Hemostasis

Question 1

What are the major players in hemostasis?

Answer 1

Platelets
Endothelial cells
Coagulation

Question 2

What are the three things that contribute to thrombosis?

Answer 2

Endothelial injury
Abnormal blood flow
Hypercoaguability

Question 3

Hypocoagulation is displayed as:

Hypercoagulation is displayed as:

Answer 3

Hemorrhage

Thromboembolic disorders

Question 4

Hemostasis and coagulation are regulated by what 3 componenets?

Answer 4

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

Question 5

What are the steps of hemostasis?

Answer 5

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

Question 6

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

Answer 6

Endothelin

Question 7

What two things initate the coagulation cascade at secondary hemostasis?

Answer 7

Tissue Factor (F3) + activated platelets

Question 8

What are some properties of endothelial cells that are prothrombotic?

Answer 8

Produce vWF
Synthesize TF
Antifibrinolytic properties: prevents fibrinolysis

Question 9

What are some properties of endothelial cells that are antithrombotic?

Answer 9

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

Question 10

What is it again that resists shear forces?

Answer 10

vWF and GP2a

Question 11

What are the three pathways of the coagulation cascade?

Answer 11

Extrinsic
Intrinsic
Common

Question 12

What is the extrinsic pathway?

Answer 12

Starts with Factor 3 (Tissue factor)

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

Question 13

What is the intrinsic pathway?

Answer 13

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

Question 14

What is the common pathway?

Answer 14

F10 –> F5 –> F2 (thrombin)

Question 15

Cats often lack what factor?

Answer 15

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

Question 16

What are the vitamin K dependent factors?

Answer 16

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

Question 17

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

Answer 17

Extrinsic and common pathways

>70% of factors have to be decreased

Question 18

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

Answer 18

FALSE; they should NEVER be used

Question 19

PTT test looks at what?

Answer 19

Intrinsic and common pathways

Question 20

D-Dimers test is a specific indicator for what?

Answer 20

Secondary fibrinolysis

Question 21

What is an increased D-Dimers indicate?

Answer 21

Hemorrhage and thrombosis

Thromboembolism

Question 22

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

Answer 22

Dogs and horses

Don’t use in cats

Question 23

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

Answer 23

Fibrin degradation products

Increased in DIC, inflammation and liver DZ

Question 24

What factors play a role in fibrinolysis?

Answer 24

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

Question 25

Antithrombin III is a protein that inhibits what?

Answer 25

Thrombin | Factors 7, 11, 9, and 10

Question 26

Proteins C and S inhibit what?

Answer 26

Factors 7 and 5 (co-factors)

Question 27

Hemophilia A is a deficiency in what?

Answer 27

Factor 8; affects the intrinsic pathway

Question 28

Hemophilia B is a deficiency in what?

Answer 28

Factor 9

Question 29

Hageman's disease is a deficiency in what factor?

Answer 29

Factor 12

Question 30

Factor 11 deficiency can be seen in what species?

Answer 30

Dogs and Holstein cattle

Question 31

How does Factor 7 deficiency present?

Answer 31

Likely in dogs with easy bruising

Question 32

T/F Disseminated Intravascular Coagulation is a primary disease

Answer 32

FALSE; it is secondary to other pathology

Question 33

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

Answer 33

``` 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 ```