How Do We Dream

7/27/2019 How Do We Dream

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How Do We ream?


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llustratins by

ill Clrus, Jhn Rice Tm wers, and imi wers

Cver illustratin by Tm wers

Text copyright 1992 by Hghlights fo ChildenIllustrations coyright 992 by Boyds Mills PressAl rights resevedPublished by Bel BooksBoyds Mls Pess, IncA ighlghts Company85 Chrch SteetHonesdale Pennsylvania 843ited i Cin

Publshe Cataloging-inPublcation Datayers Jack

How do we dream? : and other questions about yor body answered by Highights science editor Jack Myers[6] co ill ; cmIncludes index

Summary Answes to chiden's questions abot the human bodyMany questons taken fom coumns in H CISBN 56397090 HC ISBN 563974002 PB Body Humanvenile literature. Body Human. Myers Jack I Title

62dc20 992Library of Congress Catao Cad mber 97760First edton, 99

Book designed by Jeffrey E Geoge he text of this book is set in oint entry Schoolbook

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5/68

How Do We Dream?And Other Questons abut Your Body

Answ b

ighligts Scic EitorJack Myrs, Ph..

BOYDS MLLS RESS


6/68

Wecome Aboard!

You have joined ou cub. We ae the cuious, wondering about al the interesting thngsthat happen in ou wold. en we don't know we ask Hee in the ecods of ou cubyou wi nd answes to some o the questions you have wondeed about.

Fo the past thy years reades o Hghlghts o Chden have been askng mequestions. And have been heping them ind answes. There have been questions couldnot answe and questions that I thnk no one coud answe Science has aways been likethat and it is ike that today even n the words greatest aboratoies. t is ouignoance-what we don't know-that dives us to ean moe hat's wat science sa about.

have been otunate n having as fends many scentists who have helped me findanswes. To a o the peope who helped us we ae grateu fo they have broadenedou undestanding

Jack Myes Ph.D\


7/68

hy do you hands

et winly ie aune when you taea bath and whydoesn't any otheat o you body etwiny

Michele Mauric

Lincolnwood, Illinois

I ave oced oo, a myads ge wry we aea a I aso appessomemes we I ae my

ur wasg dshess s wa appes Yourouer ayer of s s a ougproe ayer made y evg cs underea. Juse oer proes, swes upwhen s soaed waerWe you of a ayer orsee of ouer sn, you ca seea as swes up ad ges

gge w mae wres.Bu do o worry. Your sw smoo ou aga as dres

You aso ased wy sdoesn' appeo oer parsof your ody. I a secaus e e oug ousdeayer of s s cer o epams of your ads If sdea s rgh, e you w fda e s o e pamwres more a e s oe ac of your ad


8/68

Why do you get aheadache if you eatice cream too fast?

Jean EnnisConewango Vaey, New York

ave wodered abou aqueso oo Ad ave obee abe o f a aswer I ere mus be some codsesve erve edgs (eseare c aed receors ebac of your mou Maybeey se off a fas voey oferve muses carred u oyour bra we ey suddeyge ced However I do o s s a very comeeexaao

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oo

o

What causes chillbumps on your skin?

Stacy PausonHouson Texa

C bumssome eoeca em goose mesae o everyoe Tey aree rased bumy aces oyour s a ge ere weyour s s cod Ts s arefe aco, oe of eauomac acos your body

does wou ay g byyor bra I a ama wfur s es o rase eac ofs ars o fuff u s furFuffed -u fur s a beersuaor ad es ee eama warm For you does do muc good Bu ceray s o ayg oworry abou eer


9/68

am sick now and ave a terribe coughI ust ad mytempeatue taken wasn't couging untite tip of tetermomete toucedte back of mytongue Wat madee do tis and watakes us coug?

Mhae eeNew Bitan ennsyvania

Cougng elp to get rd of

anytng tat touce ortckle te larynx (te back ofyour troat) or te tracea (tetube gong down to your lungf any foregn matter getdown tere, t naturally agood dea to get rd of t. at'wat a coug uppoed to do.

n cougng you take n amall breat and quckly tartto breate out. ere audden openng of te end of

te tracea and out come audden blat of ar. Snce t areflex acton, we cougweter we want to or notWen you ave a cold teremay be a contnued tckng orrrtaton of te larynx andcougng may be ard to Wy does pepper

make many peope(incuding me)

sneeze?aie Tague

E Doado Sping Mioui

A neeze a refex acton.Sometme you can feel aneeze comng on. ut nkyou cannot jut decde youw to neeze and ten make

a very good oundng neeze.Uualy a neeze tarted

by tcklng or rrtaton of temembrane lnng te nde oyour noe e neezng refex ueful n blowng out of yournoe any dut partcle caungrrtaton. Some ubtancelke pepper contan cemcaltat rrtate entvemembrane. Some of u aremore enve tan oter. Igue you and I are among temore entve one

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10/68

Everybody n myfamly knows how towhstle except me.How do you makethe whistlng soun d?

Romwell OrtigozaKklnd, Wshngton

'm not an especialy goodwhistler, but I never thoughtmuch about what it takes towhistle. I notice that when

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whistle my tongue has to be ina special position with ts tipnot far back of my lips. Justmaking a small hole with mylips and blowing won't do t

A whistle must besomething like using a buge or

cornet or tuba or flute. Theseare al wind instruments Theymake sound from a smallvibration that makes thewhole ar column vbrate.That's what you try to do nwhistling set up a vibration atyour lips that makes the air inyour nose and mouth and

throat vibrateMter 've said all that

know haven't taught you towhistle and I doubt that can.Al I can suggest is that you tryvarious positions of yourtongue.

asked my wfe aboutwhisting and was amazed todscover that she can't. Wehave been marred for morethan fiy years and neverknew that. So guess somepeople can get aong prettywell even f they cant everwhistle.

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11/68

What ca uses aerson (or an ima l) toawn? Does it rea llmean the bod needsrest?

Evelyn GrffMsspequ Ne York

Our brathing s partlyndr atomatc or rflxcontrol You can thnk aboutyour brathing and dcd tobrath rapidly or sowly. Butmost of th tim you do notthnk about t at all and lt thautomatic control do th job.

Th spcial automaticcontrol of brathing worksfrom a plac in th bas of thbrain calld th rspratory

Wh is it that whenou blow out ofpursed lips ouproduce cool air, butwhen ou bow out ofwide oen lips oublow hot air?

Edwrd LnierL Grnge Gergi

know what you man. d suspct thr s mor thanon rason. Your brathprobably is at your body

tmpratur whn it coms out

cntr. Its job s to kpchcking on th carbon doxidin your bood. Whn thr istoo much carbon dioxd in th

blood th cntr spds upyour brathng to hp takaway th carbon dioxid.

awnng s startd by thatautomatc control A yawnusually appns whn you artird or bord and probablybrathing slowly and not vrydply. Th automatic controturns on to mak you tak adp brath. Thats what youcall a yawn

Somtim you may b in apac whr you would bmbarrassd if you wr toyawn. On way to hlp prvntyawnng is to purposybrath mor dply Thatsasr to do (and not sonoticabl) if you can gt upand walk around.

of your mouth no mattr hw itcoms out.

Whn your brath coms outslowly it fls warm but yound to put a hand up clos toit. Whn you purs your lipsth ar coms out mor rapidlyThn it picks up coldr outsidair that gos along with it.That coolr dra of air ismovng rapidly across yourhand And moving cool airsms vn coolr just bcausits moving and bttr abl totak hat away from yourhand.

That dos not sm lik avry xciting xplanation but think that s what's

happning.

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12/68

If you fall downand get a cut, whatcauses it to hurt?

Sheran RudohNorwood Massahusetts

e urtng or pan reaycome from a lot of meageet to your brn by nerveendng tat are damaged byte cut. Wen a cut or brue_ urt tat eem pretty bad.ut te urtg reay el pprotect your body. It ayngto you "Hey don't do tatagan.

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M aun Vivan gota paper cut. Why dopaper cuts hurt morethan other cuts?

Ma KohanCuyahoga Fas Oho

I tnk by paper cut youmean cuttng nto yourelf

t te edge of a pece of

pape I ave ad tat appento me. I agree tat t urelyurt ut I ave not een anexplanaton of wy t oud beepecally urtful.

It mgt b e j ut te urpreof gettng urt by a pece ofpaper It alo mgt be tatpaper o tn tat wen tcut t cut deeply.


13/68

When your body

ges scraped or has acu or a bte, howdoes go aboutheang tself?

ennifer CrockBth Iinois

Heang a cut lkereparng a part of yourmacnery. A anmal aveome ablty to repr damagedpart and t o commontat te reparng a a pecalname: regeneraton

n ome of te mpleranma regeneraton remarkable. A tarf canrebuld a new tentacle tat cut off an eartworm ca nrepace muc of t b ody tat ot a crab can rebuld a newclaw wen one l ot. n larger

and more complcated anmal

regeneraton more lmtedou cannot grow a new arm orleg but you do ave omemportant repar abtyepecally for damaged kn.

our kn a peca andmportant part of your body

tat people eldom tnkabout. e outer layer of kn made from te toug peceof cell tat are no onger alve.Underneat tere a layer ofcel alway multpyng andmakng new cell tat arebeng pued toward teurface. Wen you ave a cutor break n your kn tegrowng kn layer pue newcell dewe and tee lowycloe up te break.

Our bone and muce andeven ome of our nerve fbercan grow more to repartemelve. Our bode cannotrepar everytn, but tnkt a good tng tat tey cando o muc. ke to tnk ofmy body a a fne pece ofmacneryo good tat t caneven make t own mnor

repar.

Why does your sknturn black, blue, orpurple when you hurt

yourself and don'bleed?

hery Ordinriopring ey Ne York

n al te oft tue of yourbody tere are many tny bloodveel te capllare Wenyou get a brue ome of te

capllare may be broken.en red cell of te blood leakout and collect n te tueunderneat te kn. atpatc of red cell and broken

down red cell een trougte kn may look blue or evenblack dependng on ow manyred cel are trapped tere

Fortunately for you yourbody can repar t cut andbrue. So te uual treatment for a brue to jutpatenty wat for te ow jobof repar to take place.

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14/68

I have a very adsunurn. It s ststartng to peel. I waswonderng what

made my sunurnpee.

