Final answer:
The autonomic nervous system controls body functions that don't require conscious thought, such as breathing and heart rate.
Step-by-step explanation:
The autonomic nervous system is the division of the nervous system that controls body functions which don't require conscious thought, such as breathing and heart rate. It is responsible for regulating involuntary activities in the body. The autonomic nervous system has two main divisions: the sympathetic nervous system which prepares the body for stress-related activities, and the parasympathetic nervous system which is associated with returning the body to routine day-to-day operations.