haemostasis Flashcards
what are the 4 stages of haemostasis
1) primary haemostatsis - platelet plug
2) secondary haemostasis - fibrin clot
3) fibrinolysis
4) anticoag defences
what cell produces platelets
megakaryocytes
life span of a platelet
7-10 days
what is exposed in endothelial damage
collagen and von willebrand factor
what causes platelet aggregation
release of thromboxane A2 and ADP
casues of primary haemostasis failure
vascular - old or vit deficiency eg scurvy (vit c)
platetelts - thrombocytopenia or reduced function eg aspirin
vw factor - vw syndrome
clinical symptoms seen in primary haemostasis failure
bleeding and purpura
mucosa bleed- eg epistaxis , conjunctival
intercranial haemorrhage
what factor is prothrombin
factor II
what does vitamin K carboxylase
2,7,9,10
proetin s and c
what sits on the phospholipid (plateelt plug) to give it a positive charge
Calcium
what charge do clotting factors have
negative charge
what are the 3 stages of secondary haemostasis
initiation
propagation
amplification
what does tissue factor bind to and then what does this activate
binds to factor VII
activates factor V and Xa complex
what activates factors XIII abd IXa
thrombin
what test is used to measure factor XIII and IXa
activated partial thromboplastin time
