Endocrine Communication
First and Second Messengers
First Messengers – non-steroid hormones outside the cell that bind to the cell surface to
produce an effect inside the cell
Second Messengers – steroid hormones released by a first messenger which cause an
enzyme cascade inside the cell
First messenger binds to a receptor on the cell surface membrane
G protein on the inside of the receptor activates adenyl cyclase which converts ATP into
cAMP
cAMP acts as a second messenger opening channel proteins and causing an enzyme
cascade inside the cell
First and Second Messengers
First Messengers – non-steroid hormones outside the cell that bind to the cell surface to
produce an effect inside the cell
Second Messengers – steroid hormones released by a first messenger which cause an
enzyme cascade inside the cell
First messenger binds to a receptor on the cell surface membrane
G protein on the inside of the receptor activates adenyl cyclase which converts ATP into
cAMP
cAMP acts as a second messenger opening channel proteins and causing an enzyme
cascade inside the cell
