Lung Development and Disorder

Question 1

5 Stages of Lung Development (and how far through formation each goes generally)

Answer 1

Embryonic - trachea and bronchi
Pseudoglandular - terminal bronchioles
Canalicular - respiratory bronchioles
Saccular - alveolar ducts
Alveolar - alveoli

Question 2

Trachea Formation

Answer 2

Respiratory diverticulum comes off foregut, eventually extending to lung bud. Tracheoesophageal ridges gotta close

Question 3

Pulmonary Agenesis

Answer 3

Not really seen in humans, no tracheoesophageal ridges and lung bud deformed or not formed.

Question 4

3 Kinds of Esophageal Atresia/Tracheoesophageal Fistula

Answer 4

A. Atresia of esophagus, tracheoesophageal fistula (most common)
B. Atresia of esophagus, fibrous cord on lower half so no fistula
C. Tracheoesophageal fistula, no atresia though

Question 5

Maternal and Neonate Sign of TEF

Answer 5

Polyhydramnios - excess amniotic fluid accumulates cause fetus can’t swallow properly
Newborn aspiration/respiratory distress cause can’t swallow

Question 6

How to Tell Type A TEF from Type B TEF on CXR

Answer 6

Type A will have air and shit in gastric stuff cause you got a fistula from trach->esoph

Question 7

3 Things in Pseudoglandular Stage (and which one main)

Answer 7

Main: Rapid branching of airway/vasculature
Proximal airway epithelial cell differentiation
Mesenchyme forms muscle, cartilage, vessels around bronchial tree

Question 8

3 Steps of Branching Morphogenesis and GF that Dictates

Answer 8

Mediated by FGF10 from mesenchyme interacting on epithelium

1. Epithelial cell proliferation and tube elongation
2. Tip arresting of epithelial bud
3. Branching (FGF10 on edges of tube causes lateral expansion)

Question 9

Congenital Cystic Adenomatoid Malformations (CCAM)

Answer 9

Rare bronchopulmonary malformations that can be detected early and potentially self-regress. Bigger ones (like Type 3, predominantly solid lesions) need resection and can have poor prognosis, inhibiting lung development and causing abnormal branching

Question 10

4 Parts of Diaphragm Formation (and other notable point)

Answer 10

Starts forming at levels C-3/4/5, but then moves down taking phrenic nerve with it

1. Septum transversum
2. Pleuroperitoneal membranes
3. Muscle from body wall
4. Dorsal mesentery

Question 11

Congenital Diaphragmatic Hernia

Answer 11

Failure of pleuroperitonal membranes to close canal, causes abdominal contents to come up into thorax, leading to ipsilateral lung hypoplasia. Possibly mediastinum displacement leading to contralateral lung hypoplasia as well

Question 12

Canalicular Stage (1.4)

Answer 12

Transformation of previable lung to the potentially viable lung via 4 major events:
Formation of acinar structures
Differentiation of epithelial cells (like Type IIs for surfactant)
Development of capillary bed (gas exchange maybe possible)
Thinning of mesenchyme

Question 13

Saccular Stage (2)

Answer 13

Differentiation of Type I cells, alveoli begin to appear (and continue mainly through childhood)/septate

Question 14

PDGF-A

Answer 14

Upregulates elastin expression, myfibroblast differentiation and secondary septum formation for alveolar development in saccular stage

Question 15

Most Important Hormonal Reg of Lung Development

Answer 15

Glucocorticoids

Question 16

Hyaline Membrane Disease (HMD)/Respiratory Distress Syndrome (RDS)

Answer 16

Surfactant deficiency, collapse, proteins leak in and edema occurs, fibrin clots form hyaline membrane and line air spaces

Question 17

Radiography of HMD

Answer 17

Ground-glass appearance

Question 18

Bronchopulmonary Dysplasia

Answer 18

Treatment w/ O2 > 21% for at least 28d+ on very preterm infants. Decreased and larger alveoli, fibrosis, and vascular remodeling