Question

Which hormone uses a second messenger mechanism? testosterone estrogen norepinephrine cortisol none of these choices?

Answer 1

Norepinephrine uses the Second Messenger System, which means, cells signal to each other what molecules have been released that will trigger a physiological reaction. 

This phenomenon is activated after the ligand  (ion or molecule) is bonded to its receptor (protein molecule), creating a variation that causes a chain-reaction, that will finally activate the Second Messenger. The latter will activate intercellular molecules that will be able to control the cell’s activity.