RespiratoryCare5thEdition
WalshTestBankA+
, Chapter1:FetalLungDevelopmentTestBank t
MULTIPLE CHOICE g
1. Whichofthefollowingphasesofhumanlungdevelopmentischaracterized bythe t t t t t t g
formation of a capillary network around airway passages?
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a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS: D g
Thecanalicularphasefollowsthepseudoglandular phase,lastingfromapproximately 17weeks to
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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 air
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passages.
g
During the pseudoglandular stage, which begins at day 52 and extends to week 16 of
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gestation, the airway system subdivides extensively and the conducting airway system
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gdevelops, 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 g
occurs. The distinction between the saccular stage and the alveolar stage isarbitrary. The
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alveolar stage stretches from 39 weeks of gestation to term. This stage isrepresented by
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the establishment of alveoli.
g g g g
REF: pp. 3-5 g g
2. Regardingpostnatal lunggrowth,byapproximatelywhatagedomostofthealveolithat t g t t t
will be present in the lungs for life develop?
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a. 6 monthsg
,b. 1 year g
c. 1.5 years g
d. 2 years g
ANS: C g
Most of the postnatal formation of alveoli in the infant occurs over the first 1.5 years of life.At
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2 years of age, the number of alveoli varies substantially among individuals.After 2years of
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age, males have more alveoli than do females. After alveolarmultiplication ends,the
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alveoli continueto increase in size until thoracic growth iscompleted.
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REF: p. 6 g g
3. Therespiratorytherapistisevaluatinganewbornwithmildrespiratorydistressdueto
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trachealstenosis.Duringwhichperiodoflungdevelopmentdidthisproblemdevelop?
g t t t t
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
ANS: A g
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 immature
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surfactantproduction by alveolar type II cells, gives rise to the constellation of
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problems knownasinfant respiratory distress syndrome.
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, REF: p. 6 g
4. Whichofthefollowingmechanismsis(are)responsibleforthepossible
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association between oligohydramnios and lung hypoplasia?
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I. Abnormalcarbohydrate metabolism g
II. Mechanicalrestriction of the chest wall g g g g
III. Interferencewithfetal breathing g g
IV. Failureto produce fetal lungliquid g g g g g
a. Iand III only g g
b. IIand III only
g g g
c. I, II,and IV only
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d. II, III, and IV only
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ANS: D g
Oligohydramnios, a reduced quantity of amniotic fluid present for an extended period oftime, g g g g g g g g g g g g t
with orwithout renal anomalies, is associatedwith lung hypoplasia. Themechanismsby which
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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
g g
5. What is the purpose of the substance secreted bythe type IIpneumocyte?
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