Final answer:
Opioid agonists are substances that bind to endogenous opioid receptors to block pain sensation, mimicking the body's natural painkillers. They are distinct from opioid antagonists, NSAIDs, and acetaminophen, with a high potential for abuse and addiction.
Step-by-step explanation:
The substances that bind to endogenous opioid receptors in the human body to block pain sensation are opioid agonists. These substances mimic natural opioids, such as endorphins, which are produced by the body to reduce pain and produce euphoria. Opioid agonists include drugs such as morphine, heroin, oxycodone, and fentanyl. They are potent painkillers with a high potential for abuse and addiction. While opioid antagonist drugs also interact with opioid receptors, they do the opposite of agonists; they block the effects of opioids rather than produce analgesic effects. On the other hand, nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen work through different mechanisms and are not primarily involved with the opioid receptors.