Question

Compare and contrast steroid and non-steroid hormones. Specifically address how each category is carried in the blood and how each interacts with the cellular membrane of target cells. Why do these two categories of steroid interact with plasma membranes in different ways?

Answer 1

Steroid Hormones	Non-steroid Hormones
1) Steriod hormones are synthesized from cholesterol.	1) Non-steroid hormones are peptide hormones and amino acid derivatives synthesized by proteins and amino acids respectively.
2) Examples are adrenal cortex hormones like glucocorticoids, mineralocorticoids and gonadal hormones like oestrogen, progesterone and testosterone.	2) Examples include insulin, anterior pituitary hormones, glucagon, antidiuretic hormone, adrenal medulla hormones, thyroid hormones etc.
3) These aur liquid soluble and hydrophobic.	3) These are water soluble and hydrophilic.
4) They are synthesized by the enzymatic reactions and not stored in granules but are bound to proteins in cytosol.	4) They are synthesized in rough endoplasmic reticulum and are transported via golgi apparatus and stored in secretory granules.
5) These hormones are secreted outside the cell by diffusion.	5) These hormones are secreted from the secretory granules on stimulation, by calcium mediated exocytosis.
6) They are transported in the blood in bound form as they are insoluble in plasma. Transport proteins are specific for hormones.	6) They are transported in the blood in free form as they are readily soluble in the plasma.
7) These hormones bind to intracellular or nuclear receptors and regulate gene transcription.	7) These hormones bind to the cell surface receptors and activates a series of intracellular signal transduction systems via second messengers.
8) Steroid hormones are lipids soluble and they can be transported easily across the lipid containing cellulase membranes and they interact with the receptors inside the cell.	8) Non-steroidal hormones are lipid insoluble and cannot be transported across the cell membranes. So they act on the receptors on the surface of the cell membrane and in turn activate intracellular pathways.