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
What happens with lungs at birth?
– Adrenaline promotes absorption of the rest
• Surfactant is released
• Fall in capillary pressure occurs with expansion of
alveoli
• Respiratory movements of the chest begin
The intraembryonic coelom is what is seen in this developed part of the body, and goes into these three layers
Diaphragm
The intraembryonic coelom (body cavity) is
initially a single space which is later divided into
the pericardial, peritoneal, and pleural spaces.
seen in diaphram development
what is primitive form of diaphragm? what is the embryonic layer?
Septum transversum, paraxial mesoderm
