Deck 1: Fetal Lung Development

Question 1

Which of the following mechanisms is (are)responsible for the possible association between oligohydramnios 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

Answer 1

D
Oligohydramnios,a reduced quantity of amniotic fluid present for an extended period of time,with or without renal anomalies,is associated with lung hypoplasia.The mechanisms by which amniotic fluid volume influences lung growth remain unclear.Possible explanations for reduced quantity of amniotic fluid include mechanical restriction of the chest wall,interference 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 stimulant.

Question 2

Which of the following phases of human lung development is characterized by the formation of a capillary network around airway passages?

A)Pseudoglandular
B)Saccular
C)Alveolar
D)Canalicular

Answer 2

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 channels,or capillaries,which begin to grow by forming a capillary network around the air passages.During the pseudoglandular stage,which begins at day 52 and extends to week 16 of gestation,the airway system subdivides extensively and the conducting airway system develops,ending with the terminal bronchioles.The saccular stage of development,which takes place from weeks 29 to 36 of gestation,is characterized by the development of sacs that later become alveoli.During 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.

Question 3

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

Answer 3

D
Of clinical relevance during late gestation,analysis of amniotic fluid for the concentration of phosphatidylglycerol and phosphatidylcholine has been shown to be a sensitive indicator of the state of fetal lung maturity.

Question 4

The respiratory therapist is evaluating a newborn with mild respiratory distress due to tracheal stenosis.During which period of lung development did this problem develop?

A)Embryonal
B)Saccular
C)Canalicular
D)Alveolar

Question 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

Question 6

Regarding postnatal lung growth,by approximately what age do most of the alveoli that will be present in the lungs for life develop?

A)6 months
B)1 year
C)1.5 years
D)2 years