Respiratory Embryology

Question 1

Where does the respiratory system begin its growth?

Answer 1

Median outgrowth of laryngotracheal groove

Question 2

What happens to the outgrowth of laryngotracheal groove?

Answer 2

The groove evaginates to form the laryngotracheal diverticulum that will elongate

Question 3

What forms at the distal end of the laryngotracheal diverticulum?

Answer 3

Respiratory bud

Question 4

The respiratory bud is the origin of?

Answer 4

Respiratory tree

Question 5

What develop to form the tracheoesophageal septum?

Answer 5

Tracheoesophageal folds

Question 6

What do the tracheoesophageal folds cause to happen?

Answer 6

Splits the foregut into ventral and dorsal portions

• ventral = laryngotracheal tube
• dorsal = esophagus

Question 7

What creates the pulmonary epithelium and glands of the trachea, larynx and bronchi?

Answer 7

Endoderm of laryngotracheal groove

Question 8

What creates the cartilage, smooth muscle and CT of the trachea, larynx and bronchi?

Answer 8

Splanchnic lateral plate mesoderm

Question 9

What pharyngeal arches contribute to larynx and laryngeal muscle development?

Answer 9

4 and 6

Question 10

For the development of the larynx, mesenchyme produces?

Answer 10

Arytenoid swellings

Question 11

What do the arytenoid swellings do?

Answer 11

Convert the primordial glottis into a T-shaped laryngeal inlet

Question 12

After the arytenoid swellings for the T-shaped laryngeal inlet, what occurs to the laryngeal epithelium?

Answer 12

It proliferates and blocks the lumen of the larynx

Question 13

Recanalization of the larynx occurs by what week?

Answer 13

10th

Question 14

During recanalization of the larynx, what form that are bounded by mucous membranes?

Answer 14

Vocal and vestibular folds

Question 15

In a neonate, what is the epiglottis in contact with?

Answer 15

Soft palate

Question 16

How old is someone if their larynx is very high up?

Answer 16

Less than 2 years old

Question 17

Laryngeal descent occurs when?

Answer 17

Over first 2 years of life

Question 18

Laryngeal atresia

Answer 18

Failure of recanalization of the larynx

“CHAOS” - congenital high airway obstruction syndrome

Question 19

What are the symptoms of laryngeal atresia?

Answer 19

Lungs enlarged and filled with fluid
Airways dilated
Diaphragm flattened

Question 20

The trachea develops from?

Answer 20

Laryngotracheal tube

Question 21

Tracheal epithelium and glands form from?

Answer 21

Endoderm

Question 22

Tracheal cartilage, muscle and CT form from?

Answer 22

Splanchnic mesoderm

Question 23

Tracheoesophageal Fistula

Answer 23

Abnormal connection between the esophagus and trachea

Question 24

What causes a tracheoesophageal fistula

Answer 24

Foregut endoderm does not proliferate rapidly enough

Question 25

Most cases of tracheoesophageal fistula include what mechanical setup?

Answer 25

Esophageal atresia (blind esophagus)

Question 26

Symptoms of a tracheoesophageal fistula include?

Answer 26

Cannot swallow Polyhydramnios - fluid cannot enter stomach for absorption May reflux gastric contents into trachea and lungs

Question 27

What does the respiratory bud create?

Answer 27

Bifurcates into primary bronchial buds

Question 28

Primary bronchial buds grow into pericardioperitoneal canals and branch to form secondary and tertiary buds. What controls the branching pattern?

Answer 28

Splanchnic mesoderm

Question 29

Stages of lung development

Answer 29

1. Pseudoglandular 2. Canalicular 3. Terminal sac 4. Alveolar

Question 30

Pseudoglandular stage lung development

Answer 30

Weeks 5-17 | All elements formed except for elements involved in gas exchange

Question 31

Can a fetus survive if born during pseudglandular stage (5-17 weeks)?

Answer 31

NO

Question 32

Canalicular stage of lung development

Answer 32

Weeks 16-25 | Vascularization, respiratory bronchioles and primitive alveoli form

Question 33

Can a fetus survive if born during canalicular stage (16-25 weeks)?

Answer 33

Maybe

Question 34

Terminal sac stage of lung development

Answer 34

Weeks 24-birth | Type 1 and 2 alveolar cells present and gas exchange can occur!

Question 35

Can a fetus survive if born during terminal sac stage (24weeks +)?

Answer 35

Yes

Question 36

Alveolar stage of lung development

Answer 36

32 weeks - 8 years | Alveoli increase in number

Question 37

When do most mature alveoli develop?

Answer 37

Postnatally

Question 38

Lung growth involves an increase in?

Answer 38

NUMBER of bronchioles and alveoli

Question 39

Fetal breathing movements

Answer 39

Intermittent pattern that conditions respiratory muscles and fills lungs with amniotic fluid for their development

Question 40

At birth, the lungs require rapid replacement of the intra-alveolar fluid with air. How can this occur?

Answer 40

- vaginal delivery pushes fluid out mouth and nose - arteries, veins, lymphatics - mechanically

Question 41

Pulmonary agenesis is the failure of ____ to split into right and left bronchial buds

Answer 41

Respiratory buds

Question 42

Can pulmonary agenesis be unilateral?

Answer 42

Yes

Question 43

Pulmonary hypoplasia

Answer 43

Due to restriction of fetal thorax due to uterine pressure and stunts their growth

Question 44

What condition can dramatically increase the risk of pulmonary hypoplasia?

Answer 44

Oligohydramnios

Question 45

Respiratory distress syndrome

Answer 45

Type 2 alveolar cells altered and cannot make surfactant!!

Question 46

When will you notice respiratory distress syndrome?

Answer 46

Shortly after birth

Question 47

What do the alveoli contain instead of surfactant with respiratory distress syndrome?

Answer 47

Glassy membrane fluid

Question 48

Signs of respiratory distress syndrome?

Answer 48

Rapid, labored breathing right after birth | - grunting, cyanosis, nasal flaring