Topic: Human Body / Everyday Physics
We’ve all felt that sharp, wildly unnecessary pain from a tiny paper cut. You can slice your finger with a sharp kitchen knife and barely notice at first, but a microscopic cut from a piece of printer paper will have you wincing for hours.
It turns out there are a couple of big reasons why something so small hurts so much:
- Your fingertips are packed with pain receptors: Hands and fingers have way higher concentrations of nociceptors (the nerve endings that signal pain to your brain) than almost anywhere else on your body.
- Paper acts like a saw: Under a microscope, the edge of a piece of paper isn’t smooth at all. It’s actually jagged and flexible, meaning it shreds and tears your skin tissue instead of making a clean slice.
- Exposed nerves: Because paper cuts are pretty shallow, they don’t usually bleed much. Blood normally clots and seals up a wound, but without it, those raw nerve endings are left completely exposed to the open air every time you move your hands.
It’s a huge amount of torture for such a tiny injury.
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