Physics of the human cardiovascular system

Contemporary measurement techniques permit the non-invasive observation of several cardiovascular functions, both from the central and peripheral points of view. We show that, within one cycle of blood through the cardiovascular system, the same dynamics characterizes heart function as well as blood flow in the capillary bed where cells exchange energy and matter. Analyses of several quite different signals derived from respiration, cardiac function and blood flow, all reveal the existence of five almost periodic frequency components. This result is interpreted as evidence that cardiovascular dynamics is governed by five coupled oscillators. The couplings provide co-ordination among the physiological processes involved, and are essential for efficient cardiovascular function. Understanding the dynamics of a system of five coupled oscillators not only represents a theoretical challenge, but also carries practical implications for diagnosis and for predicting the future behaviour of this life giving system.