How does a local anesthetic numb the area without damaging the nerves?
(Lansing State Journal, December 18, 1996)
A nice way to understand how local anesthetics act on the nervous system is by comparing the nervous system to a stereo system.
A stereo system conducts electrical impulses throughout the nervous system. When you turn on your stereo, you are allowing electrons to flow through the stereo power cord into your stereo. In the nervous system, the on/off switches are a series of channels that have gates that swing open and closed. If enough of these gates are open, sodium and potassium, ions, the electrons of the nervous system, travel through axons, which are the power cords of nerve cells.
Local anesthetics essentially "pull the plug" on nerve cells by blocking the ion channel gates and preventing the flow of ions into the nerve axons.
Local anesthetics do not damage the nerves they affect because they do not permanently block the ion channel gates.