Pediatric Respiratory Care,
6th Edition by Brian
,Chapterv1:vFetalvLungvDevelopmentvTestvB
ank
MULTIPLEvCHOICE
1. Whichvofvthevfollowingvphasesvofvhumanvlungvdevelopmentvisvcharacterizedvbyvthevformationvofvav
capillaryvnetworkvaroundvairwayvpassages?
a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS:v D
Thevcanalicularvphasevfollowsvthevpseudoglandularvphase,vlastingvfromvapproximatelyv17vweeksv
tov26vweeksvofvgestation.vThisvphasevisvsovnamedvbecausevofvthevappearancevofvvascularvchannels,v
orvcapillaries,vwhichvbeginvtovgrowvbyvformingvavcapillaryvnetworkvaroundvthevairvpassages.vDurin
gvthevpseudoglandularvstage,vwhichvbeginsvatvdayv52vandvextendsvtovweekv16vofvgestation,vthevai
rwayvsystemvsubdividesvextensivelyvandvthevconductingvairwayvsystemvdevelops,vendingvwithvthevt
erminalvbronchioles.vThevsaccularvstagevofvdevelopment,vwhichvtakesvplacevfromvweeksv29vtov36vo
fvgestation,visvcharacterizedvbyvthevdevelopmentvofvsacsvthatvlatervbecomevalveoli.vDuringvthevsacc
ularvphase,vavtremendousvincreasevinvthevpotential
gas-
exchangingvsurfacevareavoccurs.vThevdistinctionvbetweenvthevsaccularvstagevandvthevalveolarvs
tagevisvarbitrary.vThevalveolarvstagevstretchesvfromv39vweeksvofvgestationvtovterm.vThisvstagevisv
representedvbyvthevestablishmentvofvalveoli.
REF:v pp.vvv 3-5
2. Regardingvpostnatalvlungvgrowth,vbyvapproximatelyvwhatvagevdovmostvofvthevalveolivthatvwillvbe
presentvinvthevlungsvforvlifevdevelop?
v
a. 6vmonths
b. 1vyear
c. 1.5vyears
d. 2vyears
ANS:v C
Mostvofvthevpostnatalvformationvofvalveolivinvthevinfantvoccursvovervthevfirstv1.5vyearsvofvlife.vAtv2v
yearsvofvage,vthevnumbervofvalveolivvariesvsubstantiallyvamongvindividuals.vAfterv2vyearsvofvage,v
malesvhavevmorevalveolivthanvdovfemales.vAftervalveolarvmultiplicationvends,vthevalveolivcontinuev
tovincreasevinvsizevuntilvthoracicvgrowthvisvcompleted.
REF:vp.v6
3. Thevrespiratoryvtherapistvisvevaluatingvavnewbornvwithvmildvrespiratoryvdistressvduevtovtrachealvste
nosis.vDuringvwhichvperiodvofvlungvdevelopmentvdidvthisvproblemvdevelop?
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
ANS:v A
, Thevinitialvstructuresvofvthevpulmonaryvtreevdevelopvduringvthevembryonalvstage.vErrorsvinvdevelo
pmentvduringvthisvtimevmayvresultvinvlaryngeal,vtracheal,vorvesophagealvatresiavorvstenosis.vPulmo
naryvhypoplasia,vanvincompletevdevelopmentvofvthevlungsvcharacterizedvbyvanvabnormallyvlowvn
umbervand/orvsizevofvbronchopulmonaryvsegmentsvand/orvalveoli,vcanvdevelopvduringvthevpseu
doglandularvphase.vIfvthevfetusvisvbornvduringvthevcanalicularvphasev(i.e.,vprematurely),vseverevre
spiratoryvdistressvcanvbevexpectedvbecausevthevinadequatelyvdevelopedvairways,valongvwithvins
ufficientvandvimmaturevsurfactantvproductionvbyvalveolarvtypevIIvcells,vgivesvrisevtovthevconstellati
onvofvproblemsvknownvasvinfantvrespiratoryvdistressvsyndrome.
REF:vvvp.v6
4. Whichvofvthevfollowingvmechanismsvisv(are)vresponsiblevforvthevpossiblevassociationvbetweenvoligo
hydramniosvandvlungvhypoplasia?
