Neonatal Flashcards
From what part of the neonatal anatomy does the respiratory tract originate from?
Originate as an outpouching from the endodermal tube that gives rise to the GI tract
When is fetal development does alveolar formation begin?
Around 28 weeks gestation
True or false: Alveoli are fully formed at birth
false– will continue to develop for years
What is the stimulus for lung development in the fetus?
Lung fluid in the airway causes a distending force that stimulate growth
What is the effect of oligohydramnios on lung development? Why?
Decreases, since lung development relies on the pressure exerted from the lung fluid for expansion
What inhibits lung from becoming too large in fetal development?
External compression
What are the two major mechanisms that regulate lung development?
- Physical factors
- Transcription factors/regulatory genes
What are the 5 phases of lung development?
- Embryonic
- Pseudoglandular
- Canalicular
- Saccular
- Alveolar
What is the order of airway development? (6)
- Bronchi
- Bronchioles
- Terminal bronchioles
- Respiratory bronchioles
- Alveolar ducts
- Alveolar sacs
What is occurring in the pseudoglandular phase of lung development? (3)
Formation of:
- major airways
- bronchial tree
- portions of the respiratory parenchyma
What is occurring during the canalicular phase of prenatal lung development? (3)
- Last generation of the lung periphery formed
- Epithelial differentiation
- Air-blood barrier formed
What are the two major events that occur in the saccular phase of lung development?
- Expansion of air space
- Surfactant detectable in amniotic fluid
What is the major event that is occurring in the alveolar phase of lung development?
Secondary septation
When in gestation does surfactant develop?
Around week 24
When is the embryonic phase occurring in gestation (weeks gestation)?
0-8 weeks
When do the first segments appear in the five lobes of the lungs?
At the end of the embryonic phase
When have the pulmonary vessels formed in development?
End of the embryonic phase
What controls the first inward breathing movement at the end of the embryonic phase of development? What is different about this movement as compared to regular physiology?
A breathing center in the brain stem.
paradoxical movement, in that when the diaphragm contracts, the thorax moves inwardly and vv
When does the pseudoglandular phase take place in development?
8-17 weeks
What do the lungs look like in the pseudoglandular phase of development? What is significant about the end of this phase?
Resemble a gland
At the end of this phase, precursors of the pneumocytes can be discerned in the respiratory sections as cubic epithelium
When in development does the developing bronchopulmonary epithelium begin to develop amniotic fluid?
Pseudoglandular phase
When does the canalicular phase happen in development?
16-26 weeks
What happens to the pneumocytes in the canalicular phase of development?
Type I pneumocytes differentiate out of the type II
What happens to the capillaries in the canalicular phase of development?
Capillaries approach the walls of the acini