Final answer:
When blood pressure rises, the sensory firing rate of baroreceptors increases, triggering a homeostatic response to lower it.
Step-by-step explanation:
In the negative feedback-regulated homeostatic control of blood pressure, if blood pressure rises, then sensory firing rate increases. This process involves baroreceptors, which are stretch-sensitive sensory receptors located in the walls of certain blood vessels and the heart. When blood pressure increases, the baroreceptors are stretched more tightly, causing them to initiate action potentials at a higher rate. This increased firing rate sends signals to the cardiovascular center in the medulla oblongata, which triggers a reflex that maintains homeostasis.
As part of the reflex to counteract the high blood pressure, parasympathetic stimulation of the heart is increased leading to a reduced cardiac output. Simultaneously, sympathetic stimulation of the peripheral arterioles decreases, causing vasodilation. These actions combined bring the elevated blood pressure down. In contrast, when blood pressure drops too low, the rate of baroreceptor firing decreases, leading to an increase in sympathetic stimulation, higher cardiac output.