Sandy Donovan - Hawk & Drool: Gross Stuff in Your Mouth

GROSSBODYSCIENCE HAWK&DROOL GROSSSTUFFINYOURMOUTH WrittenbySandyDonovanIllustratedbyMichaelSlack Text copyright 2010 by Sandy Donovan Illustrations copyright 2010 by Michael Slack All rights reserved. International copyright secured. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any meanselectronic, mechanical, photocopying, recording, or otherwisewithout the prior written permission of Lerner Publishing Group, Inc., except for the inclusion of brief quotations in an acknowledged review. Millbrook Press A division of Lerner Publishing Group, Inc. 241 First Avenue North Minneapolis, MN 55401 U.S.A. p. cm. (Gross body science) Includes bibliographical references and index. (Gross body science) Includes bibliographical references and index.

ISBN 9780822589662 (lib. bdg. : alk. paper) 1. SalivaJuvenile literature. 2.

MouthDiseasesJuvenile literature. 3. Dental plaqueJuvenile literature. I. Slack, Michael H., 1969 ill. Title. III. III.

Title: Hawk and drool. QP191.D66 2010 612.3'13dc22 2008050699 Manufactured in the United States of America 2 BP 2/1/10

Sometimes you hawk it up. Other times you drool it out. You might know saliva by its nickname spit. Its that slimy stuff that helps you hawk, drool, and make spitballs. Or win spitting contests.

Not that you know anything about either one of these. Yes, spit has its uses when it comes from your own mouth. But maybe youd rather not see or, even worse, touch other peoples spit. Its one of the more disgusting parts of the human body, after all. You may not want to think too much about it, really.

But spit isnt really any nastier than other parts of your body. But spit isnt really any nastier than other parts of your body.

Spit is made up of ordinary body things: mostly water and chemicals. And it helps you do lots of things besides wet down spitballs. Things you really wouldnt want to live without eating, for instance. Take a closer look, and decide for yourself how disgusting spit really is. WHAT IS THAT SLIMY, SLOPPY STUFF? Saliva. Drool. Dribble. Dribble.

Whatever you call it, everyone has it. The inside of your mouth lives in a
constant bath of spit and you cant get rid of it. In fact, youre swallowing saliva all the time. And merely thinking about that probably made you take a swallow just now! You could make a thousand spitballs a day, and you wouldnt run out of saliva. Your body keeps on making it, twenty- four hours a day, seven days a week. (Nothing gross about water, right?) But it has a few important ingredients added in. (Nothing gross about water, right?) But it has a few important ingredients added in.

One is mucus the stuff that makes saliva slimy. MMMM... YUMMY. Another is lysozyme, a chemical that kills the germs that grow in your mouth. Theres also something called salivary amylase, a chemical that helps break down food. So where exactly does saliva come from? Ever heard of a saliva factory? Well, youre walking around with one tucked right between your nose and your chin.

Thats right! Your mouth is your own personal saliva maker. Inside your mouth are hundreds of glands. salivary Each of these little groups of cells makes and releases saliva into the mouth. Throughout the day, they make more saliva to prepare for eating. Certain thoughts or activities can really

spur these glands into action. Ever notice how your mouth starts watering right before you take a bite of something yummy? Thats your salivary glands springing into action.

You dont even have to take a bite for the effect to work. Try walking past a bakery window loaded with cupcakes, and your glands will probably kick into high gear. Heck, just thinking about a bakery window full of cupcakes will probably do the trick. What gets
your saliva flowing? A double cheeseburger with a side of fries? Or a hot fudge sundae, loaded with extra whipped cream? Salivamadeinthesalivaryglandsreallystartsdrippingwhenyouthinkofsomethingtasty!

A typical mouth makes enough saliva in one day to fill about six cans of soda, each day, every day. And guess what? You swallow almost all of that spit! Salivamadeintheglandstravelstothemouththroughtubescalledducts. You have hundreds of glands, salivary but most of the action takes place in the following three main pairs: Parotid glands are found on the upper part of each cheek, near your top molars (back teeth).

Submandibular glands are found on the bottom of the mouth, by the lower front teeth. Sublingual glands are located right under the tongue. So when your mouth starts watering, you usually notice it near your back teeth, under your tongue, or right behind your lower front teeth. But up to one thousand more salivary glands very tiny ones are scattered throughout your

mouth. Among other places, theyre inside your lips and cheeks, on the back of your tongue, and at the back of your throat. Thats why theres no escaping it anywhere in the mouth.

Spit is everywhere.

With each sneeze, up to one hundred thousand drops of mucusy saliva come spewing out of your mouth. So remember to cover your mouth as well as your nose! Thinking about all that gooey saliva you make and
swallow might make you squirm. But in fact, its a good thing youre a walking saliva factory, because your body needs saliva. And not just for hawking, drooling, and making spitballs. (Thats right.

Theres more to life than spitballs.)

Cakebecomesgoowithalittlehelpfromsaliva! For one thing, you wouldnt be able to eat without saliva. Sure, maybe you could drink. And slurp down a bowl of soup or a smoothie. But bread? Chips? A slice of pizza? Forget about it. Before you can swallow any of those foods, you need to change them from a basically dry, solid shape into a mashed-up ball that will both fit and move down your throat. And guess what is perfectly suited for that job? Yep, this is what saliva was made for.

As soon as you take a bite, saliva goes to work. It covers every bit of solid food with a gross, mucusy coating. After a little help from your teeth and your tongue, that bite of sandwich, pizza, or chips no longer resembles the food you put in your mouth. Instead, its a softened-up ball of goop. Then its on to your stomach, where your body will break it down for energy.