Zoology - Chemical Coordination and Integration Question with Solution | TestHub

Secondary messengers are associated with response to peptide hormones they are insoluble in lipid and soluble in water. They do not enter inside the cell but bind with the extracellular receptors and generate the second messenger. Whereas steroid hormones, thyroxine, estrogen all are lipid-soluble, they directly enter the cell and bind with intracellular messengers. They do not need a second messenger.