hemostasis Flashcards
hemostasis
stoppage of bleeding
occurs in response to blood vessel damage
triggered by chemicals or activated by damaged cells and platelets
functions to prevent blood loss and build framework for tissue repair
vascular phase
vascular spasm of damaged vessel
(smooth muscle contracts reducing blood flow)
endothelins
secreted during vascular phase
stimulate contraction of smooth muscle in blood vessel wall
make endothelium sticky
stimulate cell division/repair
platelet phase
platelets adhere to collagen fibers
platelets aggregate as they become sticky
results in platelet plug
activated platelets release granules containing substances as
serotonin
thromboxane A2 and ADP
PDGF
calcium
serotonin
stimulates vascular spasm and platelet aggregation
thromboxane A2 and ADP
stimulates platelet aggregation
PDGF
platelet derives growth factor; promotes vessel repair
calcium
promotes coagulation
coagulation phase
results in a clot
coagulation
blood clotting
blood goes from liquid to gel
clot
a tangle of fibrin and cells
hemostasis overview
vascular spasm
platelet plug forms
activation of platelets
coagulation
2 coagulation pathways
intrinsic and extrinsic pathways
intrinsic pathways
initiated within blood
triggered when clotting factor 12 and platelets are activated by collagen
requires PF3 (platelet phospholipid)
slow (2-3 min)
extrinsic pathways
initiated by chemicals external to blood
activated by a chemical released by damaged cells
releases TF (tissue factor)
faster (< 2 mins)
hemophilia
genetic defect in one or more of the genes that code for clotting factor
thrombus
clot that forms in blood vessel or heart that partially or completely obstruct blood flow
embolus
any detached, intravascular mass that is capable of clogging blood vessels
