 |
|
 |
 |
The second major division of the nervous system, the peripheral nervous system, carries messages to and from the central nervous system. It comprises two parts: the somatic and the autonomic nervous systems.
The somatic nervous system is composed of the sensory (afferent) neurons that carry messages to the central nervous system and the motor (efferent) neurons that carry messages from the central nervous system to the skeletal muscles of the body.
The autonomic nervous system carries messages between the central nervous system and the internal organs. It is broken into two parts: the sympathetic and parasympathetic divisions. The first acts primarily to arouse the body; the second, to relax and restore the body to normal levels of arousal.
The sympathetic and parasympathetic divisions of the autonomic nervous system.
The sympathetic division generally acts to arouse the body, preparing it for "fight or flight." The parasympathetic follows with messages to relax.
|
|
|
|
 |
 |