Opioid peptides.
D001341:Autonomic Nervous System / Q000502:physiology; D004723:Endorphins / Q000502:physiology*; D004745:Enkephalins / Q000502:physiology; D006801:Humans; D008032:Limbic System / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology; D011957:Receptors, Opioid / Q000502:physiology
D004723:Endorphins; D004745:Enkephalins; D018377:Neurotransmitter Agents; D011957:Receptors, Opioid