Final answer:
Opioids relieve pain by blocking the release of substance P (option 2). They include drugs such as oxycodone, heroin, morphine, and codeine that bind to specific receptors in the body.
Step-by-step explanation:
Opioids relieve pain by blocking the release of substance P, a neurotransmitter involved in the transmission of pain signals to the brain. Thus, the correct answer is option 2) substance P. These drugs, which include opioids such as oxycodone, heroin, morphine, and codeine, bind to opioid receptors in the brain, spinal cord, and gastrointestinal tract, altering the perception of pain and often producing a sense of euphoria.
Opioid drugs are known for their potent analgesic effects, which mimic the endogenous opioid neurotransmitter system of the body. Natural opioids are derived from opium, found in the poppy plant, and synthetic versions are also created to provide pain relief. However, due to the potential for abuse and addiction, opioids should be used with caution, as they present grave public health concerns regarding misuse and abuse, highlighted by research supported by the National Institutes of Drug Abuse.