Embryonic lung development Flashcards
What is lung surfactant
Lung matures by glucocorticoids
Enables alveolar cells to touch each other without sticking
Surfactant made by type II pneumocytes
Reduces surface tension
What are 4 factors that influence lung development
- Intra-thoracic space
Size of space for lungs to develop in
Can be impaired by conditions
e.g. diaphragmatic hernia – common – diaphragm fails to close & abdominal contents enter thoracic cavity (compresses lungs & impairs growth) - Intra-uterine space
Size of uterus & amount of amniotic fluid
Can be impaired by lack of amniotic fluid – leads to uterine compression - Fetal breathing movements
Regular activation of respiratory muscles essential for normal development of fetal lungs - Lung liquid production
Lungs need adequate secretion of fluid to maintain appropriate balance of volume & pressure during development
What are the 5 stages of lung development
What do lungs develop from
Embryonic endoderm constructs lining of 2 tubes
1st tube is digestive tube
2nd is respiratory tube which forms 2 lungs
Lung buds form by process of branching morphogenesis
Regional specificity of mesenchyme determines differentiation of developing respiratory tube
In region of neck grows straight forming trachea
After entering thorax it branches to form 2 bronchi & lungs
Subsequent divisions generate bronchi, bronchioles & alveoli
Most divisions occur in utero
At birth lungs are immature but functional
Describe what is happening in the diagram
A. Formation of laryngotracheal tube
Buds into 2 bronchi
B. Further budding may be unequal
C. Final septation distinguishes pharynx from larynx & trachea from esophagus