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.

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.

nerve impulse

See impulse.

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.

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.

impulse

1. a sudden pushing force.
2. a sudden uncontrollable act.
3. a nerve impulse.

cardiac impulse
movement of the chest wall caused by the heartbeat. Called also apex beat.
nerve impulse
the electrochemical process propagated along nerve fibers.
References in periodicals archive ?
Glial cells that make myelin: In the CNS, cells called oligodendrocytes produce myelin (the fatty coating wrapped around axons), which enables them to send very rapid nerve impulses.
Myelin is the substance that insulates nerve axons, and without sufficient myelination, nerve impulses are not properly transmitted and neurological function is impaired.
One possibility might be that both factors cause constriction of tiny arteries that supply blood to the inner ear and damage cells that convert sound vibrations into nerve impulses.
The study shows that the genders differ in how each transmits the nerve impulses that control muscle force.
He begins with an analysis of how it constructs a representation of the outside world from the nerve impulses it receives - which prove to be few in number, requiring it to fill in a great deal of information.
Cardiac ablation is the scarring of microscopic areas of the heart to block nerve impulses responsible for the arrhythmia.
The scientists placed isolated glial cells, which do not carry nerve impulses but still provide essential neural support, in culture and then deprived them of oxygen and glucose for 5 hours.
Fifteen years later Dr Otto Leowi was to receive the Nobel Prize for his research into the nerve impulses that were to help many who suffer from Parkinson's disease and depression.
Nerve impulses to and from the brain travel at up to 170mph.
There, odor receptors, or nerve cells, translate the molecules into nerve impulses (electric signals).
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.