Blood coagulation Flashcards

1
Q

Steps of normal hemostasis

A

Vasospasm (reduce blood flow and enhance platelet aggregation+coagulation). Formation of platelet plug. Thombin catalyzes fibrinogen to fibrin. Fibrin clot formation. Fibrinolysis by plasmin.

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2
Q

When are the different coagulation pathways activated?

A

Intrinsic pathway: surface contact with a foreign body or extravascular tissue.
Extrinsic pathway: Thromboplastin

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3
Q

Coagulation factors that are dependent on vitamin K

A

II - prothrombin.
VII - proconvertin (no longer considered a coagulation factor).
IX - plasma thromboplastin component.
X - Stuart factor.

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4
Q

Major rate limiting step in coagulation cascade

A

Activation of factor X

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5
Q

Thrombin - effects

A

Catalyzes fibrinogen to fibrin, and is a powerful stimulus for platelet aggregation.

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6
Q

Stimulus for platelet aggregation and coagulation

A

Atherosclerosis, venous pooling, thrombophlebitis

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7
Q

White vs red thrombi - location and mechanism

A

White thrombi: arterial circulation - often caused bu platelet aggregation.
Red thrombi: venous ciculation - often caused bu coagulation.

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8
Q

Main types of anticoagulants

A

Vitamin K antagonists.
Drugs that potentiate antithrombin III.
Drug that directly inhibit thrombin or active factor X.

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9
Q

Which coagulation factors are inhibited by warfarin, and in which pathway are these factors found?

A
IX - intrinsic
VII - extrinsic
X - both pathways
Prothrombin - both pathways
(all are inactive factors)
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10
Q

Which coagulation factors are inhibited by heparin?

A

All active coagulation factors

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11
Q

Intrinsic coagulation pathway - cascade

A

1) Surface contact
2) XII (Hageman factor) activation
3) XI activation
4) IX activation
5) X (Stuart factor) activation
6) II (prothrombin) activation.
7) activation of fibrin, and formation of stabilized fibrin by factor XIII

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12
Q

Extrinsic coagulation pathway - cascade

A

1) Tissue factor.
2) VII (proconvertin) activation
3) Activation of X (Stuart factor)
4) II (prothrombin) activation.
5) activation of fibrin, and formation of stabilized fibrin by factor XIII

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13
Q

Drugs that may increase prothrombin time (15 drugs)

mnemonic, letter for each drug) ADD CAMP CHARTS FA(st

A
Amiodarone
Cimetidine
Disulfiram
Fluconazole
Metronidazole
Phenylbutazone
Sulfinpyrazone
Trimethoprim-sulfamethoxazole
Aspirin (high doses)
Cephalosporins, third-generation
Heparin, argatroban, dabigatran, rivaroxaban, apixaban
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14
Q

Body factors that may increase prothrombin time

A

Hyperthyroidism, hepatic disease

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15
Q

Drugs that may decrease prothrombin time

A
Barbiturates
Cholestyramine
Rifampin
Diuretics
Vit K
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16
Q

Body factors that may decrease prothrombin time

A

Hereditary resistance, hypothyroidism