platelet activation Flashcards
platelets are derived from
megakaryocytic
production of platelets is regulated by
thrombopoietin
platelets aid in
homeostasis after vascular injury
platelets activate due to
endothelial injury & stimuli from other activated platelets
3 actions of platelets
- adhesion
- aggregation
- secretion
von willebrand factor is synthesized by
megakaryocytes
vWF is stored in
weibel-palade bodies & alpha granules of platelets
vWF is released on
vascular injury
roles of vWF in hemostasis
- carrier protein for factor VIII
- binds platelets
vascular damage causes
exposure of collagen
sub endothelial collagen binds
vWF
vWF bind __ on platelets
GP1B
first step in forming platelet plug
vWF binding GP1B on platelets
platelet aggregation is mediated by
GPIIa/IIIa receptor
platelet activation causes
GPIIb/IIIa to change conformation and becomes capable of binding
in platelet aggregation GPIIb/IIIa binds
fibrinogen or vWF and links platelets together
platelet factor 4 is released from
alpha granules
platelet factor 4 binds to
endothelial cells
heparin induce thrombocytopenia
antibodies bind PF4-heparin causing platelet activation
serotonin is stored in
dense granules of platelets
adenosine diphosphate is released from
dense granules of platelets
adenosine diphosphate binds
P2Y1 and P2Y12 G protein receptors causing decreased cAMP (increasing platelet activation)
thromboxane A2 is a
powerful platelet activator
aspirin role
inhibits COX so decrease in thromboxane A2 bn vb
