Final answer:
Heroin and morphine have analgesic effects because they are opioids that bind to specific receptors, altering pain perception and mimicking the body's own painkillers, but their potential for misuse represents a public health concern.
Step-by-step explanation:
Heroin and morphine have an analgesic effect because they are opioids, which means they are able to attach to specific opioid receptors in the brain, spinal cord, and gastrointestinal tract, altering the way a person experiences pain. Morphine, which is found in opium, is a major pain-relieving drug; it contains two hydroxyl functional groups that contribute to its analgesic properties. Heroin, a semisynthetic derivative of morphine, is even more potent and can produce the same analgesic effect as morphine but at a much lower dose. Opioids like morphine and heroin also mimic the effects of endogenous opioid neurotransmitters, which are naturally produced by the body to reduce pain and create a feeling of euphoria. However, due to their high potential for abuse, the misuse and abuse of opioid medications like hydrocodone and oxycodone have become significant public health concerns.