Pain receptors, also called nociceptors, are free (bare) nerve endings located in the skin, muscles, joints, bones, and internal organs (viscera). They are specialized sensory receptors that detect signals from damaged tissue or the threat of damage. These receptors are primarily found in the peripheral nervous system and are absent within the central nervous system itself. The nociceptors detect noxious stimuli such as mechanical, thermal, or chemical damage and send pain signals to the spinal cord and brain for processing. Their cell bodies reside mainly in the dorsal root ganglia and trigeminal ganglia.
In summary:
- Pain receptors are free nerve endings found mainly in the skin, muscles, joints, bones, and internal organs.
- Their cell bodies are in the dorsal root ganglia (body) and trigeminal ganglia (face).
- They detect harmful stimuli and transmit signals to the spinal cord and brain where pain is perceived.