ARTICLE-A-DAY™
The Human Body
6 Articles
Check articles you have read:
Skin: The Great Protector
267 words
Move Your Muscles!
990 words
Now Hear This! Care for Your Ears
975 words
Three Cheers for Ears!
971 words
Pumping Up the Heart
343 words
Rise Up
892 words
Page 1 of 19
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Skin: The Great Protector
Skin: The Great Protector
Your body is constantly unde r attack. Dirt and g e rms surround your body. Only one thing stands
be twe e n dirt and the org ans inside your body-skin.
The Largest Organ
Skin may not se e m ve ry important, but it is. It prote cts your body from burns, dirt, g e rms, and
dang e rous rays from the sun. It ke e ps fluids inside your body. And it contains all the ne rve s that
allow you to fe e l thing s.
Skin is the larg e st org an in your body. If you stre tche d out an adult's skin into a flat she e t, it
would cove r an are a of about 21 square fe e t. A square foot is a square whose side s e ach me asure 1
foot.
Skin may cove r a larg e are a, but it is ve ry thin. It is only about 1/8 inch thick. De spite be ing so thin,
skin is made of thre e laye rs. The oute rmost laye r is the e pide rmis. Just be low the oute rmost laye r
is the de rmis. Be ne ath those two laye rs is the subcutane ous tissue .
The Layers
The e pide rmis contains a che mical calle d ke ratin. Ke ratin make s skin toug h and wate rproof.
Ke ratin ke e ps g e rms out of your body.
The de rmis is mainly made of blood ve sse ls and ne rve e nding s. The de rmis provide s the
e pide rmis with food and oxyg e n.
The lowe st laye r, the subcutane ous tissue prote cts the body from blows. It also re g ulate s the
body's te mpe rature .
All thre e laye rs of your skin prote ct you. Be cause your skin prote cts you, you should prote ct it by
ke e ping it cle an and e ating a he althful die t. You should use sunblock whe n you are in the sun. If
you take care of your skin, it will last a life time .
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Move Your Muscles!
Move Your Muscles!
By Sharo n Guynup
Muscles keep you on the go. Here’s how they work and
why you need to keep them in tip-top shape.
Photos.com
Picture this: You’ re out shooting hoops with your frie nds. As you take a jump shot, you sudde nly
fe e l your le g twist be ne ath you. Ouch! You mig ht have spraine d your ankle . But why did you sprain
it? How can you ke e p from hurting it ag ain? What is a sprain, anyway?
It all has to do with your muscle s (more on that sprain late r). Whe n you walk down the stre e t,
ride your bike , or e ve n ye ll he llo to a frie nd, you are using muscle s. The g ood ne ws: Eve ryone can
have strong e r muscle s and pre ve nt injurie s.
Muscles: A Lot of Work!
More than 630 muscle s ke e p your body g oing . The y make up about 40 pe rce nt of your body
we ig ht. Some muscle s—like your he art—work without your having to do a thing . Those are calle d
involuntary muscles. Othe r involuntary muscle s include those that he lp you dig e st your food and g o
to the bathroom. Anothe r type of muscle is skeletal muscle. Those are the muscle s you control. The y
he lp you run, jump, and do all kinds of activitie s. And the y can be injure d if you don’ t take prope r
care of the m.
Ske le tal muscle s are diffe re nt size s and shape s, de pe nding on the ir job. Back muscle s are some
of the big g e st and strong e st muscle s in your body be cause the y hold you uprig ht. Smalle r
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Move Your Muscles!
muscle s in your hands le t you be nd your fing e rs.
Ske le tal muscle s work in a simple way. The y re act whe n the y re ce ive e le ctrical sig nals from your
ne rve s and brain. For e xample , whe n you swing a bat to whack a base ball, a ne rve sig nal trave ls
from your brain to your arm muscle s, making the m move . Ne rve sig nals also le t your brain know
whe the r a muscle has be e n hurt (if you twist your arm while swing ing that bat).
