Nerve Impulse

nerve impulse

[′nərv ‚im‚pəls] (neuroscience) The transient physicochemical change in the membrane of a nerve fiber which sweeps rapidly along the fiber to its termination, where it causes excitation of other nerves, muscle, or gland cells, depending on the connections and functions of the nerve.

Nerve Impulse

a wave of excitation that spreads along a nerve fiber; it transmits information from the peripheral receptor (sensory) endings to the nerve centers inside the central nervous system, and from there to the performing apparatus—the skeletal musculature, the smooth muscles of the internal organs and vessels, and the glands of external and internal secretion.

The main bioelectric manifestation of a nerve impulse is the action potential (AP), or peaked fluctuation of electrical potential, caused by changes in the ionic permeability of the membrane. Increase in permeability during AP leads to intensification of cation flow (Na⁺ and Ca²⁺) to and from the interior of the nerve fiber (K⁺). As a result, the decomposition of compounds rich in energy—adenosine triphosphate and phos-phocreatine—and the decomposition and synthesis of proteins and lipids are intensified; glycolysis and tissue respiration are activated; certain biologically active compounds (acetylcholine, norepinephrine) are freed from the bound state; and the heat production of the nerve fiber is increased.

The velocity at which a nerve impulse travels varies from 0.5 m/sec (in the thinnest fibers of the autonomic nervous system) to 100–120 m/sec (in the thickest motor and sensory nerve fibers). The propagation of a nerve impulse is ensured by local currents that arise between the excited, negatively charged parts and the resting parts of the fiber.

Under natural conditions, series of nerve impulses run continuously along the nerve fibers, both in the peripheral parts of the nervous system and in its central parts. The frequency of these rhythmic discharges depends on the strength of the stimulus that produces them. During moderate motor activity the discharge frequency is 50–100 impulses per second in the motor nerve fibers; in the majority of sensory fibers it attains 200 a second. Some nerve cells (for example, the interneurons of the spinal cord) discharge at a frequency reaching 1,000–1,500 a second.

B. I. KHODOROV

nerve impulse

impulse

[im´puls] 1. a sudden pushing force.2. a sudden uncontrollable determination to act.3. nerve impulse.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, gambling" >pathological gambling, pyromania" >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

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.

单词	nerve impulse
释义	Nerve Impulse nerve impulse [′nərv ‚im‚pəls] (neuroscience) The transient physicochemical change in the membrane of a nerve fiber which sweeps rapidly along the fiber to its termination, where it causes excitation of other nerves, muscle, or gland cells, depending on the connections and functions of the nerve. Nerve Impulse a wave of excitation that spreads along a nerve fiber; it transmits information from the peripheral receptor (sensory) endings to the nerve centers inside the central nervous system, and from there to the performing apparatus—the skeletal musculature, the smooth muscles of the internal organs and vessels, and the glands of external and internal secretion. The main bioelectric manifestation of a nerve impulse is the action potential (AP), or peaked fluctuation of electrical potential, caused by changes in the ionic permeability of the membrane. Increase in permeability during AP leads to intensification of cation flow (Na⁺ and Ca²⁺) to and from the interior of the nerve fiber (K⁺). As a result, the decomposition of compounds rich in energy—adenosine triphosphate and phos-phocreatine—and the decomposition and synthesis of proteins and lipids are intensified; glycolysis and tissue respiration are activated; certain biologically active compounds (acetylcholine, norepinephrine) are freed from the bound state; and the heat production of the nerve fiber is increased. The velocity at which a nerve impulse travels varies from 0.5 m/sec (in the thinnest fibers of the autonomic nervous system) to 100–120 m/sec (in the thickest motor and sensory nerve fibers). The propagation of a nerve impulse is ensured by local currents that arise between the excited, negatively charged parts and the resting parts of the fiber. Under natural conditions, series of nerve impulses run continuously along the nerve fibers, both in the peripheral parts of the nervous system and in its central parts. The frequency of these rhythmic discharges depends on the strength of the stimulus that produces them. During moderate motor activity the discharge frequency is 50–100 impulses per second in the motor nerve fibers; in the majority of sensory fibers it attains 200 a second. Some nerve cells (for example, the interneurons of the spinal cord) discharge at a frequency reaching 1,000–1,500 a second. B. I. KHODOROV nerve impulse impulse [im´puls] 1. a sudden pushing force.2. a sudden uncontrollable determination to act.3. nerve impulse.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, gambling" >pathological gambling, pyromania" >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 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. nerve impulse noun Synonyms for nerve impulse noun the electrical discharge that travels along a nerve fiber Synonyms nervous impulse neural impulse impulse Related Words electrical discharge action potential
随便看	suprematists supreme supreme administration of the northern oblast supreme administrative commission for the preservation of government supreme allied commander supreme allied commander atlantic supreme allied commander, atlantic supreme allied commander europe supreme allied commander, europe supreme allied commander europe atlantic representative in europe supreme allied commander europe exercise supreme allied commander operations supreme allied commander south east asia supreme antiquities council supreme assembly of the islamic revolution in iraq supreme authority supreme being supreme being, cult of the supreme certifying commission supreme commander supreme commander allied expeditionary force supreme commander in chief supreme control chamber supreme cosmic power supreme council for islamic revolution in iraq

Nerve Impulse

nerve impulse

Nerve Impulse

nerve impulse

impulse

nerve impulse

nerve impulse

nerve impulse

nerve impulse

Synonyms for nerve impulse

noun the electrical discharge that travels along a nerve fiber

Synonyms

Related Words