An analysis of the nonlinear behaviour of the human thermal vasomotor control system.

Abstract Specific aspects of the activity of the human thermoregulatory system are analysed from the point of view of the associated biological rhythms. Fluctuations in digit blood flow were examined and analysis of them showed that they were consistent with a nonlinear model of the control system. Experiments were undertaken in which periodic thermal stimuli were applied which caused the entrainment of digit blood flow. A theoretical study was subsequently undertaken in which the experimental results were compared to the activity of a Van der Pol oscillator.