Chapter 11 Cell Communication Overview: The Cellular Internet Cell-to-cell communication is essential for multicellular organisms Biologists have discovered some universal mechanisms of cellular regulation The combined effects of multiple signals determine cell response For example, the dilation of blood vessels is controlled by multiple molecules Copyright ? 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 11-1 Concept 11.1: External signals are converted to responses within the cell Microbes are a window on the role of cell signaling in the evolution of life Copyright ? 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Evolution of Cell Signaling