How does the noxious stimulus evoke a response at the nociceptor?
The noxious stimulus interacts with transduction channels at the nerve ending. Some channels respond to thermal stimuli (TRPV1), cold (TRPM1, TRPM8), and chemical/mechanical stimuli (TRPA1).
Nociceptive stimuli activate these transduction channels and initiate the influx of a sodium and calcium current, thus causing depolarization and the propagation of current down the axon.
This conversion of heat, cold, chemical, or mechanical energy to an electrical impulse at the nerve terminal is called transduction .