Pain is a complex protective mechanism. It is an essential part of evolution that protects the body from danger and harm.
The body has pain receptors that are attached to 2 main types of nerves that detect danger. One nerve type relays messages quickly, causing a sharp, sudden pain. The other relays messages slowly, causing a dull, throbbing pain.
Some areas of the body have more pain receptors than others. For example, the skin has lots of receptors so it is easy to tell the exact location and type of pain. There are far fewer receptors in the gut, so it is harder to pinpoint the precise location of a stomach ache.
If pain receptors in the skin are activated by touching something dangerous (for example something hot or sharp), these nerves send alerts to the spinal cord and then to part of the brain called the thalamus.
Sometimes the spinal cord sends an immediate signal back to the muscles to make them contract. This moves the affected body part away from the source of danger or harm.
This is a reflex reaction that prevents further damage occurring. It happens before you feel pain.
Once the ‘alert!’ message reaches the thalamus, it sorts the information the nerves have sent, taking into account previous experience, beliefs, expectations, culture and social norms. This explains why people have very different responses to pain.
The thalamus then sends the information on to other parts of the brain that are linked to physical response, thought and emotion. This is when you may feel the sensation of pain, think ‘That hurt! What was it?’, and feel annoyed.
The thalamus also contributes to mood and arousal, which helps to explain why your interpretation of pain partly depends on your state of mind.