parameters and initial conditions from Tables \[tab:tableOfParams\] and \[tab:reaction\_parameters\]. Table \[tab:tableOfSS\] compares steady-state concentrations of metabolites and reaction rates with experimental observations.

Chua [*et al.*]{} [@Chua2010Iron] injected radio-labeled transferrin bound iron into the serum of mice and measured the total uptake of the liver after 120 minutes. The uptake rate, when expressed as mol/s, was close to that found at steady state by the computational model (Table \[tab:tableOfSS\]).

A technical aspect of note in this steady state solution, is that it is very stiff. This originates because one section of the model is orders or magnitude faster than the rest: the cycle composed of iron binding to ferritin, internalization and release. Arguably this could be resolved by simplifying the model, but the model was left intact because this cycling is an important aspect of iron metabolism and allows the representation of ferritin saturation. Even though the stiffness is high, our software is able to cope by using an appropriate numerical method.

Response to Iron Challenge {#response-to-iron-challenge .unnumbered}
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An oral dose of iron creates a fluctuation in serum transferrin saturation of approximately 10% [@Girelli2011Time]. The fixed serum iron concentration in the simulation was replaced by a transient increase in concentration 