what makes some things more painful than other things?

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Why does plucking an eyebrow hair hurt so much less than plucking a nose hair? Or stubbing a toe, getting a paper cut, etc.

There’s also different kinds of pain, how does the body differentiate between the injuries and how does it calculate how painful it should feel?

In: Biology

It all has to do with the nervous system and nerve endings. The nerve endings on your face are far less concentrated than the ones in your nasal cavity and are also constantly exposed to external stimuli (making them more resilient). Pain is your brain interpreting signals received by nerve endings in and on your body so it makes sense that nerves constantly exposed to external stimulus would have a lower pain response as they’ve become “numb” to the stimuli or have died completely.

The skin also creates its own protective barriers. A perfect example would be calluses. I play guitar daily and have thick calluses on my fingers. The nerve endings in my fingers are still intact, but the “armor” on my fingertips allows me to touch very hot or cold items for a longer period of time than my wife or children could.

Pain differences may occur bec diff areas of the body have different number of pain receptors in them. Your lips have a lot, for example.

You can also vary in distribution of the chemicals that send messages about hurt or sooth to the brain. Persons with fibromyalgia, for ex, have a shortage of soothing chemicals in the spinal cord. So their pain levels are high all over.

Modern theories of pain are changing. It used to be thought that pain came only from physical damage at the site..but it can persist past when that area is healed and people missing a limb can have very strong pain in the missing limb!

Thinking is shifting toward a sensitization idea…that the nerves in the area get sensitized by the damage experience and learn to react strongly to any later stimulus in the area, even gentle ones, like a nervous cat to a sudden sound. They are trying treatments in which the person does an easy painful action and stays with it until the nerve calms down reliably. Then tries a bit nore painful action and so on, just like you’d encourage a wild cat to come near…very gentle retraining of the nerves in the affected area.

What you feel (burning, tingling, ache etc) may be related to the nature of the original damage or it may be influenced by your learning and culture…but still being explored as we dont have reallly good measures of pain.