Development of the Respiratory System Flashcards
what week does the respiratory system start developing
week 4
what is the first sign appearing in week 4 that starts resp. development
laryngeotracheal groove forms caudal to 4th pharyngeal pouch
as the laryngealtracheal groove protrudeventrally it becomes an endodermal outgrowth known as the ?
lung bud or resp. diverticulum
the lung bud is an endodermal outgrowth from what ?
from the dorsally oriented foregut
as the resp. lung bud develops ventrally , a ____________ develops to seperate it from the dorsal foregut
tracheosophageal septum
what is the remaining connection b/w the pharynx and resp. lung bud in adults called
primordial laryngeal inlet
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 ?
tracheoesophageal fistula
what is esophageal atresia
blind pouching of the esophagus b/c of a posteriorly deviating tracheoesophageal septum
which occurs more superior and which occurs inferior b/w a tracheoesophageal fistula and an esophageal atresia
tracheoesophageal fistula occurs inferior
esophageal atresia occurs superior
tracheoesophageal fistula and esophageal atresia together put a patient at risk for what ?
polyhydramnios
-too much amniotic fluid b/c esophagus cant drain it to stomach
what are the common symptoms a patient woud experience w/ an esophageal atresia
drooling
- regurgitation
- cant swallow = infection of lungs occurs b/c ingested food goes to trachea then to lungs instead of stomach
endoderm gives rise to what resp. structures
epithelial lining
glands of airways
splanchnic mesoderm gives rise to what resp. structures
- smooth m. inside trachea and bronchi
- CT of airways
what does the esophagus develop from
part of foregut just caudal to pharynx
what does the hypopharyngeal eminence give rise too
mesenchyme of cranial part - tongue
mesenchyme of caudal part - epiglottis
laryngeal cartilages and musculature arise from what pharyngeal arch pairs
4 and 6
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 ___________ ?
- superior laryngeal n.
- recurrent laryngeal n.
as the lung bud continues to grow ventrally into the splanchnic mesoderm, it divides to form __________.
What day does this occur
2 primary bronchial buds (future primary bronchi)
-day 28
once the lung bud has split, the primary bronchial buds growing w/in the splanchnic mesoderm are buldging into what ?
the pericardioperitoneal canal
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
splanchnic mesoderm - visceral pleura (lining over lungs)
somatic mesoderm - parietal pleura (lining of thoracic cavity)
primary bronchial buds divide into what ?
what day does this occur
3 secondary bronchial (lobar )buds on rights
2 secondary bronchial (lobar) buds on Left
-day 30
each secondary bronchial bud will supply _____ lobe of the lung
one
what do secondary bronchial (lobar) buds develop into ?
10 tertiary (segmental) bronchial buds on right 8-9 tertiary (segmental) bronchial buds on left
what makes up a bronchpulmonary segment
tertiary bronchus+surrounding tissue
explain the movement of air starting at the trachea
trachea –> primary bronchi –> secondary bronchi —> tertiary bronchi –> bronchioles —> terminal bronchioles —> resp. bronchioles —> alveolar ducts —> terminal sacs/primitve alveloi
what are the 4 stages of lung development, and what weeks do they occur in
pseudoglandular : week 6-16
canalicular : week 16-26
terminal sac : week 26-birth
alveolar : 32 weeks to 8 yrs.
what does lung tissue look like during the pseudoglanular stage of development (6-16)
collection of exocrine glands
can a fetus survive during the pseudoglandular stage
NO, b/c resp. bronchioles and alveolar sacs not developed yet so cant do gas exchange
what does lung tissue look like during the canalicular stage of resp. dev. (16-26
highly vascular
can a fetus survive if born during the canalicular stage
YES, b/c respiration is possible since resp. bronchioles present
-most likely die though
blood-brain barrier is established during what stage of resp. dev.
terminal sac stage (26-birth)
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 ?
Type I alveolar cells - cells allowing gas exchange
Type II - produce and secrete pulmonary surfactant
what are pneumocytes
Type I and type II alveolar cells
what is the function of pulmonary surfactant
-reduce surface tension preventing collaps upon exhaling
when do Type II alveolar cells start producing surfactant
weeks 20-22 but not enough to survive untill week 26
what is respiratory distress syndrome
disease premature babies could suffer from due to insufficient surfactant
when do alveoli become fully functional ?
during alveolar stage (week 32-8 years)
T/F All alveoli develop and mature before birth
F, 95 % mature postnatally
