Snapshot A newborn begins to produce nonbilious emesis after feeds. This is associated with white frothy nasal and oral secretions which recur after suctioning. Physical examination is significant for abdominal distension with crying. A nasogastric tube is unable to fully pass into the esophagus. A plain chest and abdominal radiograph shows excessive air in the stomach. There is coiling of the nasogastric tube in the blind esophageal pouch. (Esophageal atresia with distal tracheoesophageal fistula) Introduction Phases of Lung Development Phases Events Comments Embryonic (26 days - 6 weeks) The lung bud developes from an outgrowth of the ventral foregut wall leading to the development of the trachea bronchial buds mainstem bronchi secondary bronchi tertiary bronchi A tracheoesophageal fistula can arise if this stage is negatively affected Pseudoglandular (6 - 16 weeks) Terminal brochioles are formed At this stage, respirations are impossible Canalicular (16 - 28 weeks) Terminal bronchioles divide into respiratory bronchioles There is a close apposition between blood vessels and lung epithelium Lung epithelium differentiates into specialized cells such as precursors to type I and II alveolar cells ciliated secretory cells neuroendocrine cells At 25 weeks gestation the fetus is capable of respirations Saccular (28 - 36 weeks) Primitive alveoli (terminal sacs) are formed from respiratory bronchioles Pneumocytes develop - Alveolar (36 weeks - ~10 years of age) Maturation of the alveoli -
QUESTIONS 1 of 1 1 Previous Next (M1.EB.17.4799) Scientists are studying human lung development by trying to identify which proteins and signaling factors trigger lung bud division and bronchiole branching. Their main focus is particularly around the 20th week of gestation, during which terminal bronchioles branch into respiratory bronchioles and further into alveolar ducts. Which of the following phases of embryonic lung development is the stage in which the scientists are interested in studying? QID: 109317 Type & Select Correct Answer 1 Embryonic 1% (1/109) 2 Pseudoglandular 4% (4/109) 3 Canalicular 39% (43/109) 4 Saccular 28% (30/109) 5 Alveolar 26% (28/109) M 2 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic