Respiratory Embryology

Question 1

median outgrowth found in floor of the primitive pharynx

Answer 1

laryngotracheal groove

Question 2

laryngotracheal groove goes on to form the

Answer 2

laryngotracheal diverticulum (lung bud)

Question 3

the _____ end of the diverticulum enlarges to form the respiratory bud

Answer 3

distal end

Question 4

the bud grows ventrocaudally and bifurcates at __ dpf

Answer 4

26-28 dpf

Question 5

branching pattern of the lung is organized and regulated by what tissue layer

Answer 5

mesoderm induces endoderm to branch

Question 6

by week 5, the primary bronchial buds branch to form

Answer 6

the secondary bronchial buds

Question 7

how many orders of airways form after birth?

Answer 7

7 orders

Question 8

by 24 weeks, the bronchopulmonary segments have formed (3)

Answer 8

segmental bronchi + mesenchyme
17 orders of branching have occured
respiratory bronchioles have formed

Question 9

lungs are considered pseudoglandular at weeks __ - __
all major elements of the lung have formed except those involved in __________
Looks like _________

Answer 9

pseudoglandular 5-17 weeks
all elements except those involved with gas exchange
looks like exocrine gland
fetus cannot survive

Question 10

lungs are considered canalicular at weeks __ - ___

what primordial structures are present?

Answer 10

weeks 16-25
primordial alveolar and sacs & respiratory bronchioles present

vascularization
overlaps pseudoglandular stage
can survive? maybe?

Question 11

between ___ weeks and ____ - the lungs are in the terminal sac phase
_________ can occur because numerous ______ have formed

Answer 11

24 weeks to birth
gas exchange can occur because numerous alveoli have formed (aka survivable)
thin epithelium with increased vascularization
Type 1 pneumocytes
Type II pneumocytes producing surfactant

Question 12

from 32 weeks to 8 years, the lungs are considered ________

Answer 12

alveolar

primitive alveoli form more primitive alveoli –> eventually mature

Question 13

approximately __ % of mature alveoli develop postnatally

Answer 13

95%

Question 14

the splanchnic mesoderm contributes which layer of pleura

Answer 14

visceral pleura

Question 15

the thoracic body wall becomes lined with what layer of pleura

Answer 15

parietal pleura

Question 16

trachea develops at the proximal end of the

Answer 16

tracheoesophageal ridge

Question 17

trachea is formed from ______ and ______ mesoderm

Answer 17

endoderm and splanchnic mesoderm (outer layer)

Question 18

esophageal atresia is also known as

Answer 18

blind esophagus - pouch structure that doesnt go anywhere else

Question 19

tracheoesophageal fistula

Answer 19

abnormal connection between trachea and esophagus

Question 20

Failure of foregut endoderm to proliferate rapidly enough in relation to the rest of the embryo could result in either

Answer 20

esophageal atresia

tracheoesophageal fistula

Question 21

complete absence of a lung or a lobe and accompanying bronchi

Answer 21

pulmonary agenesis 
typically unilateral (bilateral would not survive) 
respiratory bud fails to separate into R/L bronchial buds

Question 22

fetal breathing movements

Answer 22

essential for normal lung development
conditions respiratory muscles
used to monitor survival
Aspirate amniotic fluid - stimulates lung development

Question 23

amniotic fluid is cleared from fetal lungs by

Answer 23

1) pressure on fetal thorax during vaginal delivery
2) pulmonary capillaries, AV
3) lymphatics

Question 24

pulmonary hypoplasia can result from

Answer 24

too little amniotic fluid (oligohydramnios)

Question 25

reduced lung size because decreased hydraulic pressure on lungs, affecting stretch receptors and lung growth

Answer 25

pulmonary hypoplasia

Question 26

Respiratory distress is mainly caused by

Answer 26

surfactant deficiency - lungs are under-inflated

Question 27

rapid, labored breathing that develops shortly after birth with tachypnea, nasal flaring, suprasternal, intercostal, or subcostal retractions, grunting and cyanosis is known as

Answer 27

respiratory distress syndrome

Question 28

disturbances in bronchial development during late fetal life can result in fluid/air filled structures known as

Answer 28

congenital lung cysts

Question 29

the intraembryonic coelom forms during week __ the cranial region represents the future ______ cavity the caudal region represents the future ___ and ___ cavities

Answer 29

week 4 cranial region --> pericardial Caudal region --> pleural and peritoneal

Question 30

head folding reshapes the ________ coelom, causing the primitive pericardial cavity to move, placing it cranially to the ____

Answer 30

reshapes the intraembryonic coelom | now located cranially to septum transversum