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Sarah Brideau
Sandrine Bergeron
How does it work?
Question: Neurons: resting potential and action potential. How do they work?
Theory about neurons
Neurons in our body send electrochemical messages. In other words, these chemical products, that are
electrically charged and are also called “ions”, provoke an electrical signal. The most important ions in
the nervous system are potassium (K+), sodium (Na+), calcium (Ca2+) and chloride (Cl-), and there also
exists negatively charged protein molecules. Nerve cells are surrounded by a semi-permeable membrane
that sometimes lets the ions go through and sometimes blocks others to pass.
Resting Potential (neuron at rest)
When a neuron is at rest, it does not send any signal, and the inside of it is more negative compared to
the outside. The objective is to equilibrate the concentration of ions on both side of the membrane, by
moving the ions across the membrane. When all the forces are balance out and the inside-outside
difference of voltage is calculated, this is called the resting potential. In general, this resting potential is
of approximately -70 millivolts (inside of neuron is 70 mV less than outside). “Conventionally, resting
membrane potential can be defined as a relatively stable, ground value of transmembrane voltage in
animal and plant cells.” “The electrical difference across the membrane of the neuron. ”
Action Potential (impulse)
Action potential happens when a neuron sends information along the axon (extension of a neuron
conducting the electric signal). This action is created by an “explosion of electrical activity” caused by a
depolarizing current (stimulus brings the resting potential to 0mV) current, followed by a repolarization
(sodium channels start to close and potassium channels open) and finally a hyperpolarization. “When a
stimulus reaches a resting neuron, the neuron transmits the signal as an impulse” and channels where
ions go through open and close. During the action potential, ions cross the membrane and this causes
electrical changes that transmit the nerve impulse.
Sarah Brideau
Sandrine Bergeron
Works cited
Chudler E.H. 1996. Lights, Camera, Action Potential [Internet]. Neuroscience For Kids;
[modified 2016 Sept 21; cited 2016 Sept 19]. Available from:
Braun C, Miller Anderson C. 2007. Pathophysiology: Functional Alterations in Human
Health. 1st ed. United States of America: Lippincott Williams & Wilkins. 218 p.