Aan ouMonaa Pnnvania

A you dcovered unburn ometng panful andarmful wc we ougt toavod oe of u wo avelgt-colored kn can ealy

get burned by te ultravoletpart of unlgtSunburn caue real

damage to te kn.Fortunatey te kn a partof our body tat can regenerateby formng new cell andreparng damage. Oterwea wound or a burn would neverea.

our kn alway grownglowly from new cel formed

underneat te urface. Cellnear te urface get queeeddown and ter materalcanged nto a toug ornynonlvng urface layer aturface layer away owlypeelng off at te outde.

Wen your kn reparngtef from a unburn tedamaged cel are pued outfater ere more of tatnon-lvng urface l ayer and tmay peel off n lttle patcetat you can e e. en you aytat your unburn peelng .,

", /

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I wen o he beachone day and go asunburn. And I fehotter than usua.

Please expain why.Ava Poac

San Dgo Cafoa

It mportant toundertand ta a unburn area burn. t occur rgt tekn urface becaue ofdamage caued by ultravoletlgt One of te reul of te

damage o enarge e tyblood veel jut unde teurface. at allow moreblood to flow to te knmakng te kn look red andfeel warm t a appened tome too and t made me feel

warm all over.We ould be more carefulabout getng too muc unGetng a deep tan everyummer look ealty butacually t not. Ultravoletgt lkely to make yourkn le fexble and morewrnkledt make yourkn older.


15/68

I'd like to know ifcacking knucklescan eay cause

atitis o makeyou finges fat. A lotof my fiends te meis is tue. I hasbecome a seiousabit fo me.

Prtim RoLodeie, New ork

My frend Kent L. rown,

M.D, know muc more aboutte anwer to your quetontan I do, o aked ep nanwerng you. Here watDr rown ay

o begn wt, no one canaboutely ay tat f you crackyour knuckle you wleventualy ave fat fnger orartrt. Everyone reponddfferenty to rrtaton,

weter t be to a jont or aplace on your kn tat youcontantly pck at or rub

We do know tat crackngknuckle tend to tretc tecapue, or coverng taturround te ont, and maygve you ome looene of teont f you keep manpuatngand crackng tem Alo, tereare medcal wrter wo feeltat mn-trauma, wcmean n t ae a mallrepeated nury to te knucklejont, coud caue artrtee mall trauma, ornjure, are repeated everytme you crack your knuckle.ey ave wat we cal acumulatve effecttat , temore you do t, te wore t

get. ee lttle repeatednure are dfferent from oneard blow wt a ammer orcatcng your fnger once andbendng t way back

rackng knucke, ten, a form of rrtaton. erepone of te tue tocontnued rrtaton may cauete oft tue (te capul e, orcoverng of te jont) totcken, and t could lead towat you are cang fatfnger. It poble tat youmgt develop artrt.

rackng knuckle a badabt, and you ould top tWy take a cance ofdeformng te jont of your

and? e and are amongte mot mportant and uefulpart of your body. ey wl bemportant wen you get a jobomeday, jut a tey are nown your coolwork and port

ere are a couple of tngyou mgt do to break te abtof crackng your knuckle oucould carry a con te ze of aalf dolar and practce

manpulatng t eac tme youave te dere to crack yourknucke. ou can go to amagc tore and pck up acon -ze pece of metal andntructon on ow tomanpulate t dd magc formany year and found tgreat fun. It can occupy yourwole attenton

Anoter tng you mgt do to twdde your tumb oucan ak your parent orteacer ow you do t. oucan twddle n one drectonand ten anoter Wen youare twddlng, you won't becrackng your j ont.

Hand are beautful. ouwant to keep tem tat way.Good luck


16/68

How come if yoclap yor handsunderwater yo can't

make a sond?Sephanie Wodejo

Bdgepor Conneiu

I tred t and agree wtyou Clappng andunderwater doen't makemuc noe, even wen youread underwater. However,f you t two tone togeterunderwater, you can ear teround. Sound can travel nwater, n fact about four tmefater tan t travel n ar

I tnk tat clappng your

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and togeter mut makemore noe tan jut te oundof te and comng togeterIf you double up your and tomake ft and brng temtogeter you cannot makenearly o muc noe a

clappng wt your and openSo I tnk tat clappng yourand togeter mut comprear and make a mall ockwave a tey come togeter gue you coud ay tat t lke a mall expoon. ngare dfferent underwater.Water more vcou (leflud) tan ar and you can'tove your and togeter orapdly And water mucarder to compre and make aclap I tnk tee are te manreaon wy clappng not oucceful underwater.

Does yor voicesond the same toother peope as itsonds to yoursef?

nne EvanUppe Sanduy Ohio

I dd not know te anwer

but I am fortunate to ave afrend, Dr. Jee Vllarrea,wo a peec expert. So I cantell you wat e ad n repy toyour queton

e anwer no Wenpeople ear recordng of terown voce ey are almotaway urpred. And tat lkely to appen even toug

oter tnk te recordng arevery good

Here a pobleexplanaton Oter people eayour voce a ound wavecarred n te ar ou earyour own voce tat way, too.ut your ear ao receveound wave carred rougte bone of your ead Sncete ound vbraton of yourvoce reac your own ear bytwo dfferent patway, tey

probaby do not arrve atexactly te ame tme.Anyway, te effect of te twopatway tat your voce lkely to ound a lttle dfferentto you tan t doe to omeoneele

am gla d tat bot of uave learned ometng moreabout our voce


17/68

Sometimes wen Igo to bed it'stundering, but wenI'm seeping I don'tear it In temorning wen my

mom wakes me up Iear er loud andcear Wy do I earer better tan tetunder?

my Whustn Txas

I am not at al ure of an

anwer but I may be able toelp you tink about yourquetion One poibility itat you are "tuned in to yourmoter voice becaue you areued to t. It i alo likely tatyour daily rytm i et towake up jut about te timetat your moter call youevery morng

Do you tink toe ideamgt elp to expan yourqueton?

I woud ike toknow wat aneardrum looks ikeand wy it is calledan eardrum

sab daRockv Maryand

e eardrum called teeardrum becaue it i a tigtlytretced membrane at teend of te outer opening in teear. e membrane i lke tetin and tgt leatertretced acro a drum

Wen you tap a drum itvbrate and make a ounde eardrum work in jut teoppoite way Sound will maket vibrate a little. oevibration are picked up by atiny bone on te nide of teeardrum wc act a a"feeler for te vibration ofte eardrum

e ear a very neat littlegadget e eadrum vibrateto a ound but alo make acover for te very delcatemacinery inide.

n order to be able to vibrateeaily te eardrum i verytin and eaily damaged ati wy it fooli to tickanyting into your ear

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18/68

Why is your mindalways hinking?

Bt Dean

Kadka Sut Dakta

lke your queton. gue never tougt about wy watnkng. Really you aveaked a very bg queton and cannot tell you al part of te

anwer u we can alk about a ltleTnkng ometng at

goe on n te bran Te brancontan mllon of tny nervecell Mo of tee ave longfber tat connect tem tooter nerve cel o nervemeage can be ent back andfort. Some of e nerve fber

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connect wt onger fber tatcarry meage from your eye

and ear from tatng cell nyour mout from melngcell n your noe, and fromoucng cell n your fngerWen you are awake yourbran recevng all knd ofnformaton by meage tatyour ene te abou eworld around you

So your bran alway alot o tnk about. our bran

can do a ot more Suppoe youtnk Two plu wo equalfour or "I love Moer ouare no ung any of toeme age from your ene ou are un g ometng atyour bran a tored up n Le' ay ta your bran canremember and can tore updea and ten put dea

togeter. ou mg ay tattat ow we earn.

Someme tnk a temot remarkable part aboutte bran at you can decdwat you want t to tnkabout. ou can "tune n onometng amot a f youwere tunng a rado to apartcular taon ou cantune n to nk about watyou are eeng or wa you areearng or you can tune n

on ome partcular dea andpay no atenton to anytngele.

Wat we ave taked aboureally doe no anwer yourqueon ut t gve you tebg dea tat te bran a verybuy place A you ay, t alway tnkng tnk tat'wat te bran for.


19/68

Wha makespeope augh?

Ayt YanhBryn Nw Yr

at' a very bg quetnSme tng tat make yulaug are pycal lketcklng. N ne eem tunertan tat very well utmt tng tat make ulaug are funny ea ea

tat ave an twt r tatn't ft tgeter r maybeea a n wr tat avemre tan ne meanng. Wlebk ave been wrtten abutwat make umr.

Of cure tere ne mre

part f te quetn. Wy peple laug at metngfunny? n't knw te anwert tat ut 'm gla tey tnk te wrl wul be apretty ull place wtutlaugter Dn't yu?

I woud ike oknow how comewhen you ickleyourself it doesn

icke, and whensomebody else ickesyou it ickles?

J PttyVanur Washngtn

tnk yu ave mae a verynteretng bervatn wa

nt ure t wa crrect untl tre t n mye en aketer peple Mt f temtnk yu are rgt

ntce tat fee a lttletngly f bru metngvery gently acr te bttmf my ft. cant tarun my rb r uner myarm but ter peple canmake me tckle tere. tnkwe can agree tat t a tarer t feel a tckle f yutckle yure

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20/68

Whee do our eascome from?

Lwrence LeeSn Frncisc ifrni

ear are alway bengmade by lttle gand lcatedabve te utde crner fyur eye. ey nrmaly jutze acr yur eye at a lwand teady rate at keepte frnt urface f yur eyemt and yur bnkngeyeld act lke wndeldwper t keep tem clean etear are carred away frmte nde crner f yur eye

by lttle tube tat lead dwnt te back f yur ne

Of cure mt f u tnk ftear a bg watery drp tatrun dwn ur ceek frm ureye Suppe metng urtyur eye lke a pece f duttat get trapped under aneyed. en te lttle gandpur ut tear fater tan teclectng tube can carry tem

away at wen yu reallyknw abut tear becauetey verflw and drp dwn[r yr eye are cryngAll t brugt abut by ample knd f autmatc nervecntrl called a reflex ereflex elp prtect yur eyeby wang tuff ut f tem.

Cryng and makng teara can appen fr terrean e reflex actn brugt abut by nerveeage ver patway tatg trug te bran. Andmetme a meage can gettarted jut by wat we aretnkng abut Feelng panand feelng very ad eemt be way tat get te cryngreflex tarted

14

Why does cryingmake your nose run?

Richie GuinckAexnder, New Yrk

e frt dea tat tearare beng made all te tme bylttle lacrmal gland lcatedjut abve te utde crner feac eye. e tear bate teutde urface f te eyeen te tear are cllected

frm te nde crner f yureye by ttle tube telacrmal duct and dranednt yur ne All t anrmal and mprtant part fte peratn f yur eye.

