Arousal (physiology)

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Arousal or excitation describes the characteristic reaction of excitable systems to respond automatically with characteristic patterns of increased activity to certain changes (as external or internal stimuli ) above a certain threshold. The term is often given a broader definition and is used both for the (excitation) process that causes such a reaction and for the (excitation) state caused by this reaction.

At the cellular level, excitability is given electrophysiologically (only) in nerve cells, muscle cells and some secretory cells. These can respond to a change in their membrane potential - for example, an electrotonically induced depolarization of the cell membrane - if this reaches a certain threshold potential , automatically (through voltage-controlled ion channels ) with a change in their membrane properties (increased permeability for certain ions), which leads to a temporary significant change the potential difference leads - for example an action potential - than the excitation .

The excitation generated in this way can be passed on by nerve and muscle cells (→ excitation conduction ) and transferred to other cells (→ excitation transmission ). However, the interneuronal transmission of the excitation of one nerve cell to another nerve cell can then be a stimulating or inhibiting signal for its excitation .

At the level of an overall organism, excitation can manifest itself in the form of increased motor and / or mental and emotional functions. For pathologically increased excitation see excitation (medicine) .

Individual evidence

  1. Josef Dudel, Randolf Menzel, Robert F. Schmidt: Neuroscience: From Molecule to Cognition . tape 2 . Springer, Berlin / Heidelberg / New York 2001, ISBN 3-540-41335-9 , pp. 92 ( limited preview in Google Book search).