During transduction, chemical mediators released from damaged cells have what effect on nociceptors?

During transduction, chemical mediators released from damaged cells have what effect on nociceptors?

• A. Chemical mediators lower activation threshold of nociceptors and increase pain
• B. Chemical mediators raise activation threshold
• C. Chemical mediators block conduction
• D. Chemical mediators reduce pain

Answer: (A)

Chemical mediators released from damaged cells sensitize nociceptors by lowering their activation threshold, so they fire more easily and pain is amplified. They act on receptors at the nociceptor endings and trigger second‑messenger cascades (for example, prostaglandins raising cAMP and activating PKA, bradykinin activating PKC) that increase the probability of opening sodium channels and the excitability of the neuron. This peripheral sensitization means subthreshold or mildly noxious stimuli can generate action potentials, producing heightened pain at the injury site. Raising the threshold, blocking conduction, or reducing pain would not describe this sensitization process.

Chemical mediators released from damaged cells sensitize nociceptors by lowering their activation threshold, so they fire more easily and pain is amplified. They act on receptors at the nociceptor endings and trigger second‑messenger cascades (for example, prostaglandins raising cAMP and activating PKA, bradykinin activating PKC) that increase the probability of opening sodium channels and the excitability of the neuron. This peripheral sensitization means subthreshold or mildly noxious stimuli can generate action potentials, producing heightened pain at the injury site. Raising the threshold, blocking conduction, or reducing pain would not describe this sensitization process.