Circle of Willis - Lecture 3 Flashcards
what forms the circle of willis
anterior communicating
internal carotid
posterior communicating
posterior cerebral
left and right sides are
mirror images of each other
what happens if one of the vessels is occluded or temporarily clipped
may be distal collateral flow via the communicating arteries
anastomoses
interconnections b/w blood vessels
what do anastomoses do
overlapping blood supply
safety mechanism
retrograde filling
examples of anastomoses
circle of willis
ophthalmic artery and external carotid
surface branches of anterior, middle, posterior
blood flow to CNS is
controlled
how is blood flow in CNS controlled
autoregulation
metabolite control
autonomic nervous system control
autoregulation
cerebral vessels themselves act to maintain constant flow
smooth muscles of arteries and arterioles are stretch
–> sensitive and respond to the changes in blood pressure
stroke
CVA
cerebrovascular accident
failure of safety mechanisms
stroke stats
3 cause of death for US adults
transient ischemic attack
TIA
recovery is complete w/in 24 hours
10% of patients will go on to have a stroke
TIA is
warning sign
very significant warning sign of a stroke
definition of stroke
rapidly developed clinical sign of focal disturbance of cerebral fxn of presumed vascular origin and more than 24 hours
sub-types of strokes
ischemic
hemorrhage
