Using pain incurred by a surgical procedure as a model for a noxious stimulus, Dr. Narcessian explained that the first step in the process is the release of potent mediators of inflammation and pain, during transduction. When the mediators reach nociceptors located on the afferent, or sensory, nerve cells, they can trigger an action potential, whose end result may be pain perception.
Sensitization enables the nociceptors to more easily fire an action potential.
Thus, less stimulus is needed to cause transduction. This peripheral sensitization may also contribute to hyperalgesia and allodynia. In hyperalgesia, a normally painful stimulus is now perceived as increased in intensity. In allodynia, a previously nonpainful stimulus causes pain. In the second phase of acute pain, transmission, the electrical signal produced by the action potential is transmitted by the C-fibers of the nervous system.