RespiratoryCare5thEditio
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n WalshTestBankA+
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, Chapter1:FetalLungDevelopmentTestBank t
MULTIPLE CHOICE v
1. Whichofthefollowingphasesofhumanlungdevelopmentischaracterized bythe t t t t t t v
formation of a capillary network around airway passages?
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a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS: D v
Thecanalicularphasefollowsthepseudoglandular phase,lastingfromapproximately 17weeks
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to 26 weeks of gestation. This phase is so named because of the appearance ofvascular
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channels,or capillaries, which begin to grow by forming a capillary networkaround the
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air passages.
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During the pseudoglandular stage, which begins at day 52 and extends to week 16
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vof gestation, the airway system subdivides extensively and the conducting airway system
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v develops, ending with the terminal bronchioles. The saccular stage of development, which
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takes place from weeks29 to 36 of gestation, is characterized by the development of sacs
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that later become alveoli.
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Duringthesaccularphase,atremendousincrease inthepotentialgas-exchangingsurfacearea t v
occurs. The distinction between the saccular stage and the alveolar stage isarbitrary.
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The alveolar stage stretches from 39 weeks of gestation to term. This stage
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isrepresented by the establishment of alveoli.
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REF: pp. 3-5 v v
2. Regardingpostnatal lunggrowth,byapproximatelywhatagedomostofthealveolithat
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will be present in the lungs for life develop?
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a. 6 months
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,b. 1 year v
c. 1.5 years v
d. 2 years v
ANS: C v
Most of the postnatal formation of alveoli in the infant occurs over the first 1.5 years of
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life.At 2 years of age, the number of alveoli varies substantially among individuals.After
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2years of age, males have more alveoli than do females. After alveolarmultiplication
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ends,the alveoli continueto increase in size until thoracic growth iscompleted.
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REF: p. 6 v v
3. Therespiratorytherapistisevaluatinganewbornwithmildrespiratorydistressdueto
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trachealstenosis.Duringwhichperiodoflungdevelopmentdidthisproblemdevelop?
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a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
ANS: A v
The initial structures of the pulmonary tree develop during the embryonal
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stage. Errorsindevelopment duringthis timemay result inlaryngeal, tracheal, or esophageal
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atresiaorstenosis. Pulmonary hypoplasia, an incomplete development of the lungs
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characterizedbyan abnormally low number and/or size of bronchopulmonary segments
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and/or alveoli,candevelop during the pseudoglandular phase. If the fetus is
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born during thecanalicularphase (i.e., prematurely), severerespiratory distress can be
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expected because theinadequately developed airways, along with insufficient and
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immature surfactantproduction by alveolar type II cells, gives rise to the
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constellation of problems knownasinfant respiratory distress syndrome.
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, REF: p. 6 v
4. Whichofthefollowingmechanismsis(are)responsibleforthepossible
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association between oligohydramnios and lung hypoplasia?
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I. Abnormalcarbohydrate metabolism v
II. Mechanicalrestriction of the chest wall v v v v
III. Interferencewith fetal breathing v v
IV. Failureto produce fetal lungliquid
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a. Iand III only v v
b. IIand III only
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c. I, II, and IV only
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d. II, III, and IV only
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ANS: D v
Oligohydramnios, a reduced quantity of amniotic fluid present for an extended period v v v v v v v v v v v
oftime, with orwithout renal anomalies, is associatedwith lung hypoplasia. Themechanismsby
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which amniotic fluid volume influences lung growth remain unclear. Possibleexplanations for
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reducedquantityof amniotic fluid include mechanical restriction of thechest wall,
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interference with fetalbreathing, or failure to produce fetal lung liquid.
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Theseclinical and experimental observations possiblypoint to a common denominator,
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lungstretch, as being a major growth stimulant.
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REF: pp. 6-7 v v
5. What is the purpose of the substance secreted bythe type IIpneumocyte?
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