Neurons process information in the form of electrical signals (nerve impulses or action potentials) that travel along their axons (long extensions of plasma membrane). Electrical charges move across the membrane as charged ions, but the plasma membranes of most cells, including neurons, are relatively impermeable to charged ions. However, proteins that act as ion channels and ion pumps are embedded in the plasma membrane and make it possible for ions to move, or to be moved, selectively across the membrane.
In this tutorial, we review how ion channels are responsible for a voltage difference (called the resting potential) across the plasma membrane of a neuron.
When a neuron is at rest, the plasma membrane is far more permeable to potassium (K+) ions than to other ions present, such as sodium (Na+) and chloride (Cl-). The electrochemical equilibrium that results from the distribution of these ion species across the membrane, together with the relative permeabilities of each ion, is responsible for the –60mV charge that can be measured across the membrane. This charge is called the resting membrane potential.
Textbook Reference: Concept 34.2 Neurons Generate Electric Signals by Controlling Ion Distributions