What Pain Means
Taking g ood care of your muscle s can he lp pre ve nt you from sitting on the side line s. This
happe ne d to Anita R., a 10-ye ar-old socce r playe r from Ne w York City. Anita fe lt pain unde r he r
rig ht kne e cap. "If I put pre ssure on it or we nt up and down the stairs a lot, it would sting and
throb," Anita says. He r doctor thoug ht that she "was kicking more [with] one le g and had more
muscle in that le g than in the othe r." Anita had to g o to physical the rapy, whe re she did e xe rcise s
to he lp he r kne e he al.
Muscle s, lig ame nts, and te ndons can te ar if you push the m too hard. A toug h run mig ht le ad to a
pain in your le g . How do you know what’ s happe ning whe n you fe e l a pain in a muscle ? He re ’ s
what mig ht be g oing on.
Aches may be cause d by te nsion, ove ruse , or muscle injury from hard e xe rcise .
Sprains and strains can also re sult from be ing active . A sprain is a stre tche d or torn lig ame nt.
Such an injury mig ht happe n if you trip or fall. One -third of all sports injurie s are sprains. A
strain is a torn or pulle d muscle or te ndon. It can happe n whe n you pick up some thing he avy.
A repetitive stress injury (RSI) is a damag e d muscle , te ndon, or lig ame nt cause d by making
the same hand or wrist motion ag ain and ag ain. Te e ns who spe nd a lot of time playing musical
instrume nts or vide o g ame s are at risk for RSIs. Two RSIs are tendonitis, a swolle n te ndon, and
carpal tunnel syndrome, which is cause d by swe lling in a tunne l-shape d are a forme d by bone and
lig ame nts in the wrist.
To avoid hurting your muscle s, warm the m up be fore e xe rcising , says David Waymann, an e xe rcise
physiolog ist at the Unive rsity of Michig an He alth Syste m. Walk or jog in place for at le ast five
minute s to g e t blood to your muscle s. "Don’ t use stre tching as a substitute for a warm-up,"
Waymann says. Afte r e xe rcising , cool down by walking slowly. Finally, stre tch for a fe w minute s
to ke e p joints and muscle s from g e tting stiff.
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Move Your Muscles!
Ke e ping your we ig ht at a he althy le ve l can ke e p your joints safe from e xtra strain, advise s Dr.
Le tha Griffin, an orthope dist in Atlanta.
Whe n you are n’ t active , muscle s can g e t we ak and shrink. Use the m or lose the m! Exe rcise
re g ularly to stre ng the n muscle s. Don’ t play whe n you’ re tire d, sick, or in pain, and don’ t ove rdo
it. Take care of your muscle s, and the y’ ll ke e p you on the g o!
Fun Facts About Muscles
Whe re are the busie st muscle s in your body? In your e ye s! Scie ntists e stimate that the e ye
muscle s move about 100,000 time s a day.
Your muscle s are always partly contracte d. That maintains muscle tone , ke e ping muscle s firm
and he althy. It is the only ske le tal muscle activity that you cannot control.
The body’ s larg e st muscle is the g lute us maximus muscle in the buttocks.
Growing pains can cause inte nse muscle ache s in your le g s. The y usually start be fore be dtime
and some time s continue throug h the nig ht. The y usually stop whe n kids stop g rowing .
Muscles On the Move
Skeletal muscles, along with bones, joints, tendons, ligaments, and
cartilage, make up the musculoskeletal system. Here’s what they do:
Join ts are fle xible conne ctions whe re two or more bone s me e t. Two e xample s are e lbows and
kne e s.
Bone s are he ld tog e the r by strong straps of tissue calle d ligamen ts. Think of lig ame nts as
se at be lts that ke e p your joints in place .
The ske le tal muscle s are attache d to bone s by toug h cords calle d ten don s. Te ndons and
bone s move along with your muscle s, such as whe n you wave your hand or tilt your he ad.
Slippe ry, rubbe ry cartilage make s the conne ctions be twe e n the bone s fle xible . Cartilag e also
prote cts bone s from we ar and te ar.
