,Chapter 1: Fetal Lung DevelopmentTest B
ank
MULTIPLE CHOICE
1. Which ofvthe following phases vofvhuman lung development is characterized by the formationof a
capillary network around airway passages?
a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS:v 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 vday 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 ofvdevelopment, which takes vplace from weeks 29 to 36 o
fvgestation, is characterized by the development of sacs vthatlater 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 ofvalveoli in the infantvoccurs over the firstv1.5 years of life. At 2
years of age, the number of alveoli variesvsubstantially 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 ofvlung development did this problem develop?
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
ANS:v A
, The initial structures of the pulmonary tree develop during the embryonal stage. Errors in develo
pment during thisvtime 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., vprematurely), 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 infantvrespiratory 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,vIII, and IV only
ANS:v D
Oligohydramnios, a reduced quantity of amniotic fluid present for an extended period of time,
with or without renal anomTalEieSs,Tv isBvaA sNsoKciSatEeLdw
LEithR l. uCnO
g vMhy poplasia. 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 isvthe 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 vthe 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 isvcomposed predominantly of an intricate blend of phospholipids, vneut
ral lipids, and proteins.
REF: p. 8
, 6. Which of the following tests vof 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 first v2
months of gestation.
The lung begins to emerge as a bud from the pharynx 26 days after conception.
ank
MULTIPLE CHOICE
1. Which ofvthe following phases vofvhuman lung development is characterized by the formationof a
capillary network around airway passages?
a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS:v 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 vday 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 ofvdevelopment, which takes vplace from weeks 29 to 36 o
fvgestation, is characterized by the development of sacs vthatlater 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 ofvalveoli in the infantvoccurs over the firstv1.5 years of life. At 2
years of age, the number of alveoli variesvsubstantially 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 ofvlung development did this problem develop?
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
ANS:v A
, The initial structures of the pulmonary tree develop during the embryonal stage. Errors in develo
pment during thisvtime 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., vprematurely), 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 infantvrespiratory 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,vIII, and IV only
ANS:v D
Oligohydramnios, a reduced quantity of amniotic fluid present for an extended period of time,
with or without renal anomTalEieSs,Tv isBvaA sNsoKciSatEeLdw
LEithR l. uCnO
g vMhy poplasia. 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 isvthe 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 vthe 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 isvcomposed predominantly of an intricate blend of phospholipids, vneut
ral lipids, and proteins.
REF: p. 8
, 6. Which of the following tests vof 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 first v2
months of gestation.
The lung begins to emerge as a bud from the pharynx 26 days after conception.
