CARE 6TH EDITION BY BRIAN K. WALSH..
,Chapter 1: Fetal Lung DevelopmentTest
B ank
MULTIPLE CHOICE
1. Which of the following phases of human lung development is characterized by the formationof a
capillary network around airway passages?
a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS: D
The canalicular phase follows the pseudoglandular phase, lasting from approximately 17
weeks to 26 weeks of gestation. This phase is so named because of the appearance of
vascularchannels, or capillaries, which begin to grow by forming a capillary network around
the air passages. Durin g the pseudoglandular stage, which begins at day 52 and extends to
week 16 of gestation, the ai rway system subdivides extensively and the conducting airway
system develops, ending with the t erminal bronchioles. The saccular stage of development,
which takes place from weeks 29 to 36 o f gestation, is characterized by the development of
sacs thatlater become alveoli. During the sacc ular phase, a tremendous increase in the
potential
gas-
exchanging surface area occurs. The distinction between the saccular stage and the
alveolar s tage is arbitrary. The alveolar stage stretches from 39 weeks of gestation to
term.This stage is represented by the establishment of alveoli.
REF: pp. 3-5
2. Regarding postnatal lung growth, by approximately what age do most of the alveoli that
willbe present in the lungs for life develop?
a. 6 months
b. 1 year
c. 1.5 years
d. 2 years
ANS:v C
Most of the postnatal formation of alveoli in the infant occurs over the first 1.5 years of life.
At 2 years of age, the number of alveoli varies substantially among individuals. After 2
yearsof age, males have more alveoli than do females. After alveolar multiplication ends, the
alveoli continue to increase in size until thoracic growth is completed.
REF: p. 6
3. The respiratory therapist is evaluating a newborn with mild respiratory distress due to
trachealste nosis. During which period of lung development did this problem develop?
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
KANS:v A
, The initial structures of the pulmonary tree develop during the embryonal stage. Errors in develo
pment during this time may result in laryngeal, tracheal, or esophageal atresia or stenosis.
Pulmo nary hypoplasia, an incomplete development of the lungs characterized by
anabnormally low n umber and/or size of bronchopulmonary segments and/or alveoli, can
develop during the pseu doglandular phase. If the fetus is born during the canalicular phase
(i.e., prematurely), severe re spiratory distress can be expected because the inadequately
developed airways, along with ins ufficient and immature surfactant production by alveolar type
II cells, gives rise to the constellati on of problems known as infant respiratory distress
syndrome.
REF: p. 6
4. Which of the following mechanisms is (are) responsible for the possible association
betweenoligo hydramnios and lung hypoplasia?
I. Abnormal carbohydrate metabolism
II. Mechanical restriction of the chest wall
III. Interference with fetal breathing
IV. Failure to produce fetal lung liquid
a. I and III only
b. II and III only
c. I, II, and IV only
d. II, III, and IV only
ANS:v D
Oligohydramnios, a reduced quantity of amniotic fluid present for an extended period of time,
with or without renal ano mTalEieSs,T isBv aA sNs oKciSatEeLd wL Ei thR l. uCn Og M
hypoplasia. The mechanismsvby which
amniotic flu id volume influences lung growth remain unclear. Possible explanations for
reduced quantity of amniotic fluid include mechanical restriction of the chest wall, interference
w ith fetal breathing, or failure to produce fetal lung liquid. These clinical and experimental
obser vations possibly point to a common denominator, lung stretch, as being amajor growth
stimulant.
REF: pp. 6-7
5. What is the purpose of the substance secreted by the type II pneumocyte?
a. To increase the gas exchange surface area
b. To reduce surface tension
c. To maintain lung elasticity
d. To preserve the volume of the amniotic fluid
ANS:v B
The primary role of mammalian surfactant is to lower the surface tension within the alveolus,
specif ically at the air–
liquid interface. This allows the delicate structure of the alveolus to expand when filled with air.
W ithout surfactant, the alveolus remains collapsed because of thehigh surface tension of the
moist al veolar surface. Surfactant is composed predominantly of an intricate blend of
phospholipids, neut ral lipids, and proteins.
REF: p. 8
, 6. Which of the following testsvof the amniotic fluid have been shown to be sensitive indicatorsof
lun g maturity?
a. Levels of prednisone
b. Levels of epidermal growth factor
c. Levels of prostaglandins
d. Levels of phosphatidylglycerol and phosphatidylcholine
ANS:v D
Ofclinical relevance during late gestation, analysis of amniotic fluid for the concentration ofphos
phatidylglycerol and phosphatidylcholine has been shown to be a sensitive indicator of the
state of fetal lung maturity.
REF: p. 8
7. Approximately how much fetal lung fluid is secreted daily?
a. About 150 to 200 ml
b. About 250 to 300 ml
c. About 350 to 400 ml
d. About 450 to 500 ml
ANS: B
Fetal lungs are secretory organs that make breathing-
like movements but serve no respiratory function before birth. They secrete
about 250 to 300 ml of liquid per day.
8. The lung bud emerges from which of the following structures?
a. The pharynx
b. The foregut
c. The mesenchyme
d. The tubular epithelium
ANS: A
The embryonal phase includes primitive lung development and is generally regarded to encompass the
firstv2 months of gestation.
The lung begins to emerge as a bud from the pharynx 26 days after conception.