parasympathetic nervous system

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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.
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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.

O. M. BENIUMOV

parasympathetic nervous system

[¦par·ə‚sim·pə′thed·ik ′nər·vəs ‚sis·təm]
(neuroscience)
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 power represented by various spectral bands in short-term HRV are indicative of how well the heart responds to changes in the body controlled by the sympathetic and the parasympathetic nervous systems.
Osvaldo Font, an MD in Puerto Rico who was recently nominated for the Nobel Prize in Medicine for his development of Electroneuromedular Therapy, has identified an electrical resistance or blockage in the spinal cord that causes a short circuit in the sympathetic and parasympathetic nervous systems. Once this accumulated energy is discharged and the current is restored, the neurological symptoms and pain fall away.
(35) The parasympathetic nervous system resynchronizes brain waves.
This is precisely where acupuncture may intervene, by bringing these processes back into balance - it influences the autonomic sympathetic nervous system (excitation), boosts the parasympathetic nervous system (relaxation), and also has an anti-inflammatory affect.
The function of the parasympathetic nervous system and vagal tone are downgraded, promoting increases in blood pressure, arrhythmias of the heart, heart disease, and other cardiovascular issues.

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