A non-spatial ODE model contains reaction rates that specify a rate of change of species total amount in a given compartment.
In a PDE model, we have two kinds of reactions
- Compartment reactions
take place everywhere within a compartment
units: rate of change of species concentration
- Membrane reactions
take place on the membrane between two compartments
units: rate of species amount crossing unit area of the membrane
When editing a reaction, an image of the location is displayed on the left, and the units are displayed below the reaction rate in the bottom right.