Care, 6th Edition
by Brian K. Walsh
,Chapter 1: Fetal Lung Development
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Test Bank
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MULTIPLE CHOICE oe
1. Which of the following phases of human lung development is characterized by the formationof
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a capillary network around airway passages?
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a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS: D o e
The canalicular phase follows the pseudoglandular phase, lasting from approximately 17 week
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s to 26 weeks of gestation. This phase is so named because of the appearance of vascularchannels
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, or capillaries, which begin to grow by forming a capillary network around the air passages. Du
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ring the pseudoglandular stage, which begins at day 52 and extends to week 16 of gestation, the
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airway system subdivides extensively and the conducting airway system develops, ending wit
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h the terminal bronchioles. The saccular stage of development, which takes place from weeks 2
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9 to 36 of gestation, is characterized by the development of sacs thatlater become alveoli. Durin
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g the saccular phase, a tremendous increase in the potential
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gas-
exchanging surface area occurs. The distinction between the saccular stage and the alveolar oe oe oe oe oe oe oe oe oe oe oe oe o
stage is arbitrary. The alveolar stage stretches from 39 weeks of gestation to term.This stag
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e is represented by the establishment of alveoli.
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REF: pp. 3-5 o e oeoeo e
2. Regarding postnatal lung growth, by approximately what age do most of the alveoli that willb oe oe oe oe oe oe oe oe oe oe oe oe oe oe eo
e present in the lungs for life develop?
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a. 6 months oe
b. 1 year oe
c. 1.5 years oe
d. 2 years oe
ANS: C o e
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 2 yearsof age
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, males have more alveoli than do females. After alveolar multiplication ends, the alveoli contin
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ue to increase in size until thoracic growth is completed.
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REF: p. 6 oe oe
3. The respiratory therapist is evaluating a newborn with mild respiratory distress due to tracheal
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stenosis. During which period of lung development did this problem develop? oe oe oe oe oe oe oe oe oe oe
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
ANS: A o e
, The initial structures of the pulmonary tree develop during the embryonal stage. Errors in de
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velopment during this time may result in laryngeal, tracheal, or esophageal atresia or stenosis oe oe oe oe oe oe oe oe oe oe oe oe oe
. Pulmonary hypoplasia, an incomplete development of the lungs characterized by anabnormal
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ly low number and/or size of bronchopulmonary segments and/or alveoli, can develop during
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the pseudoglandular phase. If the fetus is born during the canalicular phase (i.e., prematurely),
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severe respiratory distress can be expected because the inadequately developed airways, alon
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g with insufficient and immature surfactant production by alveolar type II cells, gives rise to t
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he constellation of problems known as infant respiratory distress syndrome.
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REF: p. 6 oeoeo e oe
4. Which of the following mechanisms is (are) responsible for the possible association betweenoli
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gohydramnios and lung hypoplasia? oe oe oe
I. Abnormal carbohydrate metabolism oe oe
II. Mechanical restriction of the chest wall oe oe oe oe oe
III. Interference with fetal breathing oe oe oe
IV. Failure to produce fetal lung liquid oe oe oe oe oe
a. I and III only oe oe oe
b. II and III only oe oe oe
c. I, II, and IV only oe oe oe oe
d. II, III, and IV only oe oe oe oe
ANS: D o e
Oligohydramnios, a reduced quantity of amniotic fluid present for an extended period of time, oe oe oe oe oe oe oe oe oe oe oe oe oe
with or without renal anomTaE lieSsT
, iB
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iaE
teLdLwEitR
hlu
. CnO
gMhypoplasia. The mechanisms by whic
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h amniotic fluid volume influences lung growth remain unclear. Possible explanations for
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reduced quantity of amniotic fluid include mechanical restriction of the chest wall, interferenc
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e with fetal breathing, or failure to produce fetal lung liquid. These clinical and experimental o
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bservations possibly point to a common denominator, lung stretch, as being amajor growth st oe oe oe oe oe oe oe oe oe oe oe eo oe oe
imulant.
REF: pp. 6-7 oe oe
5. What is the purpose of the substance secreted by the type II pneumocyte?
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a. To increase the gas exchange surface area oe oe oe oe oe oe
b. To reduce surface tension oe oe oe
c. To maintain lung elasticity oe oe oe
d. To preserve the volume of the amniotic fluid oe oe oe oe oe oe oe
ANS: B o e
The primary role of mammalian surfactant is to lower the surface tension within the alveolus, s
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pecifically at the air– oe oe oe
liquid interface. This allows the delicate structure of the alveolus to expand when filled with air.
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Without surfactant, the alveolus remains collapsed because of thehigh surface tension of the mo
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ist alveolar surface. Surfactant is composed predominantly of an intricate blend of phospholipid
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s, neutral lipids, and proteins.
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REF: p. 8 oe oe
, 6. Which of the following tests of the amniotic fluid have been shown to be sensitive indicatorsof
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lung maturity? oe
a. Levels of prednisone oe oe
b. Levels of epidermal growth factor oe oe oe oe
c. Levels of prostaglandins oe oe
d. Levels of phosphatidylglycerol and phosphatidylcholine oe oe oe oe
ANS: D o e
Of clinical relevance during late gestation, analysis of amniotic fluid for the concentration ofph
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osphatidylglycerol and phosphatidylcholine has been shown to be a sensitive indicator of the s oe oe oe oe oe oe oe oe oe oe oe oe oe
tate of fetal lung maturity.
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REF: p. 8 oe oe
7. Approximately how much fetal lung fluid is secreted daily?
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a. About 150 to 200 ml
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b. About 250 to 300 ml
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c. About 350 to 400 ml
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d. About 450 to 500 ml
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ANS: B oe
Fetal lungs are secretory organs that make breathing-
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like movements but serve no respiratory function before birth. They secrete
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about 250 to 300 ml of liquid per day.
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8. The lung bud emerges from which of the following structures?
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a. The pharynx
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b. The foregut
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c. The mesenchyme
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d. The tubular epithelium
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ANS: A oe
The embryonal phase includes primitive lung development and is generally regarded to encompass the first 2 month
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s of gestation.
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The lung begins to emerge as a bud from the pharynx 26 days after conception.
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