Embryology 3

Question 1

what does splanchnic mean?

Answer 1

surrounds organs

Question 2

development of airways: where does the tubular outgrowth come from?

Answer 2

from the foregut (oesophagus)

Question 3

what will the tubular outgrowth develop into?

Answer 3

trachea and lung buds

Question 4

what happens before the lung buds start proliferating?

Answer 4

trachea separates from oesophagus

Question 5

what do the lung buds do when they start proliferating? what do they form?

Answer 5

invaginate the pleural cavities laterally, forming visceral and parietal pleural and pleural cavity

Question 6

what structure begins to develop between thorax and abdomen?

Answer 6

transverse septal “shelf”

Question 7

how many components make up the transverse septal “shelf”?

Answer 7

4

Question 8

what happens if problems occur in development?

Answer 8

congenital abnormalities

Question 9

on which week does the tubular outgrowth come out of the foregut?

Answer 9

4th week

Question 10

which of the 3 layers makes up the visceral and parietal pleura?

Answer 10

mesoderm

Question 11

which part of the mesoderm gives the visceral and parietal pleura

Answer 11

visceral: mesoderm which covers the outside of the lung
parietal: mesoderm which covers the body wall from the inside

Question 12

when does the lung bud begin pseudo glandular?

Answer 12

7th week

Question 13

when do canals develop on the distal end of the buds? (canalicular development)

Answer 13

17th week

Question 14

when does saccular development take place? (primitive alveoli)

Answer 14

27th week

Question 15

when do the alveolar start developing?

Answer 15

40th week

Question 16

which component of the transverse septal “shelf” forms the tendinous part of the diaphragm?

Answer 16

septum transversum

Question 17

which components of the transverse septal “shelf” forms the muscular part of the diaphragm?

Answer 17

2 pleuroperitoneal membranes (form primitive diaphragm), peripheral body of wall muscle (form peripheral parts of diaphragm)

Question 18

which component of the transverse septal “shelf” forms crura of diaphragm? (and median portion of diaphragm)

Answer 18

mesentery of oesophagus

Question 19

at what point is the primitive gut tube formed?

Answer 19

folding of embryo, week 3

Question 20

what are the two extremities of the gut called at week 3?

Answer 20

hindgut and foregut

Question 21

which sac forms the inside of the gut?

Answer 21

yolk sac

Question 22

where do the trachea and lungs develop?

Answer 22

from ventral wall and foregut

Question 23

where does the respiratory primordium (tissue at its earliest stage) come from?

Answer 23

median outgrowth called the laryngotracheal groove (diverticulum) from ventral part of the foregut

Question 24

which of the 3 layers gives the diverticulum?

Answer 24

endoderm

Question 25

what is the diverticulum surrounded by on its outside?

Answer 25

mesoderm, then enlarges to form trachea + lung buds

Question 26

how does the forgut and the respiratory diverticulum get separated?

Answer 26

oesophagotracheal septum develops between oesophagus and trachea, completely separating them

Question 27

what is a fistula?

Answer 27

an abnormal or surgically made passage between a hollow or tubular organ and the body surface, or between two hollow or tubular organs, i.e.: between 2 epithelialized surfaces

Question 28

how common is tracheoesophageal fistula (TOF)? what type of abnormality is it?

Answer 28

TOF is a common congenital abnormality

Question 29

what is atresia?

Answer 29

a condition in which an orifice or passage in the body is (usually abnormally) closed or absent

Question 30

does the visceral pleural come from the splanchnic or the somatic mesoderm?

Answer 30

splanchnic

Question 31

does the parietal pleural come from the splanchnic or the somatic mesoderm?

Answer 31

somatic

Question 32

EMBRYONIC PERIOD what day does the lung appear? under which form?

Answer 32

26th day, in the form of a respiratory diverticulum in the ventral part of the digestive tract

Question 33

EMBRYONIC PERIOD what does the respiratory diverticulum create?

Answer 33

a median trachea and two lateral pockets

Question 34

EMBRYONIC PERIOD what other component develops at the same time?

Answer 34

vascular connections

Question 35

EMBRYONIC PERIOD at which aortic arch do the pulmonary arteries individuate?

Answer 35

6th aortic arch

Question 36

FOETAL PERIOD what happens during the pseudoglandular stage?

Answer 36

setup of all pulmonary structures except elements needed for gas exchange

Question 37

FOETAL PERIOD what happens during the canalicular stage?

Answer 37

- terminal bronchioles give rise to tubes that make up the respiratory part of the lung - differentiation of epithelium into cuboidal secretory cells (type 2 pneumocytes) which will synthesise the surfactant, and flat cells (type 1 pneumocytes)

Question 38

FOETAL PERIOD what happens during the saccular stage?

Answer 38

- formation of alveolar sacs separated by primary septa - alveolar sacs will be progressively divided into smaller subunits by secondary septa, leading to the formation of alveoli

Question 39

POSTNATAL PERIOD what happens during the alveolar stage?

Answer 39

- formation of alveoli from terminal sacs - about 95% adult-like alveoli formed postnatally - alveoli enlarge - number of respiratory bronchioles (and alveolar ducts and alveoli) increase as lungs enlarge - by 8y of age number of alveoli reaches adult number

Question 40

how many alveoli does an adult have?

Answer 40

about 300m

Question 41

what does RDS/HMD stand for?

Answer 41

surfactant + respiratory distress syndrome (= hyaline membrane disease)

Question 42

what percentage of neonates are affected by RDS?

Answer 42

2%

Question 43

what percentage of neonatal disease is RDS?

Answer 43

30%

Question 44

what is the major cause of RDS?

Answer 44

surfactant deficiency

Question 45

what other congenital conditions can come from the respiratory system development?

Answer 45

- accessory lobes - lobe of azygos vein (vein ends up surrounded by lung) - agenesis of lung

Question 46

where is the septum transversum located in week 3? (before formation of diaphragm)

Answer 46

opposite C3-C5

Question 47

which way does it migrate during development of diaphragm?

Answer 47

caudally (getting closer to thoracic region)

Question 48

which spinal nerves does it bring with it? how does this compare with the root of the phrenic nerves?

Answer 48

C3-C5, coincidence? i think not

Question 49

what 3 types of congenital abnormalities can affect the diaphragm?

Answer 49

- failure of the diaphragm to completely close during development - herniation of the abdominal contents into the chest - pulmonary hypoplasia

Question 50

what is a hernia?

Answer 50

general term to describe a bulge or protrusion of an organ through the structure or muscle that usually contains it

Question 51

what two types of hernia can you get with the diaphragm?

Answer 51

diaphragmatic hernia, opposed to hiatal hernia

Question 52

what is a diaphragmatic hernia?

Answer 52

tendinous part of diaphragm moves anteriorly, posteriorly or centrally

Question 53

what is a hiatal hernia? what are the 2 types of hiatal hernia?

Answer 53

protrusion of the stomach across the diaphragm because the diaphragm is too weak: - sliding hiatus hernia (stomach goes up oesophagus a wee bit) - paraesophageal hiatus hernia (stomach protrudes NOT in the oesophagus)