Muscle s contain fibe rs. Slow - tw itch muscle fibers can work hard for a long time without
g e tting tire d on a long run or bike ride . Fast- tw itch fibers he lp with quick move me nts, such as
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Move Your Muscles!
jumping to catch a ball or sprinting . Most muscle s are a mixture of slow- and fast-twitch
fibe rs.
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Now Hear This! Care for Your Ears
Now Hear This! Care for Your Ears
Eve ryone in the pe t store he ard it. It was a young child's voice , but ve ry, ve ry loud. "HELLO, MR.
TURTLE!" it said. "HELLO! HELLO!"
"Sh-h-h," said the voice 's mothe r. "Why are you ye lling so loudly at the turtle ?"
"He doe sn't have any e ars!" the child waile d. "He can't he ar me unle ss I talk loud."
"Ye s, he doe s," the mothe r e xplaine d. "You just can't se e the m. The y are n't on the outside of his
he ad like ours."
The child in the pe t store was looking for the turtle 's outer ears. Turtle s don't have the m, but
humans do. The oute r e ar doe s se ve ral jobs. It g athe rs sound wave s and produce s e arwax. It e ve n
allows you to ide ntify whe re sounds come from.
The oute r e ar is calle d the pinna (PIN-uh) or auricle (OR-ric-le ). It is made up of cartilag e and
skin. The re are no bone s in your oute r e ars, but re ad on! The oute r e ar g athe rs in sound wave s
moving throug h the air be cause of its she ll shape .
Ne xt the sound wave s g o down the funne l-shape d e ar canal. Spe cial g lands in the skin of the
oute r e ar canal produce e arwax. This sticky, g ummy wax pre ve nts the skin of the oute r e ar canal
from be coming dry and scaly. Earwax also traps dirt and discourag e s inse cts from e nte ring the
e ar. Whe n the wax be come s dry, it flake s off, carrying dust and dirt with it. The n the se g lands
make ne w e arwax.
Ears working as a pair he lp te ll you whe re a sound is coming from. If a sound come s from your
le ft, the n the sound wave s e nte ring your le ft e ar will arrive at your brain slig htly be fore the
sound wave s e nte ring your rig ht e ar. Your brain the n te lls you that the sound is coming from your
le ft. Your brain also use s how loud a sound is to de cide whe re it came from. This proce ss is calle d
sound localization (low-kul-ih-ZAY-shun).
The Middle Ear
The e ardrum is made up of thre e laye rs. The oute r laye r is a thin part of the skin of the e ar canal.
The ce nte r laye r of the e ardrum vibrate s with the sound colle cte d by the oute r e ar. It is prote cte d
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Now Hear This! Care for Your Ears
by the othe r laye rs be cause it continue s to g row. It can he al itse lf if it be come s torn or puncture d.
The inside laye r is a me mbrane that continue s in the middle e ar.
The middle e ar be g ins at the e ardrum, which is like the he ad of a drum. It vibrate s with sound.
He re is whe re your "e ar bone s" come into play. Thre e tiny bone s, calle d ossicles (OS-ik-ulz), are
be hind the e ardrum. The y he lp carry the sound. The malleus (MAL-le -us), or hammer, which looks
some thing like a hamme r, is the first bone . It attache s to the e ardrum. The se cond bone is the
incus (IN-kus), or anvil. It attache s to the hamme r. The third bone is the stapes (STAY-pe e z), or
stirrup. It attache s to the anvil. Whe n the e ardrum vibrate s with sound, it se ts first the hamme r,
the n the anvil, and the n the stirrup into motion.
The middle e ar also he lps balance the pre ssure on the inside of the e ardrum. This he lps prote ct it
from injury. The Eustachian (you-STAY-shun) tube conne cts to the back of the throat and acts like
a pre ssure valve .
The tube de cre ase s pre ssure whe n you coug h or swallow, cre ating a popping sound. Some time s
whe n you are in an airplane , your e ars "pop" se ve ral time s. That's your Eustachian tube ope ning
and re ducing the pre ssure be hind your e ardrum.