Cryng mean tat yu are

makng tear extra fatevefater tan tey can be draneaway at al mean tatte lacrmal duct are dranntear nt yur ne extra faS yur ne run becaue t led wt tear.


21/68

Why do onionsmae people ry?

Dina RogersPort Jefferson Station New or

lke up te anwer n teMerck Cemca Inex.

fun tat nn cntan -prpeny ulfencac wc tugt t be telacrmatr n nn' Alacrmatr metng tatmake yur eye water.

Nw we knw wat tecemcal ut I am nt uretat elp very muc wen weave t peel nn.

When you ry, thetears are salt waterHow does the satwater get into yourbody?

Kathryn SagerbergHouston exas

Katryn yu are verybervant an yu ake aenble quetn.

Actually all te flu fyur by are at leat a lttlebt alty. Al ftem ave mealt lve n tem analway a lttle f tecmmnet f alt um

clre. (at' te ne tattate altet) ur bcntan a lttle le tan percent um clre anyur tear prbably cntanalmt tat muc Jut frcmparn eawater cntanabut 3 percent umclre.

u are alway lng mealt n yur urne yu nee

a cntnue ntake f alt nyur et. Generally tat' ntmuc f a prblem nce tere me alt n almt all f tef yu eat. Salt a cmmnmateral n all anmal anplant.


22/68

Why do we gethapped lips?

Chn PoWbuy Nw Yo

Lps ae coveed by a tissuemuch ike that inside youmouth. Thats a aye that issot an d wet athe than tough

6

and dy ike you skin.

Sometimes you ips may dyout and even cack open Fome that tends to happen whenI get too much sun o on veydy days. have eaned thatwhen that happens shouduse somethng geasy to smeaon my ips and potect them.Most dugstoes have stu topotect ips.

While you stil avyou baby teethwhee ae youpermanent teeth?Why do they

suddenly stat to poout at a etain time?nny Gow

Roya Oa Mchg

Teeth ae omed deep in thbone o you aws As the teegow and get bigge, they othemseves into position.

You pemanent teeth aeaeady omed and gowing

sevea yeas beoe you babteeth a out. As youpemanent teeth gow theypush out against the oots othe baby teeth. Then the ooto you baby teeth becomesmae, the baby teeth beginto get oose, and inay theycome out athe easiyneyou get in a huy and puthem out .

.

J\{ AY H D\ LftRMAN1 C1f

I'-


23/68

My ig and isage an my efand. Can youexpain tis?

Cathy KansHammond Indana

I cannot reay answer yourquestion, but can tak aboutit There are ots of reasonswhy one hand can be argerthan the other Sometimes thisis noticeabe ony temporariybecause something ca usessweing in one and not in theother.

Many peope aways have

noticeabe differences betweentheir right and eft s ides asbetween their two hands. Isusp ect that if we made carefumeasurements we wou d findthat most peope have at eastsome sma differences. Ourbodies are remarkabe piecesof machinery but they are not

a exacty aike. And there aemore differences inside thanwe can see outside We knowony parts of the reasons fordifferences.

There is a much biggerquestion Why are we as muchaike as we are? Why are yourtwo hands and ears and feet asmuch aike as they are? Why

do pigs awys ook ike pigsand squirres aways o ok ikesquirres and humans awaysook ike humans?

Those questions are partyanswered by genetics the partof bioogy that has to do withinheritance. They are asoparty answered by the study

of deveopment. How doanimas take te inormationcarried in one itte ce afertiized egg and use thatinformation to make the hoebig anima body? This is one ofthe most important probemsof bioogy today And we are aong way from answering a ofits questions.

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24/68

Sometimes in bed Istare at the ceiling fora whie Suddenly,

the patterns on theceiling seem to moveWhy does thishappen?

Mah WknonSpng aey Wnn

When you are ooking at anobect, the ens near the frontof your eye makes an image of

the obect. The mage fas on a

thin ayer, the retina, near theback of your eye The retinacontans two knds of ghtsensitive ces the ods and thecones. They are connected bynerve pathways to your brain

Right now in readng this,

you are using the cones, whichare tghty packed together ata specia pac e on the retina. Inbright ight the tighty packedcones give your sharpest vsioso that you can see tiny obects,even a thread or a hair.

In dim ight your conesarent sensitive enough andyou can use ony your rods.They are much more sensitive,

but they are not tghty packed

together and they do not givyou a very sharp vsion

When you ie in b ed in adarkened room ooking at thceiing heres what mayhappen: Your eyes may beooking at a pattern on the

ceiing but they dont see itvery sharpy. That means thyour eyes may not hod steato one spot. So the spot mayseem to move ust because yoeyes are wandering around itte

If this epanaton s correthen a pattern on the ceiingwi not move any more if yoturn the ghts on Try it an

see if te pattern stands sti


25/68

ow do our tasteuds work?

nde EssGne ndin

can' e you a you migh

ike o know, pay becauseno a gea dea is known Thease buds ae ie coecionso specia ces ocaed on hesuace o you ongue. Someae especiay sensiive ospecia ases and ae goupedin paicua aeas swee ahe ip, bie in he back, souon he sides. Aeas sensiive osa ae supposed o be a ove.

The sensiive ces o hease buds ae conneced o aspecia aea o he bain byneve pahways And dieenneve messages (neve codes)ae used o dieen ases.Bu exacy wha happes omake a sensiive ce send aneve messagemuch o hais si no known

Why is it that yourtongue feels strangeafte you eat a lot ofpineapple?

y Chn

bny Cn

Pineappe is a ui ha hasa sweesou ase. The sweepa comes om suga. Thesou pa comes om panacids. The acids ae vey weakones and won' hu you. Buhey ae ikey o eave you

ongue eeing a ie sange don ge he eec you doom pineappe bu do om asou pan caed hubab hais sed a o o make pies.

Tste buds lke this one on e srfce of yor tonguee connected by nees to spec prt of yor brn.

1


26/68

Why do we throw

up?Jnny Rvs

Cnsn Rhod Isnd

hrowing up or vomiting isan automatic reex action. tworks when somethingirritates the ining o yourstomach or sma intestinehat way your body can

20

I love roeroasters, but when Iride one I don't feegood afterwardsWhy do you think thishappens?

Jnny Jn MysWoodnd His Ciforni

I think that the thri o aroer coaster comes rom thesudden change in orces onyour body, up and down androm side to side. When you go

quicky get rid o somethingthat might be bad or you

he reex action o vomitingis brought about by nervemessages that go through aspecia contro center ocatedin the base o the brain.Naturay it is caed thevomiting center. Nervemessages rom other parts othe body aso can reach thecenter and make you vomit.

over a hump and start downthere is an instant o timew hen you are amostweightess. You ee that youmight go oating o in space.And at the bottom o a dipeverything in you is pressing

down extra hard. hose areunny and scary eeings.A those sudden changes in

movement aso make it hardor your baance contromechanism. That works inspecia parts o your ears tohep you keep your baanceWhen you have ong periods oback-and-orth motionikeon a rocking shipthe baanc

contro has so much troubethat it can make you seasickAnd some peope get carsick tmotions o a car.

I think a roer coaster giveyou the thri o suddenchanges in motion but usuayust not quite enough to makeyou sick.

One specia pace thatsometimes gives troube is in

the inner ear. heres somespecia machinery there to teyou when youre right side upand to hep keep your baancehat baancing machinery canget ooed by backandorthmotion. As you probaby havenoticed some peope areespeciay sensitive. I hopeyoure not one o those.


27/68

Wha makes yoursomach grow?

Lis TurrHfod Egd

I am not sue o the answebut the nose pobaby does notcome om the stomach. I thnkt comes om the athevoent chunng that goes ona the tme n the ong tubebeow you stomach thentestne I suspect that thenose s moe notceabe whenthe ntestne aso contansbubbes o gas poduced by the

many hamess bactea thatve theeI thnk you w hea noses

om movements o thentestnes amost any tme youput you ea aganst someonestummy. Sometmes the nosesae oude and then ou maysay that you stomach sgowng

I have been ryngo undesandsnorng. My brohesnores and mymoher says 's fromhs breahing.

K ouisM outh Dkot

Amost eveyone may snoeunde some condtons, but tseems that some peope aebette at t than othes

Snong can be caused by anumbe o thngs that patybock the passage o a dung

beathng. Then the patybocked passage o a makesthe nose we ca snong.

I t seems that a ths s moekey to occu to a pesonseepng on hs o he backAnd t seems to occu moeoen n ode peope

The nose o snong doesntseem to bothe peope whosnoeust othe peope. Mywe sometmes wakes me up tostop my snongwhch hadnot been botheng me a bt Iaso have notced tat snongs not mted to humans I oncehad a dog who snoed oudyand vey eguay

You tod me that you

bothe snoes You ddnt teme about youse Ae you asnoe too?

. - -

2 1


28/68

How come mostpeope's ai tunsgay wen tey getode?

Dana HeterSuce Pne Aabaa

can te you pat but nota of the answe to you

question ach hai is made bya specia itte ha foice thatis undeneath the suface ofyou skn ach foice sowyputs togethe e bundes ofpotein fibes that make up ahai. So a ai is awaysgowing by being pushed out ofthe foce that makes it. Asyou know, cutting offte end ofa hai does not keep it fom

22

gowing So the hai you havetoday is not the same hai youhad a few yeas ago.

Hai coo must come fomsome pigment that is added bythe foice wen each ha smade am not sue ust wat

pigments ae used to gve haits natua coos Watevethey ae, guess that somepeope have hai foices thatstop makng hai coo whenthey get ode. think haooks gay because of the ackof added coo

I have hai foces on myhead tat seem to be doing apoo o b. Some of them aemang gay ais. Bu most ofthem have ust stoppedwokng. hee s a moecommon way to say that: I ambad on top.

My mom and dadae stating to avegay ais My mom

says tat if you pick agay hai, two wigow in the samepace Is tis tue?

Nkk Madsnntn Wsnsn

Pung out a gay hai wipobaby ead a hai foice tomake anothe. But it won'tmake exta ha foices. So

don't see how you woud gettwo gay hais by puing one.Howeve, I can undestand thesaying Someone wo iswoied about getting gayais wi pobaby keepgetting moe of tem even ifsome ae pued out

Peope ae funny that wayWhen they ae young theycant wait to get gown up And

when they do get gown up,they woy about ookng odeLife is moe fun if you eaxand enoy it


29/68

Why do peoplehave hair?

