As soon as they begin to flow into the cell, that will increase the concentration of our sodium inside the cell, increasing the positive charge, and that will lead to depolarization of the membrane, and that will cause an action potential. Now, the action potential will in turn lead to the contraction of our muscle. So this is exactly what we mean by the transfer of an electrical signal. The electrical signal, in the form of the action potential, is transferred from this synaptic terminal onto the muscle cell, and that ultimately leads to the contraction of our muscle. Now, what exactly happens next? So our muscle contracts, and let's suppose we want to stop the contraction of the muscle.