All-or-none law

The all-or -nothing law refers to the phenomenon that a reaction to a stimulus is not either completely or triggered. On the strength of the reaction parameters no grading (differentiation) can be observed, because the reaction to the stimulus is always at maximum strength.

Reasoning with example

Excitable cells (eg nerve cells, heart cells) communicate via so-called action potentials ( parts of the electrical excitation of a nerve cell).

To trigger an action potential, and to achieve neural transmission along the nerve cell, only a critical threshold potential of 15 must be - 20 mV are exceeded, the intensity of the stimulus intensity is uninteresting, because this is determined only by the number of action potentials.

The more action potentials are triggered a nerve cell in a defined period, the stronger the attraction that triggers the discharge of a partial region of a certain summation.

The further depolarization moves on from there off automatically and very quickly. One speaks of a uniform and maximum response in terms of a continuous -led agitation.

Subliminal signals can be amplified by noise and trigger an action potential. This phenomenon is referred to as stochastic resonance.

Swell

• All-or -nothing law - science -online.de
• Knowledge storage Biology ISBN 3-06-011731-4
• Nerves, senses, ISBN 3-580-65693-7 hormones