Peripheral nervous system

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The peripheral nervous system or PNS is one of the 2 main parts of nervous system. This network is consisting of the nerves and ganglia excluded from the brain and spinal cord. It is a complex network of nerve fibers branching out from the brain and spinal cord to all the parts of the body. It’s vital task is to receive sensory information internally and externally and relay that to the brain for processing.

The PNS is divided into two parts: somatic nervous system and autonomic nervous system. Other textbooks include sensory systems.

The Somatic Nervous System

The tasks such as chewing, swallowing, and wiggling of toes are performed by this somatic nervous system. It is stimulated voluntarily or involuntarily by external factors like food, sound, or by conscious desire to move.

The Autonomic Nervous System

Involuntary actions like breathing, blinking and digesting are regulated by this autonomic nervous system. It also let us responds to danger and emotions; and direct our intestines to digest the food.


Neurotransmitters are endogenous chemicals that allow the transmitting of signals between neurons across synapses.

The main neurotransmitters of the PNS are

Acetylcholine was the first to be discovered. Its functions include stimulating muscles and scheduling REM sleep.

Noradrenaline is the fight or flight chemical responsible for reacting well to stressful situations.

There are also other neurotransmitters known as (NANC) Non-noradrenergic, non-cholinergic transmitters. Examples are the peptides: neuropeptide Y, GnRH, CGRP and non-peptides: GABA, ATP, dopamine.

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