A few loose ends.
D000818:Animals; D001307:Auditory Perception / Q000502:physiology; D002940:Circadian Rhythm; D003118:Color Perception / Q000502:physiology; D004723:Endorphins / Q000502:physiology; D006801:Humans; D009420:Nervous System / Q000254:growth & development; D009462:Neurology / Q000639:trends*; D012559:Schizophrenia / Q000503:physiopathology
D004723:Endorphins