The reactive response of life

Abstract

Abstract This chapter focuses on another type of reactive rheostasis, the well-defined, sequential regulated change in physiology that underlies gestation in mammals and brooding in birds. It shows that female energy balance during pregnancy is maintained through short-term homeostatic regulation of glucose, while the long-term change in insulin action is driven by the coordinated activity of an entirely separate genetic and anatomically driven response. These reactive rheostatic responses, unlike programmed rheostasis, have a defined period which can vary from a few weeks to several months. The chapter concludes that, given the considerable variation in parental physiology and behavior across the animal kingdom, it is hard, if not impossible, to formulate a single overarching model that can encompass the reactive rheostatic regulation of embryo development.