  We present and analyse a model for cell signalling processes in biological
tissues. The model includes diffusion and nonlinear reactions on the cell
surfaces, and both inter- and intracellular signalling. Using techniques from
the theory of two-scale convergence as well the unfolding method, we show
convergence of the solutions to the model to solutions of a two-scale
macroscopic problem. We also present a two-scale bulk-surface finite element
method for the approximation of the macroscopic model. We report on some
benchmarking results as well as numerical simulations in a biologically
relevant regime that illustrate the influence of cell-scale heterogeneities on
macroscopic concentrations.
