Development of the Trachea, Lungs and Thoracic Diaphragm

Question 1

What is the embryological origin of the respiratory system?

Answer 1

The respiratory system develops from the foregut endoderm and surrounding splanchnic mesoderm.

Question 2

At what week of gestation does the respiratory system begin to develop?

Answer 2

The respiratory system begins to develop in the fourth week of gestation.

Question 3

What is the role of the laryngotracheal groove in respiratory development?

Answer 3

The laryngotracheal groove is the site where the respiratory diverticulum forms from the foregut.

Question 4

How does the respiratory diverticulum (lung bud) form?

Answer 4

The respiratory diverticulum forms as an outgrowth of the ventral wall of the foregut.

Question 5

What embryonic structure gives rise to the trachea and bronchi?

Answer 5

The trachea and bronchi arise from the laryngotracheal tube, which originates from the respiratory diverticulum.

Question 6

What is the function of the tracheoesophageal septum?

Answer 6

The tracheoesophageal septum separates the trachea from the esophagus during development.

Question 7

What congenital defect results from abnormal partitioning of the tracheoesophageal septum?

Answer 7

Tracheoesophageal fistula results from improper partitioning of the tracheoesophageal septum.

Question 8

What are the four main stages of lung development?

Answer 8

The four stages of lung development are pseudoglandular, canalicular, saccular, and alveolar.

Question 9

During which stage of lung development does surfactant production begin?

Answer 9

Surfactant production begins during the saccular stage, around weeks 24–28.

Question 10

What is the significance of surfactant in neonatal survival?

Answer 10

Surfactant reduces alveolar surface tension, preventing collapse and aiding in neonatal respiration.

Question 11

What is the pseudoglandular stage of lung development?

Answer 11

The pseudoglandular stage (weeks 5–16) is characterized by the formation of the bronchi and terminal bronchioles.

Question 12

What are the key characteristics of the canalicular stage of lung development?

Answer 12

The canalicular stage (weeks 16–24) involves vascularization and formation of respiratory bronchioles.

Question 13

What major changes occur during the saccular stage of lung development?

Answer 13

The saccular stage (weeks 24–36) features terminal sac formation and initial surfactant production.

Question 14

What is the alveolar stage of lung development, and when does it occur?

Answer 14

The alveolar stage (week 36 to 8 years) is marked by alveolar maturation and septation.

Question 15

How does lung maturation continue after birth?

Answer 15

After birth, alveolar development continues until approximately 8 years of age.

Question 16

What are the derivatives of the splanchnic mesoderm in lung development?

Answer 16

The splanchnic mesoderm forms connective tissue, cartilage, and smooth muscle of the lungs.

Question 17

What role does the endoderm play in respiratory system development?

Answer 17

The endoderm forms the epithelial lining of the trachea, bronchi, and alveoli.

Question 18

What is pulmonary hypoplasia, and what conditions can cause it?

Answer 18

Pulmonary hypoplasia is underdevelopment of the lungs, often caused by oligohydramnios.

Question 19

What is congenital diaphragmatic hernia (CDH), and how does it affect lung development?

Answer 19

Congenital diaphragmatic hernia (CDH) allows abdominal organs to compress the lungs, impairing development.

Question 20

What is the origin of the pleural cavities?

Answer 20

The pleural cavities arise from the intraembryonic coelom.

Question 21

How do the right and left primary bronchi develop?

Answer 21

The right and left primary bronchi develop as asymmetric buds from the trachea.

Question 22

What are the secondary bronchi, and how many does each lung have?

Answer 22

The right lung has three secondary bronchi, while the left lung has two.

Question 23

How do the segmental bronchi form, and how many are present in each lung?

Answer 23

Segmental bronchi form from tertiary bronchial branching, with ten in the right lung and eight to nine in the left.

Question 24

What factors regulate branching morphogenesis in lung development?

Answer 24

Fibroblast growth factors (FGFs) and sonic hedgehog (SHH) regulate branching morphogenesis.

Question 25

How does amniotic fluid contribute to lung development?

Answer 25

Amniotic fluid helps expand the developing lungs, promoting growth and differentiation.

