The physiology of the neurotransmitter dopamine was discussed. Its function in some endocrine systems (adrenal) was listed, but the majority of the time was spent in the action within the brain. The function in the reward system was stressed, and how schizophrenia is affected by it. The euphoria produced by dopamine, and how certain drugs, like cocaine, affect the dopamine-pleasure response. The increase in dopamine receptors caused by increased secretion, leading to tolerance to dopamine producing chemicals and the requirement for more drug was presented.