Respiratory embryology Flashcards
What happens in day 25 of respiratory embryology
diverticulum of foregut endoderm and associated mesoderm; 1st outpouching
describe the process of day 25 of respiratory embryology
foregut goes to oesophageal septum to respiratory diverticum
what happens in the 4th week of respiratory embryology
splanchnic mesoderm sprouts and by end of 4th week splits into 2 buds
what happens in the 5th week of respiratory embryology
lung buds enlarge to form left and right main bronchi
- septum developing between trachea and oesophagus starts budding off
when is the pseudoglandular phase
weeks 5-16
what happens during the pseudoglandular phase of respiratory embryology
major airways defined and respiratory bronchioles formed
what is the appearance of the lungs during the pseudoglandular phase
very immature, look like endocrine tissue nests of angiogenesis, cartilage and smooth muscle, cilia, lung fluid
when are lung lobes visible
after 8 weeks
when is the canalicular phase
weeks 16-25
what happens during the canalicular phase of respiratory embryology
vascularisation
terminal bronchioles begin to develop
Some formation of alveoli
when is alveolarization 1
25 weeks to birth
when is alveolarization 2
birth to 3.5 yrs
what happens during alveolarization 1
alveolar sacs develop
type I and II pneumocytes develop
surfactant begins to be produced
simple alveoli present with thick interstitium
what happens during alveolarization 2
thinning of alveolar membrane and interstitium
increasing complexity of alveoli
what are the 3 main phases of respiratory embryology
pseudoglandular, canalicular, alveolar
what type of cells are type I pneumocytes
simple squamous cells
what type of cells are type II pneumocytes
simple cuboidal cells
what is the important property of surfactant
amphipathic (can bind to both hydrophobic and hydrophilic molecules simultaneously) so binds to water and air within alveoli to reduce surface tension
what is the effect of the presence of surfactant in the lungs
allows lung expansion with minimal effort
describe foetal circulation in the heat
shunting of blood R to L
describe the 1,2,3 of foetal circulation
1 umbilical vein
2 umbilical arteries
3 foetal shunts
what does the umbilical vein do
carries oxygenated blood from placenta to the foetus
what do the umbilical arteries do
carry deoxygenated blood from foetus to placenta
what are the 3 foetal shunts
ductus venosus, foramen ovale, ductus arteriosus
what does the birth process do to the lungs
fluid squeezed out of lungs by birth process
what happens to ion channels in the lung at birth
switch from secretory to absorptive
what causes increased surfactant release following birth
adrenaline stress
what does the first breath do to the lungs/ respiratory system/ circulation
oxygen vasodilates pulmonary arteries
umbilical arteries constrict to form medial umbilical ligaments
ductus arteriosus constricts to form ligamentum arteriosum
why does blood move into the lungs following birth
PA pressure decreases exponentially, aortic pressure increases so blood moves into lungs by diffusion to be oxygenated
what happens in premature babies with surfactant deficiency
respiratory distress syndrome
what are risk factors for respiratory distress syndrome
prematurity and asphyxia/ cold/ stress/ twins
what is the management of respiratory distress syndrome in infants
warmth, surfactant replacement, oxygen and fluid, continuous positive airway pressure, positive pressure ventilation if needed
