Lung Development Flashcards
What are the 4 phases?
Embryonic 7 weeks
Pseudoglandular 17 weeks
Canalicular 27 weeks
Alveolar remaining
When does the blood gas barrier form?
canicular
What happens in the pseudoglandular phase?
Pre acinar airways are all present
Start developing cartilage, smooth muscle and glands
What growth factors induce or inhibit lung development?
FGF = branching EGF = epithelial proliferation
Inhibitory
TGFbeta = surfactant and inhibit proliferation of epithelial
Retinoids acid = inhibit branching
What is VEGF?
Stimulator hormone
Produced by epithelial cells on the tip of the lung bud and stimulates proliferation
What happens in the canalicular phase?
Air spaces start to enlarge
Thinning of epithelial to for blood barrier
Epithelial differentiate into type 1 and 2
When do babies become viable?
24 wks
How do alveolar walls form?
1 - Saccule wall: epithelium on both sides, double capillary network
2 - Secondary septa matrix
3 - coalesce (capillaries),
elastin and muscle still at tip, less matrix
How much of the adult alveoli should you have at term?
1/3
How does blood flow increase after birth?
Expanding alveoli dilates arteries
Vasodilators released
Inhibition of vasoconstrictors
Decrease in pulmonary R –> 10x increase blood flow
What lung growth anomalies can occur?
Agenesis = no vessels Aplaisa = bronchus but no lung Hypoplasia = everything is smaller
What causes cystic pulmonary airway malformation?
Defect in pulmonary mesenchyma
Normally blood supply
Due to cysts/herniation
What is am intralobar sequestration?
cysts no connected airways supply blood l,r shunting in aorta
What is congenital large hyperlucent lobe?
weak cartilage, extrinsic alveolar pressure
l u > r m > r u
m>f
