Also found in: Dictionary, Thesaurus, Legal, Encyclopedia, Wikipedia.
Related to all-or-none law: all or none phenomenon, all or nothing response
1 the principle in neurophysiology stating that a stimulus must be strong enough to reach threshold to trigger a nerve impulse. Once theshold is achieved, the entire impulse is discharged. A weak stimulus will not produce a weak reaction.
2 the principle that the heart muscle or nerve, under any stimulus above a threshold level, will respond either with a maximal strength response or with none at all. Also called Bowditch's law.
The property of cardiac muscle in which stimulation from a single myocyte travels to the atrium and ventricle before contracting, resulting in a coherent and co-ordinated pump activity.
A rule applied to the activation of individual muscle or nerve cells, where the response to stimuli (depolarisation) only occurs above a certain threshold, usually –55 mV, after which a complete action potential occurs that is maximum in intensity—i.e., the strength of the nerve impulse is not dependent on, or a function of, the strength of the stimulus.
A “soft” rule in behavioural studies, which refers to the observation that a behavioural stimulus will produce either a complete response or none at all.