Modeling intestinal absorption and other nutrition-related processes using PSPICE and STELLA

In summary, SPICE models are constructed by translating a highly organized biological system into a network diagram by using a disciplined, systematic method for converting flows through barriers and chemical reactions into branches in a network connecting the compartments in the tissue according to the identity of the flowing entities. The first step in building a simulation model is essentially the same as the first step in learning about the method. Simple mechanisms are mastered first; and then as proficiency and understanding of the system grow, these can be connected and elaborated to produce simulations more closely approximating the real complexity of the living system. Other methods exist that may be easier to deal with initially, but often they cannot be utilized as generally as SPICE owing to their inherent limitations. One program available on Apple machines that has a high degree of user friendliness is STELLA. We will make some brief comparisons here, since STELLA is often an easier way to get started in simulation and often perfectly adequate for smaller problems.