Ace the CVS Pharmacy Exam 2026 - Your Prescription for Success!

The threshold potential for non-pacemaker action potentials is typically around -55 mV to -60 mV. This is the membrane potential that must be reached for a neuron or muscle cell to initiate an action potential. When the membrane potential depolarizes to this threshold, voltage-gated sodium channels open, allowing sodium ions to rush into the cell, which leads to the rapid depolarization characteristic of action potentials.

In the context of your answer, while -70 mV is a common resting membrane potential for many types of cells, it is not the threshold needed to initiate an action potential. Instead, the threshold is closer to -60 mV, which is the correct range for initiating action potentials in non-pacemaker cells. Cells typically have a resting membrane potential that is more negative, but the critical factor is that the depolarization must reach that threshold to trigger the rapid changes in membrane potential that define action potentials.