Haemostasis Flashcards
lifespan on platelets
7 days
stages of haemostasis
primary (platelet plug)
secondary (fibrin clot)
fibrinolysis
symptoms of problems with primary haemostasis
spontaneous bruising and purpura
mucosal bleeding e.g. epistaxis, conjunctival, menorrhagia
intracranial haemorrhage
retinal haemorrhages
how can you screen for problems with primary haemostasis
platelet count
give an overview of secondary haemostasis
intrinsic and extrinsic pathways lead to the producton of prothrombin activator (Xa)
this cause the conversion of prothrombin to thrombin
thrombin in turn facilitates the conversion of fibrinogen to fibrin which forms the fibrin clot
what is the extrinsic pathway
Tissue factor activates factor VII to get factor VIIa which in turn activates factor X to Xa
what is the intrinsic pathway
Involves factors IXa and VIIIa which activate X to Xa
what does the extrinsic pathway do
initiates
what does the intrinsic pathway do
amplifies
what is fibrinolysis
breakdown of the fibrin clot
how does fibrinolysis occur
tissue plasminogen activator convets plasminogen to plasmin
plasmin breaks down the fibrin clot to form fibrin degradation products
what does prothrombin time measure
extrinsic pathway
what does APTT time measure
intrinsic pathway
name the naturally occurring anticoagulants
serine protease inhibitors - antithrombin II
protein C and protein S
