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Parasympathetic nervous system

(Science: anatomy, neurology) One of the two divisions of the vertebrate autonomic nervous system.

parasympathetic nerves emerge cranially as pre ganglionic fibres from oculomotor, facial, glossopharyngeal and vagus and from the sacral region of the spinal cord.

most neurons are cholinergic and responses are mediated by muscarinic receptors. The parasympathetic system innervates, for example: salivary glands, thoracic and abdominal viscera, bladder and genitalia.

Compare:. Sympathetic nervous system. Originates in the brain stem and lower part of the spinal cord; opposes physiological effects of the sympathetic nervous system: stimulates digestive secretions; slows the heart; constricts the pupils; dilates blood vessels.Working hand in hand with the sympathetic nervous system, the parasympathetic system is responsible for involuntary actions, i.e they are not done consciously.