Pain is complex. We now understand that their are many inputs outside of localized tissue damage that contribute to the pain experience. In the last 10-15 years lots of good research and amazing writing has come out on the complex physiology of pain. It has changed the way we treat and manage pain for the better. In this post I review some of the important concepts from the 2003 breakthrough book, Explain Pain.
The initiation of pain
Pain occurs when the brain responds to stimulus from the rest of the body. It is constructed from combining signals from the emotional memory centres of the brain, the nerve endings in our skin (mechanical, chemical, and heat), the immune system and our nervous system.
The activation of mechanical, temperature, or chemical receptors within a neuron can initiate a nociceptive signal (danger signal). These signals are going all the time and only sometimes do they result in pain. Nociception is the most common precursor to pain, but thoughts, memories, and experience can also evoke pain and danger signals within the brain. In Melzecks, body neuromatrix, he outlines the different internal and external inputs that contribute to our experience of pain.