Parahormones

biologically active substances, diverse in chemical structure, that affect the metabolism and many of the physiological processes of the body.

Parahormones are not, as a rule, formed in the endocrine glands (unlike hormones), but rather in other tissues and organs. The biological effect of parahormones is brief, since they are either destroyed or they combine with tissue proteins. Included among the parahormones are acetylcholine, certain precursors and products of the conversion of adrenalin, histohormones (for example, gastrin, heparin, and secretin), and histamin, serotonin, and certain other biogenic amines.