The Inner Ear
The inne r e ar has two jobs: It chang e s sound into ne rve sig nals, and it he lps you ke e p your
balance . A round structure calle d the cochlea (COKE-le e -uh) is fille d with liquid and line d with tiny
hairs. The se chang e as sound vibrations pass throug h the liquid and se t various hairs in motion.
The y chang e sound into ne rve sig nals, which your brain can unde rstand.
Diffe re nt pitche s of sound and diffe re nt volume s will vibrate various hairs and diffe re nt numbe rs
of hairs. The ne rve sig nals are the n take n by the auditory (AUD-uh-tore -e e ) ne rve to your brain.
Thre e small loops locate d be hind the cochle a are calle d semicircular canals. The y, too, are fille d
with liquid and line d with hairs. The y he lp you to ke e p your balance . Each time you move , the
moving liquid and the move me nt of the hairs te ll your brain what position your he ad is in.
Your brain te lls your body which muscle s to move to he lp ke e p you uprig ht. But some time s your
brain g e ts tricke d. Your e ye s te ll your brain that you have stoppe d twirling around, but the liquid
in your e ars ke e ps moving . One me ssag e says you are still moving . The othe r me ssag e says you
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Now Hear This! Care for Your Ears
have stoppe d. You fe e l dizzy until your brain g e ts only one me ssag e .
Protect Your Ears
You now know that your e ars do some important jobs. For the m to be the ir he althie st, you must
he lp prote ct the m from infe ction and injury. Follow the se simple ste ps:
1. Ke e p your oute r e ars cle an and dry. A little soap and warm wate r on a cle an washcloth are all
you ne e d. Dry your e ars care fully with a soft towe l.
2. Do not put anything in your e ars. Pe riod. Obje cts can injure the canal or e ve n the e ardrum. This
can le ad to infe ction.
3. Cove r your e ars in cold we athe r to pre ve nt frostbite .
4. Prote ct your he aring from ve ry loud noise . Turn down the volume on your he adphone s. We ar
e arplug s in noisy place s.
5. Using a sunscre e n? Don't forg e t to rub some on and be hind your e ars.
With prope r care , your e ars will g ive you a life time of he aring e njoyme nt. Take time to notice all
the sounds you can he ar whe n you are inside and outside . Close your e ye s. Now ide ntify all the
sounds you can he ar. Appre ciate your se nse of he aring .
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Three Cheers for Ears!
Three Cheers for Ears!
Jake pulle d a portable CD playe r from his backpack and se ttle d in for the long bus ride to the
scie nce muse um. "You're lucky," Sam said as he plunke d himse lf down on the se at be side him.
"My mom won't le t me liste n to music with he adphone s. She says if it's too loud, it can make you
g o de af."
"I sure hope not," said Jake . "My g randpa is losing his he aring . Now he has to we ar a he aring
aid."
At the muse um, Jake and Sam de cide d to find out if Sam's mom was rig ht. The y he ade d ove r to the
human body e xhibit and stood in front of a g ig antic mode l of an e ar. A muse um g uide was
e xplaining how e ars he lp you he ar. "That flap on the side of your he ad is only a part of your whole
e ar," she said. "Tiny, complicate d structure s inside your e ar do the main job of he aring ."
Jake and Sam move d close r to the mode l. "He y, look, it says the re 's a drum," said Sam.
"And a hamme r," adde d Jake .
"That's rig ht," the g uide e xplaine d. "The e ardrum is a thin pie ce of skin that's stre tche d tig ht like
a drum. It vibrate s or move s ve ry fast whe n sound wave s hit it. The se vibrations are carrie d to
thre e tiny bone s calle d the hamme r, anvil, and stirrup. The y conduct, or pass, the vibrations to
your inne r e ar, whe re the y are chang e d into ne rve sig nals and se nt to your brain. Your brain
make s se nse of the sounds you he ar."
What Is Hearing Loss?
"What happe ns whe n you can't he ar?" Jake aske d.
"That de pe nds," the g uide re plie d. "If some thing like wax, for e xample , g e ts stuck in your e ar
canal, it can block sound wave s from g e tting to your e ardrum. This type of proble m is calle d
conductive he aring loss."
