Reversal of polarity or change in electrical potential.
A brief change in the electrical potential of an axon that is the physical basis of the nervous system impulse.
Temporary change in electrical potential which occurs between the inside and the outside of a nerve or muscle fibre when a nerve impulse is sent.
Change in electrical charge (activity) developed in a muscle or nerve cell after stimulation that leads to its discharge or contraction. Occurs as a result of the movement of various chemicals such as sodium, potassium, and calcium between cells.
The change in electrical charge within a nerve or muscle when stimulated.
The change in voltage that occurs across the membrane of a nerve or muscle cell when a ‘nerve impulse is triggered. It is due to the passage of charged particles across the membrane and is an observable manifestation of the passage of an impulse.
A local reversal of the charge across an excitable cell membrane that is propagated quickly along the length of the membrane. In humans, most of the cells that conduct action potentials are neurons or muscles. As with all cells, neuron and muscle cell membranes actively maintain an excess of negative ions inside the cell, which gives them, at rest, a cross-membrane charge of about -75 to -80 mV. If ion channels in one area of the membrane are caused to open briefly (as when the membrane is stimulated by a neurotransmitter), then charged ions move across the membrane, reducing the charge differential. When the cross membrane charge reaches a threshold level (often about -40 to -60 mV), sodium ion channels (voltage-sensitive or voltage-gated channels) briefly open in the vicinity. Sodium ions rush into the cell, and temporarily the cross-membrane potential rises to a peak of about +40 to +50 mV – the height of the action potential in that region. This flood of ions also depolarizes adjacent membrane regions, which quickly reach their threshold levels, opening their voltage gated channels. In this way, the depolarization spreads rapidly along the membrane.