Which statement best describes the endogenous modulators discussed?

Which statement best describes the endogenous modulators discussed?

• A. Enkephalin blocks gate; Endorphin works in the CNS
• B. Enkephalin increases gate; Endorphin works in PNS
• C. Enkephalin works in brain; Endorphin blocks gate
• D. Enkephalin blocks signal at peripheral nerve; Endorphin works in muscles

Answer: (A)

Endogenous modulators regulate pain by dampening how signals are transmitted through the nervous system. Enkephalins act primarily at sites in the spinal cord to inhibit excitatory neurotransmission from nociceptive fibers, effectively closing the pain gate at the dorsal horn and reducing downstream pain signaling. Endorphins, in contrast, are most active in the central nervous system and modulate pain through opioid receptors to lessen the perception of pain. So the idea that enkephalin blocks the gate while endorphin primarily works within the CNS aligns with how these natural opioids modulate pain at different levels of the nervous system. The other descriptions either place enkephalin in the wrong location or describe opposite effects, which do not fit how these modulators influence pain signaling.

Endogenous modulators regulate pain by dampening how signals are transmitted through the nervous system. Enkephalins act primarily at sites in the spinal cord to inhibit excitatory neurotransmission from nociceptive fibers, effectively closing the pain gate at the dorsal horn and reducing downstream pain signaling. Endorphins, in contrast, are most active in the central nervous system and modulate pain through opioid receptors to lessen the perception of pain. So the idea that enkephalin blocks the gate while endorphin primarily works within the CNS aligns with how these natural opioids modulate pain at different levels of the nervous system. The other descriptions either place enkephalin in the wrong location or describe opposite effects, which do not fit how these modulators influence pain signaling.