  Energy-based bond graph modelling of biomolecular systems is extended to
include chemoelectrical trans- duction thus enabling integrated
thermodynamically-compliant modelling of chemoelectrical systems in general and
excitable membranes in particular.
  Our general approach is illustrated by recreating a well-known model of an
excitable membrane. This model is used to investigate the energy consumed
during a membrane action potential thus contributing to the current debate on
the trade-off between the speed of an action potential event and energy
consumption. The influx of Na+ is often taken as a proxy for energy
consumption; in contrast, this paper presents an energy based model of action
potentials. As the energy based approach avoids the assumptions underlying the
proxy approach it can be directly used to compute energy consumption in both
healthy and diseased neurons.
  These results are illustrated by comparing the energy consumption of healthy
and degenerative retinal ganglion cells using both simulated and in vitro data.
