Could someone please help explain the terms used in action potential?This is for Biology 30. The terms are the following: polarized, depolarized, hyperpolarized, refractory period, repolarized and...

Could someone please help explain the terms used in action potential?

This is for Biology 30.

The terms are the following: polarized, depolarized, hyperpolarized, refractory period, repolarized and threshold level.

Expert Answers
hart379 eNotes educator| Certified Educator

When a neuron (nerve cell) is stimulated there is something called an all-or-none response.  That means that the stimulation that the nerve receives has to have a minimum strength in order to be felt at all.  That minimum strength is called the threshold.  For example, if you have a long line of dominoes and you very gently tap the first domino, nothing will happen.  However, when you touch it with enough force to make it fall over, you have reached the threshold.  Once you met the threshold all of the dominoes will fall, not just the first one.

Polarized refers to the state that the neuron is in when it is resting or not being stimulated.  Depolarization occurs when the threshold has been reached and the ions are being exchanged across the membrane. This is called an action potential and is equivalent to the time when the dominoes are falling.  Repolarization is the return of the neuron to its resting state.  The refractory period is the amount of time it takes before the nerve cell can be restimulated.  If the dominoes fall over, you cannot knock them over again until they are reset, the amount of time needed to reset is called the refractory period.  Sometimes during polarization, the cell overshoots how many ions it is supposed to put out and that is called hyperpolarization.