ABSTRACT
While one of the major challenges in biology is to understand the complex regulatory processes within a cell, one can easily see that the problem is amplified by orders of magnitude when one tries to understand how a multicellular organism orchestrates the regulatory processes between like and unlike cells. Claude Bernard first introduced the idea that there had to be a cybemetic-like control system in multicellular organisms in order to regulate, adaptively, growth, development, maintenance of normal function, and wound healing. After exposure of a cell to either endogenous or exogenous chemicals, the cell has a variety of means to adapt to environmental changes. The most obvious is the interaction of extracellular signaling molecules to specific membrane receptors. In multicellular organisms, not only is orchestration of cells between different tissues necessary but also the coordination of activities, proliferation and differentiation of cells within excitable and nonexcitable tissues.
