Final answer:
A decrease in baroreceptor firing rate is observed with lowering of blood pressure, leading to increased sympathetic stimulation that raises the heart rate to elevate blood pressure.
Step-by-step explanation:
A decrease in baroreceptor firing rate from the carotid arch results from falling blood pressure and heart rate increases. Baroreceptors are sensors located in the carotid arteries and arch of the aorta that detect changes in blood pressure. When blood pressure drops too low, the firing rate of baroreceptors decreases, resulting in a sequence of physiological responses. This involves an increase in sympathetic stimulation of the heart and peripheral vessels, which leads to an increase in heart rate and vasoconstriction, thereby raising the blood pressure back towards normal.