Click on image to view larger version.
Figure 15. Biological systems such as mammalian organisms maintain homeostatic equilibrium through signalling at all levels of biological organisation. These signals originate from various sites: those that control the entire organism, specific tissue functions, defined cell functions and intracellular functions. The signals always involve cell responses that govern various levels of biological organisation. The signalling serves to secure system integrity and survival in the face of perturbations constantly brought about by exposure to a multitude of endogenous and environmental toxic agents. Small and moderate degrees of perturbations tend to initiate adaptive responses, whereas severe perturbations may lead to system failure and death.
