Haemostasis Flashcards
what is haemostasis?
the arrest of bleeding and the maintenance of vascular patency
what are the requirements for haemostasis?
permanent state of readiness
prompt response
localised response
protection against unwanted thrombosis
what are the components of a normal haemostatic system
formation of platelet plug
formation of fibrin clot
fibrinolysis
anticoagulant defences
what does primary haemostasis involve
formation of platelet plug
what does secondary haemostasis involve
formation of fibrin clot
where are platelets formed
formed in bone marrow by budding from megakaryocytes
what happens when there is endothelial damage
collagen is exposed and Von Willebrand Factors is released and so are other protein s to which platelets have receptors - this causes platelt adhesion at injury site
what can cause failure of platelet plug to form?
vascular problem
reduced platelet number or function
von willebrand factor problems
what are the consequences of the platelt plug not forming?
spontaneous bleeding
mucosal bleeding0 nose bleeds, GI blled, menorrhagir
intracranial haemorrhage
retinal haemorrhages
how to screen for primary haemostasis problem?
platelet count
name the causes of fibrin clot formation failure
single clotting factor deficiency- e.g haemophilia
multiple clotting factor deficiency
increased fibrinolysis
what causes the break down of fibrin
plasmin
what tests to do for secondary haemostasis problem?
prothrombin time
activated partial thromboplastin time
name the naturally occurring anticoagulants
serine protease inhibitors
protein C and protein S
what is thrombophilia?
deficiency of naturally occuring anticoagulants
increased chanced of DVT/PE
