[PBSDS BUMPER]
We all know how the journey through the digestive system ends, but few give much thought to
how it begins. If the mouth is the doorway, saliva is the greeter, one of the most important
substances produced by the body, yet one of the most overlooked, and to many, one of the
grossest… conjuring up words like "bleep"
Wait, what did I say? “Bleep”? “M-O-I-S-T”… I can’t say “Bleep”?
Ok, fine then. Let’s move on(moist).
[IOTBS INTRO]
Perhaps the best way to really appreciate saliva,
is to learn what it’d be like to live without it. I give you the time-honored
scientific tradition of, the saltine challenge
(PARTY NOISES)
Six crackers, no water, one minute on the clock.
(MUSIC)
I can't swallow
There's nothing in my mouth
To make saliva, cells pump out salts, and because of osmosis, that draws out water.
Unlike with tears or sweat, the salt is then taken back up by the glands, leaving you with
something that’s about 99% water. The other 1% is proteins and other molecules which give
saliva that sticky feel you know and… well, have feelings about, but that 1% is also where
most of the cool spit happens.
But not all saliva is secreted equal, we pump out two different brands of mouth juice.
Unstimulated saliva is secreted by hundreds of tiny glands all over our mouth, and we
make it essentially all the time. This saliva contains a special ingredient called mucin,
which is a protein that loves to soak up water, creating a kind of gel which forms a thin,
protective coating all over your mouth parts. Mucin is basically why saliva sounds like this
[GROSS WET MOUTH NOISES]
On the other gland, stimulated saliva is… what it sounds like, it flows when we smell
something delicious or… chew. Really doesn’t matter WHAT you chew, could be anything, but
I suggest food… or maybe gum. We have special sensors beneath our teeth, when they feel
the pressure of mastication, they send a signal to crank up the spit factories.
Super sour or salty foods also stimulate saliva, basically to dilute the acids or salts and
protect your mouth. You can test this, just put a drop of lemon juice on your tongue and
wait for the floodgates to open.
Lots of people think sugar causes tooth decay, but it’s really caused by acids released
by bacteria who EAT the sugar. Saliva dilutes that nasty stuff, so you can keep your teeth.
Since we make less saliva when we’re asleep, that’s prime-time for tooth decay… but
you always brush before bed, right?
You probably know there’s two salivary glands under your tongue, but most saliva that comes
from chomping and tasting is made by the parotid gland, situated between your ear and mouth.
It’s not here, or here so much… but right here.
Obviously, this type of saliva makes eating possible by lubricating your food…
but it also contains a bunch of proteins. The exact saliva protein mix varies throughout
the day, but the most abundant is amylase. Amylase is an enzyme, it chops long, complex
sugars like starch into simple ones, because glucose is what cells crave.
Try this: Hold a bite of cracker in your mouth without swallowing and let your saliva go
to work. After a few minutes, a sweet taste begins to take over as the starch in the cracker
is broken down into sugar.
Sweet
Proteins are one of the reasons babies drool so much. Baby saliva contains enzymes that
help digest milk, so when milk’s your only food, you make a lot of drool.
In fact, enzymes from saliva that break down starch, protein, and fat are manufactured
on large scales and added to laundry and dishwashing detergents to help them literally digest stains.
In most cultures, spitting ON someone
is just about the grossest, worst thing you can do, yet we don’t mind swapping spit
with the people we love. At least that was true before you watched this video.
I don’t expect that we’ll all stop being a little weirded out by saliva anytime soon,
but if you take a second to chew on the idea, when it comes to multipurpose liquids, saliva
even puts sriracha to shame.
Ya know what? Drool rules. Stay curious.