Lungs and thorax

Question 1

What is the name of the primitive body cavity that is incorporated by embryo?

Answer 1

Intra embryonic coelom

Question 2

What drives rostral and caudal folding?

Answer 2

Neural tube expansion

Question 3

What causes lateral folding?

Answer 3

As amnion surrounds embryo brings sides closer together

Question 4

What does rostral folding do to positioning of rostral structures?

Answer 4

Moves them ventrally (to front)

Question 5

What structures move ventrally/inferiorly in folding?

Answer 5

Septum transversum (diaphragm)

Buccopharyngeal membrane (mouth)

Cardiogenic region (heart)

Primitive pericardial cavity

Question 6

What causes heart to lie caudally of brain?

Answer 6

Rostral folding

Question 7

What drives caudal folding?

Answer 7

Growth of developing spinal cord

Question 8

Describe the composition of the buccopharnygeal and cloacal membranes?

Answer 8

Just endoderm and ectoderm due to apoptosis of mesoderm

Question 9

What does caudal folding do?

Answer 9

Cloacal membrane and allantois (forms bladder) moves ventrally

Leads to formation of hindgut tube

Displaces connecting stalk so it merges with neck of yolk sac and both form umbilical cord

Question 10

What forms umbilical cord?

Answer 10

Caudal folding and expansion of amniotic cavity displaces connecting stalk so it merges with neck of yolk sac

Question 11

What does lateral folding do to germ layers?

Answer 11

Fusion of 3 germ layers at ventral midline

Question 12

What does lateral folding do?

Answer 12

Ventral movement of lateral plate mesoderm (parietal and visceral) these fuse forming lining and encloses intraembryonic coelom/cavity (body cavity)

Question 13

What does somatic mesoderm do?

Answer 13

Coat inside of body wall

Question 14

What does splanchnic/visceral mesoderm do?

Answer 14

Coats endodermal gut tube and associated structures

Question 15

Describe what happens to amnion in embryonic folding?

Answer 15

Collapses around embryo and encloses it due to lateral folding (ends of amnion meet)

Question 16

How does vitelline duct form?

Answer 16

As gut tube forms, neck of yolk sac narrows forming vitelline duct

Question 17

What does gut tube become suspended in as it attaches dorsal wall?

Answer 17

Coelomic cavity

Question 18

What is coelomic cavity surrounded by?

Answer 18

Splanchnic mesoderm

Question 19

What forms ventral body wall?

Answer 19

2 sides of amnion meet in midline through lateral folding and fuse

Question 20

What eventually forms the diaphragm?

Answer 20

Septum transversum (from mesoderm)

Question 21

What is the septum transversum derived from?

Answer 21

Mesoderm

Question 22

What is intraembryonic coelom partially divided into and what by?

Answer 22

Thoracic (pericardial) and abdominal (peritoneal) portions by septum transversum

Question 23

What seals of pericardial peritoneal canals?

Answer 23

Pleuroperitoneal membranes (develop from pleuroperitoneal folds)

Question 24

How does the pericardium divide?

Answer 24

Pleuropericardial folds originate along lateral body wall and fuse medially

Divide primitive pericardial cavity into definitive pericardial cavity and 2 pleural cavities

Question 25

What 4 elements make up the diaphragm, what do they give rise to in the adult diaphragm?

Answer 25

Septum transversum - central tendon Pleuroperitoneal membrane - posterior diaphragm Paraxial mesoderm of body wall - muscular rim Dorsal oesophogeal mesentry (L1-L3) gives rise to diaphragmatic cruca

Question 26

What part of the diaphragm does the septum transversum give rise to?

Answer 26

Central tendon

Question 27

What part of the diaphragm does the pleuroperitoneal membrane give rise to?

Answer 27

Posterior diaphragm

Question 28

When does septum transversum arise?

Answer 28

Day 22

Question 29

Where does septum transversum originally lie then what happens to it?

Answer 29

Lies rostral to cardiogenic region Then carried ventrally by rostral folding so wedges between cardiogenic region and neck of yolk sac

Question 30

What does septum transversum attach to?

Answer 30

Anterior body wall (T7), lateral body wall, oesophogeal mesentry (T12)

Question 31

What layer are epithelium of alveoli, bronchi and trachea and larynx from?

Answer 31

Endoderm

Question 32

How and when does respiratory system first develop?

Answer 32

Buds off ventral wall of foregut in week 4

Question 33

What layer (and type) gives rise to muscles, cartilage and connective tissue of the respiratory system?

Answer 33

Splachnic mesoderm

Question 34

What happens as respiratory bud elongates?

Answer 34

Forms trachea and lung bud appears at caudal end.

Question 35

When does lung bud split into left and right bronchi?

Answer 35

Day 28

Question 36

How does entire bronchial tree form?

Answer 36

Lung endoderm develops by branching morphogenesis and budding forms entire bronchial tree

Question 37

What coats the lung endoderm, what does it give rise to?

Answer 37

Mesenchymal tissue from splanchnic mesoderm - diff into cartilaginous rings around trachea etc

Question 38

What does lung endoderm differentiate to?

Answer 38

Respiratory epithelium

Question 39

At what point can gaseous exchange between blood and air occur?

Answer 39

7th month

Question 40

Does the septum transversum initially fully divide the thorax and abdomen?

Answer 40

No leaves huge canals called the pericardioperitoneal canals.

Question 41

What canals does the septum transversum leave?

Answer 41

Pericardioperitoneal canals

Question 42

Where do the lung buds grow into (canals)?

Answer 42

Pericardioperitoneal canals.

Question 43

Is the central tendon of the diaphragm muscular?

Answer 43

No

Question 44

What closes the pericardioperitoneal canals?

Answer 44

Pleuroperitioneal membranes