Sympathetic and parasympathetic divisions typically function in opposition to each other.

The subdivisions of the autonomic nervous system: In the autonomic nervous system, preganglionic neurons connect the CNS to the ganglion. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system.

The ANS is classically divided into two subsystems: the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS). Whereas most of its actions are involuntary, some, such as breathing, work in tandem with the conscious mind. The ANS affects heart rate, digestion, respiratory rate, salivation, perspiration, pupillary dilation, micturition (urination), and sexual arousal. The autonomic nervous system (ANS) is the part of the peripheral nervous system that acts as a control system, functioning largely below the level of consciousness and controlling visceral functions. Association nerves integrate sensory input and motor output these nerves number in the thousands.They include information related to smell, vision, eyes, eye muscles, the mouth, taste, ears, the neck, shoulders, and the tongue. Cranial nerves are the nerve fibers that carry information into and out of the brain stem.Spinal nerves are peripheral nerves that carry motor commands and sensory information into the spinal cord.The human nervous system: The major organs and nerves of the human nervous system.

Somatic nervous system example