blood and disorders Flashcards
(40 cards)
what is the most common cause of idiopathic thrombosis?
factor v leiden mutation
what is factor v leiden and what does it increase the chances of
inherited activated protein c resistance so clots are more likely to form
what are the 4 natural coagulation inhibitors
activated protein c –> proteolytically inactivates FVa, FVIIIa
factor S –> cofactor for aPC
antithrombin –> directly inactivates thrombin, factor Xa, FXIa
tissue factor pathway inhibitor –> direct inhibitor of FVIIa/ TF and FXa
what happens in fibrinolysis
tpa (tissue plasminogen activator) activates plasminogen –> plasmin –> degrades fribrin and clot breaks down
describe the mutation in factor v leiden disease
point mutation
Arg 506 –> Glu 506
Factor V leiden is resistant to cleavage by apc
mutation in one of the 3 cleavage sites for apc
what do dense granules in platelets secrete
ADP, ATP, serotonin, calcium, phosphate
what do alpha granules in platelets secret
fibrinogen, FV, VWF, growth factors
what is thrombocytopaenia?
platelet disfunction leading to bleeding - loss or dysfunction of platelets
what is haemophlilia a
deficiency of FVIIIa
what is haemophilia b
deficiency of FIXa
what are factors VIIIa and FIXa cofactor for
FX–> FXa
what is the prevalence of VWF disease
around 1%
what is the role of VWF
to stabilise FVIIIa, platelet adhesion and platelet aggregation
where is VWF secreted
platelet alpha granules and weibel palade bodies of endothelial cells
what are the 3 types of VWF deficiency
1 = heterozygous, 2 = functional deficiency, 3 = complete deficiency
what is the platelet type of VWF disease
mutation in GPI prevents VWF binding
which cofactors are vitamin k dependent and why
1972 and proetin c and protein s
Glu –> GLa –> binds calcium so can stick to negative phospholipids on platelet surfaces and helps activation
vitamin k dependent gamma carboxylation
name some minor bleeding events
nosebleed (epistaxis)
bruising
menorrhagia
why might major bleeding occur
naurysm rupture surgery trauma drugs sepsis
what is AAA
abdominal aortic aneurysm leads to major internal bleeding 50% mortality
what may happen in sepsis
disseminated intravascular coagulation
bleeding and thrombosis at the same time
bleeding because clotting factors used up
clotting because infection leads to TF exposure so coagulation pathway activated
multyiple organ failure
what sort of bleeding occurs with VWF disease
mild to severe bleeding
menorrhagia nose bleeds bleeding after toth extraction easy bruising risk of GI bleeding petechia (small bleeds on skin) muscular or joint bleeds
what is the treatment for VWF deficiency
VWF plasma concentrate
desmopressin (DDAVP) that releases VWF from endothelium
platelets
why might thrombocytopaenia be acquired
DIC, blodd loss, leukaemia, drug inducsed, immune thrombocytopenic purpura
