Question

How do adenohypophyseal hormones, except GH (Growth Hormone), affect their target cells?

A) They use insulin as a second messenger.
B) They affect target cells through direct cellular communication.
C) They rely on cyclic AMP as a second messenger.
D) They do not influence target cells in any way.

Answer 1

Adenohypophyseal hormones, with the exception of GH (Growth Hormone), affect their target cells by relying on cyclic AMP as a second messenger.

Step-by-step explanation:

Adenohypophyseal hormones, except GH (Growth Hormone), affect their target cells by c) relying on cyclic AMP as a second messenger.

Hormones like epinephrine and glucagon bind to a regulatory site on the cell membrane, where an enzyme called adenyl cyclase is present. Adenyl cyclase converts ATP to cyclic AMP (cAMP), which activates certain protein kinases. These protein kinases then phosphorylate specific enzymes, either activating or inhibiting them, resulting in the stimulation or inhibition of different cellular reactions.