"Ew-w-w! Earwax is g ross," said Sam.
"Actually, e arwax prote cts your e ars," the g uide e xplaine d. "It contains spe cial che micals that
fig ht infe ctions and pre ve nt dust and dirt from g e tting inside . Plug your e ars with your fing e rs,
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Three Cheers for Ears!
and you'll know what conductive he aring loss is like ."
"The sounds outside are soft, but my own voice sounds re ally loud," said Sam.
"Has anyone e ve r had an e ar infe ction?" the g uide aske d.
Most of the kids nodde d.
"We ll, an infe ction can also make you lose your he aring for a while ." The g uide continue d, "If the
tube that g oe s from your middle e ar to the back of your throat g e ts blocke d, g e rms can g e t
trappe d inside . Your e ar will hurt and fe e l like it's re ady to burst. Whe n the doctor looks with a
spe cial flashlig ht, the e ardrum appe ars re d and doe sn't move in and out as it should. If you have
an e ar infe ction, you may have to take me dicine for it. Some time s doctors have to ope rate to ope n
up blocke d tube s or put in ne w tube s to ke e p the middle e ar from g e tting infe cte d.
"Sensory (SEN-suh-re e ) he aring loss me ans part of the inne r e ar is not working . A pe rson may
he ar some sounds but not othe rs, or sounds may be muffle d. Se nsory he aring loss can be cause d
by a numbe r of thing s. Some time s the e ars don't de ve lop prope rly be fore a baby is born. The re
are also some se rious infe ctions that can cause se nsory he aring loss in kids. Se nsory he aring loss
is usually pe rmane nt. Kids with se nsory he aring loss may ne e d to we ar he aring aids."
Did You Know?
Your e ars are amazing structure s. He re are some fascinating facts about e ars and he aring .
The thre e bone s in your e ar that he lp you he ar are the smalle st bone s in your body.
The famous compose r Ludwig van Be e thove n (1770-1827) starte d to lose his he aring whe n he
was just 26. He wrote some of his g re ate st music without be ing able to he ar it.
He aring te sts te ll how we ll your e ars work. To take the te st, you we ar he adphone s and sit in a
spe cial room so you don't he ar any stray noise . A machine make s diffe re nt tone s. You liste n
first with one e ar and the n the othe r and raise your hand e ach time you he ar a sound. The tone s
start loud and g e t softe r and softe r until you can't he ar the m anymore . That te lls the doctor
how we ll you can he ar.
Eve r wonde r why your e ars fe e l funny in a tunne l or on an airplane ? The re is air both inside
and outside your e ardrum. To balance the air pre ssure , you ne e d to le t more air into the inside
of your e ar. Yawning , che wing , swallowing , or blowing your nose until your e ars "pop" he lps
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Three Cheers for Ears!
you he ar normally ag ain.
Now Hear This
"What about loud music?" Sam wante d to know. "Can that make you lose your he aring ?"
"Any kind of loud noise can damag e your he aring if it g oe s on for a while ," the g uide e xplaine d.
"If the music is so loud that your e ars start hurting or you have to ye ll to be he ard ove r it, the re 's a
g ood chance your e ars could be injure d."
"What if you liste n with he adphone s?" aske d Jake . "Sam's mom says the y're bad for your e ars."
"She 's partly rig ht. If some one standing ne ar you can he ar music coming throug h e arphone s you
are we aring , the music is too loud." The g uide we nt on, "Liste ning to loud noise can cause tinnitus
(TIN-uh-tus), which is the te rm for ring ing in your e ars. If the noise isn't too loud and you don't
liste n too long , your he aring can re turn to normal. But you can damag e your he aring pe rmane ntly
if the noise is too loud or you are e xpose d to it too long . That's why construction worke rs we ar
e ar prote ction. The ir e quipme nt can be e xtre me ly loud.
"Using he adphone s can be dang e rous if the volume is too hig h. Don't crank it up, and you should
be fine as long as you g ive your e ars a re st once in a while ."
