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以下，是这次环球托福为正在进行托福备考的考友们整理了托福TPO24阅读真题及答案LakeBreathingDuringSleep。我们建议考友们，先做真题，后看答案进行验证自己的正
确率。之后stemhasexclusivecontroloverbreathingandthebody
usesless
oxygenandproduces
lesscarbon
dioxide.
Also,
during
sleep
the
automatic
metabolicsystemislessresponsivetocarbondioxidelevelsandoxygenlevelsin
during
,
theremaybeabriefcessationorreduction
ofbreathingwhen
falling
asleep
asthe
sleeper
waxesandwanesbetweensleep
andwakefulness
andtheir
,oncesleepisfullyobtained,thereisan
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increase
ofcarbondioxide
andadecrease
ofoxygenin
the
blood
that
persists
during
NREM.
,severalchangesin
theair
passageshavebeenobserved.
It
takes
twice
asmucheffort
to
breathe
during
sleepbecauseofgreaterresistancetoairflowintheairwaysandchangesinthe
theupperairwayopenwhenbreathingtendtobecomemorerelaxedduringsleep,
especiallyduringREM(thephaseofsleepinwhichthereisrapideyemovement).
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Withoutthismuscularaction,inhalingislikesuckingairoutofaballoon
—the
resistance
"good"side,
suchascongestion
fromallergies
or
acold,
thenresistance
increases
dramatically.
Coupledwith
these
factors
is
the
loss
ofthe
complex
interactions
amongthe
muscles
thatcanchangetherouteofairflowfromnosetomouth.
Otherrespiratory
regulating
mechanismsapparently
ceasefunctioning
during
sleep.
Forexample,
during
wakefulness
there
isanimmediate,aut