coagulation cascade Flashcards
what role do NO and PGI2 play in coagulation
inhibits platelets and keeps them inactive, preventing them being able to bind to endothelial lining
what to glycosaminoglycans do (GAGs) - heparin sulfate
activates anti-thrombin-3
this inactivates clotting factors II, IX and X
what does thrombomodulin do
binds thrombin (II)
activates protein C
protein C degrades factors V and VIII - inactivates
what are the three stages of haemostasis
vascular spasm
formation of a platelet plug
coagulation
what happens in the platelet plug stage
platelets release prothrombin activator when bound to exposed collagen
this activates prothrombin (produced in liver and vitamin K dependant) to be converted to thrombin
thrombin cuts fibrinogen into fibrin
coagulation phase
fibrin accumulates at damaged site
reinforcing the clot
what does VwF do
by injured endothelial cells
platelets bind to VwF - via Gp1b
what does factor XII do
interacts with negative charges on platelets, converts to an active form
factor VII activates factor XI
what does factor XI do
activates factor IX
what does factor IX do
interacts with factor VIII
factors VII and IX combine to drive the conversion on factor X to its active form
what does factor X do
reacts with factor V
this activates prothrombin activator
what factor does thrombin interact with
factor XIII, becomes activated and is able to cross link fibrin strands to prevent thrombus dislodging
factor III (tissue factor)
reacts with factor VII, activating it
factor VII can help to activate factor IX or converge into the common pathway (factor X)
