lung development

Question 1

what is the main lung structure?

Answer 1

1. primary bronchus
2. secondary bronchus
3. tertiary bronchus
4. bronchiole
5. terminale bronchiole
6. alveoli

Question 2

What is Fick’s law of difussion?

Answer 2

V = D * (P1-P2) * A / T

Question 3

what are the functions of Type I and II pneumocytes?

Answer 3

Type I = thin and sides fused together, for gas exchange
Type II = produce surfactant

Question 4

Why do we need surfactant lipids?

Answer 4

to lower surface tension
to change proliferation and cyto-toxicity of lymphocytes

Question 5

what do the surfactant proteins do?

Answer 5

Enhance chemotaxis
aggregation and opsonization of micro-organisms
inhibit the growth of organisms

Question 6

What progenitor cells do we have in the lungs?

Answer 6

1. undefined SMG duct cells
2. basal cells
3. variant club cells
4. BASC’s
5. AEC II

Question 7

From which germ layer, does the Lungs develop?

Answer 7

endoderm > epithelial cells

Question 8

in what 5 stages does lung development occur? state the approximate weeks

Answer 8

1. embryonic stage (4-7)
2. Pseudoglandular (5-17)
3. Canalicular (16-26)
4. Saccular (24 - born)
5. Alveolarisation (36 weeks-21 years?)

Question 9

What happens in the embryonic stage?

Answer 9

left and right primary bronchi and major pathways are being developed. There is undifferentiated columnar epithelium.
NKX2.1 controls the lung development here
FGF10 is for elongation, TGFB1 ‘inhibits’ growth

Question 10

what happens in pseudoglandular stage?

Answer 10

• there is gland like histology
• differentiation of epithelium in proximal airways
• further branching down to terminal bronchioles

Question 11

What happens in canalicular stage?

Answer 11

• ingrowth of vessels/capillaries continues
• maturation of club cells, first AEC I and II cells
• primitive alveolar capillary membrane develops
• formation of respiratory bronchioles at typ of terminal bronchiole by budding and branching

Question 12

What happens at the saccular stage?

Answer 12

• formation of alveolar sacs by budding and branching of bronchioles
• maturation of AEC II and differentiation of AEC I
• expansion of the capillary network

Question 13

What happens at the alveolar stage?

Answer 13

• expansion of alveoli by septation
• expansion of the capillary network
• 90% of this development occurs after birth!

Question 14

Untill what week is a birth considered premature?

Answer 14

before 37 weeks

Question 15

What is RDS?

Answer 15

Respiratory distress syndrome
- smaller surface area and thick membrane for gas exhange
- not enough surfactant
- can cause epithelial injury
- edema
- inflammation

Question 16

What is the treatment for RDS?

Answer 16

mechanical ventilation
- pressure injury
-volume injury
- O2 toxicity

Question 17

What is bronchopulmonary dysplasia?

Answer 17

chronic lung disease requiring O2 and ventilation beyond 36 weeks GA. There is alveolar simplification and dysmorphic pulmonary vascularisation

Question 18

What are the treatments for bronchopulmonary dysplasia?

Answer 18

• SC-based therapy
• PEEP
• retinoic acid and nutrition
• postnatal steroids (induces surfactant production)
• antenatal steroids(induces surfactant production)