This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
How does chronic hypertension affect the range of arterial pressure over which the cerebral circulation can maintain relatively constant blood flow? 
Select and explain. 
A. Very little change occurs, B. The vasculature primarily adapts to higher arterial pressure, C. The vasculature primarily loses regulation at low arterial pressure, D. The entire range of regulation shifts to higher pressures
D: The entire range of regulation shifts to higher pressures
Answer: D: The entire range of regulation shifts to higher pressures 
Explanation: Ans. D. THE entire range of regulation shifts to higher pressuresThe autoregulatory range is shifted to higher pressures because the arteries and arterioles increase their resistance. The functional and structural changes increase the arterial pressure at which autoregulation of blood flow occurs, but increase the lowest pressure at which blood flow can be maintained.