Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
Speaker 1: I'm Lauren vocal Bam, and I've got another brain Stuff
Speaker 1: classic episode for you today from our former host, Christian Sager.
Speaker 1: The topic why do we Itch? Hey everybody, I'm Christian
Speaker 1: Sager and this is the brain Stuff where I tell
Speaker 1: you about itching. Why do we itch? Why does it
Speaker 1: feel so good to scratch an itch? Well? To answer this,
Speaker 1: we must first turn to one of the body's most unappreciated,
Speaker 1: hardworking organs, the skin. So let's start with your skin,
Speaker 1: the original clothing, your birthday suit. Skin is pretty cool stuff.
Speaker 1: It is your body's largest organ. If you were to
Speaker 1: stretch out the skin of the average adult, you know,
Speaker 1: like if you wanted to make some cool book bindings
Speaker 1: or masks or sheets or whatever, you stretch that out,
Speaker 1: that would cover twenty two square air feet and weigh
Speaker 1: eight pounds. That's about enough to cover the twin bed
Speaker 1: in a creepy Serial Killers apartment. But while it's still
Speaker 1: attached to your body, skin protects you from germs signals.
Speaker 1: The immune system regulates body temperature and allows us to
Speaker 1: experience the crucial sense known as touch, one type of
Speaker 1: nerve ending in particular is responsible for the sensation of itching. Now,
Speaker 1: as it turns out, and itch is just the street
Speaker 1: name for something called paritis. Yet it's difficult to say.
Speaker 1: It is the irritation of skin cells or associated nerve
Speaker 1: cells caused by some external stimuli, like say tickling. Itching
Speaker 1: is a built in defense mechanism that alerts your body
Speaker 1: to the potential of being harmed. Think of that feeling
Speaker 1: you get when an insect crawls along your skin. That's
Speaker 1: your body saying watch out, that bug is out for
Speaker 1: your blood. Now, this itching sensation comes from receptors. Yeah,
Speaker 1: remember the whole paritis thing. That's just as difficult to say,
Speaker 1: But these are specialized nerve endings in your skin. Let's
Speaker 1: stick with this insect example. When the bug lands on
Speaker 1: your skin, it may not bother you at first, but
Speaker 1: soon it will begin to rub back and forth across
Speaker 1: your skin as it walks along looking for the best
Speaker 1: place to bite you. Once the bug scratches your skin,
Speaker 1: surface layer receptors in the dermis of the skin will
Speaker 1: become irritated. In a split second, these receptors send a
Speaker 1: signal through fibers in the skin to your spinal cord
Speaker 1: and then up to the cerebral cortex in your brain.
Speaker 1: The same fibers that send itching signals are also used
Speaker 1: to send pain signals to the brain, which once led
Speaker 1: some scientists to believe that itching was a form of
Speaker 1: light pain. That notion has since been dispelled by research
Speaker 1: which showed that pain and itching illicit opposite responses. Pain
Speaker 1: causes us to withdraw, and itching causes us to scratch.
Speaker 1: As soon as we feel an itch, our first natural
Speaker 1: response is to scratch the spot of the itch with
Speaker 1: our fingernails. The reason for this response is simple, we
Speaker 1: want to remove the irritant as soon as possible. Once
Speaker 1: you've scratched the area of irritation, you are likely to
Speaker 1: feel some relief. When your brain realizes that you've scratched
Speaker 1: away the irritant, The signal being sent to your brain
Speaker 1: that you have an itch is interrupted and therefore no
Speaker 1: longer recognized. Even if you don't remove the irritant, scratching
Speaker 1: will at least cause pain and divert your attention away
Speaker 1: from the itching. The irritant that caused the itching is
Speaker 1: very small, maybe only a few microns in length, so
Speaker 1: it only disturbs a few nerve endings When you use
Speaker 1: your finger nail to scratch the spot where the irritant is,
Speaker 1: you not only remove the irritant, but you irritate a
Speaker 1: lot more nerve endings than the irritant. In many cases,
Speaker 1: an itching sensation can be related to various ailments or diseases,
Speaker 1: from dry skin or poison ivy to more serious life
Speaker 1: threatening internal issues. So if you have continual chronic paritis,
Speaker 1: visit your local medical professional. They should be able to
Speaker 1: help you find a solution, which is great because we
Speaker 1: all know there are a few things worse than an
Speaker 1: itch you can't scratch. Today's episode was written by Ben
Speaker 1: Bolan and produced by Tyler Clang. Check out our online
Speaker 1: shop at t public dot com slash Brainstuff. Every purchase
Speaker 1: supports us directly, and of course, for more on this
Speaker 1: and lots of other topics that will get unto your
Speaker 1: skin in a good way, visit our home planet, how
Speaker 1: stuff works dot com.