Respiratory embryology

Question 1

What happens in day 25 of respiratory embryology

Answer 1

diverticulum of foregut endoderm and associated mesoderm; 1st outpouching

Question 2

describe the process of day 25 of respiratory embryology

Answer 2

foregut goes to oesophageal septum to respiratory diverticum

Question 3

what happens in the 4th week of respiratory embryology

Answer 3

splanchnic mesoderm sprouts and by end of 4th week splits into 2 buds

Question 4

what happens in the 5th week of respiratory embryology

Answer 4

lung buds enlarge to form left and right main bronchi

- septum developing between trachea and oesophagus starts budding off

Question 5

when is the pseudoglandular phase

Answer 5

weeks 5-16

Question 6

what happens during the pseudoglandular phase of respiratory embryology

Answer 6

major airways defined and respiratory bronchioles formed

Question 7

what is the appearance of the lungs during the pseudoglandular phase

Answer 7

very immature, look like endocrine tissue nests of angiogenesis, cartilage and smooth muscle, cilia, lung fluid

Question 8

when are lung lobes visible

Answer 8

after 8 weeks

Question 9

when is the canalicular phase

Answer 9

weeks 16-25

Question 10

what happens during the canalicular phase of respiratory embryology

Answer 10

vascularisation
terminal bronchioles begin to develop
Some formation of alveoli

Question 11

when is alveolarization 1

Answer 11

25 weeks to birth

Question 12

when is alveolarization 2

Answer 12

birth to 3.5 yrs

Question 13

what happens during alveolarization 1

Answer 13

alveolar sacs develop
type I and II pneumocytes develop
surfactant begins to be produced
simple alveoli present with thick interstitium

Question 14

what happens during alveolarization 2

Answer 14

thinning of alveolar membrane and interstitium

increasing complexity of alveoli

Question 15

what are the 3 main phases of respiratory embryology

Answer 15

pseudoglandular, canalicular, alveolar

Question 16

what type of cells are type I pneumocytes

Answer 16

simple squamous cells

Question 17

what type of cells are type II pneumocytes

Answer 17

simple cuboidal cells

Question 18

what is the important property of surfactant

Answer 18

amphipathic (can bind to both hydrophobic and hydrophilic molecules simultaneously) so binds to water and air within alveoli to reduce surface tension

Question 19

what is the effect of the presence of surfactant in the lungs

Answer 19

allows lung expansion with minimal effort

Question 20

describe foetal circulation in the heat

Answer 20

shunting of blood R to L

Question 21

describe the 1,2,3 of foetal circulation

Answer 21

1 umbilical vein
2 umbilical arteries
3 foetal shunts

Question 22

what does the umbilical vein do

Answer 22

carries oxygenated blood from placenta to the foetus

Question 23

what do the umbilical arteries do

Answer 23

carry deoxygenated blood from foetus to placenta

Question 24

what are the 3 foetal shunts

Answer 24

ductus venosus, foramen ovale, ductus arteriosus

Question 25

what does the birth process do to the lungs

Answer 25

fluid squeezed out of lungs by birth process

Question 26

what happens to ion channels in the lung at birth

Answer 26

switch from secretory to absorptive

Question 27

what causes increased surfactant release following birth

Answer 27

adrenaline stress

Question 28

what does the first breath do to the lungs/ respiratory system/ circulation

Answer 28

oxygen vasodilates pulmonary arteries
umbilical arteries constrict to form medial umbilical ligaments
ductus arteriosus constricts to form ligamentum arteriosum

Question 29

why does blood move into the lungs following birth

Answer 29

PA pressure decreases exponentially, aortic pressure increases so blood moves into lungs by diffusion to be oxygenated

Question 30

what happens in premature babies with surfactant deficiency

Answer 30

respiratory distress syndrome

Question 31

what are risk factors for respiratory distress syndrome

Answer 31

prematurity and asphyxia/ cold/ stress/ twins

Question 32

what is the management of respiratory distress syndrome in infants

Answer 32

warmth, surfactant replacement, oxygen and fluid, continuous positive airway pressure, positive pressure ventilation if needed