Development of the Respiratory System

Question 1

what week does the respiratory system start developing

Answer 1

week 4

Question 2

what is the first sign appearing in week 4 that starts resp. development

Answer 2

laryngeotracheal groove forms caudal to 4th pharyngeal pouch

Question 3

as the laryngealtracheal groove protrudeventrally it becomes an endodermal outgrowth known as the ?

Answer 3

lung bud or resp. diverticulum

Question 4

the lung bud is an endodermal outgrowth from what ?

Answer 4

from the dorsally oriented foregut

Question 5

as the resp. lung bud develops ventrally , a ____________ develops to seperate it from the dorsal foregut

Answer 5

tracheosophageal septum

Question 6

what is the remaining connection b/w the pharynx and resp. lung bud in adults called

Answer 6

primordial laryngeal inlet

Question 7

if development of the resp. system results in an abnormal connection b/w the espohagus and trachea b/c of abnormal development of the tracheoesophageal septum, what is the result ?

Answer 7

tracheoesophageal fistula

Question 8

what is esophageal atresia

Answer 8

blind pouching of the esophagus b/c of a posteriorly deviating tracheoesophageal septum

Question 9

which occurs more superior and which occurs inferior b/w a tracheoesophageal fistula and an esophageal atresia

Answer 9

tracheoesophageal fistula occurs inferior

esophageal atresia occurs superior

Question 10

tracheoesophageal fistula and esophageal atresia together put a patient at risk for what ?

Answer 10

polyhydramnios

-too much amniotic fluid b/c esophagus cant drain it to stomach

Question 11

what are the common symptoms a patient woud experience w/ an esophageal atresia

Answer 11

drooling

• regurgitation
• cant swallow = infection of lungs occurs b/c ingested food goes to trachea then to lungs instead of stomach

Question 12

endoderm gives rise to what resp. structures

Answer 12

epithelial lining

glands of airways

Question 13

splanchnic mesoderm gives rise to what resp. structures

Answer 13

• smooth m. inside trachea and bronchi

- CT of airways

Question 14

what does the esophagus develop from

Answer 14

part of foregut just caudal to pharynx

Question 15

what does the hypopharyngeal eminence give rise too

Answer 15

mesenchyme of cranial part - tongue

mesenchyme of caudal part - epiglottis

Question 16

laryngeal cartilages and musculature arise from what pharyngeal arch pairs

Answer 16

4 and 6

Question 17

the laryngeal muscles arising from the 4 pharyngeal arch are innervated by ____________, whereas the mm. arising from the 6th pharyngeal arch are innervated by the ___________ ?

Answer 17

• superior laryngeal n.

- recurrent laryngeal n.

Question 18

as the lung bud continues to grow ventrally into the splanchnic mesoderm, it divides to form __________.
What day does this occur

Answer 18

2 primary bronchial buds (future primary bronchi)

-day 28

Question 19

once the lung bud has split, the primary bronchial buds growing w/in the splanchnic mesoderm are buldging into what ?

Answer 19

the pericardioperitoneal canal

Question 20

the pericardioperitoneal canal eventually changes name to the pleural cavities. With that said, what gives rise to the visceral pleura and what gives rise to the parietal pleura

Answer 20

splanchnic mesoderm - visceral pleura (lining over lungs)

somatic mesoderm - parietal pleura (lining of thoracic cavity)

Question 21

primary bronchial buds divide into what ?

what day does this occur

Answer 21

3 secondary bronchial (lobar )buds on rights
2 secondary bronchial (lobar) buds on Left
-day 30

Question 22

each secondary bronchial bud will supply _____ lobe of the lung

Answer 22

one

Question 23

what do secondary bronchial (lobar) buds develop into ?

Answer 23

10 tertiary (segmental) bronchial buds on right
8-9 tertiary (segmental) bronchial buds on left

Question 24

what makes up a bronchpulmonary segment

Answer 24

tertiary bronchus+surrounding tissue

Question 25

explain the movement of air starting at the trachea

Answer 25

trachea –> primary bronchi –> secondary bronchi —> tertiary bronchi –> bronchioles —> terminal bronchioles —> resp. bronchioles —> alveolar ducts —> terminal sacs/primitve alveloi

Question 26

what are the 4 stages of lung development, and what weeks do they occur in

Answer 26

pseudoglandular : week 6-16
canalicular : week 16-26
terminal sac : week 26-birth
alveolar : 32 weeks to 8 yrs.

Question 27

what does lung tissue look like during the pseudoglanular stage of development (6-16)

Answer 27

collection of exocrine glands

Question 28

can a fetus survive during the pseudoglandular stage

Answer 28

NO, b/c resp. bronchioles and alveolar sacs not developed yet so cant do gas exchange

Question 29

what does lung tissue look like during the canalicular stage of resp. dev. (16-26

Answer 29

highly vascular

Question 30

can a fetus survive if born during the canalicular stage

Answer 30

YES, b/c respiration is possible since resp. bronchioles present
-most likely die though

Question 31

blood-brain barrier is established during what stage of resp. dev.

Answer 31

terminal sac stage (26-birth)

Question 32

Type I and Type II alveolar cells are both produced at week 26 during the terminal sac stage of resp. dev. What do each of them do ?

Answer 32

Type I alveolar cells - cells allowing gas exchange

Type II - produce and secrete pulmonary surfactant

Question 33

what are pneumocytes

Answer 33

Type I and type II alveolar cells

Question 34

what is the function of pulmonary surfactant

Answer 34

-reduce surface tension preventing collaps upon exhaling

Question 35

when do Type II alveolar cells start producing surfactant

Answer 35

weeks 20-22 but not enough to survive untill week 26

Question 36

what is respiratory distress syndrome

Answer 36

disease premature babies could suffer from due to insufficient surfactant

Question 37

when do alveoli become fully functional ?

Answer 37

during alveolar stage (week 32-8 years)

Question 38

T/F All alveoli develop and mature before birth

Answer 38

F, 95 % mature postnatally