6th E
h
dition by Brian
h h
,Chapter 1: Fetal Lung DevelopmentTest B
ank
MULTIPLE CHOICE
1. Which of the following phases of human lung development ishcharacterized by the
formationof a ca pillarynetworkharound airwaypassages?
a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS: D
The canalicular phase follows the pseudoglandular phase, lasting from approximately
17 weeks t o 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 syst em subdivides
extensively and the conducting airway system develops, ending with the therminal bro
nchioles. 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 sacchular phase, a tre mendous increase in the potential
gas-
exchanging surface area occurs. The distinction between the saccular stage and the
alveolar s ta ge is arbitrary. The alveolar stage stretches from 39 weeks of gestation to
term.This stage is repr esented by the establishmenthof alveoli.
REF: pp. 3-5
2. Regarding postnatal lung growth, by approximately whathage do most of the alveoli
that willbe p resenthin the lungs for lifehdevelop?
a. 6 months
b. 1 year
c. 1.5hyears
d. 2 years
ANS:v C
Most of the postnatal formation of alveoli in the infant voccurs over the first 1.5 years
of life. Ath2 y earshof age, the number of alveoli varies substantially among
individuals. After 2 yearsof age, m ales have more alveoli than do females. After
alveolar multiplication ends, the alveoli continue to in crease 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 no sis. During which period of lung development did this problem
develop?
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
hANS: A
, The initial structures of the pulmonary tree develop during the embryonal stage. Errors
in develo pme nt during this time may resulthin laryngeal, tracheal, or esophageal
atresia or stenosis. Pulmo nary hy poplasia, an incomplete development of the lungs
characterized by anabnormally low n umber an d/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 distres s can
be expected becausehthe inadequately developed airways, along with ins ufficienthand
imma ture 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 h ydramnios 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 amniotichfluid present for an extended period of time,
withhor withouthrenalh ano mTalEieSs,Tv isBv aA sNs oKciSatEeLd wL Ei thR l. uCn Og Mhypoplasia.
Theh mechanismsvbyh whichh amniotich fluhi d volume influences lung growth remain unclear.
Possible explanations for
reduced quantity of amniotic fluid include mechanical restriction of the chest hwall,
interference w ith fetal breathing, or failure to produce fetal lung liquid. These clinical
and experimental obser vati ons possibly point to a common denominator, lung
stretch, as being amajor growth stimulant.
REF: pp. 6-7
5. Whathis the purpose of the substance secreted by the type II pneumocyte?
a. To increase the gashexchange 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 hlower the surface tension within the
alveolus, specif ic ally aththe air–
liquid interface. This allows the delicate structure of the alveolus to expand when filled
with air. W itho ut surfactant, the alveolus remains collapsed because of thehigh surface
tension of the moist al veola r surface. Surfactant isvcomposed predominantly of an
intricate blend of phospholipids, neut ral lipid s, and proteins.
REF: p. 8
, 6. Which of the following tests of 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 pha tidylglycerol and phosphatidylcholine has been shown to be a sensitive
indicator of the state of fet al 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:hB
Fetal lungs are secretory organs that make breathing-
like movements but serve no respiratory function before birth. They
secrete abo ut 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:hA
The embryonal phase includes primitive lung developmenthand is generally regarded to encompass
the first 2 months of gestation.
The lung begins to emerge as a bud from the pharynx 26 days after conception.
h
dition by Brian
h h
,Chapter 1: Fetal Lung DevelopmentTest B
ank
MULTIPLE CHOICE
1. Which of the following phases of human lung development ishcharacterized by the
formationof a ca pillarynetworkharound airwaypassages?
a. Pseudoglandular
b. Saccular
c. Alveolar
d. Canalicular
ANS: D
The canalicular phase follows the pseudoglandular phase, lasting from approximately
17 weeks t o 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 syst em subdivides
extensively and the conducting airway system develops, ending with the therminal bro
nchioles. 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 sacchular phase, a tre mendous increase in the potential
gas-
exchanging surface area occurs. The distinction between the saccular stage and the
alveolar s ta ge is arbitrary. The alveolar stage stretches from 39 weeks of gestation to
term.This stage is repr esented by the establishmenthof alveoli.
REF: pp. 3-5
2. Regarding postnatal lung growth, by approximately whathage do most of the alveoli
that willbe p resenthin the lungs for lifehdevelop?
a. 6 months
b. 1 year
c. 1.5hyears
d. 2 years
ANS:v C
Most of the postnatal formation of alveoli in the infant voccurs over the first 1.5 years
of life. Ath2 y earshof age, the number of alveoli varies substantially among
individuals. After 2 yearsof age, m ales have more alveoli than do females. After
alveolar multiplication ends, the alveoli continue to in crease 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 no sis. During which period of lung development did this problem
develop?
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
hANS: A
, The initial structures of the pulmonary tree develop during the embryonal stage. Errors
in develo pme nt during this time may resulthin laryngeal, tracheal, or esophageal
atresia or stenosis. Pulmo nary hy poplasia, an incomplete development of the lungs
characterized by anabnormally low n umber an d/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 distres s can
be expected becausehthe inadequately developed airways, along with ins ufficienthand
imma ture 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 h ydramnios 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 amniotichfluid present for an extended period of time,
withhor withouthrenalh ano mTalEieSs,Tv isBv aA sNs oKciSatEeLd wL Ei thR l. uCn Og Mhypoplasia.
Theh mechanismsvbyh whichh amniotich fluhi d volume influences lung growth remain unclear.
Possible explanations for
reduced quantity of amniotic fluid include mechanical restriction of the chest hwall,
interference w ith fetal breathing, or failure to produce fetal lung liquid. These clinical
and experimental obser vati ons possibly point to a common denominator, lung
stretch, as being amajor growth stimulant.
REF: pp. 6-7
5. Whathis the purpose of the substance secreted by the type II pneumocyte?
a. To increase the gashexchange 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 hlower the surface tension within the
alveolus, specif ic ally aththe air–
liquid interface. This allows the delicate structure of the alveolus to expand when filled
with air. W itho ut surfactant, the alveolus remains collapsed because of thehigh surface
tension of the moist al veola r surface. Surfactant isvcomposed predominantly of an
intricate blend of phospholipids, neut ral lipid s, and proteins.
REF: p. 8
, 6. Which of the following tests of 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 pha tidylglycerol and phosphatidylcholine has been shown to be a sensitive
indicator of the state of fet al 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:hB
Fetal lungs are secretory organs that make breathing-
like movements but serve no respiratory function before birth. They
secrete abo ut 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:hA
The embryonal phase includes primitive lung developmenthand is generally regarded to encompass
the first 2 months of gestation.
The lung begins to emerge as a bud from the pharynx 26 days after conception.