Jud BrwnPwna mnt

Answeing "why is otendiicut. can te you somethings that wi hep you thinkabout ou hai

Maybe the ist dea is thathumans beong to a cass oanimas c aed the mammasWe say that because humans

and a othe mammas havetwo eatues in common:mammay gands and hai. tis tue that some mammasike the hinoceos andhippopotamus and the whaesdo not have much habutaways a tte.

Hai makes a goodpotective coveing and many

anmas need it to keep wamMost humans do not havemuch ha and we have towea cothes to keep wam have noticed though that

thee ae athe agedieences between peope inhow much hai they have andhow it is distibuted ove theibodies.

Maybe you wee thinkingthat humans do not eay needhai but do not beieve that isso happen to be one o thosepeope who has ost most othehai on top o my head Being

bad does not hut my eeingsbut it cetany is no advantage. Thee is no cushion upthee to potect me when bump into a tee imb o acupboad doo And on a codday it can ee a bit chiy upthee So beeve that havingha is a good idea and woudnt knock it

My hair s sensitiveand t always turnslght n the sun Whatmakes t turn?

Li ChhiSan Js Cafni

thnk you aeady knowthat hais ae made and sowypushed out om tte haioces in the skin. So the haiyou see no onge contains anyiving ces. Hai coo comesom pigments such asmeanin added to the hai as iis made.

Most pigments ae sowydestoyed o beached by beingout n the sun. Maybe you havnoticed that cooed cothesbecome ighte n coo atebeing in the sun a ong tme think the same thing happensin hai

you hai is vey back thbeaching o some o itspigment woud not benotceabe B ut you hadoes not have much pigment

and is aeady ight-cooedthen the beaching o some oits pigment wi be notceabeand it wi become ighte incoo.

\2


30/68

Why does alcoholget people drunk?

Sevea young pesons havewitten to ask me thisquestion. The answe is moe

compcated than you mightthink. asked othe peopeabout the que ston a nd gotmany pats to the answe. wi ty to put them atogethe

Chemicay thee ae manydieent acohos . A o themae poisons o amost a ivingthngs. One paticua kindethy acoho (CH CH OH) isthe east poisonous. Thats theone we mean when we takabout the acoho peope dink.Ony a chemst eve sees pue100 pecent acoho. Most othe dinks that peope takehave a much smaepecentage o acoho

te a peson swaows adink containing acoho theacoho s absobed apidy intothe boodsteam. It is then

sowy emoved and buned upchangng entiey in thepocess to cabon doxide andwate, mosty by action o theive The eects o acoho onthe body come om its eect onthe bain. And they dependupon the amount o acohothat buids up n theboodsteam.

As with many othe poisons

a sma amount o acoho hassome specia eects n sma amounts it acts as a stimuant.Peope who ae "uptighttense and nevousae apt tobecome moe eaxed andtakatve, and seem to osethei woies. Fo this eason,some peope dnk a itteacoho ate a had days wok.

24

The toube with acohobegins with ust a itte moeust a sighty higheamountin the boodsteamThen t becomes a depessant.Depessants make peopesowe at thnking and sowe

at movng But peope ae aptto think they ae smate andaste Thats bad. You caneasiy undestand why theyshoud not be diving a ca.

Thees anothe pat aboutdinking too much acoho thatis even wose. Peope ae keyto ose seconto Then theyae ikey to dink even moe.Pesons who ae dunk ae notvey nice to be aound and can

--:

IIIJ

'. J

be dangeous to themsevesand othes.

And he is a sti geatepobem with acoho: Somepeope ae compusivedinkes. ven a sma amounto acoho "sets them o and

they keep on dnking. Thesepeope ae caed acohoics.The Amecan MedicaAssociation says they have thedisea se o acohoism

We dont know what causesacohoism. Some scientiststhnk it occus because o asma dieence in the way abodys chemica machineywoks.

So a no one has ound acue. The ony teatment o anacohoic is to neve take adnk o acohonot even aitte one. That may soundsimpe, but o an acohoic itsnot

Thee is a wondeu goupo men and women who cathemseves AcohoicsAnonymous They havethousands o meetings a ove

the county (AcohoicsAnonymous is isted in amostevey oca teephone book.And inomation is avaiabeby mai om Box 459 NewYok N 10163. The peopewho beong to AcohoicsAnonymous have ound a wayto hep each othe stopdinking and stay stoppedThats a way o teatment o

acohoism.This i s a ong answe to asimpe question. Acohoicdnks have been made othousands o yeas. They waways be aound us So thinkeveyone shoud undestandhow acoho aects the bodyand that o some peope it ispat o a seous disea se.


31/68

Wat arefingenais made of?

Bec BsndSmpsnve Suth rn

Fingenais ae made o aspeca kind o potein caedkeatin, the same kind o stuthat a cows hoos and honsae made o

hee ae many dieentkinds o potens You need thepoten o meat o mik o pant

seeds in you diet. But don'tchew you ingenais Youcant dgest the keatinpotein

Wen you tun on afasligt and pu

you finges on op ofte ig, you ingesbecome bigt edWy do tey do is?

Stefne BeyeWdmere Ne rk

When a ight is bightenough to go though somepat o you b odyke youingesyou ind out aboutthe coo o you bood hebood going though the ittetubes in you nges containsenough oxygen that it s ed

his woks best n a dakoom and it woks bette oyou than o an adut becauseyou nges ae thinne

25


32/68

If you get cickenpox a first time, whyae you immune to it

and can't get it asecond time?

Ls rettePomno Beh or

Chicken pox is a diseasecaused by a paticua kind ovius. A vius is a vey smapatice, a smae than mostiving ces. think it is ai tosay that a vius comes aiveony when it attaches to aiving ce and buows inside.Then it mixes up the cemachiney and makes moevius patices. The chickenpox vius, once it gets into onece o you body, mutipies tomake moe vius patices,which get into othe ces.

You body aso has a deenseagainst those mutipying

ius patices Most o thatdeense stats with some o thecooess white) ces o youoodsteam They ecognizethe vius as something oeign.They begin making poteinmoecues, which ae inside

out copies o the viuspaticesike tuning a goveinside out to it you othehand These new poteinmoecues have a s pecia nameantibodies. ach antibodypotein moecue can put a

vius patice out o business.As you body makes moeand moe antibodies, it beginsto mop up the vius paticesThe eects o the chicken poxvius ae not vey sevee andmost peope begin to get we ina ew days

N ow you see how you getimmune to chicken pox. Maybeyou can guess that thee is asecond pat o the answe toyou question. You wi stayimmune and neve get chickenpox again i you bood ceskeep making antibodiesagainst the chicken pox vius.Thats what usuay happens.

Thee ae othe diseas escaused by othe kinds oviuses. You body woks inthe same way against a othem. But it does not aways

win so easiy, and theimmunity does not aways astso ong.

Thee ae many othe patsto the stoy o immunity have taked about a pat thatanswes you question.

Why do we closeour eyes wen wesneeze?

Mess JonesNewber Soth Cron

had not noticed that but think you ae ight. Somepeope have watched do cosethei eyes duing a sneeze. Youae vey obsevant.

do not know ust why thatshoud be A sneeze is acompicated eex action. That

means an automatic action,not one you have to thinkabout. t is compicated in thatit esuts om a whoe seies omovements. Fist, you take aquick beath inwad, and thenyou beathe outwad veyoceuy. Usuay you tonguegets in the act and paty coseso the back o you mouth sothat ai is oced out apidy

though you nose The whoeeex woks to gt id osomething that was iitatingthe sot ining o you nose.

Now it seems that, at easto some o us, cosing the eyesis aso pat o the cop catedeex. This is not a competeanswe to you question, but itis the best can do


33/68

I would like oknow wha ESP s. Iwould ike o have a

few examples of i,oo.Susan Haddad

Whitewater Wisonsn

SP stands o tasensoyPeception. I wi ty to te youwhat that means.

We have many egendsabout peope with supenatua powes Some wee

supposed to be abe to teahead o time that an eventwoud happen n the utue.Some othem wee suppos ed tobe abe to te what someoneese, maybe mies away, was

thnkng o doing ven todaythee ae peope who caim tohave such specia powes

vey once in a whiesomeone has a stange deamthat tuns out to be tue.Suppose you had a deam ikethis You aunt Jane is stting

in a ocking cha with he caton he ap. Suddeny the odchai beaks, Aunt Jane andthe ca t a ove backwad, andshe beaks he gasses. hensuppose you ate discoveedthat what you deamed hadactuay happenedevenabout the cat and the bokengasses and even on the veynght o you deam You

cetainy woud be supised.You wou d say to youse thatthee must be some way thatyou coud te what washappening to Aunt Jane.

What we have been takng

about might be epaned wehumans sometimes had aneta sense, a sense othe thanseeing, heaing, touching,tasting, o smeing Thatwoud be saying we havetasensoy Peception.

Poving that thee is such a

thing as tasensoyPeception is vey diicut. tcannot be poved by humanepeiences ike the deam wetaked about

How about a the othedeams that neve come tue?ven the most unikeycombnations o eventssometimes happen ust bychance. Poving that thee is

no such thing as tasensoyPeception is aso veydiicut I think that mostscientists who ought to knowabout this, ike psychoogists,do not beieve in it

27


34/68

Is it true tat weae bue bood?

ay ighingaChkaha Okahma

The answe s yes But youbood is bue ony in a speciapat o you body.

The coo o bood comesom a stu caed hemogobin.t is caied in you ed boodce s ts ob is t o cay oxygen

28

o

om you ungs out to a theces o you body The coo ohemogobin depends on howmuch oxygen it has.

Ate passing though theungs you hemogobin has au oad o oxygen and is ed.That ed bood is pumped bythe heat out though youateies. I you have a cut, it isikey to be ths ed ateabood that eaks out

Fom the ateies the edbood ows though vey tiny

tubes caed capiaies, whichcay it cose to a o the tinyces o you body. Thats whethe bood oses its oxygen

When that happens, thehemogobin changes coo andi it oses amost a o itsoxygen, it becomes dak bue.Bood om the capiaiesows into age veins andback to the heat and ungs.

So it is ony you venousbood, the bood in you veinsthat may be bue.


