Which function is controlled by the autonomic nervous system?

• A. Pain perception
• B. Sight
• C. Running
• D. Heart rate

Answer: (D)

The autonomic nervous system governs involuntary bodily functions, such as heart rate, digestion, and breathing. It has two branches that regulate these processes automatically: the sympathetic system speeds things up during activity or stress, increasing heart rate, while the parasympathetic system slows things down during rest. Pain perception is a sensory process carried by somatic pathways and higher brain centers, not directly controlled by the autonomic system. Sight involves the visual pathways from the eye to the brain, and running is a voluntary motor activity controlled by the somatic nervous system. Because heart rate is a classic involuntary function directly regulated by the autonomic nervous system, it is the correct choice.