Kinetorheological aspects of biorheology

The relationship between stress and strain is the rheological equation of state. In the case of sophisticated systems such as biological tissue, this is rarely a simple relationship. The relationship is seen to be even more complex when it is recalled that in most living tissues, the tissue is not in chemical equilibrium, but is at best in some controlled steady state. At worst, it is undergoing major fluctuations or transitions because the chemical reactions or fluxes are altering the system. It is shown, in particular, that in addition to the changes in composition, the effective rheological relaxation times of the system are shortened due to contributions deriving from the reaction rate constants. These and other points are illustrated by considering a process of irreversible monomolecular degradation of a large macromolecular species.