Hemostasis Flashcards
What are the major players in hemostasis?
Platelets
Endothelial cells
Coagulation
What are the three things that contribute to thrombosis?
Endothelial injury
Abnormal blood flow
Hypercoaguability
Hypocoagulation is displayed as:
Hypercoagulation is displayed as:
Hemorrhage
Thromboembolic disorders
Hemostasis and coagulation are regulated by what 3 componenets?
Vascular wall: endothelial cells have procoagulant and anti-coagulant on them
Platelets
Coagulation cascade
What are the steps of hemostasis?
Vasoconstriction: very transient and fast
Primary hemostasis: hemostatic plug formed; reversible
Secondary hemostasis: polymerizes fibrin; irreversible
What is the endothelial derived vasoconstrictor that follows injury to vessel wall?
Endothelin
What two things initate the coagulation cascade at secondary hemostasis?
Tissue Factor (F3) + activated platelets
What are some properties of endothelial cells that are prothrombotic?
Produce vWF
Synthesize TF
Antifibrinolytic properties: prevents fibrinolysis
What are some properties of endothelial cells that are antithrombotic?
Have heparin like modules
Thrombomodulin binds thrombin
Tissue factor pathway inhibitor: deactivates TF, F7 and F10
What is it again that resists shear forces?
vWF and GP2a
What are the three pathways of the coagulation cascade?
Extrinsic
Intrinsic
Common
What is the extrinsic pathway?
Starts with Factor 3 (Tissue factor)
Activates F7 –> F10 (Common pathway) AND F9 (Intrinsic)
What is the intrinsic pathway?
Factor 12 –> Factor 11 –> F9 –> F8 (co-factor) –> F10 (Common)
What is the common pathway?
F10 –> F5 –> F2 (thrombin)
Cats often lack what factor?
Factor 12; not a big deal as F7 can still activate the intrinsic pathway via F7 –> F9