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GASEOUSEXCHANGE
AND
RESPIRATORY
SYSTEM
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Gaseous exchange occurs at gasexchange surfaces．
• The part of the organism throughwhich
oxygen enters and goes out of thebody is called the gas
exchangesurface．
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Proper!es of gaseousexchange
surface• The" shou#$ %e h!n o a##o& gases o
$!'use across he exchange surface• The" shou#$ %e c#ose o
an e(c!en ranspor s"se) o a*e gases o an$ fro) he ce##s
&h!ch nee$ he)• The" shou#$ %e *ep )o!s o sop he
ce##s on he surface fro) $r"!ng an$ $"!ng•
Shou#$ ha+e a #arge surface area for exchange of gases so ha
a #o of gas can %e exchange$ a sa)e !)e,• Shou#$ ha+e a
goo$ supp#" of ox"gen
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4
GAS EXCHAGE
!hat factors are important in gasexchange"
!hat factors a#ect gastransfer"
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$%& Gaseous exchange occurs in therespiratory system．
• asal ca'ity
• (harynx• )arynx
• !indpipe*trachea
• +ronchi
• )ungs
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$
The ,espiratory -rgans
Conducting .one – ,espiratory passages
that carry air to thesite of gas exchange
– /ilters0 humidi1es andwarms air
,espiratory .one – Site of gas exchange
–
Composed of • ,espiratorybronchioles
• Al'eolar ducts
• Al'eolar sacs
Conducting .one labeled
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2
ose
• (ro'ides airway
• 3oistens and warms
air• /ilters air
• ,esonating chamber
for speech• -lfactory receptors
External nose
Conducting zone will be covered frst
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The )arynx 5'oicebox6
• Three functions7
8% (roduces 'ocali.ations 5speech6
9% (ro'ides an open airway 5breathing6
:% Switching mechanism to route air and foodinto proper
channels• Closed during swallowing
•
-pen during breathing
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8;
/ramewor< of the larynx
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88
Trachea 5the windpipe6
•=escends7 larynx through nec< into mediastinum
• =i'ides in thorax into two main 5primary6 bronchi
• 8$*9; C*shaped rings
of cartilage co'ers the
trachea• /lexible for bending
but stays open despite
pressure changes
during breathing• !all of trachea has layers• common to
many tubular• organs >
-#ers. &ar)s an$
)o!sens !nco)!ng a!r
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89
)ungs
•
Each is cone*shaped with anterior0 lateraland posterior surfaces
contacting ribs
• Superior tip is apex0 ?ust deep to cla'icle
• Conca'e inferior surface resting on
diaphragm is the base
apex apex
base base
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8:
)ungs and(leura
• @nside lungs 1ne air sac > li outerlayerVisceral
pleura > directlyon lung
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/EAT,ES -/ ,ES(@,AT-,D
S,/ACE * A)E-)@
• They are 'ery thin．
• They ha'e an excellent transportsystem．
pulmonary artery , capillarities , pulmonary
vein
• They ha'e a large surface area%
over 100m2
•
They ha'e a good supply of oxygen%
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