(classical music)
(chalk scribbling)
- Hey, I'm Julie and
welcome to BrainStuff.
Most of us think that the spit
inside of our mouth is gross.
I mean, it's not as
nasty as the acidic bile
that a xenomorph's gaping maw has,
but it's still pretty nasty.
Saliva is actually an
incredibly complex fluid
that facilitates lots
of necessary functions.
It lubricates our mouths,
moistens our food,
assists in digestion, protects our teeth,
and even defends our
mouths from microorganisms.
Saliva is made by a group of
cells called salivary glands
that deliver it into our
mouths through ducts.
Now, humans have four
kinds of salivary glands.
First, there's the parotid
glands which are opposite
our front, lower molars,
kinda nearly parallel
to our ear lobes.
These secrete a thin
liquid that's full of rich
antibacterial proteins and compounds
that remineralize our teeth.
They don't care whether
or not you're chewing
on bread or plastic, they will go to work
on anything in your mouth.
Next, there's the
submandibular glands which
are shaped kinda like
eggs and they're embedded
below the floor of the
mouth just above the throat.
Now, these produce a more viscous fluid
used to lubricate the throat and mouth.
Also, below the floor of the mouth,
there's the sublingual glands
which are shaped like almonds.
They produce similar
lubricating secretions.
And finally, there's a
fourth salivary gland
that covers the tongue and
the lining of our mouths
with hundreds of smaller glands.
You know how sometimes
you feel small bumps
on your inner lip?
Well, that's them, and while
they lubricate the mouth,
they also protect it against infections.
Okay, so that's a lot
of saliva being secreted
by those four different glands.
It's mostly made of water,
but it also contains enzymes
that break down food for
digestion and do the whole
"protection from infection" thing.
So, when it's not digesting
and making things taste great,
saliva is also a lethal killer!
Of germs!
In fact, spit is so good at
cleaning, some art conservators
use it on fragile surfaces
instead of chemical solutions.
In some cultures, a mother will even spit
into her infant's mouth to
teach their immune systems
how to produce antibodies
and destroy pathogens.
Because, of all the antibodies already
in the mother's saliva,
this introduces the infant
to bacteria without getting them sick.
And finally, did you know
that our saliva contains
our entire genetic blueprint?
If you're trying to get
away from a crime scene,
do not spit on anything
because it only takes
half of an eye-dropper drop worth of spit
to sample your DNA.
You can even take a
sample yourself, send it
through the mail, and get
your own genetic information.
So, what is your favorite
thing about spit?
Let us know in our YouTube
comments and, while you're at it,
please subscribe to BrainStuff channel.
That way you'll know
whenever we've dropped
more everyday science for you to devour.
