1. Which’of’the’following’phases’of’human’lung’development’is’characterized’by’the’formation’o
f’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’vascular’channel
s,’or’capillaries,’which’begin’to’grow’by’forming’a’capillary’network’around’the’air’passages.’D
uring’the’pseudoglandular’stage,’which’begins’at’day’52’and’extends’to’week’16’of’gestation,’th
e’airway’system’subdivides’extensively’and’the’conducting’airway’system’develops,’ending’wit
h’the’terminal’bronchioles.’The’saccular’stage’of’development,’which’takes’place’from’weeks’2
9’to’36’of’gestation,’is’characterized’by’the’development’of’sacs’that’later’become’alveoli.’Durin
g’the’saccular’phase,’a’tremendous’increase’in’the’potential
gas-
exchanging’surface’area’occurs.’The’distinction’between’the’saccular’stage’and’the’alveolar’
stage’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’will’b
e’present’in’the’lungs’for’life’develop?
a. 6’months
b. 1’year
c. 1.5’years
d. 2’years
ANS:’ 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’years’of’a
ge,’males’have’more’alveoli’than’do’females.’After’alveolar’multiplication’ends,’the’alveoli’co
ntinue’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’tracheal’st
enosis.’During’which’period’of’lung’development’did’this’problem’develop?
a. Embryonal
b. Saccular
c. Canalicular
d. Alveolar
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:’ D
Oligohydramnios,’a’reduced’quantity’of’amniotic’fluid’present’for’an’extended’period’of’time,
with’or’without’renal’anomTaE lieSsT s’A
,’iB asNsoKcS
iaE dLwEitR
teL h’.
luCnO hypoplasia.’The’mechanisms’by’’which’
g’M
amniotic’fluid’volume’influences’lung’growth’remain’unclear.’Possible’explanations’for
reduced’quantity’of’amniotic’fluid’include’mechanical’restriction’of’the’chest’wall,’interferenc
e’with’fetal’breathing,’or’failure’to’produce’fetal’lung’liquid.’These’clinical’and’experimental’
observations’possibly’point’to’a’common’denominator,’lung’stretch,’as’being’a’major’growth’s
timulant.
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:’ B
The’primary’role’of’mammalian’surfactant’is’to’lower’the’surface’tension’within’the’alveolus,’s
pecifically’at’the’air–
liquid’interface.’This’allows’the’delicate’structure’of’the’alveolus’to’expand’when’filled’with’air.
’Without’surfactant,’the’alveolus’remains’collapsed’because’of’the’high’surface’tension’of’the’m
oist’alveolar’surface.’Surfactant’is’composed’predominantly’of’an’intricate’blend’of’phospholip
ids,’neutral’lipids,’and’proteins.
REF:’p.’8
, 6. Which’of’the’following’tests’of’the’amniotic’fluid’have’been’shown’to’be’sensitive’indicators’of
lung’maturity?
’
a. Levels’of’prednisone
b. Levels’of’epidermal’growth’factor
c. Levels’of’prostaglandins
d. Levels’of’phosphatidylglycerol’and’phosphatidylcholine
ANS:’ D
Of’clinical’relevance’during’late’gestation,’analysis’of’amniotic’fluid’for’the’concentration’of’p
hosphatidylglycerol’and’phosphatidylcholine’has’been’shown’to’be’a’sensitive’indicator’of’the
’state’of’fetal’lung’maturity.
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