Complex Dynamics in Physiological Control Systems

This chapter examines in greater detail some of the possible mechanisms through which complex dynamics can arise. It highlights a number of control mechanisms that can give rise to the spontaneous variability that is so much a trademark of physiological signals. Nonlinear component properties and delays in the transmission of feedback information provide a potent source of periodic, quasiperiodic, and chaotic behavior. There are several oscillatory components in the body, and the interactions among these oscillators as well as the effect of external rhythms, such as the environmental light, can produce complex and unexpected consequences. Moreover, most physiological parameters are time‐varying. The chapter shows that a variety of factors, such as mixed feedback, time delays, nonlinear coupling, and time‐varying properties, can contribute to the complex dynamical behavior of physiological control systems. It also examines the dynamics that can result from a simple model of obstructive sleep apnea (OSA).