Although hormones are chemically diverse, they generally belong to one of four different chemical groups
(i) Steroid, hormones These hormones are manufactured by endocrine cells from cholesterol, an important type of lipid in the human body. Examples include cortisol, aldosterone, estrogen, progesterone and testosterone.
Allinone Chemical Coordination and Integration
(ii) Amino acid derivatives The thyroid hormones (T3 and T4) are synthesised from the amino acid tyrosine and iodide respectively. Adrenaline (also known as epinephrine) and noradrenaline (also known as norepinephrine) are produced hy the medulla of the adrenal gland, are also derived from tyrosine. Melatonin is synthesised from the amino acid tryptophan.
(iii) Protein hormones These hormones are long, folded chains of amino acids. Included among these hormones are insulin, glucagons, parathyroid hormone, growth hormone, prolactin, etc.
(iv) Peptide hormones Hormones such as oxytocin and antidiuretic hormone are smaller than protein hormone. They are made of a short chain of amino acids.