Resp System Development and Histo Flashcards
when does development begin
week 4
what is the first developmental structure
respiratory diverticulum (lung bud) appears as outgrowth of foregut
what is the lining of larynx, trachea, bronchi, and lungs
endodermal origins
what forms cart, muscular, and CT components of trachea and lungs?
splanchnic meso
what occurs as lung bud beings to grow caudally
tracheoesophageal ridges begin to separate the lung bud from foregut
tracheoesophageal suptum
fusion of tracheoesophageal ridges
dorsal: eso
vent: trachea and lung buds
esophageal atresias
abnormalities in partitioning of eso and trachea by tracheoesophageal septum
*can be w/ or w/o fistulas
what keeps resp diverticulum and pharynx in open communication
laryngeal orifice (initially a sagittal slit which changes to a T shaped opening)
what do laryngeal carts and mm arise from?
pharyngeal arches IV and VI
what innervates structures from pharyngeal arches IV and VI
IV: sup laryngeal n
VI: recurrent laryngeal n
what does laryngeal mesenchyme transform into
- thyroid cart
- cricoid cart
- arytenoid cart
what does epiglottis form from
mesenchyme of caudal hypopharyngeal eminence
what does lung bud divide to form
2 primary bronchial buds
- R forms 3 secondary buds, L forms 2
- R forms 10 tertiary buds, L forms 8
what forms pleural cavities
as lung buds grow caudally and laterally they expand into the pericardioperitoneal canals which will gradually narrow
what gives rise to visceral pleura of lungs
splanchnic meso
what gives rise to parietal pleura
somatic meso lining thor body wall
what is the end of the conduction system
terminal bronchioles (small brs from resp trees)
what do term bronchioles divide into
resp bronchioles (beginning of resp division) *term sacs formed at end of resp trees
periods of development
- pseudoglandular period (5-16wks): babies cannot survice b/c no sacs/cells present
- canalicular period (16-26 wks): term bronch->resp bronch->alveolar ducts
- term sac period (26wks-birth): term sacs form, capillaries are established, babies born early need breathing help
what lines term sac walls
simple squ epi, mostly type I, some type II
fnctns of resp system
- air condition
- air filtration
- gas exchange
2 fnctional divisions
- conducting: nasal cav, naso/oro/laryngopharynx, larynx, trachea, bronchi, bronchioles, term bronchioles, NO GAS EXCHANGE
- resp: resp bronchioles, alveolar ducts, alveolar sacs, alveoli
olfactory epi
- pseudostrat col epi
- have olfactory receptor cells, supporting cells, basal cells, brush cells
- bowmans glands produce mucous
- no goblet cells
conducting division
- cleans, warms, humidifies air
- cilia of resp epi sweep mucous w/ trapped particulate toward pharynx
- has cart, seromucous glands, mucous cells, elastic fibers in CT, highly vascular
nasal cavity
- tall pseudostrat col epi
- basal cells, goblet cells, thin BM, thick LP w/ BVs
pharynx
- naso: ciliated pseudostrat columnar
- oro: nonkeratinized strat squ
- laryngo: nonkeratinized strat squ
larynx
- cartilages in LP
- vest fold covered w/ resp epi
- vocal folds covered w/ nonkeratinized strat squ epi also on epiglottis
trachea
- resp epi in lining
- mucoua: resp epi on thick BM
- submucosa: LCT
- cart layer w/ trachealis m
- adventitia
how does bronchi begin to differ from trachea
- cart rings are replaced w/ hyaline cart and disappear
- SM increases as cart decreases
- height of resp epi decreases as bronchi decrease in diameter
bronchi
-mucosa, muscularis, submucosa, cart layer, adventitia
bronchioles
- no cart in walls, no glands in submucosa, epi height gets smaller
- changes from resp epi->ciliated simple col->ciliated simple cub epi
are goblet cells present in term bronchioles
no
clara cells
present in term bronchioles, protect bronchiolar epi, produce surfactant
respiratory division
resp bronchioles->alveolar ducts->alv sac->alveoli
resp bronchiole
cuboidal epi
prox: ciliated cells and clara
dist: just clara
alveolar ducts
almost no walls, only alveoli as peripheral boundary, knobs of SM
alveolar sacs
spaces surround by clusters of alveoli
alveoli
150-250 million/lungs, interalveolar septa demarcate and separate adjacent alveoli
cells of alveoli
- type I: squamous, provide minimal diffusion barrier
- type II: irregular cuboidal cells, produce surfactant, progenitor for type I
- alveolar macros: called dust cells, little black dots, sit on alveolar surface or in alveolar sapce
- endothelial cells
- fibroblasts
air blood barrier
composed of
- surface lining and cytoplasm of alveolar cells
- fused basal laminae of alveolar cells and cap endo cells
- cytoplasm of endothelial cells
* type I alveolar cells, endothelial cells, dual basal lamina
