Sept29 M1-Developmental anomalies of the respiratory system

Question 1

what allows first bifurcation of two lung buds

Answer 1

caudal endoderm of trachea bifurcates in mesenchyme (which will be pleura)

Question 2

name of mesenchyme surrounding all endoderm of resp and what will provide

Answer 2

splanchnic mesenchyme, will form CT and cartilage around trachea + smooth muscle

Question 3

how trachea develops (2)

Answer 3

Overgrowth of cells in lumen

Amniotic fluid flows in there for recanalization and budding

Question 4

characteristic of lungs budding

Answer 4

asymmetric. right lung more aligned with trachea

Question 5

what azygos vein normally does and what can do (abnormal) when lung develops

Answer 5

supposed to go over right bronchus. sometimes indents in right upper lobe (still lsurrounded by parietal pleura)

Question 6

name of result when azygos vein goes through right upper lobe

Answer 6

azygous lobe

Question 7

how many times one lung bud branches

Answer 7

22

Question 8

how early diaphragm movements contribute to lung formation

Answer 8

help amniotic fluid circulation

Question 9

initial lung buds: mesenchyme in contact, something in particular

Answer 9

fibroblast and mesenchyme have receptors for GFs for proliferation at these tips

Question 10

lung epithelium description at embryo. when branching starts

Answer 10

pseudostratified

Question 11

how lung epithelium changes with budding

Answer 11

becomes thinner and eventually cuboidal

Question 12

lung epithelium closer to mesenchyme: description + what phase

Answer 12

end budding phase: squamous and in direct contact with vessels and capillaries in mesenchyme

Question 13

what proliferation of mesenchyme at initial budding alloes

Answer 13

further bifurcations and thinning of mesenchyme, more ducts

Question 14

2 factors expressed at endodermal tips and role

Answer 14

Fibroblast GF and Shh (sonic hedgehog) : proliferation

Question 15

when production of blood vessels stimulated in lung and how

Answer 15

at cuboidal epith phase. VEGF produced and angioblasts (precursors) stimulated

Question 16

time of end of lung development where gas exchange capability is possible

Answer 16

24-26 weeks

Question 17

terminal sac phase (26 weeks to birth) what happens in lungs

Answer 17

• ducts bud into resp bronchioles in mesenchyme + angiogenesis
• endoderm: pneumocyte type 1 (surface) and type 2

Question 18

post alveolar phase (lung dev after birth) what happens

Answer 18

terminal sacs further divided by secondary mesenchymal septa (alveoli form)
from 70M at birht to 300M at 8 years

Question 19

first genetic defect possible in lung formation

Answer 19

defective gene expression during endodermal-mesenchyme interaction (trachea sep from esophagus + budding)

Question 20

genetic defect possible in lung formation at budding step + consequence (2)

Answer 20

defective shh expression. affects tracheo-esophageal septum dev + lung branching

Question 21

ultimate consequence of shh defect

Answer 21

lung hypoplasia

Question 22

defective apoptosis consequence on lung dev (gut too)

Answer 22

no recanalization of gut and trachea (atresia)

Question 23

how gut atresia can affect lung dev

Answer 23

leads to abnormal amniotic fluid turnover, affects branching of lung

Question 24

cause of atresia

Answer 24

failure of normal mesenchyme-endodermal interaction that would facilitate apoptosis of lumen endodermal cells

Question 25

atresia excess consequence

Answer 25

endodermal cells degenerate : segment of agenesis

Question 26

how BP affects lung dev

Answer 26

defective vasculature so hypoplasia and maybe atresia of gut: bad amniotic fluid circul to lung

Question 27

consequence of incomplete apoptosis on gut wall

Answer 27

mesenchyme can project in and cause doubling of gut tube

Question 28

mesenchyme overgrowth consequence

Answer 28

smooth muscle hypertrophy: stenosis of lumen

Question 29

stenosis def + 2 causes

Answer 29

narrowing of gut lumen. reduced endodermal cell prolif or excessive mesenchyme prolif

Question 30

esophageal atresia def + consequence

Answer 30

top and bottom of esophagus not linked: vomiting

Question 31

esophago-tracheal (or TO) fistula def +consequence

Answer 31

esophagus links to trachea. most food goes in bronchi

Question 32

trachea atresia def

Answer 32

top and bottom of trachea not linked

Question 33

OT fistula + atresia of esophagus consequence

Answer 33

regurgitation and trachea linked to bottom of esophagus so air in stomach

Question 34

one fatal error in esophagus and tracheal dev

Answer 34

failure of TO septum to separate (fatal)

Question 35

polyhydramnios def

Answer 35

excess amniotic fluid

Question 36

polyhydramnios one cause

Answer 36

gut atresia

Question 37

oligohydramnios def

Answer 37

deficit of amniotic fluid

Question 38

give 1 cause of oligohydramnios + consequence + syndrome name

Answer 38

kidney agenesis (essential to produce amniotic fluid) - hypoplasia of the lung - death at birth - Potters syndrome