Respiratory Dev Flashcards
When do lung buds appear
week 4
pseudoglandular period time span
weeks 5-16
canalicular period timespan
week 16-26
Terminal sac period timespan
week 26 to birth
what type of embryonic layer makes up the protective layer of the lungs?
pleura is made up of lateral plate mesoderm
what embryonic layer makes up the lungs?
endoderm
where does respiratory diverticulum appear? What comes out of thsi layer?
from the foregut, appears lung buds
what direction does lung development occur?
proximal to distal
Pseudoglandular stage
Week 5 – 16
– Branching has continued to
form terminal bronchioles. No
respiratory bronchioles or
alveoli are present.
Canalicular period
Week 16 - 26
– Each terminal bronchiole
divides into 2 or more
respiratory bronchioles,
which divide into 3-6
alveolar ducts.
Terminal sac period
Week 26 - birth
– Terminal sacs (primitive
alveoli) form, and capillaries
establish close contact.
Alveolar period
8 months to childhood
– Mature alveoli have well
developed capillary contacts.
– 20-70 million alveoli at birth;
300-400 million by age 8
Preterm infants born prior to #### weeks rarely survive
20
This is established in late canalicular period
blood air barrier
seen in diaphram development
