Flashcards in Respiratory Embryology Deck (12):
why germ layer forms the respiratory system?
endoderm forms the lining of the trachea and bronchial tree
all other lung tissue (smooth muscle, cartilage...) is formed by the by visceral mesoderm
an abnormal connection between the oesophagus and the trachea. It's a common birth defect
stages of lung maturation
embryonic (26 days- 6 weeks)
pseudoglandular (6-16 weeks)
canalicular (16-28 weeks)
saccular (28-36 weeks)
alveolar (36 weeks- early childhood)
function of type I pneumocytes
they are flattened, thin, squamous: this gives them a thin distance for gaseous exchange
function of type II pneumocytes
these retain their cuboidal shape and produce surfactant, which prevents the lungs from collapsing
respiratory distress syndrome
causes about 20% of the deaths of all newborns. Occurs due to lungs collapsing due to premature babies not having enough surfactant
birth defect which causes the oesophagus to end in a blind-ended pouch rather than connecting normally to the stomach
embryonic stage events?
respiratory diverticulum forms. Initial branching gives lungs, lobes and segments
pseudoglandular stage event?
14 more generations of branching. Terminal bronchioles
terminal bronchioles--> respiratory bronchioles--> alveolar ducts
terminal sacs form, capillaries establish close contact