Final answer:
Receptors in the heart and blood vessels signal the hypothalamus when blood pressure becomes too high or too low, illustrating the interaction between the cardiovascular and nervous systems.
Step-by-step explanation:
The receptors in the heart and blood vessels that signal the hypothalamus when blood pressure becomes too high or too low demonstrate the interaction of the cardiovascular and nervous systems. The receptors in this case are baroreceptors, which detect changes in blood pressure. When blood pressure rises too high, the baroreceptors trigger parasympathetic stimulation of the heart, causing a decrease in cardiac output and peripheral arteriole vasodilation, resulting in a decrease in blood pressure. On the other hand, when blood pressure drops too low, the baroreceptors trigger an increase in sympathetic stimulation of the heart and peripheral vessels, causing an increase in cardiac output and vasoconstriction, leading to an increase in blood pressure.