I can't help you conceptualize these specific problems but having worked on similar problems in the past I'd advise you to look into ordinary differential equat

I can't help you conceptualize these specific problems but having worked on similar problems in the past I'd advise you to look into ordinary differential equations applied to those systems. They're used a lot for modelling in medical science and even if you're not interested in the dynamics of it they might lead you to the relevant literature for your problems and will address the parameters you're interested in and how they relate to each others.