Which statement describes the relationship between Aδ and C fibers?

Which statement describes the relationship between Aδ and C fibers?

• A. Aδ fibers convey slow, dull pain.
• B. C fibers convey fast, sharp pain.
• C. Aδ fibers convey fast, sharp pain and C fibers convey slow, dull pain.
• D. Nociceptors do not participate in pain.

Answer: (C)

The key idea is that two types of nociceptive fibers carry different kinds of pain. Aδ fibers are thinly myelinated and conduct signals quickly, producing fast, sharp, well-localized pain (the immediate “pinprick” sensation). C fibers are unmyelinated and conduct signals slowly, producing a dull, aching, poorly localized pain that lasts longer. So the statement that Aδ fibers convey fast, sharp pain and C fibers convey slow, dull pain matches what these fibers actually do. The other options mix up the qualities—Aδ don’t convey slow dull pain, C fibers don’t convey fast sharp pain—and nociceptors do participate in pain signaling.

The key idea is that two types of nociceptive fibers carry different kinds of pain. Aδ fibers are thinly myelinated and conduct signals quickly, producing fast, sharp, well-localized pain (the immediate “pinprick” sensation). C fibers are unmyelinated and conduct signals slowly, producing a dull, aching, poorly localized pain that lasts longer. So the statement that Aδ fibers convey fast, sharp pain and C fibers convey slow, dull pain matches what these fibers actually do. The other options mix up the qualities—Aδ don’t convey slow dull pain, C fibers don’t convey fast sharp pain—and nociceptors do participate in pain signaling.