At what membrane potential is spike potential triggered?

The spike potential, also known as action potential, is triggered when the membrane potential reaches a certain threshold that is typically around -40 mV. This threshold represents the point at which the voltage-gated sodium channels open, allowing an influx of sodium ions into the neuron. This influx causes rapid depolarization of the membrane, resulting in the characteristic spike of the action potential.

When neurally active, a neuron usually rests at a membrane potential of about -70 mV. For action potentials to occur, the membrane must be depolarized to around -40 mV. This is a crucial step in nerve signal transmission and plays a significant role in how neurons communicate with each other. As such, the threshold of -40 mV is essential for initiating the series of events leading to a successful action potential.