,Chapter 1: Fetal Lung Development Test Bank iY iY iY iY iY iY
MULTIPLE CHOICE iY
1. Which of the following phases of human lung development is characterized by
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theformation of a capillary network around airway passages?
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a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS: D iY
The canalicular phase follows the pseudoglandular phase, lasting from approximately 17 weeks
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to 26 weeks of gestation. This phase is so named because of the appearance of vascular
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channels,or capillaries, which begin to grow by forming a capillary network around the air
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passages.
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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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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 that
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later become alveoli.
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During the saccular phase, a tremendous increase in the potential gas- exchanging surface
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areaoccurs. The distinction between the saccular stage and the alveolar stage is arbitrary.
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The alveolar stage stretches from 39 weeks of gestation to term. This stage is represented
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by the establishment of alveoli.
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REF: pp. 3-5 iY iY
2. Regarding postnatal lung growth, by approximately what age do most of the alveoli iY iY iY iY iY iY iY iY iY iY iY iY
thatwill be present in the lungs for life develop?
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a. 6 months
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,b. 1 yeariY
c. 1.5 years iY
d. 2 years
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ANS: C iY
Most of the postnatal formation of alveoli in the infant occurs over the first 1.5 years of life.
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At 2years of age, the number of alveoli varies substantially among individuals. After 2 years
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of age, males have more alveoli than do females. After alveolar multiplication ends, the
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alveoli continueto increase in size until thoracic growth is completed.
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REF: p. 6 iY iY
3. The respiratory therapist is evaluating a newborn with mild respiratory distress due
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totracheal stenosis. During which period of lung development did this problem develop?
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a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
ANS: A iY
The initial structures of the pulmonary tree develop during the embryonal stage. Errors in
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development during this time may result in laryngeal, tracheal, or esophageal atresia or
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stenosis. Pulmonary hypoplasia, an incomplete development of the lungs characterized by an
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abnormally low number and/or size of bronchopulmonary segments and/or alveoli, can
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develop during the pseudoglandular phase. If the fetus is born during the canalicular phase
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(i.e., prematurely), severerespiratory distress can be expected because the inadequately
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developed airways, along with insufficient and immature surfactant production by alveolar
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type II cells, gives rise to the constellation of problems known as infant respiratory distress
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syndrome.
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, REF: i Y p. 6 iY
4. Which of the following mechanisms is (are) responsible for the possible
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associationbetween oligohydramnios and lung hypoplasia?
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I. Abnormal carbohydrate metabolism iY iY
II. Mechanical restriction of the chest wall iY iY iY iY iY
III. Interference with fetal breathing iY iY iY
IV. Failure to produce fetal lung liquid iY iY iY iY iY
a. I and III only
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b. II and 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 iY
Oligohydramnios, a reduced quantity of amniotic fluid present for an extended period of time,
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with or without renal anomalies, is associated with lung hypoplasia. The mechanisms by
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which amniotic fluid volume influences lung growth remain unclear. Possible explanations
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for reducedquantity of amniotic fluid include mechanical restriction of the chest wall,
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interference with fetalbreathing, or failure to produce fetal lung liquid. These clinical and
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experimental observations possibly point to a common denominator, lung stretch, as being a
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major growth stimulant.
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REF: pp. 6-7iY iY
5. What is the purpose of the substance secreted by the type II pneumocyte?
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