The cause of fibromyalgia is unknown; however, it is believed to involve a combination of genetic and environmental factors with half the risk attributed to each. The condition runs in families and many genes are believed to be involved.
Agonist: A substance that acts like another substance and therefore stimulates an action. Agonist is the opposite of antagonist. Antagonists and agonists are key players in the chemistry of the human body and in pharmacology.
FULL AGONISTS, PARTIAL AGONISTS, ANTAGONISTS. Three types of opioids are classified by the effect that they have on the mu receptors on cells. They are the full agonist, the partial agonist and the antagonist. As used here, an agonist is something that stimulates or produces an effect. Agonist is derived from the Late Latin agnista which means contender which is derived from the Greek agonists which also means contestant which came from agon which means contest. An agonist is a chemical contestant or contender.