The half-life of most hormones in the blood is relatively short. For example, when researchers inject radioactively labeled
insulin into an animal, half of the labeled
hormone disappears from the blood within 30 min.
What is the importance of the relatively rapid inactivation of circulating hormones?
Inactivation provides a rapid means to change hormone concentrations.
Rapid inactivation of hormones allows secretory granules to store the hormone until needed again.
Hormone regulation depends solely on immediate inactivation of hormones to prevent a continued response.
Rapid
inactivation ensures hormones only act locally.
In what ways can the organism make rapid changes in the level of a circulating peptide hormone?
by changing the specificity of the hormone receptors
by changing the shape of the hormone receptors on the cell surface
by changing the rate of hormone release from storage
by changing the rate of conversion from prohormone to active hormone
by changing the rate of hormone transport