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POD Test Two > Hemodynamic 2 Lecture > Flashcards

Hemodynamic 2 Lecture Flashcards

1
Q

Define hemostasis

A

Result of a set of well-regulated processes that achieve two important functions

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2
Q

What are the functions of hemostasis?

A

Maintain blood in a fluid, clot-free state in normal vessels

Poised to induce a rapid and localized hemostatic plug at a site of vascular injury

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3
Q

Define thrombosis

A

Pathologic opposite to hemostasis
- Inappropriate activation of normal hemostatic processes, such as formation of a blood clot in uninjured vasculature or thrombotic occlusion of a vessel after relatively minor injury

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4
Q

What are factors responsible for both hemostasis and thrombosis depends on what?

A

The vascular wall
Platelets
The coagulation cascade

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5
Q

Why is endothelial integrity important?

A

Injury to endothelial cells can affect local blood flow and or coagulability; abnormal blood flow (stasis or turbulence) can cause endothelial injury

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6
Q

What causes thrombosis?

A

Endothelial injury
Hypercoagulatability
Abnormal blood flow
- May work together or independently

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7
Q

What are the sequences of hemostasis?

A

A brief period of arteriolar vasoconstriction , attributable to neurogenic mechanisms
Augmented by the local secretion of factors such as endothelin (a endothelium-derived vasoconstrictor)
Exposure of highly thrombogenic sub-endothelial extracellular matrix allows platelets to adhere and become activated

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8
Q

Process of primary hemostasis?

A

Endothelial injury exposes highly thrombogenic sub-endothelial and releasing secretory granules
Within minutes, the secreted products have recruited additional platelets to form a hemostatic plug

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9
Q

Process of secondary hemostasis?

A

Endothelial tissue factor (procoagulant factor) is exposed
Acts in conjuntion with the secreted platelet factors to activate the coagulation cascade, culminating in the activation of thrombin
Thrombin converts fibrinogen to fibrin leading to deposition
Thrombin induces additional platelet recruitment and granule release

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10
Q

Process of thrombus and antithrombotic?

A

Polymerized fibrin and platelet aggregates, form a solid plug to prevent any further hemorrhage
Counter regulatory mechanisms are set to restrict the hemostatic plug to the injury site

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11
Q

What is the coagulation cascade?

A

Coagulation involves a series of pro-enzyme activation reactions
At each stage, a precursor protein is converted to an active protease
Final protease to be generated is thrombin (Factor IIa)
Thrombin converts fibrinogen to fibrin

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12
Q

What is coagulation?

A

Initial reaction complex complex (enzyme Factor IXa, substrate Factor X, reaction accelerator Factor VIIIa)
Activated factor Xa then becomes the enzyme for the second adjacent complex in the cascade with the help of the reaction accelerator factor Va

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13
Q

What does factor Xa do?

A

Converting the prothrombin substrate to thrombin

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14
Q

What is von Willebrand factor for?

A

Facilitates endothelial injury leads to adhesion of platelets to the underlying extracellular matrix

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15
Q

What activates the extrinsic clotting cascade?

A

Endothelial cells are also induced by bacterial endotoxin or by cytokines to synthesize tissue factor

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16
Q

What Factors IXa and Xa do what?

A

Binding activates endothelial cells to augment the catalytic activities of these coagulation factors

17
Q

What suppresses fibrinolysis?

A

Endothelial cells secreting plasminogen activator inhibitor proteins

18
Q

What are give antithrombotic properties?

A 
Antiplatelet effects
Heparin-like molecules
Thrombomodulin
Endothelial tissue plasminogen activator
Tissue factor pathway inhibitor
19
Q

What are antiplatelet effects?

A

Non-activating platelets specifically inhibited from adhering to the uninjured endothelium by prostacyclin and NO

20
Q

What do heparin-like molecules do?

A

Act as cofactors allowing antithrombin to inactivate thrombin, factor Xa, and others

21
Q

What does thrombomodulin do?

A

Binds to thrombin converting it to an anticoagulant activating protein C
- Activating protein C inhibits clotting by proteolytic cleavage of factors Va and VIIIa in the presence of protein S

22
Q

What does endothelial tissue plasminogen activator promote?

A

Fibrinolytic activity to clear fibrin deposits

23
Q

What does tissue factor pathway inhibitor do?

A

Inhibits activated factor VIIa and Xa

24
Q

How does platelet adhesion work?

A

von Willebrand factor functions as an adhesion bridge between subendothelial collagen and GpIb platelet receptor complex (in association with factor V and IX)
Ag

25
Q

How does platelet aggregation work?

A

Involves linking platelets via fibrinogen bridges bound to the platelet GpIIb-IIIa receptors

26
Q

What does the Fibrinolytic system do?

A

Tissue plasminogen activator leads to teh dissolution of thrombi by converting the symogen plasminogen to its active form, plasmin
Plasminogen and plasmin bind to fibrin at binding sites richin lysine residues, which is requored for alpha2-antiplasmin to bind to form stable complex
Plasmin mediates the degradation of fibrin by direct cleavage of fibrin into soluble fragments

27
Q

What are platelet problems?

A

Bleeding occurs very fast as soon as you injure yourself and is mostly on the skin, in the nose, mouth, GI tract, and urinary tract

28
Q

What are coagulation factor problems?

A

The bleeding is more “deep” in the body such as in the joints, muscles and in other body cavities

29
Q

What are the four fates of a thrombus?

A

Propagation
Embolization
Dissolution
Organization and recanalization

30
Q

Define propagation

A

obstructing some critical vessels

-Thrombus get bigger with further platelet aggregation and fibrin deposition

31
Q

Define embolization

A

dislodges and transported to other sites

32
Q

Define dissolution

A

Removed by fibrinolytic activity- plasmin

33
Q

Define organization and recanalization

A

Induce inflammation and fibrosis

Reestablish vascular flow

POD Test Two (8 decks)

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