Cell signaling

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 through  that  cells  communicate   with  each  other  is  through  means  of  extracellular signaling   molecules   or   hormones.   These   molecules   are   secreted and synthesized through signaling cells and produce a specific response in goal cells which have specific receptors for the signaling molecule.  Various cells can respond differently to the similar signaling molecule depending on the kind of receptor and the intracellular reactions initiated. The Cell signaling can be distributed  into  three  distinct  kinds  based  on  the  distance  over  that  the  signaling molecule  acts. In the endocrine signaling signaling molecule like insulin acts on goal cells distant from its site of synthesis in cells of an endocrine organ like the pancreas. The endocrine cells secrete the signaling molecule into the bloodstream if an animal or the sap (if a plant) that carries it to the goal cells elsewhere in the organism. In the paracrine signaling, signaling molecule affects only goal cells close to the cell from that it was secreted. The communication from one nerve cell to another through chemical neurotransmitters is an instance of paracrine signaling. The third kind of cell signaling is autocrine signaling, whereas a cell responds to a molecule which it has produced itself.