Nociception (also
nocioception or
nociperception, from latin
nocere 'to harm or hurt') is the encoding and processing of
harmful stimuli in the
nervous system, and, therefore, the ability of a body to sense potential harm. It is the
afferent activity in the
peripheral and
central nervous systems produced by stimulation of specialized
free nerve endings called
nociceptors or "pain receptors" that only respond to tissue damage caused by intense chemical (e.g., chilli powder in the eyes), mechanical (e.g., pinching, crushing) or thermal (heat and cold) stimulation. Once stimulated, a nociceptor sends a signal along a chain of nerve fibers via the
spinal cord to the
brain. Nociception triggers a variety of
autonomic responses and may also result in a subjective experience of
pain in
sentient beings. Nociceptive neurons generate trains of
action potentials in response to intense stimuli, and the frequency of firing determines the intensity of the pain.
