Which type of pain do A fibers transmit?

Which type of pain do A fibers transmit?

• A. First pain (fast pain)
• B. Second pain (slow pain)
• C. Diffuse pain
• D. Intermittent pain

Answer: (A)

A fibers carry impulses very quickly because they are large-diameter and heavily myelinated, which gives rise to the sharp, well-localized sensation that occurs immediately after a noxious stimulus—the first pain. This fast pain is what you notice right away when you prick your finger, for example. In contrast, the slower, dull, throbbing pain that follows is transmitted by C fibers, which are smaller and unmyelinated, resulting in the second pain that lingers and is less well localized. So the type of pain transmitted by A fibers is the fast, sharp, first pain.

A fibers carry impulses very quickly because they are large-diameter and heavily myelinated, which gives rise to the sharp, well-localized sensation that occurs immediately after a noxious stimulus—the first pain. This fast pain is what you notice right away when you prick your finger, for example. In contrast, the slower, dull, throbbing pain that follows is transmitted by C fibers, which are smaller and unmyelinated, resulting in the second pain that lingers and is less well localized. So the type of pain transmitted by A fibers is the fast, sharp, first pain.