Zoology - Chemical Coordination and Integration Question with Solution | TestHub

Second messengers are the organic molecules whose production or release usually amplifies a signal such as a hormone and are received at the cell surface. Sodium (Na) is not a second messenger in hormone action. Related Theory Second messengers are molecules that relay signals received at receptors on the cell surface such as the arrival of protein hormones, growth factors, etc. to target molecules in the cytosol and/or nucleus. Second messengers also serve to greatly amplify the strength of the signal. Binding of a ligand to a single receptor at the cell surface may end up causing massive changes in the biochemical activities within the cell. There are 3 major classes of second messengers: (i) cyclic nucleotides (e.g., cAMPand cGMP) (ii) inositol trisphosphate (IP3) and diacylglycerol (DAG) (iii) calcium ions $\left({\mathrm{Ca}}^{2+}\right)$