Respiratory Embryology

Question 1

When does development of respiratory system begin?

Answer 1

around week 4

Question 2

respiratory diverticulum

Answer 2

forms as an extension off of the ventral wall of the foregut

Question 3

opening of respiratory diverticulum

Answer 3

becomes the larynx (laryngeal orifice)

Question 4

pharyngeal arches

Answer 4

6 arches total develop; all with their own blood supply, nervous supply, and veinous drainage

Question 5

pharyngeal arches

Answer 5

6 arches total develop; all with their own blood supply, nervous supply, and veinous drainage

Question 6

outer surface of pharyngeal arches

Answer 6

covered with ectoderm

Question 7

inner lining of pharyngeal arches

Answer 7

endoderm

Question 8

between endoderm and ectoderm in pharyngeal arches

Answer 8

mesoderm

Question 9

pharyngeal pouches

Answer 9

on inner surface of arches

Question 10

pharyngeal clefts

Answer 10

on external surface of arches

Question 11

muscle and cartilage of larynx

Answer 11

derived from mesoderm of pharyngeal arches 4 and 6

Question 12

splanchnic visceral mesoderm

Answer 12

gives rise to the cartilaginous, muscular, and CT components of trachea and lungs

Question 13

tracheoesophageal ridge/septum

Answer 13

causes closure between the foregut and respiratory diverticulum so that they are two separate entities

Question 14

the foregut becomes the _

Answer 14

esophagus

Question 15

the respiratory diverticulum becomes the _

Answer 15

trachea with two lung buds

Question 16

tracheoesophageal fistula

Answer 16

when the TE septum does not close off properly

Question 17

esophageal atresia

Answer 17

most common occurrence when TE septum does not close off properly; proximal part of esophagus has a blind-end while distal is connected to trachea via fistula

Question 18

EA + TEF symptoms

Answer 18

excessive accumulation of saliva and mucus, gagging after swallowing, abdominal distention, reflux of stomach contents into lungs, polyhydramnios

Question 19

development of bronchi

Answer 19

lung buds –> primary bronchial buds –> divide into secondary (lobar) bronchial buds (3 on R, 2 on L) –> tertiary (segmental) bronchial buds

Question 20

bronchopulmonary segments

Answer 20

different sections of lung tissue suppled by different tertiary bronchus

Question 21

terminal bronchiole

Answer 21

last of bronchioles without alveoli

Question 22

respiratory bronchioles

Answer 22

some alveoli where exchange can occur

Question 23

alveolar duct

Answer 23

channel with multiple alveoli in its wall

Question 24

alveolar sac

Answer 24

space that has multiple alveoli surrounding it

Question 25

embryonic lung development (weeks 4-7)

Answer 25

from lung bud to tertiary bronchioles; errors can lead to TE fistula

Question 26

pseudoglandular stage (weeks 5-17)

Answer 26

terminal bronchioles surrounded by capillaries but no alveoli; respiration is impossible

Question 27

canalicular stage (weeks 16-25)

Answer 27

from terminal bronchioles to alveolar ducts; lumen developing and begin to get pneumocytes at week 20

Question 28

pneumocytes

Answer 28

alveolar cells

Question 29

pneumocyte type I

Answer 29

squamous cells for exchange

Question 30

pneumocyte type II

Answer 30

produce surfactant

Question 31

saccular stage (weeks 26-birth)

Answer 31

alveolar ducts --> terminal sacs

Question 32

alveolar stage (week 36 to 8 years)

Answer 32

terminal sacs --> adult alveoli; number of alveoli increases exponentially in first few years of life

Question 33

aeration of lungs

Answer 33

at birth, fluid must be cleared: 1. pressure on thorax during natural delivery forces fluid out 2. fluid is absorbed into capillaries and lymphatics

Question 34

respiratory distress syndrome

Answer 34

insufficient pulmonary surfactant to reduce surface tension and prevent collapse

Question 35

primitive embryonic body cavity

Answer 35

space between parietal and visceral layers

Question 36

coelomic cavity

Answer 36

where visceral and parietal mesoderm layers meet; gives rise to pleural, pericardial, and peritoneal cavities

Question 37

septum transversum

Answer 37

developing diaphragm --> starts out in cervical region (C 3,4,5) --> mesoderm origin

Question 38

phrenic nerve

Answer 38

starts at neck and travels through thoracic cavity through pericardium to the diaphragm

Question 39

pericardio-peritoneal canal

Answer 39

connects thorax with abdomen --> form pleuroperitoneal folds to close off canal

Question 40

diaphragmatic hernia

Answer 40

what happens if the pleuroperitoneal folds do not close the canal

Question 41

left pericardioperitoneal canal

Answer 41

is larger and closes off later than right --> diaphragmatic hernia will be on left side and left lung will be compressed

Question 42

pulmonary agenesis

Answer 42

absence of a lung or lobe and its bronchi; caused by failure of bronchial buds to develop

Question 43

pulmonary hypoplasia

Answer 43

poorly developed bronchial tree associated with congenital diaphragmatic hernia and any disorder that causes oligohydramnios