"the nervous system is responsible for responses such as pupil dilation, increased heart rate, and increased respiration."

The sympathetic nervous system (SNS) is responsible for responses such as pupil dilation, increased heart rate, and increased respiration. It is a part of the autonomic nervous system (ANS) that regulates the body's unconscious actions and is involved in the fight or flight response. The other system is the parasympathetic nervous system (PNS), which relaxes the body.