T9-Respiratory development

Question 1

Where is the laryngeotracheal groove located?

Answer 1

On the floor of the primordial pharynx between the 4th and 6th pharyngeal arch

Question 2

What is the starting point of laryngeotracheal diverticulum?

Answer 2

the laryngeotracheal groove

Question 3

How does the laryngeotracheal diverticulum (LD) grow

Answer 3

it extends ventrally and drops caudally

Question 4

What does the LD enlarge into

Answer 4

a respiratory bud

Question 5

How do tracheoesophageal folds form

Answer 5

they form as the laryngotracheal diverticulum separates from the primordial pharynx

Question 6

How is the tracheoesophageal septum formed

Answer 6

it forms when the tracheoesophageal folds fuse

Question 7

When is the tracheoesophageal septum fully formed

Answer 7

by the end of the 5th week

Question 8

What does the respiratory bud go on to form?

Answer 8

Two primary bronchial buds

Question 9

The single point of connection between primordial pharynx and developing trachea is called what

Answer 9

laryngeal inlet

Question 10

What germ cell layer forms lumenal compoments of the respiratory system

Answer 10

endoderm

Question 11

What does splanchnic mesoderm of respiratory system form

Answer 11

cartilage, CT, visceral pleaura, blood vessels

Question 12

Further division of primary bronchi buds form what

Answer 12

secondary and tertiary bronchial buds which differentiate into associated bronchi

Question 13

What forms around bronchial buds

Answer 13

splanchnic mesoderm

Question 14

Horseshoe shaped cavity

Answer 14

intraembryonic coelom

Question 15

Cranial end of intraembryonic coelom

Answer 15

pericardial coelom

Question 16

Lateral sides of intraembryonic coelom

Answer 16

pericardioperitoneal canal

Question 17

Caudal end of the intraembryonic coelom

Answer 17

peritoneal cavity

Question 18

This is on either side of tracheoeophogeal tube

Answer 18

pericardioperitoneal canal

Question 19

What are pericardioperitoneal canals lined with

Answer 19

visceral pleura and parietal pleura

Question 20

Visceral pleura is from

Answer 20

splanchnic mesoderm

Question 21

Parietal pleura is from

Answer 21

somatic mesoderm

Question 22

What happens as the bronchial buds grow

Answer 22

They push into pericardioperitoneal canals eventually causing the visceral pleura to contact the parietal pleura on the other side

Question 23

Pseudoglandular stage When does it happen

Answer 23

between weeks 5 and 17

Question 24

Pseudoglandular stage Features and events

Answer 24

-period of major growth and development -terminal bronchioles look like a “gland” -gas exchange not possible; fetus born here is not viable

Question 25

Canalicular stage When does it happen

Answer 25

between weeks 16 and 25

Question 26

Canalicular stage Features and events

Answer 26

- terminal bronchioles form respiratory bronchioles - lung tissue becomes highly vascularized - some respiratory bronchioles have developed terminal sacs so respiration is possible

Question 27

Terminal sac stage When does it happen

Answer 27

from about 24 weeks to birth

Question 28

Terminal sac stage Features and events

Answer 28

- more terminal sacs bud off respiratory bronchioles - capillaries form adjacent to terminal sacs; blood air barrier is established - alveolar epithelium differentiate into pneumocytes and secretory alveolar cells (secrete surfactant)

Question 29

Alveolar stage When does it happen

Answer 29

later fetal period to about 8 years old

Question 30

Alveolar stage Features and events

Answer 30

- maturation of terminal sacs into alveoli - thin alveolar capillary which allows gas exchange - increased surfactant seceretion

Question 31

What is surfactant

Answer 31

a phospholipid and protien secretion from type II secretory alveolar cells

Question 32

What does surfactant do

Answer 32

helps keep alveolar sacs open, reduces alveolar surface tension, and increases lung compliance

Question 33

What does insufficient surfactant production cause

Answer 33

alveolar collapse, increased work of respiration and respiratory distress

Question 34

What stage does this image represent

Answer 34

Psudoglandular stage

Question 35

What stage does this image represent?

Answer 35

Canalicular stage

Question 36

What stage does this image represent?

Answer 36

Terminal sac stage

Question 37

What stage does this image represent?

Answer 37

Alveolar stage

Question 38

What does the diaphragm do?

Answer 38

Forms the physical partition between the thoracic and abdominal cavities

Question 39

Lable parts of the diaphragm

Answer 39

A. Central tendon B. Striated muscle fibres C. Crura D.Vena cava (T8) E.Oesophageal(T10) F.Aortic (T12)

Question 40

What 4 components does the diaprhagm develop from?

Answer 40

1. Septum transversum 2. Pleuroperitoneal membranes 3. Dorsal mesentery of esophagus 4. Muscular ingrowth from body wall

Question 41

Formation of diapraghm: Septum transversum

Answer 41

Primordium of the central tendon of the diaphragm In the 3rd week: Appears cranial to the pericardial cavity After head folds ventrally during the 4th week, ST is caudal to the pericardial cavity

Question 42

How does the ST grow

Answer 42

It grows dorsally from the ventrolateral body wall forming a semi-circular shelf that separates the heart and the liver fuses with the mesenchyme ventral to the esophagus + pleuroperitoneal membranes

Question 43

Formation of diaphragm: Pleuroperitoneal membrane

Answer 43

Fuses with the ST and DME ; sealing off the pericardioperitoneal canals in the 6th week (right canal first), from the primordial diaphragm

Question 44

Formation of diaphragm: Dorsal mesentary of esophagus

Answer 44

Contributes to median portion of the diaphragm Fuses with ST and pleuroperitoneal membranes Myoblasts that grow here develop into the crura

Question 45

Formation of the diaphragm: Muscular ingrowth from body wall

Answer 45

Contributes to the peripheral components of diaphragm