,
, Chapter 1: Fetal Lung Development Test Bank fi fi fi fi fi fi
MULTIPLE CHOICE fi
1. Which of the following phases of human lung development is characterized by the f
fi fi fi fi fi fi fi fi fi fi fi fi fi
ormation of a capillary network around airway passages?
fi fi fi fi fi fi fi
a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS: D fi
The canalicular phase follows the pseudoglandular phase, lasting from approximately 17 weeks to
fi fi fi fi fi fi fi fi fi fi fi fi fi
26 weeks of gestation. This phase is so named because of the appearance of vascular channels, or ca
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
pillaries, which begin to grow by forming a capillary network around the air passages.
fi fi fi fi fi fi fi fi fi fi fi fi fi
During the pseudoglandular stage, which begins at day 52 and extends to week 16 of gestation, the
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi f
airway system subdivides extensively and the conducting airway system develops, ending with th
i fi fi fi fi fi fi fi fi fi fi fi fi
e terminal bronchioles. The saccular stage of development, which takes place from weeks 29 to 36
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
of gestation, is characterized by the development of sacs that later become alveoli.
fi fi fi fi fi fi fi fi fi fi fi fi
During the saccular phase, a tremendous increase in the potential gas-
fi fi fi fi fi fi fi fi fi fi
exchanging surface area occurs. The distinction between the saccular stage and the alveolar stage
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
is arbitrary. The alveolar stage stretches from 39 weeks of gestation to term. This stage is represen
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
ted by the establishment of alveoli.
fi fi fi fi fi
REF: pp. 3-5 fi fi
2. Regarding postnatal lung growth, by approximately what age do most of the alveoli that w fi fi fi fi fi fi fi fi fi fi fi fi fi fi
ill be present in the lungs for life develop?
fi fi fi fi fi fi fi fi
a. 6 months
fi
, b. 1 yearfi
c. 1.5 years fi
d. 2 years
fi
ANS: C fi
Most of the postnatal formation of alveoli in the infant occurs over the first 1.5 years of life. At 2 ye
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
ars of age, the number of alveoli varies substantially among individuals. After 2 years of age, male
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
s have more alveoli than do females. After alveolar multiplication ends, the alveoli continue to incr
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
ease in size until thoracic growth is completed.
fi fi fi fi fi fi fi
REF: p. 6 fi fi
3. The respiratory therapist is evaluating a newborn with mild respiratory distress due to tr
fi fi fi fi fi fi fi fi fi fi fi fi fi
acheal stenosis. During which period of lung development did this problem develop?
fi fi fi fi fi fi fi fi fi fi fi
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
ANS: A fi
The initial structures of the pulmonary tree develop during the embryonal stage. Errors in developm
fi fi fi fi fi fi fi fi fi fi fi fi fi fi
ent during this time may result in laryngeal, tracheal, or esophageal atresia or stenosis. Pulmonary hy
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
poplasia, an incomplete development of the lungs characterized by an abnormally low number and/o
fi fi fi fi fi fi fi fi fi fi fi fi fi
r size of bronchopulmonary segments and/or alveoli, can develop during the pseudoglandular phase.
fi fi fi fi fi fi fi fi fi fi fi fi fi
If the fetus is born during the canalicular phase (i.e., prematurely), severe respiratory distress can be e
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
xpected because the inadequately developed airways, along with insufficient and immature surfacta
fi fi fi fi fi fi fi fi fi fi fi
nt production by alveolar type II cells, gives rise to the constellation of problems known as infant res
fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi
piratory distress syndrome. fi fi
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