Membrane potential
The (a) resting membrane potential is a result of different concentrations of Na+ and K+ ions inside and outside the cell. A nerve impulse causes Na+ to enter the cell, resulting in (b) depolarization. At the peak action potential, K+ channels open and the cell becomes (c) hyperpolarized.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"OpenStax College, How Neurons Communicate. October 17, 2013."
http://cnx.org/content/m44748/latest/Figure_35_02_02.jpg
OpenStax CNX
CC BY 3.0.
