parasympathetic nervous system

Also found in: Dictionary, Thesaurus, Medical, Legal, Acronyms, Wikipedia.

parasympathetic nervous system:

see nervous systemnervous system,
network of specialized tissue that controls actions and reactions of the body and its adjustment to the environment. Virtually all members of the animal kingdom have at least a rudimentary nervous system.
..... Click the link for more information.

Parasympathetic nervous system

A portion of the autonomic system. It consists of two neuron chains, but differs from the sympathetic nervous system in that the first neuron has a long axon and synapses with the second neuron near or in the organ innervated. In general, its action is in opposition to that of the sympathetic nervous system, which is the other part of the autonomic system. It cannot be said that one system, the sympathetic, always has a excitatory role and the other, the parasympathetic, an inhibitory role; the situation depends on the organ in question. However, it may be said that the sympathetic system, by altering the level at which various organs function, enables the body to rise to emergency demands encountered in flight, combat, pursuit, and pain. The parasympathetic system appears to be in control during such pleasant periods as digestion and rest. The alkaloid pilocarpine excites parasympathetic activity while atropine inhibits it. See Autonomic nervous system, Sympathetic nervous system

Parasympathetic Nervous System


the part of the autonomic nervous system whose ganglia are located very close to or in the innervated organs. The centers of the parasympathetic nervous system are found in the mesencephalon and medulla oblongata and in the sacral part of the spinal cord. The fibers of the parasympathetic nervous system proceed to the viscera as part of the third (oculomotor), seventh (facial), ninth (glossopharyngeal), and especially the tenth (vagus) cranial nerves and as part of the pelvic nerve.

In many cases, the parasympathetic and sympathetic nervous systems are directly opposed to one another in their effect on organs. Whereas sympathetic stimulation will act to accelerate and intensify heart contractions, raise the blood pressure, and dilate the pupils, parasympathetic stimulation will act to slow and weaken the heartbeat, lower arterial pressure, and contract the pupils. Efferent neurons of the parasympathetic nervous system are typically situated in the innervated organ proper and not in the separate trunk, as is the case in the sympathetic nervous system. The mediator substance formed in the nerve endings of the parasympathetic nervous system is acetylcholine; the predominant mediator substance in the sympathetic nervous system is norepinephrine.


parasympathetic nervous system

[¦par·ə‚sim·pə′thed·ik ′nər·vəs ‚sis·təm]
The craniosacral portion of the autonomic nervous system, consisting of preganglionic nerve fibers in certain sacral and cranial nerves, outlying ganglia, and postganglionic fibers.
References in periodicals archive ?
The parasympathetic nervous system takes care of restorative functions of the body.
Normally, Hull says, elevated blood pressure prompts the brain to stimulate the parasympathetic nervous system and thus to lower the heart rate.
A study on effects of meditation on parasympathetic nervous system functional status in meditators.
Rocking on an exercise ball may provide an efficient method of stimulating the sacral afferents of the parasympathetic nervous system.
Damage to the parasympathetic nervous system may account for nearly half of the typical symptoms-including gallbladder disease, unrefreshing sleep, depression, joint pain, chronic diarrhea, and sexual dysfunction-that afflict those with Gulf War syndrome, according to a study by the University of Texas Southwestern Medical Center at Dallas.
Functional Components * Somatic nervous system * Autonomic nervous system/sympathetic nervous system * Parasympathetic Nervous System e.
First, the parasympathetic nervous system is typically associated with our conscious brain and mediates calm vegetative activities.
This change in HR indicates that in the cases, there is overactivation of the sympathetic nervous system/withdrawal of parasympathetic nervous system leading to shifting of the sympathovagal balance in the sympathetic side.
A combination of asanas, breathing exercises, relaxation techniques, and meditation practiced for a month or more triggers neurohormonal mechanisms in the form of stable autonomic nervous system equilibrium with a tendency toward parasympathetic nervous system dominance.
28) They concluded that the parasympathetic nervous system predominates in the heart rate changes.
Ultimately, Slow Medicine helps readers find greater balance, by shifting from the high-speed sympathetic nervous system (the flight-or-fight mode) to the slower parasympathetic nervous system (the rest-and-digest mode), which in turn activates the body's internal healing response mechanisms, effectively catalyzing a domino effect of wellness in every area of one's life.

Full browser ?