Question 26

What is the embryological origin of the diaphragm?

Answer 26

The diaphragm develops from mesodermal structures, including the septum transversum and pleuroperitoneal membranes.

Question 27

What are the four main components that contribute to diaphragm formation?

Answer 27

The four components of diaphragm formation are the septum transversum, pleuroperitoneal membranes, dorsal mesentery of the esophagus, and body wall musculature.

Question 28

What is the role of the septum transversum in diaphragm development?

Answer 28

The septum transversum contributes to the central tendon of the diaphragm.

Question 29

What embryonic structures contribute to the central tendon of the diaphragm?

Answer 29

The central tendon of the diaphragm is derived from the septum transversum.

Question 30

How do the pleuroperitoneal membranes contribute to diaphragm development?

Answer 30

The pleuroperitoneal membranes close the pericardioperitoneal canals, preventing abdominal contents from entering the thorax.

Question 31

What is the role of the dorsal mesentery of the esophagus in diaphragm formation?

Answer 31

The dorsal mesentery of the esophagus contributes to the crura of the diaphragm.

Question 32

How do the body wall muscles contribute to diaphragm formation?

Answer 32

The body wall muscles form the peripheral parts of the diaphragm.

Question 33

What is congenital diaphragmatic hernia, and what causes it?

Answer 33

Congenital diaphragmatic hernia occurs when the diaphragm fails to close completely.

Question 34

What is the clinical significance of Bochdalek hernia?

Answer 34

Bochdalek hernia results from a posterolateral diaphragmatic defect, typically on the left side.

Question 35

What is the clinical significance of Morgagni hernia?

Answer 35

Morgagni hernia is a rare anterior diaphragmatic defect, often asymptomatic.

Question 36

What is eventration of the diaphragm, and how does it occur?

Answer 36

Eventration of the diaphragm occurs when muscle development is incomplete, causing paradoxical movement.

Question 37

What nerve innervates the diaphragm, and what is its embryological origin?

Answer 37

The diaphragm is innervated by the phrenic nerve (C3–C5), derived from cervical somites.

Question 38

What are the consequences of phrenic nerve damage in neonatal development?

Answer 38

Phrenic nerve damage can cause respiratory distress due to diaphragmatic paralysis.

Question 39

How does fetal breathing movement affect lung maturation?

Answer 39

Fetal breathing movements help condition the respiratory muscles and stimulate lung development.

Question 40

How does the fetal circulation support lung development before birth?

Answer 40

Fetal circulation bypasses the lungs via the foramen ovale and ductus arteriosus.

Question 41

What changes occur in the pulmonary circulation at birth?

Answer 41

At birth, pulmonary vascular resistance decreases, allowing increased blood flow to the lungs.

Question 42

What is the fate of the ductus arteriosus after birth?

Answer 42

The ductus arteriosus closes after birth to become the ligamentum arteriosum.

Question 43

How does congenital tracheomalacia affect the airway?

Answer 43

Congenital tracheomalacia causes airway collapse due to weak cartilage support.

Question 44

What is bronchopulmonary dysplasia, and what causes it?

Answer 44

Bronchopulmonary dysplasia results from prolonged mechanical ventilation and oxygen therapy.

Question 45

What congenital anomalies can affect the trachea?

Answer 45

Tracheal anomalies include tracheal stenosis, tracheomalacia, and tracheoesophageal fistula.

Question 46

What is pulmonary sequestration, and how does it develop?

Answer 46

Pulmonary sequestration is a nonfunctional lung tissue mass with an abnormal blood supply.

Question 47

How does the lung's blood supply develop embryologically?

Answer 47

The lung’s blood supply develops from the aortic arch and vitelline arteries.

Question 48

What is the role of fibroblast growth factors (FGFs) in lung development?

Answer 48

Fibroblast growth factors (FGFs) promote lung bud formation and branching.

Question 49

What is the importance of retinoic acid in respiratory system development?

Answer 49

Retinoic acid helps initiate lung development by stimulating FGF expression.

Question 50

What is the function of T-box transcription factors (TBX) in lung branching?

Answer 50

T-box transcription factors (TBX) regulate lung branching and differentiation.