Which of the following stimulate vasoconstriction of the cerebral arteries?
A. Low blood pressure
B. Low pH levels (acidic)
C. Low oxygen (O2) concentrations
D. Low carbon dioxide (CO2) concentrations
ANS: D
Rationale: Cerebral arteries regulate blood flow that is based primarily on blood pressure and metabolites. Vasodilation will occur if the blood pressure or the O2 or pH levels are too low or if the CO2 or lactic acid levels are excessive. Conversely, vasoconstriction will occur when the blood pressure or the O2, or pH levels are excessive or if the CO2 or lactic acid levels are too low.
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