Opioids: These are a class of drugs that include morphine and work by binding to opioid receptors in the brain to produce pain relief and euphoria.
Endorphins: These are natural chemicals produced by the body that also bind to opioid receptors. They play a role in regulating pain, mood, and pleasure.
Tolerance: With prolonged use of opioids like morphine, the body can develop tolerance, meaning higher doses are needed to achieve the same effects.