Final answer:
An increase in blood pressure results in higher rates of baroreceptor firing, triggering actions such as parasympathetic stimulation and vasodilation, which in turn reduce cardiac output and blood pressure.
Step-by-step explanation:
When there is an increase in blood pressure, baroreceptors within the cardiovascular system detect the change by increased rate of firing due to being stretched more tightly. In response, the cardiovascular center in the medulla oblongata initiates actions that result in parasympathetic stimulation and vasodilation, aimed at lowering the blood pressure. This includes a decrease in cardiac output and a decrease in sympathetic stimulation, which causes the peripheral arterioles to dilate. These measures help to reduce the blood pressure back towards normal levels, maintaining vascular homeostasis.