Embryo respiratory system Flashcards
Lower respiratory tract includes
larynx, trachea, bronchi, lungs
First respiratory formation
laryngotracheal groove
Laryngotracheal groove arises from…
4th-6th pharyngeal arches
LRT structures are made from which germ layer(s)?
from splanchnic mesoderm and endoderm
Splanchnic mesoderm in the LRT gives rise to…
cartilage, smooth muscle, connective tissue
Endoderm in the LRT gives rise to the..
epithelium, glands of larynx, trachea, bronchi, lungs
LT diverticulum
as lungs elongate, it separates trachea and lungs
TE septum
TE folds fuse to separate trachea and esophagus
TE fistula
incorrect separation of trachea and esophagus- can result in esophageal atresia (blind ending)
most likely due to incomplete fusion of TE folds
maturation of lungs (4 phases)
- pseudoglandular
- canalicular
- terminal sac period
- alveolar
pseudoglandular period (5-17 weeks)
thick tissue between respiratory epithelium and capillaries
survival not possible
canalicular period (16-26 weeks)
survival is possible but unlikely
terminal sac period (24 weeks- birth)
surfactant is produced- good prognosis for survival
terminal branches of bronchi come in close contact with alveoli/blood vessles
Alveolar period (birth - 8 years)
mature alveoli develop and multiply during this period
surfactant produced by…
type 2 pneumocytes
2 things that surfactant does in the lungs:
- reduces surface tension at air-blood barrier to facilitate gas exchange
- prevents the collapse of alveoli
if born prior to 24-26 weeks will suffer from this disease:
respiratory distress syndrome
- inadequate surfactant
- insufficient alveolar surface area
- inadequate vasculature
can be treated with prenatal steroids to produce more surfactant asap
differences in chest xray of infant and older child
infant- more white (dense) bc still some fluid left in lungs and fewer alveoli
for normal lung development, in utero you need:
- adequate space for lung development
- fetal breathing movements to condition muscles
- adequate amniotic volume (to protect the space for lung development- to protect muscle of uterus from clamping down on fetus)
