Normal & Abnormal Development of the Respiratory System - Severson Flashcards
Where does the laryngotracheal groove and diverticulum develop?
- Groove:
- Ventral wall of the primitive pharynx
- caudal to the 4th and 6th pharyngeal pouches
- Ventral wall of the primitive pharynx
- Diverticulum:
- groove deepens to form respiratory diverticulum
What germ layer contributes to the epithelial lining?
Endoderm
What germ layer contributes to the supporting wall of the developing trachea?
- Connective tissue, cartilage, and smooth muscle develop from → splanchnic mesenchyme of the foregut
- (except laryngeal cartilage develops from neural crest mesenchyme)
What is the purpose of the tracheoesophageal folds and septum?
They play a significant role in the separation of the esophagus and developing respiratory system (trachea).
What branchial arch cartilages contribute to the laryngeal cartilages?
4th & 6th pharyngial arches
What cells form the cartilaginous tissue?
Neural crest cells
What branchial arches give rise to the laryngeal muscles?
4th & 6th pairs of pharyngeal arches
What nerves innervate the laryngeal muscles?
- Vagus nerve
- Superior laryngeal (sensory fibers)
- Recurrent laryngeal (motor fibers)
What germ layers contribute to the laryngotracheal tube?
- Surface epithelium → endoderm
- Tracheal glands → endoderm
- (develop from an ingrowth of surface epithelium)
- Cartilage, connective tissue, & muscle → splanchnic mesoderm
What germ layer gives rise to the tracheobronchial glands?
Endoderm
What germ layer gives rise to the supporting walls of the laryngotracheal tube?
Splanchnic mesoderm
What tissue forms the visceral and parietal pleura?
- Visceral → splanchnic mesoderm
- Parietal → somatic mesoderm
What developmental defect has occurred when a tracheoesophageal fistula is present?
Esophageal atresia
(blind ending esophagus)
When would gastric secretions possibly cause penumonitis?
when food or gastric contents enter the lungs
(happens if esophageal atresia occurs)
When would lipid pneumonia occur?
***
When and why does polyhydramnios occur?
- When?
- tracheoesophageal fistula (esophageal atresia)
- Why?
- Amniotic fluid accumulates (polyhydramnios) because amniotic fluid cannot pass to the stomach and intestines for absorption and subsequent transfer via the placenta to the mother’s blood.
How do the bronchi and lungs develop?
(Hint: 6 steps)
- Laryngotracheal groove →
- Respiratory diverticulum →
- Tracheal bud →
- Primary bronchial buds →
- Secondary bronchial buds →
- Segmental branches (bronchopulmonary segments)
What is the usual cause of lung hypoplasia?
Congenital diaphragmatic hernia
(uterus creats increased pressure on chest wall)
How may oligohydramnios cause lung hypoplasia?
- there is an insufficient amount of amniotic fluid
- causes pulmonary hypoplasia by allowing the uterine wall to compress the fetal thorax
Why does renal agenesis contribute to oligohydramnios?
Bilateral renal agenesis causes oligohydramnios because lack of urine production reduces the amount of amniotic fluid.
What is Potter’s syndrome?
pulmonary hypoplasia and bilateral renal agenesis
What are type I and type II alveolar cells?
- Type I
- squamous epithelium pneumocytes of endodermal origin
- small, thin
- squamous epithelium pneumocytes of endodermal origin
- Type II
- pneumocytes lining the alveoli that begin to secrete pulmonary surfactant
- large, protrude
- pneumocytes lining the alveoli that begin to secrete pulmonary surfactant
What cells produce surfactant?
Type II Alveolar Cells
What is surfactant?
- phospholipids and two proteins
- lowers surface tension at the air-alveolar interface
