The
animation to the left
shows an idealized neuron. The red ovals represent Na+ ion
channels and the green ovals represent K+ ion channels. You can
start the movie and it will show an action potential (shown as a
colored curve) move down the axon. When the sodium channels open
during the depolarization (the red section of the action
potential curve), the Na+ rushes in because both of the greater
concentration of Na+ on the outside and the more positive voltage
on the outside of the axon. When the Na+ channels close and the
K+ channels open (the green section of the action potential
curve), the K+ now leaves the axon due both to the greater
concentration of K+ on the inside and the reversed voltage
levels.
Thus, in many ways the action potential is not the movement of voltage or ions but the flow of these ion channels opening and closing moving down the axon. This movement of the ion channels explains why the action potential is slow relative to the normal flow of electricity. The normal flow electricity is the flow of electrons in an electrical field and electricity travels at the speed of light while these ion channels movment is considerably more slowly. These are mechanical movements and cannot move nearly at the speed of light.
Now proceed to a quiz to review this material.
Return
to the beginning of the Neural tutorial quizes.
Return to Psychology contents.
