Resp_L03_Flashcards

Question 1

What are the five phases of prenatal lung development?

Answer 1

Embryonic, pseudoglandular, canalicular, saccular, and alveolar.

Question 2

In which phase of prenatal lung development do alveolar ducts and surfactant form? At what embryonic age does this occur?

Answer 2

Saccular phase (~26 - 36 weeks)

Question 3

What does it mean when one says breathing movements in a fetus are paradoxical?

Answer 3

When the diaphragm contracts, the thorax moves invward (chest collapses) and vice versa (normal is other way around).

Question 4

What cell types exist in the parenchyma of the lung in the pseudoglandular phase (weeks 8 - 17)?

Answer 4

Type II pneumocytes only

Question 5

In what phase of prenatal lung development do type I pneumocytes differentiate?

Answer 5

Canalicular phase (weeks 16 - 26)

Question 6

The onset of functional maturation of the lung is marked by appearance of what features in the alveolar type II cells of the fetus?

Answer 6

Lamellar bodies (indicate production of surfactant)

Question 7

What ratio is used to measure fetal lung maturity? What is the “target” ratio? At what ratio does a neonate have a greater tendency to develop IRDS?

Answer 7

Lecithin/sphingomyelin ratio; >1.8 or 2 = goal,

Question 8

What are the four types of surfactant-specific proteins found in surfactant?

Answer 8

SP-A, SP-B, SP-C, and SP-D

Question 9

Which surfactant-specific proteins function as innate immune defenses? Are these present in comercially-produced surfactant?

Answer 9

SP-A and SP-D; SP-A is not present in comercially-produced surfactant.

Question 10

Which surfactant-specific proteins are critical for surface activity (such as surface tension)? Are these present in comercially-produced surfactant?

Answer 10

SP-B and SP-C; yes

Question 11

What is a common inhibitor of surfactant production in the fetus?

Answer 11

Maternal diabetes

Question 12

What are three characteristics of alveolar maturation in late fetal life?

Answer 12

Increased number & size of alveoli, thinning of ceonnective tissue septa between alveoli, and flattening of alveolar epithelium.

Question 13

What are two types of stimuli that encourage the first breath in a neonate? Give examples of each.

Answer 13

Chemical stimuli (increased PCO2, decreased PO2) and environmental stimuli (cooling, light, sound, J receptors stimulated by pressure)

Question 14

What is the main/most important function of the first breath?

Answer 14

Establishes functional residual capacity

Question 15

What is the main factor that leads to absorption of fetal lung fluid in the neonate? What brings this about in the birthing process?

Answer 15

Perinatal epinephrine surge, brought on by the forceful nature of a delivery.

Question 16

What are two factors that enhance absorption of fetal lung fluid?

Answer 16

Thyroid & steroid hormones, alveolar-capillary pressure gradient.

Question 17

How efficient is the breathing apparatus in the newborn? What does this mean in terms of energy expenditure?

Answer 17

Not very efficient due to chest shape and poor respiratory muscle development; leads to loss of energy with every breath.

Question 18

How does the ventilation-perfusion relationship of the neonate evolve? What two factors result in this change?

Answer 18

Initially low, normalizes over several months. Two factors: # of pulmonary arteries decrease overtime to match # of alveoli; and there is a decrease in vascular resistance in the lungs as baby starts to breath allowing more blood flow to the lungs.

Question 19

How does the breathing pattern of the neonate change from when it is in the uterus to post-partum?

Answer 19

Episodic inside the uterus, continues post-partum.

Question 20

Respiratory pauses such as periodic breathing or central apnea can still occur in a neonate. Wha tis the most important thing that can be done when this happens?

Answer 20

Arousal; wake the baby up!

Question 21

How does the neonate’s body react to hypoxia compared to a more aged/mature baby? Is this good or bad?

Answer 21

Neonate: hypoxia leads to decreased ventilation (should normally lead to increased ventilation). Can be bad.