Anatomy- Respiratory Embryology

Front 1

What comprises the lower respiratory system?

Back 1

from the pharynx down

Front 2

When does the lower respiratory system develop?

Back 2

Week 4

Front 3

What does the lower respiratory system begin as?

Back 3

median laryngotracheal groove of the primitive pharynx

Front 4

The endoderm lining the median laryngotracheal groove gives rise to what?

Back 4

the epithelium and glands of:
1. the larynx
2. trachea
3. bronchi
4. and the pulmonary epithelium

Front 5

What arises from the splanchnic mesenchyme and where is it?

Back 5

1.connective tissue
2. cartilage
3. smooth muscle of structures in the area
1. found surrounding the foregut

Front 6

The laryngotracheal groove deepens into a diverticulum ventrally which enlarges distally to form what?

Back 6

a lung bud (2 total)

Front 7

What separates the forming diverticulum from the primitive pharynx?

Back 7

longitudinal tracheoesophageal folds

Front 8

What do the longitudinal tracheoesophageal folds fuse to form and what does this structure do?

Back 8

1.tracheoesophageal septum
2. divides the forgut into:
-ventral laryngotracheal tube
-dorsal esophagus

Front 9

What is a fistula between the esophagus and the trachae and what disorder is associated with this?

Back 9

1. abnormal connection/communication between the esophagus and trachea
2. superior esophageal atresia

Front 10

What is polyhydramnios?What is it associated with? Why?

Back 10

1.excess of amniotic fluid
2. esophageal atresia and tracheoesophageal fistula
3. these problems do not allow amniotic fluid to pass to the stomach and intestines for absorption and transfer to the placenta for disposal

Front 11

The lung bud develops into 2 what?

Back 11

2 endodermal buds

Front 12

What space do the endodermal buds grow in? What does this space become?

Back 12

1. pericardioperitoneal cavities
2. pleural cavities

Front 13

What happens early in week 5 in regards to respiratory development?

Back 13

each bronchial bud enlarges into the primordium of a primary bronchus

Front 14

What do the bronchial buds enlarge into?

Back 14

primordium of a primary bronchus

Front 15

Which primary bronchus is larger and orientated more vertically?

Back 15

right

Front 16

What happens by week 7 in regards to respiratory development?

Back 16

The primary bronchi divide into secondary bronchi and then into tertiary bronchi

Front 17

What happens by week 24 in regards to respiratory development?

Back 17

the tertiary bronchi divide another 14 more times and the respiratory bronchioles have developed. They will divide another 7 times before birth.

Front 18

As the bronchi develop, what does the surrounding mesenchyme do?

Back 18

It synthesizes the surrounding cartilages, smooth muscle, connective tissue, and capillaries.

Front 19

The lungs acquire a layer of visceral pleura from what?

Back 19

splanchnic mesenchyme

Front 20

The thoracic body wall becomes lined by a layer of parietal pleura derived from?

Back 20

somatic mesoderm

Front 21

What are the three periods of development of the lungs and what are their weeks?

Back 21

1. pseudoglandular period (5-17 weeks)
2. canalicular period (16-25 weeks)
3. terminal sac period (24 weeks to birth)
4. alveolar period (later fetal period to 8 years)

Front 22

What weeks is the pseudoglandular period?

Back 22

5-17 weeks

Front 23

What happens during the pseudoglandular period?

Back 23

1. by week 17 all major elements of the lungs have developed, except for those involved in gas exchange.
2. the lungs look like an endocrine organ

Front 24

What period of development of the lungs is respiration not possible?

Back 24

pseudoglandular period

Front 25

What weeks is canalicular period?

Back 25

16-25 weeks

Front 26

What happens during the canalicular period?

Back 26

1. lumen of bronchi and terminal bronchioles become larger and lungs become vascularized
2. by week 24, respiratory bronchioles have developed and respiration is possible(chances of survival are slim)

Front 27

What happens in respiratory development by week 24?

Back 27

respiratory bronchioles have developed and respiration becomes possible.

Front 28

What weeks is the terminal sac period?

Back 28

24 weeks to birth

Front 29

What happens during the terminal sac period?

Back 29

1. more terminal sacs develop and capillaries enter into close relationship with them.

Front 30

What types of cells are the terminal sacs lined with and what does each cell do?

Back 30

1. Type 1 alveolar cells (pneumocytes)
2. Type 2 pneumocytes- secrete surfactant

Front 31

What is the purpose of surfactant?

Back 31

1. counteracts the surface tension forces
2. facilitates expansion of terminal sacs

Front 32

When does surfactant reach adequate levels?

Back 32

2 weeks before birth

Front 33

What 2 things are critical to the survival of premature infants in relation to breathing?

Back 33

1. adequate pulmonary vasculature
2. sufficient surfactant

Front 34

What weeks is the alveolar period?

Back 34

late fetal period to 8 years

Front 35

What percentage of mature alveoli develop after birth?

Back 35

95%

Front 36

How do lungs of an adult look in comparison to those of a newborn on xray?

Back 36

adult lungs look denser

Front 37

What is the state of developing lungs at birth in relation to amniotic fluid?

Back 37

lungs are half-filled with amniotic fluid at birth

Front 38

How do the lungs at birth clear the amniotic fluid in them?

Back 38

1. through mouth and nose by pressure on the thorax during delivery
2. into the pulmonary capillaries
3. into the lymphatics and pulmonary arteries and veins