How is it that humans have receptors for cannabinoids in our brains? What’s the real difference between the effects of indicas and sativas? What’s happening when you build up such a tolerance that you no longer feel high? For the answers to these, and more about the amazing ways cannabis interacts with the human body, we're turning to cannabis educator Emma Chasen. CEO of Eminent, a cannabis consulting firm in Portland, Oregon, she holds a specialized biology degree in Medical Plant Research from Brown University.