Embryology Flashcards
What purpose does the lung have in the foetus?
No purpose
What forms during the 4th week?
Lung buds form, appears as respiratory diverticulum
What does the endoderm form?
Epithelial lining
What does splanchnic mesoderm form?
Cartilages, connective tissue
What Happens between week 5 - 16?
Pseudoglandular phase begins, R + L bronchi into terminal bronchioles
What happens between week 16 - 26?
Canalicular phase, terminal bronchioles to resp bronchioles—> each form a few alveolar ducts
What happens between 26 weeks to 8 months?
Saccular phase, alveolar ducts grow sacs on end (alveoli)
What happens from 8 months to birth?
Alveolar phase - alveoli mature
What are the 3 types of circulation in a fetus?
3 shunts
2 umbilical arteries
1 umbilical vein
What are the 3 shunts are where are they passing blood to?
Foramen ovale (R and L atrium), ductus venosus (bypass liver), ductus arteriosus (blood from pulmonary artery to aorta)
What do the 2 umbilical arteries do?
Return O2 blood from fetus to mother
What does the 1 umbilical vein do?
Supplies O2 blood from mother to fetus
What Happens during the first breath?
Fluid squeezed out of lungs
Surfactant produced
Air inhaled
Oxygen vasodilates pulmonary arteries
Surfactant Produced by? Produced from? Function? Dramatic increase when?
Type 2 pneumocytes
34 weeks gestation
Decrease surface tension in alveoli
Dramatic increase 2 weeks pre birth
What happens to surfactant in premature babies?
Surfactant deficient
Decreased lung compliance
Can cause death
