Hemostasis and Thrombosis

Question 1

What is hemostasis?

Answer 1

Maintenance of clot-free blood within the vascular system while allowing for the formation of a solid plug of blood under conditions of vessel wall injury (ie. thrombosis)

Question 2

What are the “key players” in hemostasis?

Answer 2

• Vascular endothelium
• Platelets
• Coagulation system

Question 3

What are some anti-platelet effects of intact endothelium?

Answer 3

• Insulate platelets from subendothelial collagen
• Prostacyclin (PGI2) synthesis
• ADPase synthesis
• Nitric oxide synthesis

Question 4

What is the function of prostacyclin (PGI2)?

Answer 4

Inhibits platelet aggregation

Question 5

What is the function of ADPase?

Answer 5

ADP activates platelets, increased ADP leads to less ATP, platelet aggregation is inhibited

Question 6

What is the function of nitric oxide?

Answer 6

Vasodilation and inhibits platelet aggregation

Question 7

The intrinsic pathway with CF XII and the extrinsic pathway with tissue factor join in the common pathway to make…

Answer 7

fibrin which allows for clot

Question 8

Does ADP or ATP activate platelets?

Answer 8

ADP (not ATP)

Question 9

What is an anti-coagulant effect of intact endothelium?

Answer 9

Heparin-like molecule synthesis

Question 10

Heparin-like molecule synthesis activates…

Answer 10

anti-thrombin III (degrades thrombin)

Question 11

Without thrombin, fibrinogen cannot join with it to form…

Answer 11

fibrin

Question 12

Normally, thrombin and fibrinogen form…

Answer 12

fibrin

Question 13

Normally, plasminogen and tPA will form…

Answer 13

plasmin

Question 14

Normally, fibrin and plasmin form…

Answer 14

fibrin split products

Question 15

Without plasmin or fibrin, what cannot be formed?

Answer 15

Fibrin split products

Question 16

What is a fibrinolytic property of intact endothelium?

Answer 16

Tissue plasminogen activator (tPA) synthesis

Question 17

What is the function of tPA?

Answer 17

Converts plasminogen to plasmin (plasmin degrades fibrin)

Question 18

What are some pro-thrombotic properties of damaged endothelium?

Answer 18

• von Willebrand’s factor synthesis
• Tissue factor synthesis
• Platelet activating factor (PAF)
• tPA inhibitor synthesis

Question 19

What is tPAi?

Answer 19

Tissue plasminogen activator inhibitor

Question 20

von Willebrand’s factor is essential for…

Answer 20

platelet adhesion

Question 21

What is the significance of tissue factor synthesis?

Answer 21

Glycoprotein activates coagulation system

Question 22

What are considered the “brick” of a thrombus?

Answer 22

Platelets

Question 23

What is secreted by platelets when they are activated?

Answer 23

• Thromboxane (TXA2)
• ADP
• Factor V
• Factor VIII
• Calcium

Question 24

Activated platelets bind to…

Answer 24

exposed collagen (vWF)

Question 25

Activated platelets are involved in initiation of...

Answer 25

coagulation cascade (role of calcium and phospholipid complex)

Question 26

A temporary "plug" of platelets becomes definitive with...

Answer 26

formation of fibrin from thrombin (leads to fused mass of platelets)

Question 27

What activates the coagulation system?

Answer 27

Factor XII or tissue factor

Question 28

What is the end product of the coagulation system?

Answer 28

Formation of fibrin monomers

Question 29

What is the "cement" of a thrombus?

Answer 29

Fibrin

Question 30

Is thrombosis normal or pathological?

Answer 30

Pathological

Question 31

What is thrombosis?

Answer 31

An aggregate of platelets, fibrin, and blood cells within the non-interrupted vascular system (clot should not be there)

Question 32

Thrombus is adherent to...

Answer 32

the vascular endothelium

Question 33

Where may thrombosis arise?

Answer 33

Arterial or venous circulation

Question 34

Surgery anywhere increases the risk of...

Answer 34

deep vein thrombosis

Question 35

What are the predisposing factors to arterial thrombi?

Answer 35

Virchow's triad: * Damage to endothelium * Alterations in blood flow * Increased coagulability of blood

Question 36

Which aspect of Virchow's triad is most predisposing to arterial thrombi?

Answer 36

Damage to endothelium

Question 37

What are three types of damage to endothelium?

Answer 37

* Ischemic damage to endocardium * Valvular damage * Free-radical induced damage

Question 38

What are some causes of free-radical induced damage?

Answer 38

* Hemodynamic stress (increased blood pressure) * Radiation * Trauma * Chemicals * Microbes

Question 39

Alterations in normal blood flow refer to...

Answer 39

role of stasis and turbulence

Question 40

What are the alterations in normal blood flow when endothelium is physically damaged?

Answer 40

* Disrupts laminar flow * Prevents renal clearance of coagulation proteins * Slows flow of anticoagulants to site of injury

Question 41

What is Leiden Factor V? What does its defect lead to?

Answer 41

A coagulant protein Factor V can't shut off coagulation leading to increased risk of thrombosis

Question 42

What are causes of increased coagulability of blood?

Answer 42

* Genetic defect in anticoagulant proteins or coagulant proteins Leiden factor V * Inherited hypercoagulability

Question 43

What is the most common genetic hypercoagulability disorder?

Answer 43

Activated protein C resistance

Question 44

APC resistance accounts for up to 65% of patients with...

Answer 44

venous thrombosis

Question 45

What is activated protein C resistance?

Answer 45

A point mutation in the factor V gene (factor V Leiden) renders it resistant to inhibition by APC (can't turn off coagulation)

Question 46

What is the effect of homocysteine? What gene prevents metabolization of homocysteine?

Answer 46

Homocysteine produces free radicals in the blood MTHFR gene: can't metabolize homocysteine

Question 47

When a patient has the MTHFR gene and can't metabolize homocysteine, what is the effect?

Answer 47

Inherited hypercoagulability

Question 48

How does neoplasia lead to hypercoagulability?

Answer 48

Releases procoagulants

Question 49

What is the effect of polycythemia vera leading to hypercoagulability?

Answer 49

Increased RBC and viscosity

Question 50

How does smoking lead to hypercoagulability?

Answer 50

Free radical damage to endothelium

Question 51

How does obesity lead to hypercoagulability?

Answer 51

Increased fat increases viscosity