, activated?

A

By the binding of thrombomodulin to thrombin.

17
Q

What is the role of Protein S?

A

Cofactor for protein C

18
Q

What is the role of Asprin and other COX 1 inhibitors?

A

prevent the formation of thromboxane in platelets. Action of aspirin on platelets is permanent.

19
Q

What is the role of Heparin?

A

activates antithrombin III and inactivates thrombin

20
Q

What is the role of Warfarin (oral anticoagulant)

A

blocks epoxide reductasein liver and prevents the regeneration of the active form of Vitamin K. Inhibits the synthesis of the mature vitK dependent clotting factors

21
Q

What is the role of streptokinase?

A

thrombolytic agent; plasminogen activator; converts plasminogen to plasmin enabling the dissolution of clots.

22
Q

The bleeding time test is an indicator of what?

A

Platelet plug formation

23
Q

Prolonged bleeding time is an indicator of what?

A
  • Low platelet count OR
  • vWF deficiency OR
  • Platelet receptor defects
24
Q

What does the clotting time test tell you?

A

Time taken for the formation of the stable fibrin

25
Q

Prolonged clotting time indicated defects in what?

A

Coagulation pathway

26
Q

The bleeding time test tells you what?

A

Test for the time taken from the initial injury to the formation of the platelet plug

27
Q

Specific defects of the intrinsic/extrinsic pathways are indicated by what?

A

Prothrombin time & Activated partial thromboplastin time (APTT/ PTT)

28
Q

The prothrombin tiime (PT) test is also known as what?

A

International normalized ratio

29
Q

Prothrombin time (PT) measures what?

A

Tests the extrinsic and the common coagulation pathways

30
Q

The Prothrombin Time (PT) test measures defects in what?

A
  • Tissue factor
  • Factor VII
  • Factor V
  • Factor X
  • Prothrombin
  • Firbinogen
31
Q

The partial thromboplastin time (APTT) tests what?

A

Intrinsic and common pathways

32
Q

The Partial Thromboplastin Time (APTT) test measures defects in what?

A
  • Factor VIII
  • Factor IX
  • Factor XI
  • Factor XII
  • Factor V
  • Factor X
  • Prothrombin
  • Firbinogen