Biological clock control of glucose metabolism timing metabolic homeostasis

Abstract

The development of the concept of homeostasis began in the mid 19th century, when Claude Bernard (1813-1878) claimed that 'la fixeté du milieu interieur' is essential for higher organisms to survive in an ever changing environment. Standing or staying the same is the literal meaning of the term homeostasis, which was introduced later by Walter B. Cannon (1871-1945) and derived from the Greek words homeios (the same) and stasis (staying). However, as Cannon emphasized, homeostasis does not mean something set and immobile that stays exactly the same all the time. In his words, homeostasis means a condition that may vary, but which is relatively constant. This definition was refined by Donald C. Jackson (1987): Homeostasis is znot a single optimal control condition but rather a variety or continuum that varies with the animal's circumstances. Set points or regulated values are not fixed, but may change depending on ambient conditions or because of changing physiological conditions or demands.