Question

A neuron at rest has a slightly negative charge. That resting charge needs to increase to _____ for an action potential to fire.

a) A positive charge
b) A highly negative charge
c) The threshold level
d) A zero charge

Answer 1

For an action potential to fire in a neuron, the resting charge must increase to the threshold level, which is approximately -55 mV.

Step-by-step explanation:

A neuron at rest is negatively charged, and for an action potential to fire, the resting charge needs to increase to the threshold level. Specifically, the neuron must depolarize from its resting membrane potential of around -70 mV to approximately -55 mV, which is the threshold of excitation. This depolarization is facilitated by the influx of Na+ ions when voltage-gated Na+ channels open in response to a sufficient stimulus. Once the threshold is reached, an action potential is triggered, leading to a rapid rise of the membrane potential to about +30 to +40 mV, followed by repolarization and return to the resting membrane potential.