Today’s Wonder of the Day was inspired by Justin. Justin Wonders, “Why Does A Paper Cut Hurt” Thanks for WONDERing with us, Justin!
As you've sorted through a pile of homework papers or dragged your finger along the edges of the pages of a book, we bet that at one time or another you've suddenly felt a jolt of pain. Ouch! What's going on here? Oh no! It's a paper cut!
Although pieces of paper don't otherwise resemble sharp knives, the edges of a piece of paper can at times be razor-sharp. If you've ever gotten a paper cut on your fingertip, you know the pain can feel disproportionate to what seems like a minor cut. So why do paper cuts hurt so badly?
One major reason paper cuts hurt so much is their usual location: your fingertips. You usually don't get paper cuts on your belly, your knees, or your back. If you did, they wouldn't hurt nearly as much. Why?
Your fingertips are very sensitive. They're built to serve as the primary means by which your brain processes your sense of touch. They can feel pressure, pain, and temperature easily. There are more nerve fibers (called nociceptors) per square inch in your fingertips than most other areas of your body.
When you get a paper cut, the paper slices through these nerve fibers, resulting in many pain signals being sent to your brain. If that wasn't bad enough, you'll notice after a paper cut that you can't just stop using your hands until it heals. You constantly need to use your hands and, as you do so, your skin moves and the wound gets pressed and pulled upon, which delays healing and renews the pain you feel each time it happens.
The typical location of paper cuts explains why a paper cut on your fingertip hurts more than a similar cut on your belly or leg. However, a paper cut tends to hurt more than a different kind of cut, like from a knife, on your fingertip. Why is that?
To answer that question, we have to look at the object doing the cutting: the paper. Unlike a knife edge, which is extremely sharp and straight, the edge of a piece of paper is dull and flexible by comparison.
Have you ever tried to cut a piece of meat with a very dull knife or watched someone do it? The knife pulls and tears at the meat rather than slicing cleanly through it. That's what paper does to your fingertip when you get a paper cut. Although you can't really see it with your eyes, the edge of a piece of paper does a lot of microscopic damage to your fingertip when it cuts it.
Adding to the pain is the fact that paper cuts tend to be shallow and bleed little. This means many damaged nerve endings are left exposed near the surface of your skin, where they can be irritated easily, resulting in more pain signals being sent to your brain.
So what can you do when you get a paper cut? Clean it thoroughly and then cover it with a bandage (or a liquid bandage). Keeping the wound closed and covered will help to reduce the amount of irritation the nerve fibers experience, thereby reducing your pain.