Zusammenfassung der Ressource
normal haemostasis
- haemostasis= normal
process of blood clotting
- occurs via a series of tightly regulated interactions
- 5 main components
- coagulation factors
- made (mainly by
liver) in inactive form
- activated
when coagn
initiated
- usually by tissue
factor (released
by vessel injury)
- coagulation inhibitors
- either circulate in
plasma or bound
to endothelium
- are necessary to prevent widespread
coagn throughout the body once
coagulatn has been initiated
- fibrinolysis
- limits fibrin
deposition @
site of injury
- due to activity of
plasmin enzyme
- platelets
- vital for haemostasis
- cos they aggregate at
sites of vessel injury
- form haemostatic plug
(which is then stabilised by fibrin)
- blood vessels
- start and limit coagulation
- intact vascular endothelium secretes
prostaglandin I2 & nitric oxide
- promote vasodilatatn &
inhibit platelet aggregatn
- damaged
endothelium
- releases tissue factor &
procoagulants (e.g. collagen
& von Willebrand factor)
- has inhibitors of
coagulation on endothelial
surface (thrombomodulin,
antithrombin & protein S)
- coagulation cascade
- endpoint=generation
of thrombin
- 2 main
pathways
to get
thrombin
- intrinsic
pathway
- extrinsic
pathway
- mostly responsible for
starting normal haemostasis
& thrombotic disease