1 Define the term threshold as it applies to an action potential.

Answer 1

In the context of an action potential, the term "threshold" refers to the critical level of depolarization that must be reached in a neuron for an action potential to be triggered. This threshold is typically around -55 mV, but it can vary slightly depending on the type of neuron.

When the membrane potential of a neuron becomes sufficiently depolarized and reaches this threshold level, voltage-gated sodium channels open, allowing Na+ ions to rush into the cell. This influx of positive charge further depolarizes the membrane and can lead to the rapid rise in membrane potential characteristic of an action potential. If the threshold is not reached, the neuron will not fire an action potential, and no significant change in membrane potential will occur.