英和和英

出典:『Wikipedia』 (2009/08/25 19:57 UTC 版)

英語による解説

引用

In physiology, electrotonus refers to the "passive" spread of charge inside a neuron. "Passive" means that voltage-dependent changes in membrane conductance do not contribute. Neurons and other excitable cells produce two types of electrical potential. The first is a non-propagated local potential called an electrotonic potential, due to a local change in ionic conductance (e.g. synaptic or sensory that engenders a local current). When it spreads along a stretch of membrane, it becomes exponentially smaller (decrement). The second is a propagated impulse called an action potential. Electrotonic potentials represent changes to the neuron's membrane potential that do not lead to the generation of new current by action potentials. Neurons which are small in relation to their length, such as some neurons in the brain have only electrotonic potentials (starbust amacrine cells in the retina are believed to have these properties); longer neurons utilize electrotonic potentials to trigger the action potential.