12.2 Haemostasis Flashcards
Thrombus vs embolus vs thromboembolus
Thrombus: Clot
Embolus: dispatched from origin (e.g. air, fat etc.)
- Thromboembolus; blood clot that is an embolus
What is the overarching goal of the coagulation cascade?
Converting prothrombin to thrombin, which cleaves fibrinogen to form fibrin, thus strengthening a blood clot.
Which of the coagulation pathways responds to markers of internal vascular damage?
Intrinsic pathway
Which of the coagulation pathways responds to markers of external damage (e.g. a cut)?
Extrinsic pathway
Give an example of one factor that can trigger the extrinsic clotting pathway
Tissue Factor
Which factor do the extrinsic and intrinsic coagulation pathways meet at?
Factor X
Which coagulation pathway would respond to subendothelial collagen?
Intrinsic (internal damage)
List some antithrombotic proteins that are important in regulating blood clotting
- Protein C
- Antithrombin
- Protein S
Describe the heparin antithrombin system
- Antithrombin inhibits thrombin, preventing fibrin formation
- Heparin increases the catalytic rate of antithrombin
How does Protein C inhibit the coagulation cascade? What augments it?
- Activated to form APC
- Inhibits factor Va and IIIa, thus preventing cleaving of thrombin
- Protein S augments it
The ultimate goal of the coagulation cascade is to produce fibrin. What is the ultimate goal in fibrinolysis?
Ultimate goal is Plasmin.
What are Serpins? Are they exogenous or endogenous?
- Serine Protease Inhibitors
- They are endogenous
List the three types of Serpins?
- Plasmin activator inhibitor 1 and 2 (PA1 and PA2)
- Alpha 2 Anti-plasmin (A2AP)
True or false: the presence of thrombin activates protein C
True
How does tranexamic acid inhibit fibrinolysis?
It prevents plasmin from binding to fibrin
