Development of the Trachea, Lungs and Thoracic Diaphragm Flashcards
What is the embryological origin of the respiratory system?
The respiratory system develops from the foregut endoderm and surrounding splanchnic mesoderm.
At what week of gestation does the respiratory system begin to develop?
The respiratory system begins to develop in the fourth week of gestation.
What is the role of the laryngotracheal groove in respiratory development?
The laryngotracheal groove is the site where the respiratory diverticulum forms from the foregut.
How does the respiratory diverticulum (lung bud) form?
The respiratory diverticulum forms as an outgrowth of the ventral wall of the foregut.
What embryonic structure gives rise to the trachea and bronchi?
The trachea and bronchi arise from the laryngotracheal tube, which originates from the respiratory diverticulum.
What is the function of the tracheoesophageal septum?
The tracheoesophageal septum separates the trachea from the esophagus during development.
What congenital defect results from abnormal partitioning of the tracheoesophageal septum?
Tracheoesophageal fistula results from improper partitioning of the tracheoesophageal septum.
What are the four main stages of lung development?
The four stages of lung development are pseudoglandular, canalicular, saccular, and alveolar.
During which stage of lung development does surfactant production begin?
Surfactant production begins during the saccular stage, around weeks 24–28.
What is the significance of surfactant in neonatal survival?
Surfactant reduces alveolar surface tension, preventing collapse and aiding in neonatal respiration.
What is the pseudoglandular stage of lung development?
The pseudoglandular stage (weeks 5–16) is characterized by the formation of the bronchi and terminal bronchioles.
What are the key characteristics of the canalicular stage of lung development?
The canalicular stage (weeks 16–24) involves vascularization and formation of respiratory bronchioles.
What major changes occur during the saccular stage of lung development?
The saccular stage (weeks 24–36) features terminal sac formation and initial surfactant production.
What is the alveolar stage of lung development, and when does it occur?
The alveolar stage (week 36 to 8 years) is marked by alveolar maturation and septation.
How does lung maturation continue after birth?
After birth, alveolar development continues until approximately 8 years of age.
What are the derivatives of the splanchnic mesoderm in lung development?
The splanchnic mesoderm forms connective tissue, cartilage, and smooth muscle of the lungs.
What role does the endoderm play in respiratory system development?
The endoderm forms the epithelial lining of the trachea, bronchi, and alveoli.
What is pulmonary hypoplasia, and what conditions can cause it?
Pulmonary hypoplasia is underdevelopment of the lungs, often caused by oligohydramnios.
What is congenital diaphragmatic hernia (CDH), and how does it affect lung development?
Congenital diaphragmatic hernia (CDH) allows abdominal organs to compress the lungs, impairing development.
What is the origin of the pleural cavities?
The pleural cavities arise from the intraembryonic coelom.
How do the right and left primary bronchi develop?
The right and left primary bronchi develop as asymmetric buds from the trachea.
What are the secondary bronchi, and how many does each lung have?
The right lung has three secondary bronchi, while the left lung has two.
How do the segmental bronchi form, and how many are present in each lung?
Segmental bronchi form from tertiary bronchial branching, with ten in the right lung and eight to nine in the left.
What factors regulate branching morphogenesis in lung development?
Fibroblast growth factors (FGFs) and sonic hedgehog (SHH) regulate branching morphogenesis.
How does amniotic fluid contribute to lung development?
Amniotic fluid helps expand the developing lungs, promoting growth and differentiation.
What is the embryological origin of the diaphragm?
The diaphragm develops from mesodermal structures, including the septum transversum and pleuroperitoneal membranes.
What are the four main components that contribute to diaphragm formation?
The four components of diaphragm formation are the septum transversum, pleuroperitoneal membranes, dorsal mesentery of the esophagus, and body wall musculature.
What is the role of the septum transversum in diaphragm development?
The septum transversum contributes to the central tendon of the diaphragm.
What embryonic structures contribute to the central tendon of the diaphragm?
The central tendon of the diaphragm is derived from the septum transversum.
How do the pleuroperitoneal membranes contribute to diaphragm development?
The pleuroperitoneal membranes close the pericardioperitoneal canals, preventing abdominal contents from entering the thorax.
What is the role of the dorsal mesentery of the esophagus in diaphragm formation?
The dorsal mesentery of the esophagus contributes to the crura of the diaphragm.
How do the body wall muscles contribute to diaphragm formation?
The body wall muscles form the peripheral parts of the diaphragm.
What is congenital diaphragmatic hernia, and what causes it?
Congenital diaphragmatic hernia occurs when the diaphragm fails to close completely.
What is the clinical significance of Bochdalek hernia?
Bochdalek hernia results from a posterolateral diaphragmatic defect, typically on the left side.
What is the clinical significance of Morgagni hernia?
Morgagni hernia is a rare anterior diaphragmatic defect, often asymptomatic.
What is eventration of the diaphragm, and how does it occur?
Eventration of the diaphragm occurs when muscle development is incomplete, causing paradoxical movement.
What nerve innervates the diaphragm, and what is its embryological origin?
The diaphragm is innervated by the phrenic nerve (C3–C5), derived from cervical somites.
What are the consequences of phrenic nerve damage in neonatal development?
Phrenic nerve damage can cause respiratory distress due to diaphragmatic paralysis.
How does fetal breathing movement affect lung maturation?
Fetal breathing movements help condition the respiratory muscles and stimulate lung development.
How does the fetal circulation support lung development before birth?
Fetal circulation bypasses the lungs via the foramen ovale and ductus arteriosus.
What changes occur in the pulmonary circulation at birth?
At birth, pulmonary vascular resistance decreases, allowing increased blood flow to the lungs.
What is the fate of the ductus arteriosus after birth?
The ductus arteriosus closes after birth to become the ligamentum arteriosum.
How does congenital tracheomalacia affect the airway?
Congenital tracheomalacia causes airway collapse due to weak cartilage support.
What is bronchopulmonary dysplasia, and what causes it?
Bronchopulmonary dysplasia results from prolonged mechanical ventilation and oxygen therapy.
What congenital anomalies can affect the trachea?
Tracheal anomalies include tracheal stenosis, tracheomalacia, and tracheoesophageal fistula.
What is pulmonary sequestration, and how does it develop?
Pulmonary sequestration is a nonfunctional lung tissue mass with an abnormal blood supply.
How does the lung’s blood supply develop embryologically?
The lung’s blood supply develops from the aortic arch and vitelline arteries.
What is the role of fibroblast growth factors (FGFs) in lung development?
Fibroblast growth factors (FGFs) promote lung bud formation and branching.
What is the importance of retinoic acid in respiratory system development?
Retinoic acid helps initiate lung development by stimulating FGF expression.
What is the function of T-box transcription factors (TBX) in lung branching?
T-box transcription factors (TBX) regulate lung branching and differentiation.