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Pumping Up the Heart
Pumping Up the Heart
Make a fist with one of your hands. Your fist is about the size of your he art.
Your he art be ats be twe e n 85 and 90 time s pe r minute . It pumps about 5 quarts of blood throug h
your body's 60,000 mile s of blood ve sse ls in one minute !
Eve n thoug h the he art is a powe rful muscle , many pe ople 's he arts don't work prope rly. A study
by Dr. Eric Rose indicate s that a me chanical pump mig ht he lp many of those patie nts.
Pump May Save Lives
Some pe ople 's he art muscle s are so we ak that the he art can't pump e noug h blood throug h the
body. That condition is calle d he art failure , and it can be de adly.
Leigh Haeger
The drawing shows some parts of the heart.
Look up what each part does.
A re port from the Ame rican He art Association says about a little more than 5 million Ame ricans
suffe re d from he art failure in 2013. Anothe r re port says that about 400,000 Ame ricans de ve lop it
e ach ye ar.
Powe rful drug s or a he art transplant can he lp many pe ople who suffe r from he art failure . But the
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Pumping Up the Heart
drug s don't always work, and he art transplants are risky.
For ye ars, doctors have inse rte d a me chanical pump in the bodie s of some patie nts who we re
waiting for a he art transplant. The pump he lpe d the he art do its job.
The study by Dr. Rose shows that the pump could be use d pe rmane ntly, inste ad of a he art
transplant. Pumps may be able to save the live s of up to 100,000 Ame ricans a ye ar, the study says.
The VAD
The me chanical pump is known as a VAD, or ve ntricular assist de vice . VADs come in se ve ral size s
and shape s. The smalle st pump size s can be implante d in a pe rson's he art and be lly. A tube g oe s
from the pump throug h the skin to a control unit place d on the pe rson's waistline . The control
unit is conne cte d to at le ast one batte ry pack that sits in a strap by the side of the pe rson’ s body.
"This te chnolog y is g oing to make hug e le aps in the ne xt two to thre e ye ars," he art surg e on
Robe rt Kormos pre dicte d.
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Rise Up
Rise Up
By Stephen Fraser
A treatment enabled a paralyzed man to stand and take
steps again.
It was an e ve ning in July 2006. The Be ave rs, Ore g on State Unive rsity’ s base ball te am, had
re ce ntly won the Colle g e World Se rie s. One of the te am’ s pitche rs, Rob Summe rs, 20, was
re trie ving his g ym bag from his parke d car whe n anothe r car hit him. “The car the n drove off,
le aving me the re with no he lp,” says Summe rs.
Courtesy Rob Summers
The impact re nde re d Summe rs paraplegic—unable to move his lowe r body. His doctors told him
he ’ d ne ve r walk ag ain—hard ne ws for an active young man to he ar.
“The y told me that I had no hope ,” says Summe rs. “My comme nt was, ‘You don’ t know me ve ry
we ll. I’ m g oing to fig ht until I g e t we ll ag ain.’ ”
Five ye ars late r, Summe rs re g aine d the ability to stand and could take ste ps on a tre admill. His
re cove ry “re mains unpre ce de nte d,” Europe an re se arche rs comme nte d in the British me dical
journal The Lancet. “We are e nte ring a ne w e ra.”
Information Highway
The car that hit Summe rs se riously injure d the lowe r part of his spinal cord—the column of ne rvous
tissue that runs throug h the backbone . It carrie s me ssag e s to and from the brain, the body’ s
ce ntral org an. Radiating outward from the spinal cord is a we b of motor neurons, which g ove rn
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move me nt. The damag e done to Summe rs’ s spinal cord stoppe d the brain’ s me ssag e s from
re aching many of the motor ne urons in his lowe r body, pre ve nting him from standing or walking .
Courtesy Rob Summers
Rob Summers after the accident that
rendered him a paraplegic.
