Development of the Respiratory System Flashcards
From which embryological structure is the respiratory system derived?
Primitive gut tube
Which structure from the primitive gut tube is the first to form the eventual respiratory system?
Respiratory diverticulum = outpouching of foregut
When does the respiratory system begin to form?
Week 4
What structure splits the respiratory diverticulum from the primitive gut tube?
Tracheo-oesophageal septum
Into which structures does the respiratory diverticulum split?
Left and right primary bronchi
How do the secondary and tertiary bronchi form?
Proliferation of primary bronchi
What is the pseudoglandular stage of respiratory system development?
Ducts develop within bronchopulmonary segments
Bronchiolar buds branch off from tertiary bronchi and proliferate
When during gestation does the pseudoglandular stage of respiratory system development occur?
Weeks 8-16
What is the canalicular stage of respiratory system development?
Respiratory bronchioles develop
When during gestation does the canalicular stage of respiratory system development occur?
Weeks 16-26
What is the terminal sac stage of respiratory system development?
Alveoli develop
When during gestation does the terminal sac stage of respiratory system development occur?
Week 26 onwards
What are the two types of cell within alveoli?
Type I pneumocyte
Type II pneumocyte
What is a type I pneumocyte?
Simple squamous epithelial cells
90% of alveoli
What is a type II pneumocyte?
Simple cuboidal cells
Produce surfactant
10% of alveoli
