Autonomic System
This part of the peripheral nervous system controls the involuntary movements in the body, such as–controlling and coordinating smooth and cardiac muscle functions, and the endocrine glands. This system is further divided into the sympathetic and the parasympathetic nervous system. These two sub-divisions of autonomic system work in opposition to each other to balance the internal homeostasis of the body. The autonomic nervous system acts as the alert/warning system. It is a manager as it manages the functions of all the bodily systems.
Parasympathetic Nervous System
The parasympathetic nervous system functions when the body is at rest. It functions totally opposite to the sympathetic system, by calming down the body. This system decreases the rate of heart beat, dilates bronchi and pupil of the eye and relaxes stomach, intestine and bladder.
Sympathetic Nervous System
The sympathetic nervous system stimulates the body to react in emergency conditions by regulating certain bodily functions, such as increasing the heart rate, enlarging the pupils, decreasing digestion, etc. This system prepares our body to defend itself or respond in any dangerous situation itself (fight or flight response).