Question: If you cut your hand does it hurt because its cut or does it hurt to let you know its cut?

Jean Bourke answered on 12 Nov 2012:

Both! The pain signal is cause by the injury: damaged and killed cells release bits of their innards into their surroundings. Other cells recognise these for what they are and sound the alarm. The alarm signal is perceived by us as pain but is actually much more complex. Immune cells go to the injury site to prevent infection. Blood vessels dilate facilitating the movement of the immune cells and increasing the flow of nutrients to the area so the injury can be healed faster and clotting begins to prevent you bleeding too much, the initial bit of bleeding helps to clean out the wound.

When you feel the pain you know you have been injured and that it is bad. It helps teach us not to do that again!

In certain diseases, such as leprosy, pain is not felt, that way you keep accidentally injuring yourself over and over again. Even though the other signals to induce healing would be sent you would not notice that you’d hurt yourself until it was too late. If you can’t feel pain and you pick up something hot, you don’t realise that it’s damaging you and you keep holding it, doing yourself more and more damage. That is how lepers become disfigured over time.

We take painkillers to ease pain because, so long as it is injured, you body will keep telling you it is. After the first few minutes you already know you’ve cut your hand, you don’t need to be told repeatedly so you take a painkiller to stop/reduce the pain signal. This will not effect the other signals and your cut will continue to heal.

There are other diseases where the patient is constantly in pain, even though there is no damage, this some times happens with amputees. Life can be very difficult of you are in constant pain and taking strong painkillers for a really long time is not good for you. There is a lot of working being done in this area. In fact a couple of days ago I read about how an amputee who’s missing arm feels like it’s stuck in a really uncomfortable, painful positions is staring to deal with it by mentally moving the arm into a more comfortable position!

So it hurts because it has been injured to let you know that you did something bad and not to do it again.

There’s an interesting article on bbc news about pain: ‘I chewed off half my tongue’: Why pain is a necessity
http://www.bbc.co.uk/news/health-20239836