Which nervous system increases heart rate during physical activity?

• A. Parasympathetic
• B. Central
• C. Somatic
• D. Sympathetic

Answer: (D)

When you start moving, the body needs more oxygen and nutrients, so the sympathetic division of the autonomic nervous system steps in to raise heart rate. It releases norepinephrine onto the heart’s pacemaker cells, increasing their firing rate (a positive chronotropic effect) and speeding conduction, which makes the heart beat faster and pump more blood. This heightened activity adjusts cardiac output to meet the muscles’ demand. The parasympathetic system does the opposite, calming the heart during rest, while the central nervous system helps coordinate these responses but doesn’t directly drive the heart rate on its own. The somatic system controls voluntary muscles and isn’t responsible for changing heart rate.