Nociception

In physiology, nociception (/ˌnəʊsɪˈsɛpʃ(ə)n/), also nocioception; from Latin nocere 'to harm/hurt') is the sensory nervous system's process of encoding noxious stimuli.

[1] Nociception triggers a variety of physiological and behavioral responses to protect the organism against an aggression, and usually results in a subjective experience, or perception, of pain in sentient beings.

TRP and potassium channels [TRPM (1-8), TRPV (1-6), TRAAK, and TREK] each respond to different temperatures (among other stimuli), which create action potentials in nerves that join the mechano (touch) system in the posterolateral tract.

[8][9][10][11][12] TRP channels that detect noxious stimuli (mechanical, thermal, and chemical pain) relay that information to nociceptors that generate an action potential.

[29] As in mammals, nociceptive neurons in these species are typically characterized by responding preferentially to high temperature (40 °C or more), low pH, capsaicin, and tissue damage.

The term "nociception" was coined by Charles Scott Sherrington to distinguish the physiological process (nervous activity) from pain (a subjective experience).

Mechanism of nociception via sensory afferents
This diagram linearly (unless otherwise mentioned) tracks the projections of all known structures that allow for pain, proprioception, thermoception, and chemoception to their relevant endpoints in the human brain. Click to enlarge.