Compare and contrast the sympathetic and parasympathetic ner

Compare and contrast the sympathetic and parasympathetic nervous systems, in terms of function, neurotransmitters used, site of pre-ganglionic cell bodies (brain or spinal cord level) and ganglion sites. How are they similar, how are they different?

Solution

Sympathetic nervous system controls the response of body towards a stimulus, in fight or flight manner, when it perceives a threat situation. Parasympathetic nervous system controls the response of body at the time of rest. PNS works to regulate digestion, urination and defecation.

In sympathetic nervous system, epinephrine and norepinephrine are primary neurotransmitters. Whereas in parasympathetic nervous system, acetylcholine is the primary neurotransmitter.

Sympathetic preganglionic fibres are shorter in size and form more synapse than parasympathetic preganglionic fibres.

SNS originates from spinal cord so it\'s ganglion site is present near spinal cord. PSNS ganglia originate from the organs that they innervate.

Similarities:

Both S N S and PSNS, are parts of Autonomic nervous system. Both originate from spinal cord and use the neurotransmitter acetylcholine. Both of them respond to unconscious processes of the body like digestion and respiration.