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
[{'content': 'Carotid baroreceptors: \nSelect and explain. \nA. Are important in the rapid, short term regulation of arterial blood pressure, B. Do not fire until a pressure of approximately 100 mm Hg is reached, C. Adapt over 1 to 2 weeks to the prevailing mean arterial pressure, D. Stretch reflexively decreases cerebral blood flow', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. Are important in the rapid, short term regulation of arterial blood pressureThe function of these baroreceptors is the rapid short-term regulation of arterial blood pressure. The receptors start firing at a pressure of approximately 40 mm Hg. They completely adapt over 1 to 2 days, not weeks. In general, changes in baroreceptor activity have little effect on cerebral blood flow. The sympathetic activity following a fall in blood pressure results in increased heart rate and contractility, which raises myocardial metabolism and coronary blood flow,', 'role': 'assistant'}]