In multicellular organisms there is a requirement for the cells to communicate with one another in order to coordinate their metabolism and growth.  The principal way by  that  cells  communicate   with  every  other  is  by  means  of  extracellular signaling   molecules   or   hormones.   These   molecules   are   secreted and synthesized by signaling cells and make a particular response in goal cells which have particular receptors for the signaling molecule.  Several cells can respond in a different way to the similar signaling molecule depending on the part of receptor and the intracellular reactions initiated.