I. Abnormalvcarbohydratevmetabolism
II. Mechanicalvrestrictionvofvthevchestvwall
III. Interferencevwithvfetalvbreathing
IV. Failurevtovproducevfetalvlungvliquid
a. IvandvIIIvonly
b. IIvandvIIIvonly
c. I,vII,vandvIVvonly
d. II,vIII,vandvIVvonly
ANS:v D
Oligohydramnios,vavreducedvquantityvofvamnioticvfluidvpresentvforvanvextendedvperiodvofvtime,
withvorvwithoutvrenalvanomTalie
E Ss,TviBsva
AsNsoKcia
S te
EdL LwEithRvlu
. CnO hypoplasia.vThevmechanismsvbyvvwhichvamnioticvflu
gvM
idvvolumevinfluencesvlungvgrowthvremainvunclear.vPossiblevexplanationsvfor
reducedvquantityvofvamnioticvfluidvincludevmechanicalvrestrictionvofvthevchestvwall,vinterferencevw
ithvfetalvbreathing,vorvfailurevtovproducevfetalvlungvliquid.vThesevclinicalvandvexperimentalvobser
vationsvpossiblyvpointvtovavcommonvdenominator,vlungvstretch,vasvbeingvavmajorvgrowthvstimulant.
REF:vpp.v6-7
5. WhatvisvthevpurposevofvthevsubstancevsecretedvbyvthevtypevIIvpneumocyte?
a. Tovincreasevthevgasvexchangevsurfacevarea
b. Tovreducevsurfacevtension
c. Tovmaintainvlungvelasticity
d. Tovpreservevthevvolumevofvthevamnioticvfluid
ANS:v B
Thevprimaryvrolevofvmammalianvsurfactantvisvtovlowervthevsurfacevtensionvwithinvthevalveolus,vspecif
icallyvatvthevair–
liquidvinterface.vThisvallowsvthevdelicatevstructurevofvthevalveolusvtovexpandvwhenvfilledvwithvair.vW
ithoutvsurfactant,vthevalveolusvremainsvcollapsedvbecausevofvthevhighvsurfacevtensionvofvthevmoistval
veolarvsurface.vSurfactantvisvcomposedvpredominantlyvofvanvintricatevblendvofvphospholipids,vneut
ralvlipids,vandvproteins.
REF:vp.v8
, 6. Whichvofvthevfollowingvtestsvofvthevamnioticvfluidvhavevbeenvshownvtovbevsensitivevindicatorsvofvlun
gvmaturity?
a. Levelsvofvprednisone
b. Levelsvofvepidermalvgrowthvfactor
c. Levelsvofvprostaglandins
d. Levelsvofvphosphatidylglycerolvandvphosphatidylcholine
ANS:v D
Ofvclinicalvrelevancevduringvlatevgestation,vanalysisvofvamnioticvfluidvforvthevconcentrationvofvphos
phatidylglycerolvandvphosphatidylcholinevhasvbeenvshownvtovbevavsensitivevindicatorvofvthevstate
vofvfetalvlungvmaturity.
REF:vp.v8
7.vApproximatelyvhowvmuchvfetalvlungvfluidvisvsecretedvdaily?
a.vAboutv150vtov200vml
b.vAboutv250vtov300vml
c.vAboutv350vtov400vml
d.vAboutv450vtov500vml
ANS:vB
Fetalvlungsvarevsecretoryvorgansvthatvmakevbreathing-
likevmovementsvbutvservevnovrespiratoryvfunctionvbeforevbirth.vTheyvsecretev
aboutv250vtov300vmlvofvliquidvpervday.
8.vThevlungvbudvemergesvfromvwhichvofvthevfollowingvstructures?
v
a.vThevpharynx
b.vThevforegut
c.vThevmesenchyme
d.vThevtubularvepithelium
ANS:vA
Thevembryonalvphasevincludesvprimitivevlungvdevelopmentvandvisvgenerallyvregardedvtovencompassvthevfirstv2
vmonthsvofvgestation.v
Thevlungvbeginsvtovemergevasvavbudvfromvthevpharynxv26vdaysvaftervconception.