-—-I_ p< ---- tu---} f- E \ oo) ‘ te& _ ps! SoFi z CS QO - { a dt c A T UPTAKE 6 CONTENT => t, TIME Since the retention of each element cf uptake is independent of all others, the activity taken up during the whole intake interval which reuwins at t is 7 t q (t) = \ UCr) re (c - t) dt (1) ° The rate of change of q(t) will be the result of flow rates into and out of the systemic region oo) u(t) - E (tr) - ag(t) Aq(t) u(t) systemic excretion rate, Ut where E(t) decay rate of systemfc activity, and systenic uptake rate, (2)