What are the two major groups of hormones?

The correct distinction between the two major groups of hormones is between steroid hormones and nonsteroid hormones. Steroid hormones are lipophilic and derived from cholesterol, allowing them to easily cross the cellular membrane and bind to intracellular receptors, which then influence gene expression and protein synthesis. Examples of steroid hormones include cortisol, testosterone, and estrogen.

Nonsteroid hormones, on the other hand, can be further categorized into peptide hormones and amine hormones. These are typically hydrophilic and cannot cross lipid membranes, so they bind to receptors on the cell surface, initiating signaling cascades within the cell. This group includes hormones like insulin and growth hormone.

The categorization into steroid and nonsteroid encompasses a broader range of hormonal characteristics, including their biochemical structure and method of action, making it the most accurate classification of hormones.