Hemostasis Flashcards

1
Q

What are the major players in hemostasis?

A

Platelets
Endothelial cells
Coagulation

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2
Q

What are the three things that contribute to thrombosis?

A

Endothelial injury
Abnormal blood flow
Hypercoaguability

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3
Q

Hypocoagulation is displayed as:

Hypercoagulation is displayed as:

A

Hemorrhage

Thromboembolic disorders

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4
Q

Hemostasis and coagulation are regulated by what 3 componenets?

A

Vascular wall: endothelial cells have procoagulant and anti-coagulant on them
Platelets
Coagulation cascade

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5
Q

What are the steps of hemostasis?

A

Vasoconstriction: very transient and fast
Primary hemostasis: hemostatic plug formed; reversible
Secondary hemostasis: polymerizes fibrin; irreversible

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6
Q

What is the endothelial derived vasoconstrictor that follows injury to vessel wall?

A

Endothelin

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7
Q

What two things initate the coagulation cascade at secondary hemostasis?

A

Tissue Factor (F3) + activated platelets

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8
Q

What are some properties of endothelial cells that are prothrombotic?

A

Produce vWF
Synthesize TF
Antifibrinolytic properties: prevents fibrinolysis

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9
Q

What are some properties of endothelial cells that are antithrombotic?

A

Have heparin like modules
Thrombomodulin binds thrombin
Tissue factor pathway inhibitor: deactivates TF, F7 and F10

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10
Q

What is it again that resists shear forces?

A

vWF and GP2a

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11
Q

What are the three pathways of the coagulation cascade?

A

Extrinsic
Intrinsic
Common

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12
Q

What is the extrinsic pathway?

A

Starts with Factor 3 (Tissue factor)

Activates F7 –> F10 (Common pathway) AND F9 (Intrinsic)

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13
Q

What is the intrinsic pathway?

A

Factor 12 –> Factor 11 –> F9 –> F8 (co-factor) –> F10 (Common)

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14
Q

What is the common pathway?

A

F10 –> F5 –> F2 (thrombin)

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15
Q

Cats often lack what factor?

A

Factor 12; not a big deal as F7 can still activate the intrinsic pathway via F7 –> F9

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16
Q

What are the vitamin K dependent factors?

A

Factors 2,7,9,10 Protein C and Protein S

17
Q

PT test looks at what? What % has to be decreased for this to prolong test?

A

Extrinsic and common pathways

>70% of factors have to be decreased

18
Q

T/F If not available, human reference intervals are okay to substitute for PT and PTT tests

A

FALSE; they should NEVER be used

19
Q

PTT test looks at what?

A

Intrinsic and common pathways

20
Q

D-Dimers test is a specific indicator for what?

A

Secondary fibrinolysis

21
Q

What is an increased D-Dimers indicate?

A

Hemorrhage and thrombosis

Thromboembolism

22
Q

What species can a D-Dimers test be run for? Which should it not be run for?

A

Dogs and horses

Don’t use in cats

23
Q

What are FDPs? When do we see an increase in these?

A

Fibrin degradation products

Increased in DIC, inflammation and liver DZ

24
Q

What factors play a role in fibrinolysis?

A

tissue Plasma Activator (tPA)
Antithrombin 3
Protein C and S
Tissue Factor Inhibitor

25
Q

Antithrombin III is a protein that inhibits what?

A

Thrombin

Factors 7, 11, 9, and 10

26
Q

Proteins C and S inhibit what?

A

Factors 7 and 5 (co-factors)

27
Q

Hemophilia A is a deficiency in what?

A

Factor 8; affects the intrinsic pathway

28
Q

Hemophilia B is a deficiency in what?

A

Factor 9

29
Q

Hageman’s disease is a deficiency in what factor?

A

Factor 12

30
Q

Factor 11 deficiency can be seen in what species?

A

Dogs and Holstein cattle

31
Q

How does Factor 7 deficiency present?

A

Likely in dogs with easy bruising

32
Q

T/F Disseminated Intravascular Coagulation is a primary disease

A

FALSE; it is secondary to other pathology

33
Q

No single test is a determinant for DIC; what are 3 or more of the criteria that fit for DIC?

A
Decreased platelets (mild to severe) 
PRolonged PT or PTT
Increased FDPs or D-Dimers 
Decreased Fibrinogen 
Decreased AT3
Presence of RBC fragments on blood smear