Hey there.
I'm Josh Clark, and this is BrainStuff.
And this is the BrainStuff where I talk to
you about itching.
Just fair warning here: you are going to itch.
Because I am a puppet master and you are my
puppet.
Just FYI.
So let's talk about skin.
It's your birthday suit!
And skin allows us to experience that ever
so important sensation touch.
Touch, in and of itself, is a very complex
thing.
It's multifaceted.
And one of those facets - one of the chief
facets among all touch - is the itch.
For a while, people thought that an itch was
just a low level type of pain.
And it makes a lot of sense.
Because itches and pain (and actually the
sensation of heat) all follow the same neural
pathways from the skin to the brain.
But a recent closer examination of your skin
has found that your itch triggers a specific
kind of receptor, called pruriceptors.
Which is tough to say, but actually, it's
a pretty legitimate term because another word
for itch (the clinical term) is "pruritus."
Which is why everybody just calls it itch.
So these special receptors (pruriceptors)
are attuned to just the most minute sense
of touch.
They're triggered by something like the ever-so-gentle
pressure of a fly's legs.
And, even closer examination of itching has
found that these pruriceptors use a specialized
neurotransmitter called MPPB to send the itch
signal from the skin to the brain.
So, it turns out that itching is not pain.
It's its own thing.
A good analogy is that itches and pain might
follow the same highway from the skin to the
brain, but they start from slightly different
points of origin, and an itch uses a different
kind of car.
So science has a better handle on itches than
it did before, but they're still a big mystery.
Why should scratching an itch bring any sort
of relief?
Well, itching appears to be a built-in warning
system for us to say that there's something
small but potentially dangerous that's just
alighted on our skin.
Right?
When we scratch whatever's causing that itch,
the prevailing theory, is that we activate
more skin cells than just the pruriceptors.
Which means that the pruriceptors' itch signal
is either drowned out by these other signals
or potentially turned off somehow.
And that makes a lot of sense, because when
you scratch an itch, your fingernail is exerting
enough pressure, and is big enough, that it
can destroy or get rid of whatever was causing
the itch in the first place.
Prurrritus.
So tell me: how many times did you itch in
this episode, puppets?
Let me know in the comments section below.
And while you're down there, make sure to
say something about my hair, or something
else important like that.
And you might as well subscribe to BrainStuff
because it's totally awesome.
And if you like this kind of thing, head on
over to HowStuffWorks.com.
