Vascular Disorders and Thrombosis II

Question 1

what are the major players in hemostasis?

Answer 1

endothelium and underlying matrix
platelets
circulating factors

Question 2

what do prostacyclin and nitric oxide do with thrombosis?

Answer 2

inhibit platelet activation, adhesion, and aggregation
vasodilate

Question 3

does ADPase promote thrombosis or prevent it?

Answer 3

prevents it: degrades pro-thrombotic ADP

Question 4

what does tissue plasminogen activator do?

Answer 4

activates plasmin to digest fibrin

Question 5

what are the membrane associated factors of endothelium that prevent thrombus?

Answer 5

thrombomodulin and circulating proteins C and S
heparin-like molecules and circulating antithrombin III
tissue factor pathway inhibitor

Question 6

what does endothelin do?

Answer 6

vasoconstricts

Question 7

what does von Willebrand Factor do?

Answer 7

enhances platelet binding to collagen

Question 8

what does platelet activating factor do?

Answer 8

recruits and activates platelets

Question 9

what does tissue factor (factor III) do?

Answer 9

initiates extrinsic coagulation pathway

Question 10

what do plasminogen activator inhibitors do?

Answer 10

inhibit fibrinolysis

Question 11

what do platelets secrete to promote aggregation?

Answer 11

calcium
ADP- also activation
thromboxane A2- vasoconstricts as well

Question 12

what is the primary producer of most circulating clotting and anticoagulant factors?

Answer 12

liver

Question 13

what clotting factors produced by the liver are vitamin K-dependent?

Answer 13

II, VII, IX, X
protein C and protein S

Question 14

what is the primary initiator of the coagulation cascade in vivo?

Answer 14

extrinsic pathway: activated by exposure of Tissue Factor (factor III) to factor VII in circulation

Question 15

what is the primary amplifier of the coagulation cascade in vivo?

Answer 15

intrinsic pathway: activated by negatively-charged substances, collagen, inflammatory pathways

Question 16

what factors are involved in the intrinsic pathway for the coagulation cascade?

Answer 16

factors XII, XI, IX, VIII

Question 17

when do the extrinsic and intrinsic pathways merge?

Answer 17

activation of factor X: factor X and V= prothrombinase complex

Question 18

what is the ratio of blood to anticoagulant for a coagulation test?

Answer 18

9:1

Question 19

what is the initiation of the cell-based model of coagulation?

Answer 19

circulating VIIa binds tissue factor on surface damaged endothelial cells
factor Xa and a small amount of thrombin are produced

Question 20

how does thrombin amplify coagulation?

Answer 20

activates platelets, cleaves von Willebrand’s Factor-VIII complex, and activates factors V, VIII, XI

Question 21

what do activated coagulation factors aggregating on activated platelets lead to?

Answer 21

production abundant Xa

Question 22

what do Xa and Va produce?

Answer 22

abundant thrombin

Question 23

what inhibits fibrinolysis?

Answer 23

alpha-2 antiplasmin
plasminogen activator inhibitor-1

Question 24

what activates plasmin for fibrinolysis?

Answer 24

tissue plasminogen activator
urokinase-type plasminogen activator

Question 25

what is plasmin derived from?

Answer 25

circulating plasminogen

Question 26

what are the two major functions of plasmin?

Answer 26

fibrinolysis inhibition of fibrin polymerization

Question 27

what is a thrombus?

Answer 27

aggregate of platelets, fibrin, and blood cells temporary patch inappropriately large or persistent blood clot

Question 28

what is thrombosis?

Answer 28

formation of a pathologic thrombus

Question 29

what is an embolus?

Answer 29

thrombus or thrombus fragment is moved from its origin to a distant vessel

Question 30

what are the factors leading to pathologic thrombosis?

Answer 30

endothelial injury abnormal blood flow hypercoagulable state

Question 31

how can blood flow be altered in virchow's triad?

Answer 31

stasis turbulence

Question 32

what can lead to hypercoagulability in virchow's triad?

Answer 32

inflammation glomerular disease protein losing enteropathy liver disease endocrine disorders neoplasia

Question 33

what are the outcomes of thrombosis?

Answer 33

hypoxia ischemia infarction/infarct

Question 34

what makes up a reperfusion injury?

Answer 34

formation reactive oxygen species inflammation/mediators

Question 35

what does the color of an infarction depend on?

Answer 35

whether offending thrombus arterial or venous types of tissue duration infarct

Question 36

what can an embolus be?

Answer 36

detached thrombus (most frequent) fat or bone marrow gas bubble tumor fragment bacterial colonies foreign objects

Question 37

what may larger, chronic thrombi be replaced by?

Answer 37

granulation tissue, fibrosis +/- mineralization recanalization

Question 38

what does recanalization entain?

Answer 38

growth of new endothelium formation of capillary channels reinstitution of small amount of blood flow around/through thrombus

Question 39

what is an antemortem thrombus like?

Answer 39

firm, adhered to vessel wall red to tan, dull, often granular

Question 40

what is a postmortem clot like?

Answer 40

soft, gelatinous, loosely or not adhered to vessel wall deep red and smooth often, can be tan/yellow if red cells settle out

Question 41

how can you distinguish an arterial thrombus from a venous one?

Answer 41

arterial is often more pale see gross or microscopic lamellations (lines of Zahn)

Question 42

how can you tell a thrombus is venous instead of arterial?

Answer 42

more red less firm should have attachment point on vessel wall similar in appearance to postmortem clot

Question 43

how does hypertrophic cardiomyopathy in cats lead to a saddle thrombus (embolism in distal abdominal aorta)?

Answer 43

left ventricle fills poorly, so left atrium is backed up left atrium remodels by dilation and local endothelial damage with stretching stasis and endothelial injury leads to clot in left atrium dislodges

Question 44

where is the defect in primary hemostatic disorders?

Answer 44

platelet arm of coagulation

Question 45

what are the characteristics of von Willebrand disease?

Answer 45

decreased or absent von Willebrand's Factor platelet numbers and function are normal reduces ability of platelets to bind to subendothelial collagen

Question 46

what are the characteristics of hemostatic disorders?

Answer 46

hematomas cavitary hemorrhage delayed bleeding from venipuncture sites

Question 47

is liver disease with loss of hepatic parenchyma and example of secondary or primary hemostatic disorders?

Answer 47

secondary hemostatic disorders

Question 48

true/false: a patient with liver disease with loss of hepatic parenchyma is at risk for hyper- and hypocoagulabilty

Answer 48

true

Question 49

what do vitamin K antagonist rodenticides inhibit?

Answer 49

factors II, VII, IX, X from binding calcium and phospholipid surface

Question 50

what happens in disseminated intravascular coagulation with clotting and clotting factors?

Answer 50

widespread activation of coagulation in small vessels massive consumption of platelets and clotting factors

Question 51

what is hypoxanthine?

Answer 51

reacts with oxygen to form free radicals in reperfusion injury