"Morphine within"—natural, opiatelike neurotransmitters linked to pain control and pleasure.

• A. Endorphins
• B. Dopamine
• C. GABA
• D. Norepinephrine

Answer: (A)

Endorphins are the body's own opiate-like chemicals that help control pain and produce a sense of pleasure. They bind to opioid receptors in the brain and spinal cord, acting as natural analgesics much like morphine does, which is why the phrase “morphine within” points to these endogenous substances. They’re released in response to pain, stress, or activities like exercise, helping dampen pain signals and can create a mood boost or feeling of well-being.

Dopamine drives reward and motivation, contributing to pleasure but not primarily as the natural pain-relief system described here. GABA is the main inhibitory transmitter that calms neural activity, not specifically opioid-like pain control. Norepinephrine governs arousal and alertness and can modulate pain in some contexts, but it isn’t the endogenous opioid that is linked to pain relief and the morphine-like effect discussed.