SURFACTANT REPLACEMENT
TEST BANK Q & A/2023.Qualified
Surfactant Replacement Test Bank Q
&A
1. According to Laplace’s law the pressure required to open an alveoli in the lung is:
a.
Directly proportional to the radius
b.
Inversely proportional to the length of the airway
c.
Directly proportional to the surface tension
d.
Indirectly proportional to the viscosity of the gas in the airway
ANS: C
In his theory of capillary action Laplace described the relationship of trans-surface pressure
and surface tension at a gas–fluid interface in a sphere as P = 2 ST/R (where P is the trans-
surface or distending pressure, ST is surface tension, and R is the radius of the sphere).
REF: pp. 245-246
2. Which of the following physiologic consequences would develop if the liquid–gas interface
were without surfactant?
a.
Large alveoli would empty into smaller ones at the end of exhalation.
b.
Every exhalation would demand ventilatory muscle activity.
c.
Every breath would require a considerable amount of pressure to expand the lung
with each inspiration.
d.
Some alveoli would collapse during exhalation.
ANS: C
The lung can be thought of as a large number of interconnected bubbles that form the interface
between the gaseous environment and the wet alveolar surface. If this interface were devoid of
surfactant, two consequences would ensue: (1) every breath would take a considerable amount
of pressure to expand the lung, comparable to the 80 to 90 cm H2O of pressure required for a
newborn’s first breath, and (2) the lung would rapidly collapse during exhalation.
REF: p. 246
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, SURFACTANT REPLACEMENT
TEST BANK Q & A/2023.Qualified
3. Which of the following physiologic conditions result from the presence of normal amounts of
pulmonary surfactant in the lung?
a.
Pulmonary compliance decreases.
b.
Uniform gas distribution during expiration occurs.
c.
The functional residual capacity is maintained.
d.
Pulmonary perfusion matches alveolar ventilation.
ANS: C
Functionally, surfactant increases lung compliance, promotes homogeneous gas distribution
during inhalation, and allows a residual volume of gas to be evenly distributed throughout the
lung during exhalation—that is, it maintains functional residual capacity. In the absence of
surfactant, distribution of ventilation becomes uneven, the lungs become stiff, and atelectasis
ensues during exhalation. The result is increased work of breathing, hypoxia, and respiratory
failure, the clinical picture exemplified by preterm infants with respiratory distress syndrome
(RDS). Surfactant functions are summarized in Box 14-1 in the textbook.
This study source was downloaded by 100000843924616 from CourseHero.com on 05-09-2022 12:59:42 GMT -05:00
https://www.coursehero.com/file/103516349/c14pdf/
TEST BANK Q & A/2023.Qualified
Surfactant Replacement Test Bank Q
&A
1. According to Laplace’s law the pressure required to open an alveoli in the lung is:
a.
Directly proportional to the radius
b.
Inversely proportional to the length of the airway
c.
Directly proportional to the surface tension
d.
Indirectly proportional to the viscosity of the gas in the airway
ANS: C
In his theory of capillary action Laplace described the relationship of trans-surface pressure
and surface tension at a gas–fluid interface in a sphere as P = 2 ST/R (where P is the trans-
surface or distending pressure, ST is surface tension, and R is the radius of the sphere).
REF: pp. 245-246
2. Which of the following physiologic consequences would develop if the liquid–gas interface
were without surfactant?
a.
Large alveoli would empty into smaller ones at the end of exhalation.
b.
Every exhalation would demand ventilatory muscle activity.
c.
Every breath would require a considerable amount of pressure to expand the lung
with each inspiration.
d.
Some alveoli would collapse during exhalation.
ANS: C
The lung can be thought of as a large number of interconnected bubbles that form the interface
between the gaseous environment and the wet alveolar surface. If this interface were devoid of
surfactant, two consequences would ensue: (1) every breath would take a considerable amount
of pressure to expand the lung, comparable to the 80 to 90 cm H2O of pressure required for a
newborn’s first breath, and (2) the lung would rapidly collapse during exhalation.
REF: p. 246
This study source was downloaded by 100000843924616 from CourseHero.com on 05-09-2022 12:59:42 GMT -05:00
https://www.coursehero.com/file/103516349/c14pdf/
, SURFACTANT REPLACEMENT
TEST BANK Q & A/2023.Qualified
3. Which of the following physiologic conditions result from the presence of normal amounts of
pulmonary surfactant in the lung?
a.
Pulmonary compliance decreases.
b.
Uniform gas distribution during expiration occurs.
c.
The functional residual capacity is maintained.
d.
Pulmonary perfusion matches alveolar ventilation.
ANS: C
Functionally, surfactant increases lung compliance, promotes homogeneous gas distribution
during inhalation, and allows a residual volume of gas to be evenly distributed throughout the
lung during exhalation—that is, it maintains functional residual capacity. In the absence of
surfactant, distribution of ventilation becomes uneven, the lungs become stiff, and atelectasis
ensues during exhalation. The result is increased work of breathing, hypoxia, and respiratory
failure, the clinical picture exemplified by preterm infants with respiratory distress syndrome
(RDS). Surfactant functions are summarized in Box 14-1 in the textbook.
This study source was downloaded by 100000843924616 from CourseHero.com on 05-09-2022 12:59:42 GMT -05:00
https://www.coursehero.com/file/103516349/c14pdf/
