Sistema nervioso somático: Diferenzas entre revisións
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==Transmisión de sinais nerviosos== |
==Transmisión de sinais nerviosos== |
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O sistema nervioso somático controla todos os sistemas musculares voluntarios do corpo, coa excepción dos [[arco reflexo|arcos reflexos]]. |
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The somatic nervous system controls all [[voluntary muscle|voluntary muscular]] systems within the body, with the exception of [[reflex arc]]s. |
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A ruta básica do sinal vervioso no sisteme nervioso somático eferente implica unha secuencia que empeza nos [[soma|corpos celulares]] das [[motoneurona]]s superiores do xiro cerebral precentral (which approximates the [[córtex motor primario]]). Os estímulos do xiro precentral transmítense desde as motoneuronas superiores e baixas polos [[axón]]s do [[tracto corticospiñal]] para controlar os músculos (voluntarios) esqueléticos. Estes estímulos son transmitidos desde as motoneuronas superiores a través do [[corno anterior da espiña dorsal]], e fan sinapse cos [[receptor sensorial|receptores sensoriais]] das [[alfa motoneurona]]s (as grandes [[motoneurona inferior|motoneuronas inferiores]]) do tronco cerebral e a medula espiñal. |
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The basic route of [[nerve signal]]s within the [[efferent nerve fiber|efferent]] somatic nervous system involves a sequence that begins in the upper [[Cell (biology)|cell bodies]] of [[motor neuron]]s ([[upper motor neuron]]s) within the [[Brodmann area 4|precentral gyrus]] (which approximates the [[primary motor cortex]]). Stimuli from the precentral gyrus are transmitted from upper motor neurons and down the [[corticospinal tract]], via [[axon]]s to control skeletal (voluntary) muscles. These stimuli are conveyed from upper motor neurons through the [[Anterior horn of spinal cord|ventral horn]] of the [[spinal cord]], and across [[synapse]]s to be received by the [[sensory receptor]]s of [[alpha motor neurons]] (large [[lower motor neuron]]s) of the [[brainstem]] and [[spinal cord]]. |
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Upper motor neurons release a [[neurotransmitter]], [[acetylcholine]], from their axon terminal knobs, which are received by [[nicotinic acetylcholine receptor|nicotinic receptors]] of the alpha motor neurons. In turn, alpha motor neurons relay the [[stimulus (physiology)|stimulus]]. |
Upper motor neurons release a [[neurotransmitter]], [[acetylcholine]], from their axon terminal knobs, which are received by [[nicotinic acetylcholine receptor|nicotinic receptors]] of the alpha motor neurons. In turn, alpha motor neurons relay the [[stimulus (physiology)|stimulus]]. |
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Revisión como estaba o 6 de febreiro de 2014 ás 18:12
 | Este artigo está a ser traducido ao galego por un usuario desta Wikipedia; por favor, non o edite. O usuario Miguelferig (conversa · contribucións) realizou a última edición na páxina hai 10 anos. Se o usuario non publica a tradución nun prazo de trinta días, procederase ó seu borrado rápido. |
O sistema nervioso somático ou sistema nervioso voluntario é a parte do sistema nervioso periférico [1] asociada co control voluntario dos movementos do corpo por medio dos músculos esqueléticos. O sistema nervioso somático consta de nervios eferentes responsables da estimulación da contracción muscular, e inclúe todas as neuronas non sensoriais conectadas cos músculos esqueléticos e a pel.
Partes do sistema nervioso somático
No noso corpo existen 43 segmentos de nervios e en cada segmento hai un par de nervios motores e sensoriais. No corpo, 31 segmentos de nervios están na medula espiñal e 12 no tronco cerebral. Ademais destes, no corpo existen miles de nervios de asociación.
Deste modo, o sistema nervioso somático consta de tres partes:
i) Nervios espiñais ou raquídeos: Son nervios periféricos que levan información sensorial á medula espiñal e ordes motoras.
ii) Nervios craniais: Son fibras nerviosas que levan información cara adentro e fóra do tronco cerebral. Inclúen os encargados do olfacto, visión, ollo, músculos do ollo, boca, gusto, oído, pescozo, ombros e lingua.
iii) Nervios de asociación: Estes nervios integran as entradas sensoriais e as saídas motoras.
Transmisión de sinais nerviosos
O sistema nervioso somático controla todos os sistemas musculares voluntarios do corpo, coa excepción dos arcos reflexos.
A ruta básica do sinal vervioso no sisteme nervioso somático eferente implica unha secuencia que empeza nos corpos celulares das motoneuronas superiores do xiro cerebral precentral (which approximates the córtex motor primario). Os estímulos do xiro precentral transmítense desde as motoneuronas superiores e baixas polos axóns do tracto corticospiñal para controlar os músculos (voluntarios) esqueléticos. Estes estímulos son transmitidos desde as motoneuronas superiores a través do corno anterior da espiña dorsal, e fan sinapse cos receptores sensoriais das alfa motoneuronas (as grandes motoneuronas inferiores) do tronco cerebral e a medula espiñal.
Upper motor neurons release a neurotransmitter, acetylcholine, from their axon terminal knobs, which are received by nicotinic receptors of the alpha motor neurons. In turn, alpha motor neurons relay the stimulus.
From there, acetylcholine is released from the axon terminal knobs of alpha motor neurons and received by postsynaptic receptors (Nicotinic acetylcholine receptors) of muscles, thereby relaying the stimulus to contract muscle fibers.
Diferenzas en vertebrados e invertebrados
In invertebrates, depending on the neurotransmitter released and the type of receptor it binds, the response in the muscle fiber could either be excitatory or inhibitory. For vertebrates, however, the response of a muscle fiber to a neurotransmitter (always acetylcholine (ACh)) can only be excitatory.
Arcos reflexos
A reflex arc is a neural circuit that creates a more or less automatic link between a sensory input and a specific motor output. Reflex circuits vary in complexity—the simplest spinal reflexes are mediated by a three-element chain, beginning with sensory neurons which activate interneurons in the spinal cord, which then activate motor neurons. Some reflex responses, such as withdrawing the hand after touching a hot surface, are protective, but others, such as the patellar reflex "knee jerk" activated by tapping the patellar tendon, contribute to ordinary behaviour.