Respiratory- Anatomy and embriology

Question 1

Lung development

Answer 1

Pag. 642

Question 2

Congenital lung malformations

- Pulmonary hypoplasia

Answer 2

Poorly developed bronchial tree with abnormal histology.

Associated with congenital diaphragmatic hernia (usually left-sided), bilateral renal agenesis (Potter sequence).

Question 3

Congenital lung malformations

- Bronchogenic cysts

Answer 3

Abnormal budding of the foregut and dilation of terminal or large bronchi.

Discrete, round, sharply defined, fluid-filled densities on CXR (air-filled if infected).

Asymptomatic but can drain poorly, causing airway compression and/or recurrent respiratory infections

Question 4

Club cells

Answer 4

Nonciliated; low columnar/cuboidal with secretory granules. Located in bronchioles.

Degrade toxins; secrete component of surfactant; act as reserve cells

Question 5

Alveolar cell types

• Peumocyte I
• Pneumocyte II

Answer 5

97% of alveolar surfaces. Line the alveoli. Squamous; thin for optimal gas diffusion.

Secrete surfactant from lamellar bodies, Cuboidal and clustered. Also serve as precursors to type I cells and other type II cells

Question 6

Surfactant

Answer 6

Collapsing pressure (P) = 2 (surface tension) / radius

dipalmitoylphosphatidylcholine (DPPC)

Surfactant synthesis begins week 20, but mature levels until around week 35.

Corticosteroids important for fetus surfactant production and lung development

Question 7

Neonatal respiratory distress syndrome

• Phatophysiology
• Risk factors
• Complications

Answer 7

Surfactant deficiency Ž alveolar collapse (“ground-glass” appearance of lung fields)

Prematurity, maternal diabetes (due to  fetal insulin), C-section delivery ( release of fetal glucocorticoids)

Complications: PDA, necrotizing enterocolitis

Question 8

Neonatal respiratory distress syndrome

- Treatment

Answer 8

Maternal steroids before birth; exogenous surfactant for infant.

Therapeutic supplemental O2 can result in Retinopathy of prematurity, Intraventricular hemorrhage, Bronchopulmonary dysplasia (RIB).

Question 9

Screening tests for fetal lung maturity:

Answer 9

lecithin/sphingomyelin (L/S) ratio in amniotic fluid (≥ 2 is healthy; < 1.5 predictive of NRDS), foam stability index, surfactant-albumin ratio.

Question 10

Respiratory tree

- Conducting zone

Answer 10

Large airways: nose till bronchi. Small airways:
bronchioles that further divide into terminal.

Warms, humidifies, and filters

Cartilage and goblet cells extend to the end of bronchi.
Pseudostratified ciliated columnar cells and Airway smooth muscle cells extend to end of terminal bronchioles

Question 11

Respiratory tree

- Respiratory zone

Answer 11

Lung parenchyma: respiratory bronchioles, alveolar ducts, and alveoli. Participates in gas exchange.

Mostly cuboidal cells in respiratory bronchioles, then simple squamous cells up to alveoli

Question 12

Lung and diaphragm anatomy

Answer 12

Pag. 645