Chemically hormones are of different nature like biogenic amines (like thyroxine, adrenaline etc.), proteinaceous or polypeptide (like hypothalamic hormones etc.) and steroids (like sex hormones and adrenocorticoids). Related Theory Hormones are chemical messengers released by glands without ducts to perform various functions. They are chemically classified under four categories- proteins and peptides, steroids, amino acids derivatives, and fatty acid derivatives.