35/68

I have heard thatwe have about200,000 mes ofblood vesses. If ths strue, how can that

many mles of bloodvesses be n us?Jui Miae

Queen iage New Yk

am not sure o the eactnumber o 200000 miles oblood essels No one haseer measured it. No one haseen counted the number othe ery tny blood essels the

capillaries Howeer we canmeasure how big around theyare and how much blood theymust hod. we now that wecan igure out about the lengthothem all put together

A grown man has about siquarts o blood. At any onetime most o that is in thetiniest blood essels thecapillaries. Each capillary is

less than onetenth as bigaround as a human hair. will not bore you with al

the numbers but when igured this out came outwith about 50000 miles ocapillaries Very iely yourigure o 200 000 miles may bemore nearly correct.

These numbers can be eryarge becaus e the capillaries

are so ery small. O coursethe blood pumped by yourheart does not trael all thosemany miles beore it gets bacto the heart again Eaccapillary is also ery shortThere are many millions othose tiny short tube$ side byside all carrying blood at thesame time

How do we get ourblood?

aughn uiHnuu Hawaii

Blood is part o themachinery o your body and ispretty wonderul stu tcontains a number o dierentthings that are made indierent ways.

ets ta about the redblood cells They mae upalmost hal o the bood.

New red blood cells are

being made all the time in yourbone marrow Thats a spongyred tissue on the inside o yourlarge bones. A s they are madethe new cells are illed withhemoglobin the stu thatmaes them red and does thebig job o carrying oygen.

Your bone marrow has toeep woring al the timebecause some red blood cellsare always breaing down andneed to be replaced

ust while you were readingthis your bone marrow madeseeral million new red bloodcells. You can see that it eepspretty busy

29


36/68

A lot of people inmy class don't eatbreakfast. Wy dowe need treemeals?

Mandy BydFun, Kenucky

The standard answer hasbee n that yor body needsnorishment s paced oer theday to fnction properly.People who hae stdied theprobem hae always said thatits important to start with agood breafast.

There hae een been some

people who had the idea thatids who didnt start with agood breafast didnt do as wellin school as they woldotherwise. Howeer, theressome dispte abot al thateen thogh I p ersonally thinits mportant to start with

I wis you wouldpease tel wy ourbodies need food.

Teesa nne eeMafed Massacuses

Sometimes it helps to thinof yor body as a special ind ofmachinea rather wonderflmachine and special becase itis yo. ie any other machne,it needs energy to mae itwor Thats one reason yoneed food. It gies yor bodythe energy it needs to eepworing. Some foods hae

30

some fel at the beginning ofthe day.

Theres another part to yorqestion. Why eat only threemeals a day There hae beenlots of hmans who didnt eatthree meals a day on a regarschedle. If yo think abotanmals n the wid, they tendto eat when food is aaiableand not on any specialschedle And some farmanimals especially pigs aregien the choice of eatingwheneer they feel lie t.

Eating three meals a dayhas become a cstom I noticedthat people in the office whereI wor all go to lnch at noon

That is their cstom and theyeat then whether or not theyare hngry In Erope mostpeople tend to tae their largermeal at noon and only a lightspper at nght. So how wediide p or meals depends aot on cstom.

more energy than others.Sgars and starches and fatsare sef as food becase ofthe energy they proide.

Yor body also needs food foranother reason It is alwaysrepairng itsel When yo areyong and growing it ismaing more body machinery.

Body machinery in all liingthings is made of proten Soyo need foods lie meat eggs,and mi to proide protenBesides the protein yor bodyneeds a collection of spareparts called itamns. Yo canget yor itamns from manyfoods, especially in frits andgreen egetables.


37/68

We have beeneaning aboutphotosynthesis in myscience cass waswondeing if ahuman being couldive ike pants ust

needng wate andsunshine

anessa WuDaas, Texas

That does sound le a greatdea But 'm araid it wouldwor ony or science ction. Inreal ie it won't wor et's

thn about t.Animas and plants are buitin ery derent ways.Anmas get ther ood byeating. o they hae to moearound to nd their oodandto eep rom being eaten bybgger animas.

Plants mae their own oodby using the energy osunlight So they just stay in

one place and dont needmachinery lie musces tomoe around O course, pantshae their own set o problemsOne problem is that they needto catch ots o sunlight Sothey mae many thn latleaes

For a plant to mae as muchood as your body uses each

day, t would need a lot oeaes. Een though plantleaes are not all aie thnit would tae about 100 squareyards o lea area. That'senough leaes to coer morethan 100 card tables And youwould need enough branchesto hold all these leaes up tocatch sunlight Maybe you canpicture yoursel with an apple

tree growing up oer yourhead gues s you can see that

animals and plants hae erydierent problems in mang aliing. n order to mae lie aplant, you wQuld need morethan j ust some o that greenstu You would need a wholenew pan or your body

3


38/68

I know that I dreamin picures But howcan people born blindsee in their dreams?Or can the?

Bd WinLos ngs, Cini

had neer thoght abotyor qeston and dd notnow an answer. So sent yorqeston to people who mghtnow the answer. Yo wll nd

below an answer gen to s byBarbara Colns o the Brallensttte o Amerca.

"The letter rom Brad Wenabot dreams prooed qte abt o dscsson arond here.The qeston has come pbeore bt no one has eer

32

researched an answer."We ased or sta

psychologst who has beenblnd snce the age o steenand a blnd conselor. Theranswers are based on personalclnca research.

"What we dream s basedpo n what we eperence Asghted person dreams npctres becase thats how heeperences le. A blnd personreles on hs other senses schas hearng and toch toeperence le. Thereore hedreams by s e o these othersenses.

"A person who cant see

cannot hae a sal dream. Asghted person who has anghtmare mght dream abotan gly-colored scaly creatrecreated rom a combnaton ohs magnaton and thngs hesees eery day. A blnd persondreamng abot the s ame

monster wold hear hs lodhollow oce and eel hs slmysn. ts nterestng to notethat a person blnd rom brthdoesnt realze he dreamsderently rom a sghtedperson.

"Some people who are blndhae partal or res dal sonThese people can see n therdreams bt only to the etentthey can see n real le.

"A person who s bornsghted and later loses hseyesght dreams n pctres.Howeer eerythng he sees nhs dreams s base d onmemory Althogh he nows

people change (by agngganng weght dyeng therhar he nee sees thesechanges n hs dreams.

a m gratel t o BarbaraCollns and the BralleInsttte or gng s ananswer to Brad's qeston.


39/68

What is the cause ofseepwaking?

Sndr okNorth By Ontrio

have heard aboutsleepwaling but do notreally now much about it. will tell you some o the thngsI have read about it.

First you should now thatall o us move around a littleeven when we thin we are astasleep. Almost everyone haseye movements and manypeople show lip movements.Everyone has dreams So Isuppose that sleepwalingmight be lie actng out adream.

--

My mom and dadsay I sleep talk. Whydo people sleep tak?

Christy sFbrok Ciorni

Thats something don't

now very much about. And suspect that no one nows agreat deal about it Scentistswho study sleep and dreamingthin that sleep talng issomething sep arate romdreaming have read that ioccurs during ight sleep butnot during the "rapid eyemovement or REM sleepwhen most dreams occur.

I guess cant help you verymuch ecept to say that don'thn sleep taling is anythingstrange or anything or you toworry about

Seepwaling has a special

ancy name somnambulismBut thefact that we have a r:tg82ancy word or it does not mean "{hat we understand it. haveread tha some people thnthat seepwalers are ju stabsent-minded dreamers Soar as I can te there is nodanger in waing up someonewho is sleepwaling

3


40/68

How come youreyeballs don't fall outwhen you lookdown?

Mc Petoend M

I guess your queston arosebecause you were thinking ofyour eyes as being separatefrom the rest of your bodyActuay, they are not

At te back of te eye s abunde of nerve fbers thatcarry messages to your bran.There are a ot more attachments made by the sx musces

for each eye. These worktogether to turn your eyes soyou can choose what you wantto ook at

You can see that your eyesare pretty we anchored andnot n danger of fang out

I know people can

be aergc to cetanfoods, dust, adanimals ut can ahuman be aergic towater?

Rche GuecPe Vge Kn

think nobody can beaergic to water The body of

every ivng thng needs tocontan a ot of water ust to bave. Your body s about 60percent water f your scaessay that you wegh 80 poundsstop and think that 48 poundsof that s water.

You can see why it s hard timagine anyone being aergcto water


41/68

I ove to goswimming, buttere's oo muccorine in te waterand I get red eyes.

Can you te me watto do?Cady ays

Nw Nh Caia

I can't solve yor problem,bt can te yo hy ithappens Chlorne is a veryreactive chemical It oxidizesmost organc matter and ii acteria t is sed in or

ater-sppy systems to lbacteria s o that the ater illnot carry any disease germsChlorine s also sed insimming pools or the samereason

chorine can do a that,hy isn't t dangeros to orbodies? Realy t is Actallychlorine is a poisonos gas Inater spplies and simmingpoos t s sed very carellyOnly very smal amonts aresed And any "extra chorne,hch does not react qiclyith st in the ater,gradaly disappears Some slost in the air Whatever s leis rapidy changed into

harmless componds by theaction o snlight So the trcin managing a simming poois to se jst enogh chlorineto ill all the bacteria and nothave very mch let over

A little chorine in the aterdoes not bother yo very mchpartly becase yor body iscovered by a togh sin Yohave a e senstive paces notcovered by sn, lie the liningo yor moth and nose andyor eyes dont lie thechlorine o smming poos,ether Bt od rather havethe chlorine than the dseasesthat old come e did notse it


42/68

" )U,

What colors docoor-blnd peoplesee?

36

Rn HendenGanee Foda

tin te answer must be

tat tey see n various saesof wite to gray to bamaybe as in an ofasionebak-an-wite movie.

However, tere are varousegrees of oor binness. amparty oor-binor, reay,not very sensitiveto reWen see a traff gt a very

ong way off I an see a gtbut an't te weter it s reor green unti I get oser

Atuay te oorsensitvees in te retina of your eyeisrminate between oorsony n brigt gt. In veryim igt your eye ant seeoors as oors.


43/68

Why do we blink?Wnd Hornby

ndanapo ndana

I guess youve noticed thatyour eyes bin ratherregularly Most people blinabout twenty-ive times aminute while they are awaeear glands in the outsidecorners o your eyes are awaysmaing tears and the bliningo your eyelids wipes thmaway hat eeps the rontsuraces o your eyes moist andcean

Blining is controlled by arelex an automatic nere

action Besides woringregularly, the automaticcontrol also wors to close your

eyelids when something isabout to strie your ace Soblining is important inprotecting your eye

ou can decide not to blinand stop bining maybe orten seconds or so. But then theautomatic control becomes toostrong here is only one saeand eective way to stopbining Close your eyeidsand go to slee p

Why do peopehave eyebrows?

oy HarvyBrown M Nw ry

Not much is wrtten abouteyebrows even in boos aboutthe human body hey do helpadd to the protection o youreyes by sticing out on thebony ridges ust above heyalso help to shield the eyesrom glare on a bright day.

