Embryology and Histology Flashcards
Which germ layer gives rise to the lung bud and the lining of the respiratory tree?
Endoderm
Which germ layer gives rise to the smooth muscle, cartilage and blood supply of the respiratory tree?
Mesoderm
How do primary bronchial buds form?
Bifurcation of the trachea, producing the right and left bronchi
How do secondary bronchial buds form?
Bifurcation of right + left bronchi, producing 3 right lobar bronchi and 2 left lobar bronchi
Give two common congenital lung defects…
Oesophageal atresia (bind ending) Tracheoesophageal fistula (communication)
Name the 5 stages of lung development (elephants play chess in sunny Africa…)
Embryonic Pseudoglandular Canalicular Saccular Alveolar
What happens in the embryonic phase of lung maturation?
Respiratory diverticulum forms off oesophagus
Initial branching produces lung, lobes + segments
What happens in the pseudoglandular phase of lung maturation?
Terminal bronchioles form
What happens in the canalicular phase of lung maturation?
Respiratory bronchioles form
What happens in the saccular phase of lung maturation?
Terminal sacs form (begin to form alveoli)
What happens in the alveolar phase of lung maturation?
Alveolar sacs mature (change from cuboidal epithelium to SSE)
State the functions of the two types of cells within the alveoli…
1: Blood - air barrier
2: Produce surfactant which prevent alveoli collapsing by reducing surface tension (lower tendency of water molecules to stick together)
What can happen to premature infants who have too little surfactant?
Respiratory distress syndrome - hypoxia and a VQ mismatch
What type of epithelium covers the vocal cords?
SSE
What does the blood-air barrier consist of?
Type 1 cell, endothelial cell, basal lamina
