Understanding anticoagulation Flashcards
After injury what are the three mechanisms activated to decrease/halt bleeding?
Vasoconstriction
Gap plugging by platelet formation
Coagulation via cascade.
These mechanisms can be activated inappropriately and predispose patients to stroke.
The endothelial surface cells of blood vessels are involved in the balance between clotting and bleeding by secreting compounds such as________, _____ ______ ______ (_-__), and ____________ (e.g.________).
The surface cells are also involved in the balance between fibrinolysis and fibrin formation.
von Willebran factor,
tissue plasminogen activator (t-PA),
and prostaglandins (e.g. prostacyclin)
The platelet response is composed of what 4 steps?
Adhesion
Secretion
Aggregation
Propagation of procoagulant activity.
The coagulation factor consist of __ plasma proteins that ciruclate in their inactive form. Coagulation of blood causes a cascading series of proteolytic reactions that result in an active ______ which activates the next clotting factor until a ______ _____ is formed.
12.
Protease
Fibrin clot.
What are the Vitamin-K-dependent factors? [4]
II
VII
IX
X
What are the contact activation factors? [4]
XI
XII
Prekalikrein
High molecular weight kininogen
What are the thrombin sensitive factors? [4]
V
VIII
XIII
Fibrinogen
Tissue injury releases
Tissue factor (extrinsic to blood) which activates the extrinsic pathway through factor VII.
Subendothelial membrance contact with factor XII initiates the intrinsic pathway.
When tissue factor, extrinsic to blood, activates the extrinsic pathway, what does it do this through?
Factor VII
How does the fibrinolysis process start?
Release of t-PA from endothelial cells.
In response to thrombin or venous stasis, t-PA is incorporated into the forming clot by binding to fibrin.
t-Pa converts inactive plasminogen into plasmin, which digests fibrin and dissolves the clot.
When is t-PA incorporated into a forming clot?
In response to thrombin or venous stasis.
How is t-PA incorporated into a forming clot?
Binding to fibrin.
How does t-PA cause clot breakdown?
t-PA converts inactive plasminogen into plasmin, which digests fibrin and dissolves the clot.
What does bleeding time measure?
The length of time to the cessation of bleeding following a standardised skin cut.
Wha are 4 factors that prolong bleeding time?
Thrombocytopenia
Platelet dysfunction
aspirin/NSAIDs
SSRIS
