Functionally related to the poppy (Papaver somniferum) alkaloid morphine, natural or synthetic Opiates have widespread effects in the central nervous system, and on smooth muscle, due to activation of specific delta, mu, and kappa opiate receptors (each controlling different brain functions). Opiates include natural ingredients of the poppy and their derivatives - opium, morphine, codeine, and heroin. Morphine preparations are used as analgesic, sedative, or anxiolytic agent, but are also abused as street drugs. (NCI04)