all-or-none response
all-or-none phenomenon
CardiologyThe 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.
Physiology
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.
Psychology
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.