Lung development Flashcards

1
Q

What is primary ciliary dyskinesia?

A

AR mutation (45 known) that impacts on ciliary function; dynein arms are absent, causing cilia to become static so mucous is not moved and cleared; will get bronchiectasis and respiratory failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are congenital bronchial cartilage defects?

A

Normally incomplete rings with irregular plates, but can be malacic (floppy) in generalised or localised (occur due to other developmental issue) fashion - always check CVD status

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is Laryngomalacia?

A

Omega shaped epiglottis with folds that collapse on inspiration - severe airway obstruction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is lung aplasia?

A

Bling ending bronchus with no lung or vessel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is Lung hypoplasia?

A

Bronchus and rudimentary lung present but all elements reduced in size and number; relatively common and 2/2 other (physical) factors such as lack of space intra/extrathoracically - can be corrected with in utero surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is cystic pulmonary airway malformation?

A

1:8,000-1:35,000 mostly diagnosed on antenatal ultrasound; lethal don’t survive but usually seen well; normal blood supply with defect in pulmonary mesenchyma causing abnormal differentiation in early weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is congenital lobar emphysema?

A

Progressive lobar overexpansion, expanding over midline and squashing other lobes due to weak cartilage or one way valve effects - association with CHD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is intralobal sequestration?

A

Lower lobes usually affected and have aberrant blood supply that do not ventilate - no communication with tracheobronchial tree.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the four phases of lung development, and at which weeks do they occur?

A

Embryonic 0-7 weeks
Pseudoglandular phase 5-17 weeks
Canalicular phase 16-27 weeks
Saccular/Alveolar phase 28-40 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the embryonic phase?

A

Lung buds and main bronchi form

Asymmetric branching occurs to produce 3 lobes on the right and 2 on the left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the pseudoglandular phase?

A

Conducting airways and bronchi/bronchioli form

Branching morphogenesis of airways to the mesenchyme, with pre-acinar airways all present by 17 weeks; development of cartilage, glands and smooth muscle continues to canalicular phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the Canalicular phase?

A

Respiratory airways and blood gas barrier forms

Peripheral airspaces enlarge, with thinning of epithelium by underlying capillaries to allow gas exchange, but forming blood gas barrier required in post-natal life; epithelium differentiates to type I (thin)/II (surfactant - surface tension and allows re-expansion) cells and surfactant detectable at 24-25 weeks - babies become viable at 24 weeks gestation due to surfactant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the Saccular/alveolar phase?

A

Alveolar walls form first as saccule walls with double capillary networks, before forming secondary septa then alveolar walls as the capillaries coalesce to form one sheet, with elastin in the wall produce by myofibroblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the factors driving morphogenesis?

A

Lung buds drive process, with progenitor multipotent cells at the tip that differentiate to a range of lung cells based on chemical environment, physical activity and growth factors; communication between the mesenchyme leads to balanced growth factor production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are Inductive factors?

A

FGF (morphogenesis) and EGF (epithelial proliferation and differentiation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are inhibitory factors?

A

TGFbeta (matrix synthesis and inhibition of epithelium proliferation) and retinoic acid (inhibits branching)

17
Q

What is Vasculogenesis?

A

Airways act as a structural template for capillary networks to form

18
Q

Summerise post-natal lung growth:

A

The number of alveoli increases until puberty/adulthood with surface area increasing until body growth is complete; arteries, veins and capillaries increase alongside the alveoli

19
Q

What is the volume, number of airways and vasculature present at birth?

A

Lungs have a small volume, related to body weight, with all airways present and differentiated, and most arteries/veins but only 33-50% of alveoli present

20
Q

What are the mechanisms that increase flow after birth?

A

Expansion of arteries dilate arteries to increase blood flow

Expansion stimulates release of vasodilators such as NO/PGI2

Vasoconstrictors present during foetal life - if not inhibited then will get pulmonary hypertension

Direct effect of oxygen on smooth muscle cells