Question

Identify the divisions of the PNS (peripheral nervous system). Briefly describe each division and elaborate if there any subdivisions of each.

Answer 1

The peripheral nervous system includes all the nerves in the body that lie outside of the spinal cord and the brain.

The peripheral nervous system is divided into :-

1. Somatic nervous system
2. Autonomic nervous system

Each system contains afferent and efferent components.

The autonomic nervous sytem is further divided into:-

1. Sympathetic nervous system
2. Parasympathetic nervous system

The somatic nervous system is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles.

The autonomic nervous system is the part of the nervous system that supplies the internal organs, including the blood vessels, stomach, intestine, liver, kidneys, bladder, genitals, lungs, pupils, heart, and sweat, salivary, and digestive glands.

The afferent arm consists of sensory (or afferent) neurons running from receptors for stimuli to the CNS.

The efferent arm consists of motor (or efferent) neurons running from the CNS to the effector organ.

The sympathetic nervous system is responsible for the fight or flight responses of the body and originates from thoracolumbar segments of the spinal cord. It uses short preganglionic neurones and long post ganglionic neurones.

The parasympathetic nervous system is responsible for the rest and digest actions of the body and originates from craniosacral segments of the spinal cord. This system consists of long preganglionic neurones and short post ganglionic neurones.