Which system represents the part of the autonomic nervous system that decreases breathing and heart rate?

The sympathetic nervous system prepares the body for 'fight or flight' responses during stressful situations. It increases heart rate, dilates airways, and generally stimulates the body's energy expenditure. Therefore, it has the opposite effect of what the question seeks regarding breathing and heart rate.

The somatic nervous system controls voluntary muscle movements and sensory information but does not regulate involuntary functions like heart and breathing rates. Its primary role involves the conscious control of skeletal muscles, making it unrelated to the autonomic regulation of these vital functions.

The central nervous system, consisting of the brain and spinal cord, processes information and coordinates responses but does not directly manage autonomic functions such as heart and breathing rates. It plays a broader role in overall body regulation rather than specifically decreasing these rates.