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Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics
Figure 1
A two domain-model for ion concentration dynamics in the intra- and extracellular space, when macroscopic transport is essentially one-dimensional.
(A) A piece of neural tissue with cross section area 
and an arbitrary extension 
in the 
-direction. The tissue contains cells (dark grey) that participate in the transport process, and cells that do not (light grey). (B) The interior of all participatory cells represented as a single, equivalent cylindrical cable (
), coated by ECS (
). The geometry is specified by three parameters, where 
and 
are, respectively, the fractions of 
occupied by the ICS of participatory cells and the ECS, and 
is the amount of membrane area per tissue volume (or, equivalently, the circumference of the equivalent cable divided by 
). Due to the presence of other cells (non-participatory), we generally have that 
. The concentration of ion species 
is denoted 
where 
represents domain 
or 
. Ionic movement is described by the transmembrane flux density (
) and the longitudinal flux densities due to electrical migration (
) and diffusion (
).
doi: https://doi.org/10.1371/journal.pcbi.1003386.g001