embryology of respiratory system Flashcards

1
Q

how does the primitive gut tube form?

A

from the folding of the endoderm of the embryo

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2
Q

3 things formed from gut tube

A

foregut, midgut, hindgut

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3
Q

when and where do the trachea and lung buds form from

A

4 weeks from the ventral wall of the primitive gut tube

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4
Q

what seperates the trachea and oesophagus?

A

oesophagotracheal septum seperates them into ventral trachea and dorsal oesphagus

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5
Q

what 2 things happen if the oesophagus and trachea don’t separate?

A

tracheoesophageal fistula and oesophageal atresia

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6
Q

what is a fistula

A

abnormal passage between 2 epithelial tubes

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7
Q

what is an atresia

A

a passage in the body that is closed off or absent

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8
Q

what does splanchnic mesoderm form?

A

visceral pleura

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9
Q

what does somatic mesoderm form?

A

parietal pleura

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10
Q

what is the space called between the 2 layers of mesoderm?

p…c…p

A

pericardioperifoneal cavity
(later called pleural cavity)

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11
Q

how does the pleural cavities close off from the heart?

A

pleuropericardial (somatic mesoderm) folds
-> pericardium of the heart

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12
Q

what are the 5 stages of lung development? and when do they happen?

e, f- p c s, pn

A

embryonic (4 weeks)
- lung buds, foregut, trachea form

foetal period
pseudo glandular (7-17 weeks)
- all lung structures develop, except the respiratory part
- no gas exchange

canalicular (17-27 weeks)
- respiratory part and alveolar duct forms
- epithelium differentiates to type l and type ll pneumocytes
- no gas exchange

saccular (27-40 weeks)
- gas exchange begins
- alveolar sacs, primitive alveoli and surfactant is 5% complete

post natal period (32 weeks - 8years)
- proliferation of alveoli from alveolar sacs, complete
- 300 million alveoli in an adult

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13
Q

What are 2 congenital lung conditions that involve neonatal?

NRDS and LA

A

neonatal respiratory distress syndrome (hyaline membrane disease)
- affects 2% of neonates, makes up 30% of neonatal disease
- surfactant deficiency -> partial collapse of alveoli
-> debris of blood elements accumulate
-> glassy hyaline appearance.

lung agenesis
- failure of lung bud to develop in embryo
- insufficient mesoderm to form pleura
- teratogens (poison)

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14
Q

what closes off pleural cavities from the peritoneal cavity of the abdomen?

A

Diaphragm

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15
Q

What are the four mesodermal structures that the diaphragm develops from?

A

1 .septum transversum -> central tendon

  1. pleuroperitoneal folds
    -> somatic mesoderm folds grow from the periphery to fuse with septum transversum
  2. skeletal muscle ingrowth from the peripheral body wall
    -> grows inwards to cover pleuroperitoneal folds forming the muscular part
  3. dorsal oesophagus mesentery
    -> attaches embryological oesophagus to the posterior thoracic wall
    -> skeletal muscle from periphery covers dorsal mesentery to form diaphragmatic crura
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16
Q

what are 2 congenital diaphragm defects?

A

failure of the diaphragm to completely close during development -> hernia

pulmonary hypoplasia
(underdevelopment of incomplete development of lung)

17
Q

what is a hernia? give an example

shh

A

protrusion of an organ through the structure/ muscle that usually contains it
e.g. sliding hiatus hernia