Enkephalin response blocks gate by interfering with which fibers?

Enkephalin response blocks gate by interfering with which fibers?

• A. A-delta and C fiber T cells
• B. A-delta fiber T cells
• C. C fiber T cells
• D. A-beta fiber T cells

Answer: (A)

The gate control system hinges on the dorsal horn acting as a switch for pain signals. Small-diameter nociceptive fibers—A-delta and C fibers—carry pain information into the spinal cord and activate neurons that send signals to the brain. Enkephalin, an endogenous opioid, is released by inhibitory interneurons in this area and dampens the pain signal by acting on those same nociceptive fibers. It reduces neurotransmitter release from A-delta and C fibers and can hyperpolarize the receiving neurons, effectively blocking the transmission of nociceptive information up the gate. So enkephalin’s action is to interfere with the small-diameter pain fibers, closing the gate to pain.

The gate control system hinges on the dorsal horn acting as a switch for pain signals. Small-diameter nociceptive fibers—A-delta and C fibers—carry pain information into the spinal cord and activate neurons that send signals to the brain. Enkephalin, an endogenous opioid, is released by inhibitory interneurons in this area and dampens the pain signal by acting on those same nociceptive fibers. It reduces neurotransmitter release from A-delta and C fibers and can hyperpolarize the receiving neurons, effectively blocking the transmission of nociceptive information up the gate. So enkephalin’s action is to interfere with the small-diameter pain fibers, closing the gate to pain.