You may have noticed thatsome ootball players paintdar streas ust below theireyes suppose they arehelping the eyebrows cut downon glare

3


44/68

When I watchmoves or get ntrouble, I crysometimes When Icry, I get heavyheadaches. Why s

that?-ge Mrie Lawho

Pasadea Md

doubt that ca expathat. he best ca do s to teyou somethg geera aboutheadaches.

Headaches are commo. doot kow ayoe who coudsay that he or she ever had a

headache Maybe oe reasothey are so commo is thatthere are may possbecauses.

Do you know whypeople feel like they

have a ump in therthroat when they aregoing to cry?

shey Kte

Gerock Wymig

thik kow what youmea, ad t s a very commoexpressio have ever seea expaatio ad do't

reay kow a aswer, but ca thik o a possibe aswer.

Cryig occurs whe theacrima gads o your eyesmake tears aster tha theyca be carried away i thette tubes that drai ito theback o your throat. Maybebeore you reay kow you'recryg there's a extra amout

38

We get aches ad pasbecause our ervous systemshave specia itte gadgetscaed pa receptors. You havea ot o these your head

mosty outsde o your sku,but ot sde your bra. thik most o my headachesoccur whe get tese ad the

o tears goig dow these tubesto your throat. hat woud givesome extra ud i your throatad make you wat to swaow.t might ee ike a ump iyour throat

musces tighte up i my ead scap, or sometmes wheget a cod ad my ose getspugged up.

Sorry cat te you more

Your doctor coud expai thbetter tha , ad i you havmay headaches t mght bewse to ask hm or her


45/68

Wen te Eart

urns around, wydon't we fee it?Cornne Etemn

Prospect Prk New ersey

Let's see if we can find theanswer by imagining that wewill do this exerimenttogether. We wil get inside amoving van, with a ightinside, but a closed u so that

we cannot see out. hen wewill as the driver to find along straight road and drive ata constant seed. ou and I aregoing to sit on the floor andlay checers.

Now if the road is straightand flat and smooth, and ifthedriver is very careful to ee usat constant seed, you and will not now we are moving at

al here is just no way tonow. And our checers willstay right there wherever weut themeverything aroundus is moving just alie. Afteryou have won the game, as myown chidren usually do, wewil as the driver to mae asudden sto We had betterhang on to something When

the truc begins to sto, wewill feel that we are movingAnd if the sto is reaysudden those checers wi be

scattered against the front ofthe van.

N ow here you are again,reading this boo. ou aresitting in a chair in a house onthe surface of the Earth,moving ever so fast but verysmoothy as the Earth rotatesand traves in its orbit aroundthe Sun. f we coudn't see theSun and the stars we would not

now that we were moving atall.Maybe you thin my answer

was not quite fair Maybe youhave heard eoe say that theEarth is sinning, and you areworried about its centrifugalforce It does sin, but turningaround just once a day is amighty slow sin Put anitting needle through the

center of an orange and try toturn it that slowly, oncearound in a day ou wil seewhat I mean by a slow sin.Even for the much bigger sizeof the Earth, the centrifugalforce tending to sin us offi s somuch smaller than the force ofgravity that we never nowabout it.

Wen you sinaround a ot, owcome you get dizzy?

Steven MrsGrd Texs

ou now that your ears dofor you the imortant job ofhearing. he inner arts ofyour ears also do another obhey give you a sense ofbalance Dee inside your earsare some secial cavities filedwith fuid. Inside thesecavities are sensitive littehairs attached to nerve celsAny movement of your headmaes the fluid slosh around

hat bends the itte hairs, andthe nerve cells tell your brainabout the movement

When you sin around,there is a short time ag beforethe fluid sins, too. So you feelthat you are sinning. Whenyou sto, the fluid eessinning for a while hat maymae you feel that you aresinning bacward. We cal

that being dizzy.


46/68

s people get older,how come they get

wrnkles?Km Haam

Wetersed, Cnnectc

Skin is n importnt tissuett does ot for us like being protective cot Te lvingprt of your skin is n innerlyer of lving cells Tey recontinully workng to mke

40

toug protein mteril ttwill become te outer lyer.Tey lso mke some elstcfbers tt elp pull te skintgt round you

tnk tt s your skin getsolder te inner lyer doesntwork s well to mke new stufAnd t mkes fewer elsticfibers Ten te skin seemsrouger nd tends to wrnkle

Sunlgt s rd on yourskn. Getting tn my mkeyou look elty but t elpsyour skin get older.

How come t hurtswhen I pnch my sknut when I pnch myhar t doesn't hurt?

m OnemuCer Landng Aask

Your skin s mny littlenerve endings tt wrn youby pin messges wensometing bd ppens to youskin. Your ir s mde byspecil lttle ir follicles inyour skin Once r spused out of ir follicle its no longer live. And t s nnerves so it cnt feel nytinwen you pnc or cut it

If ir were like skingettng rcut would bepretty pinful.


47/68

Why do peopeave moes on heirskin?

Charity HuntAa ssoui

Athough mot of u do otthik very much about ourki, we are fortuate to have

uch a good protective ayer.he ki actuay ha aumber of ayer, a verycarefuy arraged, together

with ome hair foice adome itte gad that makeoi ad ome that make weat.Oe of the udereath ayeri made of ce with a pigmetthat give the ki it coor.

A oe a a cooedpatch of ki where the ayeromehow got mixed up adthere are a ot of extra pigmet

ce. Mot moe ever caueay troube d we jut ivewith them f a moe beed orgrow or chage i coor the

it i wie to how it to a doctorRemovig a moe i a maloperatio ad houd be doeoy by a doctor

Amot everyoe ha a fewmoe. Mot moe are a partf u from birth I thik ofmie a ma accidet thatoccurred whe wa becomiga baby

41


48/68

Why do our facesturn red when wesand on our heads,but our toes don'turn red when we

sand up sraight?Hoy Lemonhoh Ohio

I like you question beauseit shows that you ae a aefuland uious obseve.

he answe lies in the wayyou body manages its fow ofblood to vaious pats of thebody. It does this mostly by

ontol of musles in the wallsof smal blood vessels, aledthe ateioles. When thesemusles tighten in one paeless blood flows thoug

You body is used to being inan upight position s theateioles in you feet wok tolimit the amount of bood down

42

thee. When you stand on youhead the ontol of ateiolesin you fae evidenty is not asgood. hen moe bood fowsinto the skin of you fae andmakes it look edde.

What maes youbush?

Ben Hogniken outh Caroina

What you ae talking about

usually happens to the skin ofyou fae. he ski n appeas edbeause exta blood is beingaied in the tiny boodvesse s ust unde the skin.

You ontol of bodytempeatue depends patly onthe ontol of how muh bloodis aie d to you skin Whenyou body is too wam it

automatially sends moeblood to yu skin hat hepyou lose moe heat When yoae too old moe bood isiulated deep inside and eto you skin.

Some of this ontol of wheyou bood goes woks fopatiula pats of you skin,

like you fae. he ontolpint is alled a ctrloated deep in the bain. Itwoks automatially (withouthinking) but in some stangway it is aeted by what yoae thinking about hatswhat auses a bush whenexta blood is sent to the skinof you fae.


49/68

What causes you tobreathe withoutthining about it?

efe AheHckoy Noth Co

We are lucy that our bodes

hae a nu mber of automatccontrols to keep all ourmachnery worng rghtMany of these control ournsde machnery and weneer now about them. Youcan tel about some of themle the control of the he artby feeng your pu lse

Breathng s nterestngbecause t can be controled n

two way. You can decde whento breathe. You can breatheextra fast or you can een holyour breath for a short tme.Bt when you are not thnkngabout t your automatccontrol taes oer So you donthae to spend a ot of tmeworryng about when to taeanother breath

The contro pont for your

automatc contro s n the baseof your bran. t gets messagesfrom many plac es n your body.And t regulates the brathngmuscles.

"

Woud you pleaseexpain why we needfresh air? For

instance, if you werein a box, why woudyou die? There is airin the box.

M Gugeybug Pesyv

he lng machnery n thecells of your body s powered bya slow "burnng of stuff thatcomes from your food. So al ofthose cells need a supply ofoxygen and are mang carbondoxde Your bood carresoxygen from the lungs to all ofhose lttle ces and then taesbac the carbon doxde. Adbreathng ar nto and out ofyour lungs brngs n oxygenand gets rd of carbon doxde.

I"(

@

Each day your body uses upabout 60 quarts of oxygen andges off about 500 quarts ofcarbon doxde. About one-ffthof the ar around us s oxygenso you could say that you taeup each day al the oxygenfrom about 3000 quarts of ar

But you could not e all day fyou were tghtly sealed up n abox about the sze of the nsdeof a smal car wth 3 000quarts of ar wo bad thngswoud happen When you hadused up about half the oxygenthe amount and concentratonle n the ar would be so smallthat your lungs and your boodcould not get oxygen fastenough. But long before thshappened you ould begaspng because of al theextra carbon doxde that yourbody had put nto the closedupoume of ar.

am glad that our planethas so much ar and so muchoxygen that there s plenty fora of us

43


50/68

ow does sweatform?

Saah ayOxnad Caifnia

Sweat s made by vey

manymaybe sevealmllontte swea glandsscateed aound n you sknThey ae moe tghtly packedon the palms of you hands andhe soles of you fee Whenseen n a micoscope eacgand looks lke a coeduptube wth an openng on thesuface of the skn s ob s o

44

make swea, whch evapoatesfom the skn and cools youbody

The makng of sweat spaty contoled fom younevous sysem by anautomac eflex Thsnomaly woks o make extasweat when you body gets toowam. When the a

tempeatue aound you sabove 99 degees Fahenhetyou need to sweat just ocontol you bo dy empeatue.You body usually makesmaybe a pnt of sweat a day.Tha muc evapoates soeasy tha you wll no notcet But hat mgh ncease toas much as fve o ten quats a

day f you ae vey wamSweat s a dlute souton

flteed ot of the blood t smostly wate wth a tle saand a vey small amount ofoganc chemcas When fsmade t s sad to be odolessEvdently te acton ofbactea on the skn causes hodos that some of us have n

ou sweatMy mothe used to tel metha t was moe polte to say"pespaton han to say"sweat. Tat may be tue npao convesaton. owevein alkng about te opeaionof he body sweat s he ghtand pope scentfc wod fous o use.


