2. Development of respiratory system [except nose]

8. Tracheo-esophageal fistula-types

9. Tracheo-esophageal fistula-types

12. Development of trachea

13. Tracheomalacia and bronchomalacia
Abnormal cartilage development
‘floppy’ airways
Collapse during inspiration [if extra thoracic] or expiration [if intra thoracic]
Presents early in infancy with cough, tachypnea, stridor and wheeze
May be associated with cardiac or respiratory abnormalities [TEF]

14. Development of bronchi and lungs

17. Maturation of lungs

23. Stages in lung development

24. Embryonic- 26 days to 6 weeksS
Respiratory diverticulum arises as a ventral outpouching of foregut endoderm and undergoes three initial rounds of branching, producing the primordia successively of the two lungs, the lung lobes, and the bronchopulmonary segments; the stem of the diverticulum forms the trachea and larynx.
Pseudoglandular 6 to 16 weeks
 Respiratory tree undergoes 14 more generations of branching, resulting in the formation of terminal bronchioles

25. Canalicular 16 to 28 weeks Saccular 28 to 36 weeks
Each terminal bronchiole divides into two or more respiratory bronchioles.
Respiratory vasculature begins to develop.
Blood vessels come into close apposition with the lung epithelium.
The lung epithelium also begins to differentiate into specialized cell types .
Saccular to 36 weeks
Respiratory bronchioles subdivide to produce terminal sacs (primitive alveoli). Terminal sacs continue to be produced until well into childhood

26. Alveolar-
36 weeks to term
Alveoli mature

27. the respiratory distress syndrome
The primary cause of this syndrome in premature infants (pulmonary insufficiency accompanied by gasping and cyanosis) is an inadequate production of surfactant
threatens the infant with immediate asphyxiation

28. increased rate of breathing and mechanical ventilation required to support the infant's respiration can also damage the delicate alveolar lining
This allows fluid and cellular and serum proteins to exude into the alveolus.

29. Continued injury may lead to detachment of the layer of cells lining the alveoli, a condition called hyaline membrane disease.
In mothers with a high risk for premature delivery, the fetus can be treated antenatally with steroids to accelerate lung maturation and the synthesis of surfactant

30. Moreover, amniocentesis can be done in late pregnancy to assess fetal lung maturity.
the sample of amniotic fluid is analyzed with thin-layer chromatography to determine the lecithin-sphingomyelin ratio (L/S; greater than 1.9 = mature; less than 1.5 =immature) and to detect phosphatidylglycerol (presence indicates lung maturity).

31. Critically ill newborns were first successfully treated with surfactant replacement therapy-the administration of exogenous surfactant-in the late 1970s.
A variety of surfactant preparations are now used for this purpose, some derived from animal lungs or human amniotic fluid, others synthetic.