Module 1 Fetal/Newborn Transition

Question 1

Gestational period for canalicular period?

Answer 1

16-26 weeks

Question 2

During the canalicular period the lumina of the __________ and the terminal ____________ become ____________ and the lung tissue becomes highly _____________.

Answer 2

bronchi; bronchioles; larger; vascular.

Question 3

What makes survival possible at the 24-26 wk range of the canalicular period?

Answer 3

Respiration becomes possible because some thin-walled terminal sacs (primordial alveoli) have developed at the ends of the respiratory bronchioles and the lung tissue is well vascularized.

Question 4

Respiration becomes possible at ___ to ___ weeks because some thin-walled __________ (primordial alveoli) have developed at the ends of the respiratory bronchioles and the lung tissue is well __________.

Answer 4

24 to 26 weeks; terminal sacs; vascularized

Question 5

Gestational period for terminal sac stage?

Answer 5

26 weeks to birth

Question 6

During the terminal sac stage, many more __________ _____ develop and the _____________ barrier is developed which permits _____________ ___________ ___________ for survival.

Answer 6

terminal sacs; blood-air barrier; adequate gas exchange

Question 7

Which cells secrete surfactant?

Answer 7

type II pneumocytes, which are secretory epithelial cells

Question 8

Surfactant production begins at ____ weeks, but does not reach adequate levels until _____________.

Answer 8

20; late fetal period.

Question 9

Gestational period for Alveolar Period?

Answer 9

32 weeks to 8 years

Question 10

_____% of mature alveoli develop postnatally.

Answer 10

95%

Question 11

The transition from dependence on the placenta for gas exchange to autonomous gas exchange depends on: (3)

Answer 11

1. Production of surfactant in alveolar sacs
2. Transformation of lungs into gas-exchanging organs
3. Establishment of parallel pulmonary and systemic circulations

Question 12

When is the adult complement of 300,000 alveoli achieved?

Answer 12

Between 3-8 years

Question 13

What three factors are essential for normal lung development?

Answer 13

1. Adequate thoracic space for lung growth
2. Adequate amniotic fluid volume
3. Fetal breathing movements

Question 14

The fluid in the lungs is cleared at birth by what 3 routes?

Answer 14

1. Through nose/mouth by pressure on thorax during delivery.
2. Into the pulmonary capillaries and arteries/veins
3. Into the lymphatics.

Question 15

What are the biochemical events that stimulate the neonate to take the first breath?

Answer 15

Relative hypoxia at the end of labor and the physical stimuli (cold, gravity, pain, light, and noise) cause excitation of the of the respiratory center.

Question 16

What mechanical events stimulate the neonate to take the first breath?

Answer 16

Release of thoracic pressure at birth and squeezing of the thorax that occurs in the last minutes of 2nd stage.