Major Types of Hormones
Hormones are chemical messengers which are produced by the endocrine glands in the body and released into the bloodstream. They play an important role in regulating many physiological processes, including metabolism, growth and development, and reproductive cycles. There are three major types of hormones: steroid, peptide, and amino acid-based hormones.
Steroid Hormones
Steroid hormones are derived from cholesterol and are lipophilic, meaning they can readily pass through cell membranes. Examples of steroid hormones include sex hormones such as estrogen and testosterone, as well as mineralocorticoids and glucocorticoids. These hormones act on target cells to regulate gene expression, resulting in a physiological response.
Peptide Hormones
Peptide hormones are formed from amino acids and are water-soluble, meaning they cannot pass through cell membranes. Examples of peptide hormones include growth hormone, prolactin, oxytocin, and antidiuretic hormone. These hormones act on target cells to activate intracellular signalling pathways, resulting in a physiological response.
Amino Acid-Based Hormones
Amino acid-based hormones are derived from amino acids and are water-soluble, meaning they cannot pass through cell membranes. Examples of amino acid-based hormones include thyroxine, epinephrine, and norepinephrine. These hormones act on target cells to activate intracellular signalling pathways, resulting in a physiological response.