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