Resp System Development and Histo

Question 1

when does development begin

Answer 1

week 4

Question 2

what is the first developmental structure

Answer 2

respiratory diverticulum (lung bud) appears as outgrowth of foregut

Question 3

what is the lining of larynx, trachea, bronchi, and lungs

Answer 3

endodermal origins

Question 4

what forms cart, muscular, and CT components of trachea and lungs?

Answer 4

splanchnic meso

Question 5

what occurs as lung bud beings to grow caudally

Answer 5

tracheoesophageal ridges begin to separate the lung bud from foregut

Question 6

tracheoesophageal suptum

Answer 6

fusion of tracheoesophageal ridges

dorsal: eso
vent: trachea and lung buds

Question 7

esophageal atresias

Answer 7

abnormalities in partitioning of eso and trachea by tracheoesophageal septum
*can be w/ or w/o fistulas

Question 8

what keeps resp diverticulum and pharynx in open communication

Answer 8

laryngeal orifice (initially a sagittal slit which changes to a T shaped opening)

Question 9

what do laryngeal carts and mm arise from?

Answer 9

pharyngeal arches IV and VI

Question 10

what innervates structures from pharyngeal arches IV and VI

Answer 10

IV: sup laryngeal n
VI: recurrent laryngeal n

Question 11

what does laryngeal mesenchyme transform into

Answer 11

1. thyroid cart
2. cricoid cart
3. arytenoid cart

Question 12

what does epiglottis form from

Answer 12

mesenchyme of caudal hypopharyngeal eminence

Question 13

what does lung bud divide to form

Answer 13

2 primary bronchial buds

• R forms 3 secondary buds, L forms 2
• R forms 10 tertiary buds, L forms 8

Question 14

what forms pleural cavities

Answer 14

as lung buds grow caudally and laterally they expand into the pericardioperitoneal canals which will gradually narrow

Question 15

what gives rise to visceral pleura of lungs

Answer 15

splanchnic meso

Question 16

what gives rise to parietal pleura

Answer 16

somatic meso lining thor body wall

Question 17

what is the end of the conduction system

Answer 17

terminal bronchioles (small brs from resp trees)

Question 18

what do term bronchioles divide into

Answer 18

resp bronchioles (beginning of resp division)
*term sacs formed at end of resp trees

Question 19

periods of development

Answer 19

1. pseudoglandular period (5-16wks): babies cannot survice b/c no sacs/cells present
2. canalicular period (16-26 wks): term bronch->resp bronch->alveolar ducts
3. term sac period (26wks-birth): term sacs form, capillaries are established, babies born early need breathing help

Question 20

what lines term sac walls

Answer 20

simple squ epi, mostly type I, some type II

Question 21

fnctns of resp system

Answer 21

1. air condition
2. air filtration
3. gas exchange

Question 22

2 fnctional divisions

Answer 22

1. conducting: nasal cav, naso/oro/laryngopharynx, larynx, trachea, bronchi, bronchioles, term bronchioles, NO GAS EXCHANGE
2. resp: resp bronchioles, alveolar ducts, alveolar sacs, alveoli

Question 23

olfactory epi

Answer 23

• pseudostrat col epi
• have olfactory receptor cells, supporting cells, basal cells, brush cells
• bowmans glands produce mucous
• no goblet cells

Question 24

conducting division

Answer 24

• 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

Question 25

nasal cavity

Answer 25

- tall pseudostrat col epi | - basal cells, goblet cells, thin BM, thick LP w/ BVs

Question 26

pharynx

Answer 26

1. naso: ciliated pseudostrat columnar 2. oro: nonkeratinized strat squ 3. laryngo: nonkeratinized strat squ

Question 27

larynx

Answer 27

- cartilages in LP - vest fold covered w/ resp epi - vocal folds covered w/ nonkeratinized strat squ epi *also on epiglottis*

Question 28

trachea

Answer 28

- resp epi in lining - mucoua: resp epi on thick BM - submucosa: LCT - cart layer w/ trachealis m - adventitia

Question 29

how does bronchi begin to differ from trachea

Answer 29

1. cart rings are replaced w/ hyaline cart and disappear 2. SM increases as cart decreases 3. height of resp epi decreases as bronchi decrease in diameter

Question 30

bronchi

Answer 30

-mucosa, muscularis, submucosa, cart layer, adventitia

Question 31

bronchioles

Answer 31

- no cart in walls, no glands in submucosa, epi height gets smaller * changes from resp epi->ciliated simple col->ciliated simple cub epi

Question 32

are goblet cells present in term bronchioles

Answer 32

no

Question 33

clara cells

Answer 33

present in term bronchioles, protect bronchiolar epi, produce surfactant

Question 34

respiratory division

Answer 34

resp bronchioles->alveolar ducts->alv sac->alveoli

Question 35

resp bronchiole

Answer 35

cuboidal epi prox: ciliated cells and clara dist: just clara

Question 36

alveolar ducts

Answer 36

almost no walls, only alveoli as peripheral boundary, knobs of SM

Question 37

alveolar sacs

Answer 37

spaces surround by clusters of alveoli

Question 38

alveoli

Answer 38

150-250 million/lungs, interalveolar septa demarcate and separate adjacent alveoli

Question 39

cells of alveoli

Answer 39

1. type I: squamous, provide minimal diffusion barrier 2. type II: irregular cuboidal cells, produce surfactant, progenitor for type I 3. alveolar macros: called dust cells, little black dots, sit on alveolar surface or in alveolar sapce 4. endothelial cells 5. fibroblasts

Question 40

air blood barrier

Answer 40

composed of 1. surface lining and cytoplasm of alveolar cells 2. fused basal laminae of alveolar cells and cap endo cells 3. cytoplasm of endothelial cells * type I alveolar cells, endothelial cells, dual basal lamina