Hemostasis & 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

Question 2

what are the key players in hemostasis?

Answer 2

vascular endothelium
platelets
coagulation system

Question 3

what are the 4 anti-platelet effects of intact endothelium?

Answer 3

1. insulates platelets from subendothelial collagen
2. prostacyclin (PGI2) synthesis
3. ADPase synthesis
4. nitric oxide synthesis

Question 4

what does prostacyclin (PGI2) do?

Answer 4

inhibits platelet aggregation

Question 5

what does ADPase synthesis do?

Answer 5

inhibits platelet aggregation

Question 6

what does nitric oxide synthesis do?

Answer 6

vasodilation and inhibits platelet aggregation

Question 7

what molecule activates anti-thrombin III?

Answer 7

heparin like molecule

Question 8

what effect does heparin-like molecule have on intact endothelium?

Answer 8

anti-coagulant

Question 9

what does anti-thrombin III do?

Answer 9

degrades thrombin

Question 10

what does tissue plasminogen activator (t-PA) do?

Answer 10

converts plasminogen to plasmin

Question 11

what property does t-PA have?

Answer 11

fibrinolytic property of INTACT endothelium

Question 12

what does plasmin do?

Answer 12

degrades fibrin

Question 13

what are the 4 pro-thrombotic properties of damaged endothelium?

Answer 13

• von willebrand factor synthesis
• tissue factor synthesis
• platelet activating factor (PAF)
• t-PA inhibitor synthesis

Question 14

what does von Willebrands factor do?

Answer 14

essential for platelet adhesion

Question 15

what does tissue factor do?

Answer 15

glycoprotein which activates coagulation system

Question 16

what are the “bricks” of a thrombus?

Answer 16

platelets

Question 17

what are the molecules that are secreted by platelets that cause activation of platelets?

Answer 17

• thromboxane (TXA2)
• ADP
• clotting factors V and VIII
• calcium

Question 18

activated platelets bind to ____

Answer 18

vWF

Question 19

activated platelets involved in initiation of the ____

Answer 19

coagulation cascade

Question 20

how does a temporary clot become definitive?

Answer 20

formation of fibrin from thrombin = fused mass of platelets

Question 21

what is the coagulation system activated by?

Answer 21

factor XII or tissue factor

Question 22

what is the end product of coagulation system?

Answer 22

fibrin monomers

Question 23

fibrin is the “____” of a thrombus

Answer 23

cement

Question 24

what is thrombosis?

Answer 24

pathological aggregate of platelets, fibrin and blood cells within the non-interrupted vascular system (where a clot should not be / not a problem here)

Question 25

what is a thrombosis adherent to?

Answer 25

vascular endothelium

Question 26

T/F: thrombosis only arise in veins

Answer 26

F: arterial or venous circulation

Question 27

what are the 3 predisposing factors to thrombi?

Answer 27

- damage to endothelium - alterations in normal blood flow - increased coagulability of blood

Question 28

what is another name for the 3 predisposing factors to a thrombi?

Answer 28

virchow's triad

Question 29

what is laminar flow?

Answer 29

normal (good) flow in a blood vessel

Question 30

what kind of flow has an obstruction of a blood vessel on either side of it?

Answer 30

turbulent flow

Question 31

what does turbulent flow increase the risk of?

Answer 31

endothelial damage

Question 32

what are 4 things that can lead to damage of the endothelium?

Answer 32

1. ischemic damage to endocardium 2. valvular damage 3. free radical induced damage (radiation, trauma, chemicals, microbes) 4. hemodynamic stress ----> high BP (more energy hitting the walls

Question 33

name 2 types of alterations in normal blood flow

Answer 33

stasis & turbulence

Question 34

what do alterations in normal blood flow cause?

Answer 34

1. physical damage to endothelium 2. disrupts laminar flow 3. prevent renal clearance of coagulation proteins 4. retards flow of anticoagulants to stie of injury

Question 35

what are some examples of causes of increased coagulability of blood?

Answer 35

- genetic defect in anticoagulant proteins or coagulant proteins: Leiden Factor V (inherited hypercoagulability) - activated protein C (APC) resistance -- Factor V Leiden - MTHFR gene (higher risk of heart disease since unable to metabolize homocysteine) - neoplasia (release of procoagulants) - polycythemia vera (^viscosity) - smoking, obesity (soft risks)

Question 36

what causes Activated protein C (APC) resistance --- factor V leiden

Answer 36

A point mutation in the factor V gene (factor V Leiden) renders it resistant to inhibition by APC

Question 37

_____ action is the most common genetic hypercoagulability disorder and accounts for up to ______ % of patients with venous thrombosis

Answer 37

Resistance APC 65%