Physiology of Rhythms and Control Systems: An Integrative Approach

There is a broad spectrum of physiological rhythms in many different systems extending over a large range of frequencies. Hie medium ultradian frequency range is characterized by relatively great variability of frequency, intense mutual interactions and interference with the homeostatic feedback regulatory circuits and behavioral influences. In spite of the resulting multiform phenomenology, certain basic rules of “relative” sliding coordination between the subunits of one system, and between the systems themselves can be identified. They are revealed through certain kinds of mutual entrainment, the occurrence of multiple integer frequency relations, instability of phases and amplitudes during transitory states, rhythm- related excitability cycles, and through variable periods of synchronization and desynchronization. This principle is illustrated by respiratory, vascular, cardiovascular and motor rhythms and their interaction found in anaesthetized animals and in man. The fact that the same general kind of rhythm coordination is found, irrespective of the particular system and frequency range, justifies the hope of a successful analysis and understanding of rhythmicity as a basic principle of physiological self-organization. In view of their general validity, irrespective of the particular physical or living system under investigation, the concepts and analytical tools of synergetics will play a key role in future research of this whole subject.