We present a numerical method for solving the system of equations of a model of
cellular electrical activity that takes into account both geometrical effects and ionic
concentration dynamics. A challenge in constructing a numerical scheme for this
model is that its equations are stiff: There is a time scale associated with “diffusion”
of the membrane potential that is much faster than the time scale associated with the
physical diffusion of ions. We use an implicit discretization in time and a finite
volume discretization in space. We present convergence studies of the numerical
method for cylindrical and two-dimensional geometries for several cases of
physiological interest.