Lung Development

Question 1

What is the approximate gas exchange area of the adult human lung?

Answer 1

100 m²

Question 2

What are the functions of alveolar epithelial cells (AECs)?

Answer 2

They provide efficient transport of gases from the alveolar space to the pulmonary circulation

Question 3

List the four necessities for the delivery of external gases to pulmonary tissue.

Answer 3

• Keeps the airway free of pathogens and debris
• Maintains humidification of alveolar gases and precise hydration of the epithelial cell surface
• Reduces collapsing forces at air-liquid interfaces within the lung
• Supplies and regulates pulmonary blood flow for efficient gas exchange

Question 4

What are the five distinct stages of lung organogenesis?

Answer 4

• Embryonic (3 to 7 weeks postconception)
• Pseudoglandular (6 to 17 weeks)
• Canalicular (16 to 26 weeks)
• Saccular (26 to 36 weeks)
• Alveolar (36 weeks to adolescence)

Question 5

What genetic factors are critical to the formation of the axial body plan?

Answer 5

Homeotic, or HOX, genetics

Question 6

What initiates lung morphogenesis during the embryonic period?

Answer 6

Formation of a small saccular outgrowth of the ventral wall of the foregut endoderm

Question 7

What gene is the earliest known marker of the prospective respiratory epithelium?

Answer 7

NKX2-1 (thyroid transcription factor-1)

Question 8

What is the primary function of mesenchyme in lung development?

Answer 8

It has a critical role in the formation of the respiratory tract

Question 9

What congenital anomalies can arise from early lung development?

Answer 9

• Laryngeal atresia
• Tracheal atresia
• Esophageal atresia
• Bronchial atresia
• Tracheoesophageal fistulas
• Bronchoesophageal fistulas
• Tracheal and bronchial stenosis
• Bronchogenic cysts
• Ectopic lobes
• Extrapulmonary sequestration
• Pulmonary agenesis

Question 10

During which period are surfactant proteins first detected?

Answer 10

Pseudoglandular period (12-14 weeks of gestation)

Question 11

What are the primary components of the airway epithelium during the pseudoglandular period?

Answer 11

• Basal cells
• Mucous cells
• Ciliated cells
• Nonciliated secretory cells

Question 12

What are some important signaling pathways involved in lung branching morphogenesis during the pseudoglandular period?

Answer 12

• FGF10
• BMP4
• TGFβ
• β-catenin
• WNT signaling pathways

Question 13

What characterizes the canalicular period of lung development?

Answer 13

• Growth and subdivision of acinar tubules
• Rapid expansion of the pulmonary capillary bed
• Formation of the alveolar-capillary membrane

Question 14

What is the result of surfactant synthesis during the canalicular period?

Answer 14

Gas exchange can be supported after birth, especially with exogenous surfactant

Question 15

What congenital defects can arise during the canalicular period?

Answer 15

• Congenital alveolar dysplasia
• Alveolar capillary dysplasia
• Pulmonary hypoplasia
• Congenital diaphragmatic hernia

Question 16

What happens during the saccular and alveolar periods?

Answer 16

• Increased thinning of the respiratory epithelium
• Development of the distal alveolar capillary network
• Maturation of type II AECs with increased surfactant synthesis

Question 17

What are the key components of the pulmonary host defense systems?

Answer 17

• Mucociliary clearance
• Innate and acquired immunity

Question 18

What is the role of mucociliary clearance in the lungs?

Answer 18

It protects the airway and lung from infection and injury

Question 19

What types of cells play a role in innate immunity within the lung?

Answer 19

• Alveolar macrophages
• Dendritic cells
• Innate lymphocytes
• Classical lymphocytes
• Polymorphonuclear cells
• Eosinophils
• Mast cells

Question 20

What is the function of collectins like SFTPA and SFTPD?

Answer 20

They bind to pathogenic organisms, enhancing their phagocytosis by alveolar macrophages

Question 21

What are some consequences of chronic inflammation in the lungs?

Answer 21

• Pulmonary fibrosis
• Abnormal alveolar remodeling associated with chronic lung disease

Question 22

What are the consequences of mutations in NKX2-1?

Answer 22

• Neurological symptoms
• Hypothyroidism
• Neonatal RDS
• Chronic interstitial lung disease

Question 23

What type of cancer is produced by respiratory epithelium?

Answer 23

Pulmonary adenocarcinoma

Pulmonary adenocarcinoma is a type of lung cancer that originates in the glandular cells of the respiratory epithelium.

Question 24

What role does chronic inflammation play in lung disease?

Answer 24

Establishes ongoing inflammatory and proliferative cascades leading to fibrosis and abnormal alveolar remodeling

Chronic inflammation can be caused by inhaled particles, infections, or immune responses.

Question 25

What are the effects of mutations in NKX2-1?

Answer 25

Neurological symptoms, hypothyroidism, neonatal RDS, chronic interstitial lung disease ## Footnote Disrupted surfactant homeostasis and pulmonary hypoplasia are caused by these mutations.

Question 26

What condition results from mutations in SOX9?

Answer 26

Respiratory insufficiency due to severe tracheobronchomalacia ## Footnote This condition is associated with campomelic dwarfism.

Question 27

What are the consequences of mutations in SOX2?

Answer 27

Tracheoesophageal fistula, anophthalmia, microphthalmia, CNS defects ## Footnote These mutations impact multiple organ systems.

Question 28

What malformations are associated with SHH and FGF signaling mutations?

Answer 28

Lung and tracheobronchial malformations in human infants ## Footnote SHH refers to Sonic Hedgehog signaling and FGF to Fibroblast Growth Factor signaling.

Question 29

What lethal congenital malformation is linked to FOXF1 mutations?

Answer 29

Alveolar capillary dysplasia with misalignment of the pulmonary veins ## Footnote This condition can lead to severe respiratory distress in newborns.

Question 30

What genetic disorder is caused by mutations in the CFTR protein?

Answer 30

Cystic fibrosis (CF) ## Footnote CF is characterized by thick mucus production affecting the lungs and digestive system.

Question 31

What condition is associated with mutations in multiple genes related to ciliary structure?

Answer 31

Primary ciliary dyskinesia (PCD) ## Footnote PCD leads to respiratory complications due to impaired ciliary function.

Question 32

What is the genetic mutation associated with emphysema?

Answer 32

Mutations in α1-antitrypsin ## Footnote Deficiency in α1-antitrypsin can lead to lung damage and emphysema.

Question 33

What mutations are related to lymphangioleiomyomatosis?

Answer 33

Mutations in tuberous sclerosis complex 1 and 2 (TSC1/2) ## Footnote This condition affects the lungs and is characterized by abnormal smooth muscle cell growth.

Question 34

What causes alveolar proteinosis?

Answer 34

Mutations in the GM-CSF receptor (GMCSFR) ## Footnote This disorder leads to accumulation of surfactant in the alveoli.

Question 35

What mutations can lead to acute respiratory failure in neonates?

Answer 35

Mutations in SFTPB and ABCA3 ## Footnote These mutations affect surfactant production and function.

Question 36

What genetic mutations are associated with chronic interstitial lung disease in infants and children?

Answer 36

Mutations in SFTPC, ABCA3, and NKX2-1 ## Footnote These mutations contribute to lung development issues.

Question 37

What mutations are linked to chronic interstitial lung disease with progression to pulmonary fibrosis in adults?

Answer 37

Mutations in SFTPA, SFTPC, ABCA3, and genes controlling telomere length (TERT, TERC) ## Footnote These mutations can have significant implications for lung health in adults.