E - Development Of The Respiratory System

Question 1

How is the respiratory system split functionally?

Answer 1

Conducting portion and the respiratory portion

Question 2

Respiratory function of the conducting portion

Answer 2

Warm, moisten and conveys air

Question 3

Respiratory function of the respiratory portion

Answer 3

Gas exchange

Question 4

How is the respiratory tract divided structurally

Answer 4

Upper and lower respiratory systems

Question 5

What does the upper respiratory system consist of?

Answer 5

Nasal and oral cavities, pharynx and associated structures

Question 6

What does the lower respiratory system consist of?

Answer 6

Trachea, bronchi, bronchioles, alveoli

Question 7

What is the respiratory system derived from?

Answer 7

The primitive gut tube

Question 8

What is the primitive gut tube?

Answer 8

The precursor to the GI tract which is endodermal derived and forms due to lateral folding of the embryo during early gestation

Question 9

When and how does respiratory development start?

Answer 9

Week 4 - an outpocketing of of the proximal gut tube (the foregut) called the respiratory diverticulum

Question 10

What begins to separate the foregut from the respiratory diverticulum to induce proper function?

Answer 10

The formation of a longitudinal ridge called the tracheoesophageal septum

Question 11

What does the respiratory diverticulum do after the formation of the tracheoesophageal septum?

Answer 11

Bifurcates (forks) into the left and right primary bronchi, and proliferate to produce secondary and tertiary bronchi

Question 12

What is tracheoesophageal Fistula?

Answer 12

Where the trachea remains continuous with the oesophagus due to abnormal formation of the tracheoesophageal septum

Question 13

What are the signs of tracheoesophageal fistula within children

Answer 13

During feeding become cyanosed (blue/purplish skin colour due to a lack of oxygen to blood) or vomit/regurgitate food

Question 14

How is tracheoesophageal fistula treated?

Answer 14

Surgical resection of the fistula

Question 15

Weeks 8-16 of respiratory development

Answer 15

Pseudoglandular phase

Question 16

What occurs during the pseudoglandular stage?

Answer 16

The ducts within the bronchopulmonary segments (the latter of which become their own portions of the lung) start to develop. Bronchiolar buds branch off from tertiary bronchi and begin to develop

Question 17

Metabolism of lungs during pseudoglandular stage

Answer 17

Metabolically active but cannot carry out gas exchange. Therefore can derive the body of oxygen. Ductus arteriosus prevents this by shunting blood from pulmonary artery to the aortic arch

Question 18

What do the lungs resemble in the pseudoglandular stage?

Answer 18

The development of the tubuloacinar glands

Question 19

Weeks 16-26 of respiratory development

Answer 19

Cananalicular stage

Question 20

What occurs during canalicular stage?

Answer 20

Respiratory bronchioles develop and bud off from the tertiary bronchioles formed in the pseudoglandular stage

Question 21

Metabolism of canalicular stage

Answer 21

Lungs are metabolically active, but still don’t undergo gas exchange. Babies born in the canalicular stage have poor prognosis

Question 22

Week 26 - birth of respiratory development

Answer 22

Terminal Sac stage

Question 23

What happens in the terminal sac stage?

Answer 23

Alveoli development

Question 24

What two cells do alveoli consist of?

Answer 24

Type I and Type Ii pneumocytes

Question 25

Type I pneumocytes

Answer 25

Simple squamous epithelial cells - make up 90% of alveolus

Question 26

Type II pneumocytes

Answer 26

Simple cuboidal cells - make up the remaining 10% and produce surfactant

Question 27

Surfactant in the lungs is…

Answer 27

Amphipathic - can bind to both hydrophilic and hydrophobic molecules - in this case water and air

Question 28

Surfactant function in lungs

Answer 28

Reduces surface tension in the alveoli, allows the alveoli in the lungs to expand at greater volumes for any given pressure

Question 29

Respiratory distress syndrome

Answer 29

Baby is born before producing Type II pneumocytes - doesn’t produce surfactant - difficult to expand lungs and take first breath

Question 30

How is Respiratory distress syndrome treated?

Answer 30

Mother is given glucocorticoids to stimulate surfactant production in foetus