Developmental aspects of lung disease Flashcards
What are the 5 main stages of lung development?
Embryonic Pseudo-glandular Canalicular Saccular Alveolar
What weeks of gestation does embryonic development of the lungs take place over?
3 - 8
Summarise what happens in the embryonic stage of development
Formation of trachea from L-T groove
Lung buds form at bottom of trachea
Formation of main pulmonary arteries and bronchi
What period of gestation does the pseudo-glandular stage take place over?
5 - 17 weeks
What happens in the pseudo-glandular stage?
Formation of ‘basic’ lungs:
- Conducting airways
- Accompanying blood vessels
Wall structure and epithelial cells differentiate
When does the canalicular stage take place?
week 16 - 26
What happens in the canalicular stage?
Respiratory airways form
Blood-air barrier thins
Surfactant appears
When is the saccular stage?
24 - 38 weeks of gestation
What happens in the saccular stage?
Saccules form
When is the alveolar stage?
36th week of gestation to about 3 years post natal
What happens in the alveolar stage?
Alveoli form and multiply
How does the number of alveoli change from birth?
about 100 million at birth
multiplies to between 200-600 million by the time you’re 3
(They think)
Aside from multiplication of alveoli, what other changes occur in the lung after birth?
Lungs change from being fluid secreting to fluid absorbing organs
Airways double in size
What is airway stenosis?
Narrowing of the airways
What is malacia?
Respiratory problem caused by soft cartilage in the airways
This leads to floppy airways, which obstructs airflow