51/68

Does affeine stuntyou gowth? Myfiend says he dinksoffee in the moning,

but he still gowsKa edeon

aey Cy Nh Daka

I rmmbr that whn wasyour ag hard th ida thatdrinng coff woud stuntyour growth. av wondrdabout that da but havnvr bn ab to find it inca boos

h caffin that is in taand coff is actuay a drug amid stimuant. You wi noticthat not a pop rspond to itin th sam way Som popbcom addictd and vn gthadachs if ty go a ongtim without coff And manypop who do drin somco do not drn it at nightbcaus t ps tm fromgoing to sp.

Many aduts sm to ndcoff to gt thmsvs awain th morning. Young popdont nd that So why drin

.coff? t may not do muchharm but no on wi argu that it s good for you.

How do ou boneskeep getting bigge?

Chhe HaeCave Machue

Bons that w s oo hardand soid n your body bon sa iving part of you. t has itsown spcia bood suppy andspcia cs for maing ortaing away th hard stuff,whic is mad mosty out ofcacium and posphat.

rougout our ivs ourbons ar sowy changing orbing rmodd. At your ag

your bons ar incrasing insi and ngt. tr middag bons tnd to dcras insi and most pop actuaydcras a itt in ight.

45


52/68

)

r

(I\\IJ5/Wha makes

people floa?Amy Riegen

Mon Indin

I guess you mean foat onwater when you areswmming think the manreason is that your ungsaways contan a szabeamount of air Even i f youbreathe out as hard as you can,your ungs w sti contan

amost three pints of ar And ifyou take a deep breath theywi contain much more. Soyour body s a itte ike abotte u o air

Peope are not a aike inther ung capacties and suppose that's why somepeope seem to foat moreeasiy than others

46

Why do peopleburp?

Roe LuoSn o Cifoni

When you get some gas nthe stomach, three things canhappen to it The gas may passon through to the smaintestine, it may be absorbednto the bood stream throughtiny bood vesses in thestomach wa, or it may comeback up through youresophagus to your mouth norder for it to come back up, aitte vave must open to et the

bubbe of gas out of thestomach That's when youburp

How does gas get nto thestomach Sometmes it getsn with a itte air that sswaowed. Sometimes it sdissoved n food or a drnk.

You have seen soda water zwith bubbes of carbon doxidwhen you pour it into a gassEven aer you drink t, thefizzing keeps on going andmakes carbon dioxde gas nthe stomach. That's a good wato get a burp

Body machinery s notexacty the same in a peop have noticed that somepeope burp more than otherbut do not know why that

There s an interestingburping probem that havewondered about Some peopwont eat cucumbers becausethey say that cucumbers makthem burp And notce that

there are now specia varetof cucumbers that are sad tobe "burpess wonder whatthe specia chemica s incucumbers that makes somepeope burp. f we know thatwe mght know more about thanswer to your queston


53/68

oud you peasee me why we

iccup and whacauses his ohappen?

D Cm

Lawc Maacustt

rs w shuld hink abouh way w normally brahbcaus a hccup s a spcalkind of msak mad by h

brahing mchansm.Jus abov your somachand blow your lungs is a shof muscls cald hdiaphragm I compllysparas h uppr or lungcaviy from h owr orabdominal caviy ofyour body.Normally hs is a ll domshapd so ha curvs

upward. Whn you brah inh daphragm dos mos ofhwork by conracing andbcoming far Ad hs

puls ar ino h lungs.You can conrol your

daphragm if you wan bumos of h im you do nohink much abou yourbrahing. You don spndmuch im dciding whn oak h nx brah You don'hav o bcaus h daphragmis also conrold by on ofhos auomaic rflx acions

of your nrvous sysm. hauomac acion uss a spciallarg nrv h phrnc nrvo carry is mssags o hdiaphragm.

In hccups hr is amisak or a las an unusualacion of h auomaic conrol.h daphragm is mad oconrac and mov downward

suddnly wh a vry srongforc ha sucks in ar vryrapdly hroug h wndpipdown no h ungs. h

auomaic conrol on kpsrpaing is rror o makhiccups com rahr rgularlyagain and again. his can bmighy annoying.

Hiccups sm o b causdby rriaion of h diaphragmor h phrnic nrv Ovrang or indgsion maycaus h somach o rubagains h daphragm Or

vn laughing a lo can irrah diaphragmh rason ha hr ar so

many curs for hiccups is hahy gnraly cur hmslvs. Howvr som poplhav had hiccups for as long assvral monhs and havndd mdical ramn og rid of hm.

7


54/68

Woud you pleaseexplain why when

running people oftenge side aches? Thisseems to happenmostly when peope

have ust hadsomething o ea ordrink

Kn RonttLo ng Con

When was a boy I used tohave sde aches and wondered about them too Ist do not know much aboutthem but maybe I can hep atte

8

Aches usuay occur whenmusces have worked too muchand get tred or fatguedSometmes a musce may asoget a cramp It tghtens up andw not reax agan hs sespecay bad f t happens

when you are swmmng. Acramp n a musce can happenn sudden vgorous exercse ormetme when a uscesuddeny gets ched.

et 's thnk a tte about howa musce works and what tneeds n ts frst fewcontractons a musce uses upmost of ts mmedate source ofenergy a speca chemca

often caed AP After tat tmust make more AP. hscan be done by usng upanother chemca caedgycogen whch breaks downto actc acd By now themusce needs a suppy of bood

to brng n oxygen and carryaway some of the actc acd

f you are gong to keeprunnng or workng hard youmusces need a good suppy obood If you have just eaten ot of your bood s beng

carred to the was of yourstomach and sma ntestneEven though your heart pump ade t can't get the muscea the bood they need henthey ar more key to ache oget cramps An athete nevershoud do any strenuousexercsng soon ater a mea

An ache or pan s tryng tote you tht somethng n you

body sn't workng rght or thayou asked t to do more than was abe to do Physcatranng s a way of gettngyour body machnery abe towork better and onger wthougettng aches and pans


55/68

a causessomeone o be anabino?

nn t Hvsnnt Qub

You have notced that one ofthe ways n whch people dfferfrom one another s n theamount of pgment or color ofour har and eyes and skn Allof us have the same pgment astuff called mel ann but wemay have dfferent amounts

An albno s a person whosebody makes no pgment at all

hat s a very rare condton ts sometmes caed annherted condton. Howeveran albno may have parentsand grandparents who are notalbnos. Just how that canhappen s one ofthe thngs youwll learn when you study thespeca part of bology called

genetcs. guess you know thatalbnsm s not mted to thehuman It can occur n most(maybe n all) wd anmals Aperfecty whte frog or snake orwol f s a very strange sght Aalbno makes you reae howmportant pgments are toanmas

at does a canecel do o you? acoor is i?

C undquCn N

Most of the cells n the bodyof an anmal or plant becomespecaled for some partculaob After that they stopgowng and dvdng to kemore new cells Sometessomethng goes wrong and onof those cels starts growngand dvdng agan when t snot supposed to. We cal that cancer cel

A cancer cell does not have

any partcular color It takes aspecaly traned medcalscentst a pathologst to tel acancer cell from a norma cel

An mportant practcalqueston n bology s whatmakes a normal cell turn nto acancer cell. Someday, when wknow enough about hownormal lvng cels work, wehope to fnd an answer.

4


56/68

Do you hink thereis human-like life inouter space?

Fancs FetcheHyde Pak Massachusetts

thnk this i lkel ust asman other scentists do OurEarth is a s peci l panet of ourSolar Sstem t gets ust theright amount of light from the

Sun and has temperatures andthe water and atmosphere thatare faorabe for iing thngsBut there are n the uniersemllions of other stars muchke our Sun So probabl thereare man planets much likeour Earth in haing condtionsaorable for lfe

No one et knows theanswer to our question Iguess es ow do ou guess?

Ezabeth WadeNoth Stonnton Connectcut

cant ge ou a competeanswer but will te ou whatI can our experence is fairlcommon When was teachingit sometimes happened thatthe chalk was using made ascreech on the blackboard

Then some of the students no

all of them) would groan orell

The sou nd we ar e talkingabout is highpitched or of highfrequenc think ou cansense it onl b our ears Themessages from our ears toour brain use a pathwa of aleast four nere fbers, whichconnect together at seeraponts in the sp na cord just

below the brain t might bethat some of those connectionsaso connect to nere fbersfrom lower n our spinal cordMabe that is how ou get theshiering feeling

know this i s not much of anexpanaton This is the kind oqueston that een big medicabooks do not talk about


57/68

How do youdream?

a Thmsnngtn Massahstts

Ppl hav wndrd abutdrams r a vry lng tim Nn knws all abut thm ButI can tl yu a litt

Drams ar prfctlynrmal and vryn sms hav thm Mst f us spnd1 / t 2 hurs drmng vry

night nlss w happn twak up during a dramngprd w d nt rmmbrur drams

Hw d w knw all that?Mstly by studying pplduring sp Whn th brainis activ thr ar smalllctrica currnts that can bdtctd vn n th surfac fyur had Th pattrn flctrcal activity is cald anlctrncphalgram

Anthr thing that canhappn durng sp is amvmnt f th ys calldREM fr "rapid y mvmnt It was fund that ththr thingsdraminglctrcal activity and REMal g tgthr S yu can tlwhn a prsn is dramingwithut vr wakng th

prsn upt is blvd that amst all

mammals and birds as havdrams bcaus thy hav

prids f brain lctrcalactivity and REM slp

Sinc draming is scmmn scintists naturallyhav suppsd that t is gdfr yu Sm vn hink thatt s smthng yur brannds t d

On rcnt rprt suggststhat yu dram just bcausyur bran is tuning up itslctrical machnry whil yuar aslp Of curs sinc wd nt knw much abut hwth machnry wrks w dn'tknw what tuning up mans,thr

Mayb th mst ntrstngpart s that w al hav drams

that w nvr knw abut Wsm t rmmbr a dramnly whn w happn t wakup in th middl f n

5


58/68

What is the use ofour Adam's apple?

Kan RoRood lno

What we call the Adam'sapple is a swellig or

proecio at he frot of thethroat t is arger i me thai wome ad is sometimescalled a secodary sexcharacteristic. This just measthat it is oe of may smallways i which males arediffere from females.

