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Flashcards in Respiratory Embryology Deck (34)
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1

What does the laryngotracheal groove become?

When does it develop?

pulmonary epithelium
glands of larynx, trachea & bronchi

week 4

2

What does the splanchnic mesoderm (from lat plate) of laryngotracheal groove become?

CT, cartilage & smooth muscle of respiratory system (surrounds the foregut)

3

Where does the lung bud come from?

laryngotracheal diverticulum (evagination of laryngotracheal groove)

4

Why are the tracheoesophageal folds important? When do they fuse?

endodermal ingrowth of laryngotracheal tube that fuses to form tracheoesophageal septum (by end of week 5)

divides cranial portion of foregut & separates respiratory system from digestive system

fuse during week 5

5

Where is the laryngotracheal tube located by end of week 5?

ventral part of foregut

primordium larynx, trachea, bronchi & lungs

6

What does the dorsal part of the tracheoesophageal septum become?

primordium oropharynx & esophagus

7

Where does the epithelial lining of the larynx come from?

endoderm of laryngotracheal tube

8

Where do the cartilages & CT of larynx come from?

mesenchyme of PA 4 & 6

9

What is the result of the proliferation of the laryngotracheal tube endoderm?

occlusion of the lumen of the tube

10

When does recanalization occur and what is the result?

during week 10

true vocal folds & vestibular folds in the larynx

11

Where does the epiglottis come from?

hypopharyngeal eminence (mesenchme of PA 3 & 4)

12

Where do the laryngeal muscles come from?

myoblasts of PA 4 & 6

13

What does the division of the laryngotracheal diverticulum produce?

trachea (late week 4/early week 5)

14

Endoderm derivatives of trachea

tracheal epithelium
tracheal glands
pulmonary epithelium (lining of lungs)

15

Splanchnic mesenchyme derivatives of trachea

tracheal cart (hyaline cart)
tracheal CT
tracheal smooth m

16

Why is splanchnic mesenchyme important in respiratory development?

lung development requires SM to signal for bronchial bud branching in week 5

17

Visceral pleura

splanchnic mesoderm of lateral plate

18

Parietal pleura

somatic mesoderm of lateral plate

19

4 stages of prenatal lung development

Pseudoglandular (weeks 5-17)
Canalicular (weeks 16-25)
Terminal sac (week 24-birth)
Alveolar (week 32-8yo)

20

Pseudoglandular stage

weeks 5-17
all major elements of lung formed
no alevoli for gas exchange

fetus is NOT survivable

21

Canalicular stage

weeks 16-25

vascularization
resp bronchioles + primordial alevolar & sacs

fetus is +/- survivable

22

Terminal sac stage

week 24-birth

increase # of alveoli
vascularization of thin epithelium
Type 1 & Type 2 pneumocytes
lymph capillaries

survivable b/c gas xchange can occur!

23

Alveolar stage

week 32-8yo

alveolocapillary membrane
primitive & mature alveoli (95% of alveoli mature post-natally)

24

What stage of lung development is the fetus definitely survivable?

terminal sac stage (week 24-birth) b/c has necessary components for proper gas exchange

25

How is splanchnic mesoderm critical for bronchi development?

as alveoli are added, need to keep developing other supporting tissue & needed for:

bronchial cartilage plates
bronchial smooth m & CT
pulmonary CT & capillaries

26

Largyngeal atresia

failure of laryngeal recanalization in week 10

obstructed upper fetal airway

airways dilated, lungs large & filled w/ fluid, diaphragm may be flat or inverted

27

Tracheoesophageal atresia

abnormal connection btwn trachea & esophagus due to failure of foregut endoderm to proliferate in relation to whole embryo

can't swallow, drool, regurgitate food (GI contents can reflux thru fistula into trachea & lungs)

lung development can be impaired

28

Pulmonary agensis

failure of splitting of R & L bronchial buds from respiratory bud

complete absence of lung or lobe & its accompanying bronchi

29

Oligohydramnios

pulmonary hypoplasia due to insufficient amniotic fluid production (renal issue)

restricted fetal thorax from uterine pressure

clubbed feet, compressed face, issues w/ hand placement & breech position

30

Respiratory Distress Syndrome

due to surfactant deficiency (type 2 pneumocytes can't produce surfactant)

lungs are underinflated & alveoli appear glassy

grunting, cyanosis