phase 1 recap - bleeding and coag

Question 1

where are platelets synthesised

Answer 1

bone marrow

Question 2

roles of platelets

Answer 2

• Adhesion to vessel wall
• Activation and granule release
• Aggregation to other platelets

Question 3

where is VWF stored

Answer 3

Weibel Palade bodies and platelet alpha granules

Question 4

what factor does VWF carry into the bloodstream

Answer 4

VII

Question 5

role of thrombin

Answer 5

converts fibrinogen to fibrin

Question 6

contrast the anti-coagulant and pro-coagulant roles of thrombin

Answer 6

anti-coagulant:
- thrombin production
- thrombin-thrombomodulin complex
- protein C converted to activated protein C
- APC binds with protein S and inactivates FV and FVIII

pro-coagulant:
- converts finrinogen to fibrin
- activates FXI, FVIII, FV, FXIII
- activates platelets

Question 7

natural anticoagulants

Answer 7

anti-thrombin:
- made in liver
inhibits thrombin and Xa

proteins C and S:
- made in liver
- breakdown Va and VIIIa

tissue factor pathway inhibitor:

fibrinolysis:
- breakdown of fibrin
- via plasmin

tissue plasminogen activator:
- released by endothelial cells
- blocked by inhibitors in bloodstreaam
- presence of fibrin allows it to act and convert plasminogen into plasmin
- also degrades its inhibitors