  We consider the monodomain model, a system of a parabolic semilinear
reaction-diffusion equation coupled with a nonlinear ordinary differential
equation, arising from the (simplified) mathematical description of the
electrical activity of the heart. We derive a posteriori error estimators
accounting for different sources of error (space/time discretization and
linearization). We prove reliability and efficiency (this latter under a
suitable assumption) of the error indicators. Finally, numerical experiments
assess the validity of the theoretical results.
