Peripheral Nervous System Health Article

Definition

The peripheral nervous system (PNS) consists of all parts of the nervous system, except the brain and spinal cord, which are the components of the central nervous system (CNS). The peripheral nervous system connects the central nervous system to the remainder of the body, and is the conduit through which neural signals are transmitted to and from the central nervous system. Within the peripheral nervous system, sensory neurons transmit impulses to the CNS from sensory receptors. A system of motor neurons transmit neural signals from the CNS to effectors (glands, organs, and muscles).

Description

The peripheral nervous system is composed of nerve fibers that provide the cellular pathways for the various signals on which the proper operation of the nervous system relies. There are two types of neurons operating in the PNS. The first is the sensory neurons that run from the myriad of sensory receptors throughout the body. Sensory receptors provide the connection between the stimulus such as heat, cold, and pain and the CNS. As well, the PNS also consists of motor neurons. These neurons connect the CNS to various muscles and glands throughout the body. These muscles and glands are also known as effectors, meaning they are the places where the responses to the stimuli are translated into action.

The peripheral nervous system is subdivided into two subsystems: the sensory-somatic nervous system and the autonomic nervous system.

The sensory-somatic nervous system

The sensory-somatic nervous system is the sensory gateway between the environment outside of the body and the central nervous system. Responses tend to be conscious.

The sensory nervous system comprises 12 pairs of cranial nerves and 31 pairs of spinal nerves. Some pairs are exclusively sensory neurons such as the pairs involved in smell, vision, hearing, and balance. Other pairs are strictly made up of motor neurons, such as those involved in the movement of the eyeballs, swallowing, and movement of the head and shoulders. Still other pairs consist of a sensory and a motor neuron working in tandem such as those involved in taste and other aspects of swallowing. All of the spinal neuron pairs are mixed: they contain both sensory and motor neurons. This allows the spinal neurons to properly function as the conduit of transmission of the signals of the stimuli and the subsequent response.