Function and Structure of Signaling Pathways

The enormous structural variety and functional capacity of multicellular organisms is due to their ability to coordinate the biochemical reactions of the various cells of the total organism. The basis for this coordination is the intercellular communication, which allows a single cell to influence the behavior of other cells in a specific manner. 

We currently know of various forms of communication between cells (fig. 3.1)  

A further intercellular communication mechanism relies on electrical processes. The conduction of electrical impulses by nerve cells is based on changes in the membrane potential. The nerve cell uses these changes to communicate with other cells at specialized nerve endings, the synapses (see chapter 16). It is central to this type of intercellular commimication that electrical signals can be transformed into chemical signals (and vice versa, see chapter 16). 

Intercellular signaling influences nearly every physiological reaction. It ensures that all cells of a particular type receive and transform a signal. In this manner, cells of the same type react synchronously to a signal. A further function of signaling pathways is the coordination of metabolite fluxes between cells of various tissues. 

In higher organisms intercellular signaling pathways have the important task of coordinating and regulating cell division. The pathways ensure that cells divide synchronously and, if necessary, arrest cell division and enter a resting state. 

---