Question

Some hormones are synthesized and are stored in vesicles until signaled to release into the blood. Other hormones are synthesized on demand. Which category of hormones is stored and which is synthesized on demand?

1. Stored: steroid; on demand: peptide & amine
2. Stored: steroid & peptide; on demand: amine
3. Stored: peptide & amine; on demand: steroid
4. Stored: steroid & amine: on demand: peptide
5. Stored: peptide; on demand: steroid & amine

Explain why the structure of each relates to it’s function you selected.

Answer 1

C) stored is peptide and amine , on demand steroid.

Steroid hormone like cortisol has 3 cyclohexyl rings and 1 cyclopentol ring all these are combined to form single structure , it is not stored but synthesized on demand because steroid is derived from cholesterol, that is a lipid . The cell membrane is made up of phospholipid bilayer, so that lipid can easily diffuse into blood without any transporters . So if steroid hormones are stored they can easily pass the membrane into circulation and can produce adverse reactions. For example cortisol wich has immunosuppressive action if stored , can easily leave the membrane and can make our body immjnosuppresive hence steroid hormone not stored .

Peptide and amine hormones are products of translation, it takes certain time for synthesis of these hormones, for example lets take insulin these are stored as granules on beta cells of pancreas , when glucose levels are increased in blood , there will be abrupt increase of insulin release to lower blood glucose , after this 1st initial release of insulin , there will be a small drop in its release, because they should be synthesized and it takes time . So peptide and amine hormones are synthesized and stored earlier . This is a protein , which is not lipid soluble so it will not diffuse out of the cell membrane.