Action Potential/Nerve Impulse
-also known as a nerve impulse is when the membrane potential conducts an impulse. ( not at rest anymore, something trigger electrical impulse on membrane)
-When an adequate amount of stimulus excites the membrane, stimulus-gated sodium (Na+) channels open, allowing Na+ to diffuse into the cell at a very fast rate.
-Having Na+ rapidly diffuse into the cells, the membrane potential quickly moves towards being zero or neutral. (Remember the membrane at rest has a charge of -70mV. When the Na+ floods in, this moves to closer to zero instead, -70mV to 0).
-This movement, an change in charge is known at Depolarization.
-As the threshold of the potential is reached, voltage-gated Na+ gates open up, an even more Na+ enters the cell, causing even further Depolarization.
-*THIS ACTION POTENTIAL IS AN ALL OR NOTHING RESPONSE. If it does not reach it's threshold, it will not trigger an action potential.
-Eventually once the action potential peaks, the membrane will start to return to it's resting membrane potential (-70mV)
-This process is helped when potassium (K+) channels open, allowing K+ to diffuse outwardly of the membrane. The K+ moving out of the cell is known as Repolarization.