What is a nociceptor?
A nociceptor is a specialized, neurologic receptor that is capable of differentiating between innocuous and noxious stimuli. In humans, nociceptors are the undifferentiated terminals of a-delta and c-fibers, which are the thinnest myelinated and unmyelinated fibers, respectively. A-delta fibers are also called high-threshold mechanoreceptors. They respond primarily to mechanical stimuli of noxious intensity.
Nociceptors are sensory neurons that respond to noxious thermal, mechanical, or chemical stimulation. The term is used for both peripheral and central neurons; however, because the receptor is located in the periphery, the term is best associated with small myelinated (A delta) and unmyelinated (C) fiber primary afferent neurons. In the central nervous system, neurons that respond to noxious stimulation are considered nociresponsive. These are the “higher order” neurons.