Nociceptors

Nociceptors are a specific type of sensory neuron that are activated by noxious stimuli and result in pain. Nociceptor dendrites can be found externally, such as in the skin, the cornea and the mucosa, or internally, such as in the muscles, joints, bladder, gut and digestive tract. The cell bodies are found in the dorsal root ganglia in the spinal cord of the central nervous system.

Nociceptors can be triggered by mechanical, thermal and chemical stimuli. They express TRPV1 channels on their surface and are therefore activated by heat and capsaicin. Some nociceptors are also activated by mechanical damage such as cutting or crushing. A special class of nociceptors are mechano-insensitive and become mechanosensitive only long after noxious stimulation, e.g. during an inflammation.

Figure 1. Spinal cord with nociceptors highlighted in red.