Respiratory System and Body Cavities

Question 1

what is the origin of the lung bud?

Answer 1

Lung bud derived from the endoderm of the gut tube. .

Question 2

what does an increase in retinoid acid (RA) cause?

Answer 2

causes an up regulation of TF that induce bud formation and continued growth.

Question 3

What is Diverticulum?

Answer 3

Expansion

Question 4

where do tracheoesophageal ridges form?

Answer 4

they form between foregut and bud

Question 5

The tracheoesophageal ridges fuse and do what?

Answer 5

The fuse to separate trachea and oesophagus

Question 6

what is molecular control?

Answer 6

A very powerful signalling molecule. It diffuses into mesoderm and changes gene expression. This then feeds back into part of endoderm and this is where respiratory diverticulum forms.

Question 7

what is the splanchnopleuric mesoderm?

Answer 7

surround lung bud as it grows (where cartilage, smooth m + capillaries form). Signals for branching come from here.

Question 8

what helps the restrict expansion of the stalk?

Answer 8

netrin 1, 4

Question 9

what is fgf10?

Answer 9

powerful growth factor

Question 10

Mutation of FGF receptor inhibits what?

Answer 10

branching

Question 11

what are possible defect during formation of lungs?

Answer 11

• Oesophageal atresia (blind ending)

- Tracheoesophageal fistula (communication)

Question 12

Name the 5 stages of the maturation of the lungs.

Answer 12

Embryonic, Pseudoglandular, Canalicular, Saccular, Alveolar

Question 13

when is the time period of the embryonic stage of the maturation of the lungs?

Answer 13

26 days- 6 weeks

Question 14

when is the time period of the Pseudoglandular stage of the maturation of the lungs?

Answer 14

6- 16 weeks

Question 15

when is the time period of the canalicular stage of the maturation of the lungs?

Answer 15

16- 28 weeks

Question 16

when is the time period of the Saccular stage of the maturation of the lungs?

Answer 16

28- 36 weeks

Question 17

when is the time period of the Alveolar stage of the maturation of the lungs?

Answer 17

36 weeks- early childhood

Question 18

what are the events of the embryonic period?

Answer 18

Respiratory diverticulum forms

Initial branching to give lungs, lobes and segments

Question 19

what are the events of the Pseudoglandular period?

Answer 19

14 more generations of branching: Terminal bronchioles

Question 20

what are the events of the Canalicular period?

Answer 20

Terminal Bronchioles -> more than or equal to 2 Respiratory bronchioles-> 3-6 alveolar ducts

Question 21

what are the events of the Saccular period?

Answer 21

Terminal sacs form; Capillaries establish close contact

Question 22

what are the events of the Alveolar period?

Answer 22

Alveoli mature

Question 23

As you move down respiratory tree epithelium move from what?

Answer 23

columnar to cuboidal

Question 24

Is cuboidal or columnar better for gaseous exchange?

Answer 24

columnar

Question 25

Cuboidal cells differentiate into 2 different cells what are they?

Answer 25

- cells flatten and become pneumocytes. | - remaining cells produce surfactant which acts to reduce surface tension and helps breathing.

Question 26

what is the septum Transversum?

Answer 26

piece of mesoderm that is main component of diaphragm. As it migrates it brings phrenic nerve with it and moves towards the heart.

Question 27

what is the septum transversum attached to?

Answer 27

Attached ventrally to body wall. Dorsally it is not completely attached because of pericardiopertioneal canals.

Question 28

what do the pleuroperitoneal folds do?

Answer 28

the grow out on either side towards septum T gradually closing off canals (contains phrenic nerve)

Question 29

what does the phrenic nerve supply?

Answer 29

diaphragm

Question 30

IVC enters where?

Answer 30

T8

Question 31

oesophagus enters where?

Answer 31

T10

Question 32

Aorta enters where?

Answer 32

T12

Question 33

congenital diaphragmatic hernia is due to what?

Answer 33

mostly due to failure of closure of pericardioperitoneal canals usually on the left side.

Question 34

how do abdominal organs move into the thoracic cavity when there is a problem?

Answer 34

though holes in diaphragm gives hypo plastic lung

Question 35

what is the pleural cavity?

Answer 35

the mesoderm which covers outside of lung develops into the visceral pleura. The somatic mesoderm covering the body wall becomes the parietal pleura.

Question 36

what happens during the separation of pleural and pericardial cavities?

Answer 36

The pleuropericardial folds roots migrate anteriorly. Apex of folds moves towards midline.