Respiratory System Development

Question 1

Where does the laryngotracheal groove and diverticulum develop?

Answer 1

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,

Question 2

What germ layer contributes to the epithelial lining?

Answer 2

Endoderm

Question 3

What germ layer contributes to the supporting wall?

Answer 3

splanchnic mesenchyme develops into the CT, cartilage and smooth muscle

Question 4

What is the purpose of the tracheoesophageal folds and septum?

Answer 4

They divide the cranial part of the foregut into a laryngotracheal tube and a dorsal portion.

Question 5

What branchial arch cartilages contribute to the laryngeal cartilages?

Answer 5

From the 4th and 6th pharyngeal arches

Question 6

What cells form the cartilginous tissue?

Answer 6

mesenchyme derived from neural crest cells

Question 7

What branchial arches give rise to the laryngeal muscles

Answer 7

develops from myoblasts of the fourth and sixth pairs of pharyngeal arches

Question 8

What nerves innervate the laryngeal muscles?

Answer 8

the vagus nerve (via the superior laryngeal and recurrent laryngeal)

Question 9

What germ layers contribute to the laryngotracheal tube?

Answer 9

the surface epithelium is of endodermal origin

Question 10

What germ layer gives rise to the tracheobronchial glands?

Answer 10

also endoderm - the tracheal glands develop from an ingrowth of surface epithelium

Question 11

What tissue forms the visceral and parietal pleura?

Answer 11

VIsceral pleura is from splanchnic mesoderm

parietal pleural is somatic mesoderm

Question 12

What developmental defect has occurred when a tracheoesophageal fistula is present?

Answer 12

It’s an abnormal communication between the trachea and esophagus from abnormal partitioning by the tracheoesophageal septum

Question 13

What is esophageal atresia?

Answer 13

When the esophagus just ends in a blind end - associated with tracheoesophagela fistulas

Question 14

When would gastric secretions possibly cause pneumonitis?

Answer 14

If there’s a tracheoesophageal fistula allowing the gastric secretions up into the lungs, basically causing digestion of the lungs

Question 15

When would lipid pneumonia occur?

Answer 15

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

Question 16

When and why does polyhydramnios occur?

Answer 16

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

Question 17

How do the bronchi and lungs develop?

Answer 17

Larngyotracheal groove - respiratory diverticulum - tracheal bus - primary bonrhial buds - secondary bonrhcial buds, segmental branches

the primary bronchial buds grow into the pericardioperitoneal canals

Question 18

What is the usual cause of lung hypoplasia?

Answer 18

usually associated with a congenital diaphragmatic hernia

Question 19

How may oligohydramnios cause lung hypolasia?

Answer 19

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

Question 20

Why does renal agenesis contribute to oligohydramnios?

Answer 20

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

Question 21

What is Potter’s syndrome?

Answer 21

pulmonary hypoplasia and bilateral renal agenesis

with facial and extremity deformities

Question 22

At what week of development are type I and II alveolar cells evident in the developing lung/

Answer 22

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

Question 23

What is the earliest developmental period that repsiration is possible/

Answer 23

respiration is possible starting in the canalicular people because of the developing alveoli

Question 24

What are type I alveolar cells?

Answer 24

pneumocytes

squamous epithelium

Question 25

What cells produce surfactant?

Answer 25

The Type II alveolar cells or pneumocytes that lines the alveoli

Question 26

When is surfactant made? What is surfactant?

Answer 26

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

Question 27

How is amniotic fluid removed from the lungs at birth?

Answer 27

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

Question 28

What is repsonsible for the occurrence of respiratory distress syndrome?

Answer 28

a deficiency of surfactant and injury to the alveolar wall

Question 29

WHy si there a protein rich, fibrin-rich exudate in the alveolar space in RDS?

Answer 29

it’s formed by the damaged pulmonary epithelium and circulating blood substance - forms a hyaline membrane in the alveolar spaces

Question 30

Who is likely to develop RDS?

Answer 30

it accounts for 20% of all infant deaths in the newborn period

Question 31

How do the lungs of a stillborn and live infant differ?

Answer 31

a live infant’s lungs are filled with wait while a sillborn infant’s lungs are still filled with fluid

Question 32

Why do the lungs of stillborn infants sink in water?1

Answer 32

filled with fluid, so they’re heavier than water

Question 33

How does the development of the idaphragm relate to the occurrence of congenital diaphragmatic hernias?

Answer 33

if the diaphragm doesn’t form, then the abdominal contents can move up into the pleural cavity and compress the developing lungs

Question 34

Where do congenital diaphragmatic hernias usually occur and what developmental anomaly is repsonsible for this condition?

Answer 34

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