Respiratory System Development Flashcards
What things develop from the endoderm of the respiratory diverticulum?
- Alveolar type I pneumocytes
- ciliated cuboidal epithelium of the bronchioles
- clara cells
- pseudostratified column ciliated epithelium
- seromucous glands of the trachea
The mesenchyme surrounding the lung buds determines the pattern of their growth and gives rise to the:
Smooth muscles
What structure is derived from neural crest ectoderm?
Laryngeal cartilage
What is a tracheoesophageal fistula?
An abnormal communication (fistula) between the trachea and the esophagus. Most common anomaly of the lower respiratory tract.
What is a Tracheoesophageal fistula frequently associated with?
Esophageal atresia
What causes tracheoesophageal fistula?
Results from abnormal partitioning of the largyngotracheal tube by the tracheoesophageal septum, producing an abnormal communication between the trachea and esophagus.
What happens in the fetus due to a tracheoesophageal fistula?
Amniotic fluid accumulates (polyhydramnios) because it cannot pass through the stomach and intestines for absorption and subsequent transfer via the placenta to the mother’s blood.
What is derived from splanchnic mesoderm?
Vascular tissue of the tracheal adventitia
What developing structure serves to separate the trachea from the esophagus?
Tracheoesophageal septum
What is an Azygos lobe?
Part of superior lobe of right lung grows medial to azygos vein instead of lateral to it. (there is a little lobe created by the azygos vein pressing into the lung)
What is Agenesis of the lungs?
Failure of the lung bud to develop (bilateral agenesis) or unilateral lung ageless where only one lung develops
What is lung hypoplasia usually associated with?
Congenital diaphragmatic hernia.
What a classic cause of pulmonary hypoplasia (other than congenital diaphragmatic hernia)?
Oligohydramnios - a condition in which there is an insufficient amount of amniotic fluid; presumably, oligohydramnios causes pulmonary hypoplasia by allowing the uterine wall to compress the fetal thorax.
What does bilateral renal agenesis cause?
Oligohydramnios because a lack of urine production reduces the amount of amniotic fluid.
What is Potter’s syndrome?
Pulmonary hypoplasia and bilateral renal agenesis.
What gives rise to the cartilaginous tissue that comprises the walls of the trachea, bronchi and bronchioles?
Splanchnic mesoderm
Into what part of the intraembryonic coelom doe the developing lung bud grow?
Pericardioperitoneal canal
What are fetal breathing movements (FBMs)?
They occur prior to birth and are essential for normal lung development. FBMs stimulates lung development and facilitates development of respiratory musculature.
What is Aeration at birth?
It is the rapid replacement of intra-alveolar fluid by air. One half of the lung fluid is derived from the lung tissue itself, while the remaining fluid in the alveoli is amniotic fluid.
Removal of the Amniotic fluid occurs:
(1) through the mouth and nose by pressure on the thorax during vaginal delivery
(2) into the pulmonary arteries, veins and capillaries
and (3) into the lymphatics.
What is hyaline membrane disease?
Caused by a deficiency of surfactant and injury to the alveolar wall resulting in a protein-rich, fibrin-rich exudations into the alveolar spaces and formation of hyaline membranes (result is respiratory distress syndrome)
How many infant deaths does respiratory distress syndrome account for?
20% of all infant deaths in the newborn period.
What is used during pregnancy to accelerate fetal lung development?
Glucocorticoids (beta-methasone) - Accelerates development of type II pneumocytes so they produce more surfactant
What reduces the severity of respiratory distress syndrome and neonatal mortality?
Administration of exogenous surfactant (surfactant replacement therapy)
What cells are responsible for production of pulmonary surfactant?
Type II pneumocytes
At what week in human fetal development does pulmonary surfactant formation begin to occur?
20 weeks
What contributes to the fluid component of the lungs at birth?
Amniotic fluid, blood vessels and lymphatics of the lung, seromucous glands, tracheal glands
Which of the following stimulates the production of surfactant during intrauterine life?
Glucocorticoids
Ultrasonography indicates oligohydramnios. What abnormality may be present in the infant at birth?
Lung hypoplasia
Newborn infant gagging and with cyanosis. Can’t catheterize the stomach. Air in the stomach. What is the diagnosis?
Tracheoesophageal fistula
