parasympathetic (redirected from parasympathetic cholinergic vasodilator fibers)

parasympathetic /para·sym·pa·thet·ic/ (-sim?pah-thet´ik) see under system.

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par·a·sym·pa·thet·ic (pr-smp-thtk)

adj.

Of, relating to, or affecting the parasympathetic nervous system.

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para·sympa·theti·cal·ly adv.

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parasympathetic (par″sim″p-thet´ik),

adj pertaining to the part of the autonomic nervous system that controls craniosacral activity.

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parasympathetic

pertaining to the parasympathetic nervous system.

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parasympathetic cholinergic vasodilator fibers

cause dilatation of blood vessels in tissues including cerebral vessels, tongue, salivary glands, external genitalia, bladder, rectum.

parasympathetic nervous system

part of the autonomic nervous system, the preganglionic fibers of which leave the central nervous system with cranial nerves III, VII, IX and X and several sacral nerves (depending on species); postganglionic fibers are distributed to the heart, smooth muscles, and glands of the head and neck, and thoracic, abdominal and pelvic viscera. Almost three-quarters of all parasympathetic nerve fibers are in the vagus nerves, which serve both the thoracic and abdominal regions of the body.

The predominant secretion of the nerve endings of the parasympathetic nervous system is acetylcholine, which acts on the various organs of the body to either excite or inhibit certain activities. For example, stimulation of the parasympathetic system causes constriction of the pupil of the eye and contraction of the ciliary muscle; increase of the glandular secretion of enzymes, as in the case of the pancreas; increased peristalsis; and a slowed heart rate. Excitation of the sympathetic nervous system often results in an effect opposite to that of the parasympathetic system; however, most organs are predominantly under the control of either one or the other of the two nervous systems that compose the autonomic nervous system.

parasympathetic outflow

the total of parasympathetic nerves which leave the central nervous system. Includes the cranial and sacral outflows.