Afte r the accide nt, Summe rs unde rwe nt two ye ars of standard the rapy—muscle massag e s,
le ssons in how to use a whe e lchair, and the like . Be fore the n, little more could be done for
paraple g ic patie nts. Summe rs had the g ood fortune , thoug h, to be chose n for an e xpe rime ntal
re se arch proje ct. “Rob was an ide al candidate ,” says one of the proje ct’ s re se arche rs, Susan
Harke ma, a profe ssor of ne urosurg e ry at the Unive rsity of Louisville in Ke ntucky. “He was young
and in othe rwise g ood he alth. He ’ s also a ve ry de te rmine d, discipline d pe rson —an e xtraordinary
young man.”
Courtesy Rob Summers
Summers stood with his father, Mike
Summers.
In a four-and-a-half-hour ope ration, the re se arch te am implante d e le ctrode s in Summe rs’ s
spinal cord. The e le ctrode s we re the n wire d to a pulse g e ne rator that was implante d in his back.
The pulse g e ne rator is re mote ly controlle d by a de vice outside the body.
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Body’s Wiring
Afte r the surg e ry, Harke ma and he r te am be g an the tre atme nt. The y switche d on the pulse
g e ne rator for two hours a day, e le ctrically stimulating the ne rve s in his spinal cord. Ne rve s can
re spond to e le ctrical stimulation be cause the me ssag e s the y carry take the form of e le ctric
sig nals. Ne rve s are the body’ s “wiring .”
On the third day of e le ctrical stimulation, Summe rs was able to stand with assistance . “It was
unbe lie vable ,” he says. “The re was so much g oing throug h my he ad at that point. I was amaze d; I
was in shock.”
By 2012, Summe rs could not only stand but also could walk slowly on a tre admill with the aid of an
assistant and a supporting harne ss. He was able move his hips, kne e s, ankle s, and toe s
voluntarily. The e xe rcise had e nable d his le g muscle s to re g ain some of the ir forme r mass.
Sensory Signals
The brain doe s more than just control move me nt. It re ce ive s me ssag e s from all parts of the body.
Many of the me ssag e s come from the e ye s, e ars, nose , skin, and muscle s. Those me ssag e s trave l
by way of the sensory neurons. Summe rs’ s spinal cord wasn’ t totally damag e d. It could still re ce ive
limite d se nsory sig nals from the muscle s in his lowe r body.
That re sidual fe e ling in his lowe r body mig ht be what e nable d the e xpe rime ntal tre atme nt to
succe e d, says Harke ma. Se nsory me ssag e s from the le g s mig ht have be e n trave ling to
Summe rs’ s e le ctrically stimulate d spinal cord, prompting it to se nd sig nals along the motor
ne urons and make the le g s move .
“Our big finding is that the spinal cord is as sophisticate d as the brain,” says Harke ma. “It has a
me mory. Whe n you walk, it re me mbe rs that you are on two le g s or one . The spinal cord basically
take s information from the brain and the n handle s all the de tails. We didn’ t know that be fore .”
Patie nts who don’ t have some physical se nsation, as Summe rs doe s, may not be he lpe d by the
tre atme nt, says Harke ma.
Body Control
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Frazier Rehab Institute; Courtesy
Rob Summers
Monitoring Summers’ Leg
Movements Right: Neurosurgeon
Susan Harkema
Spinal cord damag e can do more than impair limb function. Victims can lose bladde r and bowe l
control. Those functions are re g ulate d by anothe r part of the ne rvous syste m—the autonomic
nervous system—that radiate s from the spinal column. It controls automatic proce sse s in the body,
such as he art rate , blood pre ssure , swe ating , and salivation. Summe rs has re g aine d function in his
bladde r and bowe ls. He also has be e n able to discontinue a varie ty of e xpe nsive me dications
pre scribe d to alle viate pain and pre ve nt he art dise ase .
“Now I can stand,” says Summe rs. “I’ ve g otte n my confide nce back to just g o out in public.” His
g oal is to stand and walk comple te ly normally. “I’ m working toward that e ve ry day.”
Broken Cord
The spinal cord carrie s ne rvous sig nals back and forth be twe e n the brain and the re st of the body.
An injury to it can cause a comple te or partial loss of function de pe nding on the se ve rity of the
damag e .
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KRT/Newscom
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