Chemical Nature of Hormones

Chemical nature of hormones : Hormones fall into six broad chemical classes. Amines are simple amines: the catecholamines epinephrine (adrenaline) and nor-epinephrine (noradrenaline) from the adrenal medulla, and melatonin from the pineal gland fall here, alongside some hormones that are chemically modified amino acids, such as thyroxine. Peptide hormones are built from short or long chains of amino acids, e.g. the hypothalamic hormones oxytocin, ADH and GnRH. Protein hormones are larger polypeptides, e.g. insulin, glucagon, TSH, FSH, LTH (prolactin), GH and relaxin. Fatty acid derivatives include prostaglandin. Steroid hormones are lipid-soluble molecules derived from cholesterol and other steroids, e.g. estrogen, testosterone and aldosterone, and their action tends to produce slower but longer-lasting responses than the other classes. Finally, a single gas, nitric oxide (NO), also acts as a hormone-like chemical messenger. This chemical classification matters directly for how a hormone reaches its target, covered next: broadly, the water-soluble classes (amines, peptides, proteins) …