Fig. 3

Dynamics of the oscillating PA-subsystem as a function of fixed c. a Maximum/minimum and period-averaged values of ACTH, a(t), as a function of circulating CRH. b Maximum/minimum and period-averaged values of cortisol o(t). Within physiological CRH levels, ACTH, GR (not shown), and cortisol oscillate. The minima, maxima, and period-averaged cortisol levels typically increase with increasing c. The plot was generated using dimensionless variables c, a, and o with parameter values specified in [13] and t d=1.44, corresponding to a delay of T d=15 min