Ken Jennings - The Human Body

LITTLE SIMON

An imprint of Simon & Schuster Childrens Publishing Division

1230 Avenue of the Americas, New York, New York 10020

www.SimonandSchuster.com

First Little Simon edition February 2015

Text copyright 2015 by Ken Jennings. Illustrations copyright 2015 by Simon & Schuster, Inc.

All rights reserved, including the right of reproduction in whole or in part in any form.

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Designed by Elizabeth Doyle

Library of Congress Cataloging-in-Publication Data

Jacket illustration copyright 2014 by Simon & Schuster, Inc.

Jennings, Ken, 1974 author.

The human body / by Ken Jennings ; illustrated by Mike Lowery. First edition.

pages cm. (Ken Jennings junior genius guides)

Includes bibliographical references and index.

Audience: 810.

ISBN 978-1-4814-0174-6 (hc) ISBN 978-1-4814-0173-9 (pbk) ISBN 978-1-4814-0175-3 (eBook) 1. Human physiologyJuvenile literature. I. Lowery, Mike, 1980 illustrator. II. Title.

QP37.J46 2015

612dc23

2014005180

Settle down and find your seats, class. Im Professor Jennings. But you probably already know that, because Im such a world-famous authority on absolutely everything. Today we will be studying the most complicated and extraordinary object in the known universe: the human body. I bet most of you know only a tiny fraction of the cool stuff that goes on inside you. Did you all remember to bring your bodies to class today, like I asked? If anyone forgot their body, please raise your hand.

All right! In that case well begin in our usual fashion by reciting the Junior Genius Pledge to this picture of Albert Einstein. Please place your right index finger to your right temple and repeat after me.

Wit hall my fellow Junior Geniuses, I solemnly pledge to quest after questions, to angle for answers, to seek out, and to soak up. I will hunger and thirst for knowledge my whole life through, and I dedicate my discoveries to all humankind, with trivia not for just us but for all.

If youre afraid youre not quite as smart as Albert Einstein, dont worry . You dont have to revolutionize physics to be a Junior Genius. You just need to pay attention to all the amazing things there are to know about the world around you. Semper quaerens is the Junior Genius motto. Thats Latin for always curious. Even Einstein had to start somewhere!

Are you ready for an in-depth look at your body from the inside? (Not literallydont worry. That would be dangerous and gross.) Lets begin!

Junior Geniuses, your body is a wonderland. Nothing personal! I just mean that if you are human, you are an amazing piece of biological machinery. If you are not human, please let me know immediately. We would like to dissect and study you for the upcoming Junior Genius Guides: Alien Beings.

The chemicals in your body are nothing specialcommon stuff you could buy with a little allowance money. In fact, you could recreate most of your body just by turning on a faucet. More than half of you is actually water!

So, if you are an eighty-pound human looking to rebuild your body with a chemistry set, buying the elements shown in the chart would set you back about $160. More than half the money would go to buying potassium, a kind-of-rare mineral found in foods such as oranges and bananas. Your body needs potassium to keep your blood pressure healthy and your muscles working.

EXTRA CREDIT

Your body doesnt need gold to survive, but you do have some in your tissues, from tiny traces of it in the food you eat and water you drink. But youre not going to strike it rich by selling your boogers and earwax to a late-night gold infomercial! The total amount of gold in your body is about the size of a grain of sand.

But when you combine the elements in your body, your value skyrockets. Lets say you sold every part of you on the open marketyour organs, your bone marrow, your DNA, your antibodies. I would advise against this, however. Not only is it illegal, but you sort of need some of that stuff. But if you had a clearance sale and everything had to go, your body could bring in about $45 million!

Thats because your body is made of very ordinary elements combined in extraordinary ways.

Like all other life on earth, human beings are carbon-based. This means that the big, complicated molecules that power us, like proteins and carbohydrates, are all based on the element carbon. Yup, the same stuff that charcoal and diamonds and graphite are made out of. Your body has enough carbon in it to provide the graphite for more than six thousand pencils!

One of the most important of these carbon-based molecules is deoxyribonucleic acid . Most people call it DNA to save time, and because its much easier to spell. DNA is a long, skinny molecule shaped like a twisted ladder (or a double helix, as a biologist would say).

Why is DNA so complicated? Because it contains all the information necessary to make you... you. Its how a skin cell knows how to divide itself into new skin cells, and how a liver cell knows how to make new liver cells. Theres a reason why dogs dont give birth to kittens and cats dont give birth to puppies, and that reason is DNA. The DNA ladder is divided into long sections called genes , which contain instructions on how to pass along heredity information. Do you have brown eyes? Eye color is a gene. Curly hair? The ability to roll your tongue? Mortons Toe? (Thats when your second toe is longer than your big toe.) Those traits are all in your genes.