10. Developmental Aspects of Lung Disease

Question 1

What is lung morphogenesis?

Answer 1

The origin and development of morphological structures

Question 2

When is Embryonic lung morphogenesis?

Answer 2

3-8 weeks

Question 3

When is Pseudo-glandular lung morphogenesis?

Answer 3

5-17 weeks

Question 4

When is Canalicular lung morphogenesis?

Answer 4

16-26 weeks

Question 5

When is Saccular lung morphogenesis?

Answer 5

24-38 weeks

Question 6

When is Alveolar lung morphogenesis?

Answer 6

36 weeks - ~2-3years

Question 7

What happens during Postnatal lung growth?

Answer 7

Alveolar septation continues
100-150 million at birth to 200-600 million at 8 years
Increased alveolar dimensions thereafter

Question 8

When is the embryonic period?

Answer 8

0-8 weeks

Question 9

When is the fatal period?

Answer 9

8-38 weeks

Question 10

Which two types of morphogenesis are referred to as organogenesis?

Answer 10

Embryonic and Pseudoglandular

Question 11

Which three types of morphogenesis are referred to as differentiation?

Answer 11

Canalicular, Saccular and Alveolar

Question 12

What happens during Organogenesis?

Answer 12

Embryonic
- Formation of major airways

Pseudoglandular

• Formation of bronchial tree and portions of respiratory parenchyma
• Birth of the acinus

Question 13

What happens during Differentiation?

Answer 13

Canalicular

• Last generations of the lung periphery formed
• Epithelial differentiation
• Air-blood barrier formed

Saccular

• Expansion of air spaces
• Surfactant detectable in amnionic fluid

Alveolar
- Secondary septation

Question 14

When does surfactant begin to appear?

Answer 14

~25 weeks

Question 15

When does birth tend to occur?

Answer 15

38 weeks

Question 16

What happens during the embryonic stage?

Answer 16

Appearance of lung buds and main pulmonary arteries, trachea and main bronchi

Question 17

What happens during the pseudoglandular stage?

Answer 17

All conducting airways and accompanying blood vessels form, wall structure and epithelial cells differentiate

Bronchi: 8-13 generations
Bronchioli: 3-10 generations

Question 18

What happens during the canalicular stage?

Answer 18

Respiratory airways form, blood-gas barrier thins, surfactant appears

Respiratory bronchioli: 3-5 generations
Alveolar ducts: 2-3 generations

Question 19

What happens during the saccular-alveolar stage?

Answer 19

Saccules and then alveoli appear

100 million by birth

Question 20

What happens for two to four years after birth?

Answer 20

Alveoli multiply 300-600 million

Airways double in size

Question 21

Which two stages are form the acinus?

Answer 21

Canalicular and Saccular-alveolar stage

Question 22

What are the embryonic signs of congenital lung disease?

Answer 22

Tracheal, laryngeal stenosis
Pulmonary agenesis
Tracheo-oseophageal fistula

Question 23

What are the pseudoglandular signs of congenital lung disease?

Answer 23

Pulmonary sequestration
Cystadenomatoid malformation
Cyst formation

Question 24

Which tissues are involved in diaphragm development?

Answer 24

Membrana pleuro-peritonealis
Mesoesophagus
Septum transversum

Question 25

Which three tubular parts of the body are contained in the mesoesophagus?

Answer 25

Aorta Esophagus Vena cava

Question 26

At which point does the diaphragm close?

Answer 26

~18 weeks

Question 27

What are some features of a diaphragmatic hernia?

Answer 27

L>R Pulmonary hypoplasia Persistent pulmonary hypertension

Question 28

What are some diaphragmatic abnormalities?

Answer 28

Hernia | Eventration

Question 29

What happens to the cells in the lungs after birth?

Answer 29

Change from fluid secreting to fluid absorbing | Pulmonary vasodilation

Question 30

What occurs when a newborn has transient tachypnea?

Answer 30

Fluid is retained in the lungs and this can be seen as a wet lung upon xray

Question 31

What is surfactant and what does it do?

Answer 31

Detergent composed of phospholipids and lipophilic proteins | Stabilises alveoli and promotes gas exchange

Question 32

Where is surfactant produced?

Answer 32

Type 2 pneumocytes | - lamellar bodies

Question 33

What neonatal condition is associated with surfactant deficiency?

Answer 33

Hyaline Membrane Disease (RDS)

Question 34

How is RDS treated?

Answer 34

``` Antenatal glucocorticoids Surfactant replacement O2 CPAP Mechanical ventilation ```

Question 35

What is associated with Chronic neonatal lung disease (BDP, CLDP)?

Answer 35

Increased severity bronchiolitis Asthma Future COPD?

Question 36

What are the antenatal origins of adult lung disease (COPD)?

Answer 36

In utero nicotine exposure Nutrition Low birth weight/prematurity (antenatal steroids) Micronutrients/vitamins

Question 37

What are the post-natal origins of adult lung disease (COPD)?

Answer 37

``` Infection (barker hypothesis) Growth ETS (+/- a1 AT deficiency) Environmental pollution Micronutrients/vitamins ```

Question 38

At which age would respiratory symptoms appear in a person with a normal childhood grown and accelerated decline?

Answer 38

~65

Question 39

At which age would respiratory symptoms appear in a person with a normal childhood grown and early decline?

Answer 39

~75

Question 40

At which age would respiratory symptoms appear in a person with a failure to attain maximal growth and normal decline?

Answer 40

~65

Question 41

What trends occur in all FEV1/FVC ratios as a person ages?

Answer 41

Decrease

Question 42

What place does COPD take on the leading causes of death in the world?

Answer 42

3rd