Biological fluid membrane generates triggering cycle and homeostasis.

A working engine has to operate in cycles, and at completion of a work cycle it should revert to its initial state. The ubiquitous unit cycle in medicine and physiology is characterized by a rapid upstroke followed by a plateau, which is in turn followed by a quick restoration to a resting state. So far, such cycles could not be derived from the basic laws of chemistry, in particular from the law of mass action; but within the context of a new biochemical control theory, which replaces the notion of conformational change by redistribution in the membrane, such a cycle can be derived from the law of mass action if the system is two dimensional, namely if the biochemical reactions are restricted to an optimally fluid membrane which is an open nonequilibrium system. The failure of this universal mechanism for triggering cycle is suggested to be a universal cause of disease. This failure involves abnormal membrane fluidity and leakage of enzyme and receptor from the membrane.