Saliva Never Goes Away

I have saliva night and day.

It never seems to go away.

Each time I eat, I swallow some,

but it’s still there when I am done.

I feel saliva everywhere:

below my tongue, a pool’s down there;

around my teeth I feel it too;

and yummy smells make more come through.

It seems that there’s no end of it.

Why do our mouths make so much spit?

And Dr. Jo, please tell me, too,

what does all that saliva do?

Saliva glands, which you can’t see,

make new saliva constantly.

You make so much in just one day

it fills four glasses, all the way!

Two cheek glands open near your teeth.

Your tongue has four more glands beneath.

All of these glands are what produce

the mix that forms saliva juice.

Your mouth can hold about one cup,

so all the rest gets swallowed up.

And this saliva slowly flows

back to the throat—then down it goes.

So why do you keep making more?

What is all that saliva for?

It might be a surprise to you

to learn how much your spit can do.

One thing saliva does is it

has enzymes that make starches split.

It also kills germs that sneak by,

and wets your mouth so it won’t dry.

Saliva also makes food paste,

a watery bolus you can taste—

’cause it turns out you cannot get

much taste from food unless it’s wet.

When you need more, there’s lots we know

will cause extra saliva flow.

Like if you see a scrumptious treat,

or watch another person eat,

or sniff a real delicious smell,

or taste some food—your senses tell

your brain to send out a command:

“Let’s get to work, saliva glands!”

Then right away, there is no wait,

your mouth will start to salivate.

Which means saliva’s there to meet

that food you sense before you eat.

But even with no food in it,

a healthy mouth still needs some spit.

Your glands produce this juice all day

to keep dryness and germs away.

Now, normally you’re not aware

that there’s always saliva there.

But if a bug flies in your mouth,

saliva helps you spit it out!

COOL FACTS ABOUT SALIVA

• The six salivary glands are arranged in pairs. They all have big names. The two glands in our cheeks are called the “parotids.” The two pairs under the tongue are the submandibulars (which means under the mandible, or lower jaw) and the sublinguals (which means under the tongue).
• Vampire bats have a special chemical in their saliva that keeps a victim’s blood flowing. Normally, when you get a small cut, your blood flows for a little while—then in a few minutes your blood makes a small clot, or plug, to stop the flow. But vampire bat saliva has the chemical desmoteplase, or DSPA, that keeps a clot from forming so quickly. So, when the bat makes a small cut in an animal’s skin, it has time to suck up enough blood to fill its stomach before a clot forms.
• Small Asian birds called swiftlets build nests made of their own gooey white saliva. The birds use their tongues to deposit drop after drop of saliva on the wall of a cave. The saliva gets hard and forms a clear cup. Here, the swiftlets can lay their eggs and raise their young. Saliva nests are also used in Chinese cooking to make bird’s nest soup!
• Without saliva, food wouldn’t have much taste. Foods have to be dissolved in saliva to stimulate your taste receptors. You can test this for yourself: first, dry your tongue with a paper towel. Try tasting a dry food like a cracker or pretzel. Then dry your tongue again and try a sprinkle of sugar or salt. Can you taste the food? Now try it with a wet tongue. You should notice a big difference.