System dynamics in response to changes in HSC detachment rate. Starting at equilibrium, the detachment rate is doubled from day 1 until the end of the simulation. The system converges to a new equilibrium with an unchanged number of niche-bound HSC (A) and with both higher inactive (B) and active HSC (C). Equilibrium 1 refers to the homeostatic state and Equilibrium 2 refers to the equilibrium reached after perturbation of parameter values. (D) The amount of free stem cells binding to the niche per unit of time.