Respiratory System Development Flashcards
Where does the laryngotracheal groove and diverticulum develop?
develop from the ventral wall of the primitive pharynx and caudal to the fourth pai of pharyngeal pouches.
the groove will deepen to form the respiratory diverticulu,
What germ layer contributes to the epithelial lining?
Endoderm
What germ layer contributes to the supporting wall?
splanchnic mesenchyme develops into the CT, cartilage and smooth muscle
What is the purpose of the tracheoesophageal folds and septum?
They divide the cranial part of the foregut into a laryngotracheal tube and a dorsal portion.
What branchial arch cartilages contribute to the laryngeal cartilages?
From the 4th and 6th pharyngeal arches
What cells form the cartilginous tissue?
mesenchyme derived from neural crest cells
What branchial arches give rise to the laryngeal muscles
develops from myoblasts of the fourth and sixth pairs of pharyngeal arches
What nerves innervate the laryngeal muscles?
the vagus nerve (via the superior laryngeal and recurrent laryngeal)
What germ layers contribute to the laryngotracheal tube?
the surface epithelium is of endodermal origin
What germ layer gives rise to the tracheobronchial glands?
also endoderm - the tracheal glands develop from an ingrowth of surface epithelium
What tissue forms the visceral and parietal pleura?
VIsceral pleura is from splanchnic mesoderm
parietal pleural is somatic mesoderm
What developmental defect has occurred when a tracheoesophageal fistula is present?
It’s an abnormal communication between the trachea and esophagus from abnormal partitioning by the tracheoesophageal septum
What is esophageal atresia?
When the esophagus just ends in a blind end - associated with tracheoesophagela fistulas
When would gastric secretions possibly cause pneumonitis?
If there’s a tracheoesophageal fistula allowing the gastric secretions up into the lungs, basically causing digestion of the lungs
When would lipid pneumonia occur?
When there’s a tracheoesophageal fistula allowing breast milk to get down into the lungs - there’s lots of lipids in breast milk so you get a lipid pneumonia
When and why does polyhydramnios occur?
when amniotic fluid accumulations becuse it 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?
Larngyotracheal groove - respiratory diverticulum - tracheal bus - primary bonrhial buds - secondary bonrhcial buds, segmental branches
the primary bronchial buds grow into the pericardioperitoneal canals
What is the usual cause of lung hypoplasia?
usually associated with a congenital diaphragmatic hernia
How may oligohydramnios cause lung hypolasia?
it’s a condition where ther eis an insufficient amount of amniotic fluid
we think that oligohydramnios causes pulmonary hypoplasia by allowing the uterine wall to compress the fetal thorax
Why does renal agenesis contribute to oligohydramnios?
if you don’t have formation of the kidneys because the bronchial buds fail to develop, you don’t have urine production
the amniotic fluid is basically just baby pee
What is Potter’s syndrome?
pulmonary hypoplasia and bilateral renal agenesis
with facial and extremity deformities
At what week of development are type I and II alveolar cells evident in the developing lung/
Alveoli start developing in the canalilcular period, but Type I and Type II alveoli aren’t evident until the Terminal sac period starting at 26 weks
What is the earliest developmental period that repsiration is possible/
respiration is possible starting in the canalicular people because of the developing alveoli
What are type I alveolar cells?
pneumocytes
squamous epithelium
What cells produce surfactant?
The Type II alveolar cells or pneumocytes that lines the alveoli
When is surfactant made? What is surfactant?
Surfactant secretion begins at 20 weeks but doesn’t become sufficient until 26-28
It serves to lower surface tension at the air-alveolar interface
How is amniotic fluid removed from the lungs at birth?
removal of the fluid occurs through the mouth and nose by pressure on the thorax during delivery
also into the pulmonary capillaries
also into the lymphatics
What is repsonsible for the occurrence of respiratory distress syndrome?
a deficiency of surfactant and injury to the alveolar wall
WHy si there a protein rich, fibrin-rich exudate in the alveolar space in RDS?
it’s formed by the damaged pulmonary epithelium and circulating blood substance - forms a hyaline membrane in the alveolar spaces
Who is likely to develop RDS?
it accounts for 20% of all infant deaths in the newborn period
How do the lungs of a stillborn and live infant differ?
a live infant’s lungs are filled with wait while a sillborn infant’s lungs are still filled with fluid
Why do the lungs of stillborn infants sink in water?1
filled with fluid, so they’re heavier than water
How does the development of the idaphragm relate to the occurrence of congenital diaphragmatic hernias?
if the diaphragm doesn’t form, then the abdominal contents can move up into the pleural cavity and compress the developing lungs
Where do congenital diaphragmatic hernias usually occur and what developmental anomaly is repsonsible for this condition?
Occurs more often on the left
failure of the pleuroperitoneal membranes to fuse with the other diaphragmatic components so there is a posterolateral defect in the lumbocostal trigone
