nerve impulse

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impulse

 [im´puls]
1. a sudden pushing force.
2. a sudden uncontrollable determination to act.
cardiac impulse a heartbeat palpated over the left side of the chest at the apex of the heart. See also point of maximal impulse.
impulse control disorders a group of mental disorders characterized by repeated failure to resist an impulse to perform some act harmful to oneself or to others. In spite of the act's being socially unacceptable or inconsistent with the rest of the person's personality or lifestyle, he or she feels pleasure or emotional release upon doing it. Disorders in this category include intermittent explosive disorder, kleptomania, pathological gambling, pyromania, and trichotillomania.
nerve impulse the electrochemical process propagated along nerve fibers.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

nerve impulse

n.
A wave of physical and chemical excitation along a nerve fiber in response to a stimulus, accompanied by a transient change in electric potential in the membrane of the fiber.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

nerve impulse

The wave-like progression of electrical depolarization that passes along a stimulated nerve fibre. The nerve impulse results from a movement of positive and negative ions across the membrane of the fibre.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

nerve impulse

the message conducted along the AXON of a NERVE (1). The impulse is a propagated negative charge on the outside of the membrane which results from a wave of DEPOLORIZATION passing along an axon. The RESTING POTENTIAL is reversed and becomes an ACTION POTENTIAL, and this passes down the axon at between 1 and 100 ms, depending on the diameter of the fibre, the presence of a MYELIN SHEATH, temperature, species of animal etc. Once an impulse is initiated it progresses without degeneration, and the strength or nature of the stimulus does not affect it; it either is generated or it is not (ALLORNONE LAW). Varying stimuli produce varying numbers of impulses (see SUMMATION). After each impulse there is a REFRACTORY PERIOD during which a second impulse may not pass.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Moreover, the new myelin was shown to be functional as conductivity of nerve impulses in the mice was enhanced.
In nerve cells, ion channels work with extreme precision: Sodium channels open for a fraction of a second to allow just enough sodium in to trigger a nerve impulse. The impulse is then transmitted to the next cell, exactly the same way, and so on throughout the body.
The UCSF study found that "opticospinal" MS, in which symptoms affect the optic nerve and spinal cord, and attacks of "acute transverse myelitis," in which the spinal cord stops transmitting nerve impulses, resulting in paralysis, were seen more frequently in African-Americans than in others.
This interrupts transmission of the pain-causing nerve impulses, therefore reducing pain.
With a reduction in nerve impulses that tighten blood vessels, blood more easily passes and blood pressure declines.
The device detects nerve disturbances before physical symptoms appear by measuring nerve impulses as they flow through the muscles.
Saxitoxin and other PSTs are potent neurotoxins that block movement of sodium through sodium channels in nerve cell membranes, halting the flow of nerve impulses and thereby causing paralysis.
The 48-page interactive book includes tabs, flaps, wheels, and plastic overlays to help you explore everyday bodily activities, such as how the brain processes information, how taste and smell sensors help us enjoy flavors of food and drink, how the brain receives nerve impulses from the eyes, and much, much more.
It turns out that, historically, aquatic organisms have been enormously important in the development of biomedical research." Petering notes, for example, that most of the basic understanding of how nerve impulses are conducted arose from studies of the large nerve axon of the squid.
Babor Mimical Control stops the nerve impulses that cause muscle contractions which may lead to wrinkling, executives at the Palm Beach, FL-based company said.
In small controlled quantities it interrupts nerve impulses and paralyses muscles and can be used to smooth fine lines and wrinkles on the face.
This membrane damage causes the cells to lose their ability to produce and carry nerve impulses along the membranes from one cell to the next.