At the upper ed of yourtrachea (widpipe) there is a

52

elargemet called the laryx(voice box. The laryxcotais your vocal cordswhich you ca tighte orloose to make differet kidsof souds say words ad sigA proective coverig over thefrot of the laryx is called thethyroid cartiage. Part of he

growigup process i boys is asudde icrease i size of helaryx. The voice chages to adeeper pitch ad he Adam'sapple becomes moreoticeable

So the Adams apple i s theproecio caused by the thickhyroid cartilage hat proectsthe laryx

What is the smalleorga i the body?

Gna QuaPaa Nw

Techically speakig that

would be the cel. While thecell is't a orga i ourgeeral sese of the word itdoes perform may importafuctios o is ow ad aspart of other orgas. Just asthere are bilios of stars i tuiverse there are billios ocells i your body.

Heres a questio for you:What is the l orga ithe huma body? You may bsurprised to lear tha it's thskisomethig else we doormaly cal a orga


59/68

Wy are somepeople bornandicapped?

na MInosEmwo, Penana

Snce I m physoogst Ike to thnk o the body s very ne nd compctedmchne Our bodes re verymuch ke but never exctyke. You ys be beto nd someone ho cn dosomethng tht you cn't d oSnce no one hs reyperect body I guess you coudsy tht e re hndcpped n some y

Some o us re morehndcpped thn others Andthere re mny ys n hchths hppens : n ho our bonesre mde n ho e ourherts or brns or musces oreyes ork nd n mny otherys.

Wat coor is tebrain?

a MGeeSnde Teas

The brn s gry n coor. In

ct, I hve herd peope reerto ther brns s ther "grymtter

Brns rom humns ndrom nms hve beenstuded very creuy Thebrns o derent nmsder n shpe but hve

recognzbe prts tht rvery much ke. hen brns sced n to, the brnshos some hte res deepnsde surrounded by gryres on the outsde It turnsout tht the hte rescontn ony nerve bers. The

gry res re pces herethe mny connectons beteennerve bers re mde

A ths does not te mchbout ho the brn does themrveous ob o thnkng butt does te hy the outse othe brn s gry.

5


60/68

How come you canput a ot of water nyour mouth and tdoes not go downyour th roat u nlessyou want it to?

Ben Villi

S. Pal Minnesa

Yo are rih in yorobservaion Neiher food norwaer js drops rom yorhroa down o yor somachYo have o make ha happenby swallowin

The back o yor mohleads o yor hroa orpharynx and ha opens ino a

be he esophas ha oeso yor somach ormally hepper end of he esophas iskep closed by a rin of mscleha acs as a valve So waern yor moh doesn js rndown o yor somach

Once yo e some waer orood a he back of yor mohyo may decide o swalow

54

w come I get ru nny nose when Ieat hot food or d rnkhot drnks, evenwhen I don't have a

cod?Ben Calson

Nowih Connei

The insde o yor nose andmoh are always makin alile flid o keep he lninsmois A nmber o hins wlmake hem prodce more f dYor moh can "waermeanin ha yo make more

flid saliva whenever yo p

ood in i and someimes whenyo s smell food Yor nose"waers especially when slinin is rriaed as when yohave a cold So sppose hayor nose "waers becase is

linin is especially sensiive ho hins in yor moh

have no noiced ha mynose behaves ha way hoh someimes e ears in myeyes rom ean or drinknsomehin oo ho However Iam no srprised ha yornose behaves diferenly hanmine Or body machinery isal basically aike b noaways exacy alike Thiswod be a prey dll world i

we were al exacy aike


61/68

What part of thebody does the mostwork?

m Bttr

Wilmer labama

Oe reaso that is hard toaswer is becase differetparts of yor body do dfferetids of wor. Yor heartmscle ad the mscles of yorarms ad legs do mechaicawor-lie the motor of aatomobile. Yor liver ad

deys do chemical workie a factory that makesplastcs ot of petrolem. Yorbrai does chemical wor thatpartly chages ito theelectrica wor of yorcommicatio ceterot

too dfferet from comptersad telephoe swtchboards.Yo eed all of these so

were ot talkig abot whchs most mportat. Bt whchdoes the most wor? Oe wayto thi abot ths s to aswhich part gets the greatestspply of blood i reatio to itssize Of corse the heart may

seem greatest bt of all theblood pmped by the heartoly a smal part goes to theheart mscle.

The lver the ideys adthe brai are all big sers ofblood. thi that for their size

the ideys probably have thegreatest blood spply.So my vote is for the ideys

as the hardest worig bt asyo ca see I sed a speciacrterio to get that aswer. Soif yo wat yo ca still fidreasos to arge for otherorgas-lie the liver or heartor brai.


62/68

I live n the Bay

Area and lateywe've had qute afew earthquakes. Iam 1 1 years old, andth s worres me. It isscary. Please help.

L CetnFrent, Cfn

am gad that yo wrote me.

Whenever somethng sggng yo t s mh etterto talk aot t than to kee tottled nsde

annot do anythng to helf yo mean stong earthqakes Bt maye an saysome thngs that wl hel yoto thnk aot the rolem.

sose that eole n yor

56

area talk aot earthqakes alot Every lae seems to havets own seal rolemsWhere ve n Texas eoeworry aot tornadoes. So weoften get warnngs on TV thatthere s a tornado wath n

or area ntl 10 oloktonght. When a tornado htsa hose t jst aot takeseverythng away so t s rettysary Peole who ved alongthe Glf Coast worry aothrranes Almost every yeara hrrane loers some artof the oast. Hrranes aresary too.

Some eole lve where

there are floods. They odworry aot eng drowned orosng ther homes jst easea rver neary gets too mhran.

gess am tryng to thnkof other eole who have sarythngs that mght haen tothem. There are a lot more weold thnk of Atally al

those thngs t togetherroaly do not hrt as manyeole as are hrt natomole adents gessjst lvng s a lttle t rskyease of the many thngsthat an go wrong Bt lvng

not as rsky as t sed to e.Peole are a ot safer and lvlonger than they sed to do.

When my rst daghterShrley was a ltte grl goto thnkng aot all thedangers and al the ways sheold get hrt. Fnay wondered how kds ever ollve to grow . Then r realzethat most kds do grow n

ste of all the thngs that ahaen. deded thatworryng wold not hel anySo deded to sensle anareflke aways wearngseat elts n a ar-and jstexet that everythng wllome ot al rght.

So why dont yo try mydea and see f t wll work?


63/68

A fact s that pantsneed carbon doxidefrom people andpeople need oxygenfrom pants. Why s tthat n the car wthoutpants you can stlive?

Ky CanTampa, Fda

ou ae ight that eoeand ants need each othebecause they tade back andfoth the gases oxygen andcabon dioxide.

If you wee eay seaed uaone in a oom so that nogases coud get in o out youwoud die The ai in the oomwoud get too much cabondioxide and ose most of itsoxygen.

The eas on you do not woyabout this in a ca is that thenyou eay ae not "seaed u .Thee is enough eakage of ai

in and out I guess it is a goodidea that cas ae not moetighty made.

How does a bsterform? And why sthere qud nsde?

in ChtZan Oh

A biste foms at a acewhee you have causeddamage, as by a bad inch o a

bun A ot of sudden changes

took ace thee The was ofthe tiny bood vesses cose bybcame eaky. Some fuideaked out of the bood to makethe cea fuid that you se e inmost bistes Sometimes thewho bood ak out andcoects to make a backooking biste. Neithe kndis any fun.

5


64/68

Do you have to besmart to become ascientist?

Jennife PineaLos Anee Caifornia

I dont know bout tht wordm tht youused. Ascentist must be ble to lernnd kee erning becuse inscience there is lwys more to

lern And scientist must do lot of thinking Justmemorizing isnt good enough.

And scientst needs nmgintion ter you hvelerned lot bout subject

nd hought bout it you needto wonder why re there somny things we do not knowbout it?

I guess you coud sy thtbeng scentist tkes lot ofhed work

! I

58

When you openyour eyes wide, whydo your pupisbecome smaer?

L. SithHaon Lousisiana

tred tht in ront of

mirror nd I think t worksust s you sy. For me itsmuch esier to see if! ut u hnd to rtly shde my eyesIf I shde them so tht lesslight flls on my eyes theuils get bigger. hen f Itke my hnd wy so thtmore lght fs on my eyes theuls get smller

he ui of your eye s thelittle blck sot n the center othe colored circe he ui sthe window of your eye theonly lce where light cn getn he coored circle round is clled the iris. It is littecrculr sheet of musce thtcn mke the uil rger orsmller. he iris muscle scontroled by nerves thtconnect to gve net refex

ction the kind of nervecotrol you never think boutht wy the iris worksutomticlly to regulte thesze of the uil nd themount of light tht it lets intyour eyes

ou cn se e ll this henby lookng t your own eyes in well-lighted mirror.


65/68

I'd ike you to clearup something for meCan e human eyeslow down the visuaspeed of somethingthat's going fasterthan i ooks ike? Afew nights ago I wasying in my bed andwatching the ceiingfan I as fourbades and it was ona medium speedwhere al you could

see was a bur ofbades Ten I sartedbinking very fastand I could see hefour bades Was Iimagining or not?

Anh TanMusang Oahma

I thnk you mde very

nterestng dscovery I thnkyou were gettng wht s ced trobocopic effect To

thnk bout t ets tk boutn nstrument tht s ced stroboscope Ths hs fshmp ke the knd used wth cmer t gves very shortfsh of ght ess thn onethousndth of second ong. tso hs tmer to mke themp fsh gn nd gn tsome stedy rte The rte cnbe chosen by turnng d togve number from 5 to 00 ormore fshes per second

Now suppose we hve whee tht s turned by neectrc motor nd we wnt toknow how fst t s turnng Wemke mrk ner the edge ofthe whee nd then turn on the

motor. Now we sowy ncresethe fshng rte of ourstroboscope unt we get toexcty the rght rte mybe30 per second We w knowtht we hve found the rghtrte becuse then the wheew seem to stop nd the mrkw seem to sty n one pce.The we w know tht themotor nd whee re turnng t

30 revoutons per second Ofcourse prt of the reson thsworks s tht your eye keeps

"seeng for tte whe fterech fsh. Tht wy theeffects of the fshes justbur ogether

Another wy to mke stroboscope s to hve shuttertht woud open for very shorttmes over nd over nd woudbe operted by tmer. Thenwe coud shne brght ght on

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How Do We Dream