Respiratory: - Lecture 4. Embryology

Question 1

What is the beginning stage of lung development?

Answer 1

Start with a respiratory diverticulum at the embryological stage

Question 2

Where does the lining of the trachea and the bronchial tree originate from?

Answer 2

The Endoderm

Question 3

Where does the smooth muscle, cartilage, muscle and other lung tissue develop from?

Answer 3

Visceral Mesoderm

Question 4

Describe Lung Bud development?

Answer 4

• Begins with a Respiratory diverticulum - this is an outpouching of the foetus oesophagus
• The Tracheoesophageal ridges then move slowly towards eachother and fuse - the two tubes are still connected. (as seen in the final left picture)
• The numbers on the left picture show the numbers of the pharyngeal arches
• This creates the Oesopagus and the trachea.

Question 5

Describe development of the bronchial tree

Answer 5

• Created by branching effect of the respiratory diverticulum
• Branch to give bronchial buds.
• Further branching event to give smaller and smaller diameter tubes

Question 6

What layer within the foetus are the gut tube and the respiratory tree developing within?

Answer 6

Development within the mesoderm.

Question 7

What layer is the gut tube covered by?

Answer 7

By Mesoderm

Question 8

What does thhe lung lining grow into?

Answer 8

Grows into the mesoderm. Lung lining is formed by the endoderm

Question 9

Describe how the bifurcation of the lung is regulated ?

Answer 9

• Initial bifurcation point to form the main bronchus
• Bifurcation on the left hand side produces 3 buds
• Bifurcation on the right hand side produces 2 buds
• They will form the lobar bronchi of the lung

Question 10

By week five what parts of the lung have formed?

Answer 10

The Lung buds

Question 11

By week 8 what parts of the lung have formed?

Answer 11

Terminal bronchioles

Question 12

Bu week six what parts of the lungs have formed?

Answer 12

The Lobar bronchi

Question 13

What common respiratory congenital defects are there?

Answer 13

Oesophageal atresia - The end of the oesopahus is blocked or rapidly ends or connect is severed.

Tracheoesophageal fistula - The oesopagus and the trachea communicate.

Question 14

What time period is the embryonic period?

Answer 14

26 days - 6 weeks

Question 15

What time period is the Pseudoglandular period?

Answer 15

6 - 16 weeks

Question 16

What time period is the Canalicular period?

Answer 16

16-28 weeks

Question 17

What time period is the saccular period?

Answer 17

28 - 36 weeks

Question 18

What time period is the Alveolar period?

Answer 18

36 weeks to early childhood.

Question 19

What part of lung maturation occurs during the embryonic stage?

Answer 19

• Respiratory diverticulum forms
• Inital branching to give lungs, lobes and segments

Question 20

What part of lung maturation occurs during the Pseudoglandular stage?

Answer 20

• 14 more generations of branching: Terminal Bronchioles

Question 21

What part of lung maturation occurs during the Canalicular stage?

Answer 21

Terminal bronchioles -> Respiratory broncioles -> 3-6 alveolar ducts.

Question 22

What part of lung maturation occurs during the Saccular stage?

Answer 22

Terminal alveolar sacs form

Question 23

What part of lung maturation occurs during the embryonic stage?

Answer 23

Respiratory diverticulum forms to the initial branches

Question 24

What do Type 2 alveoli cells secrete?

Answer 24

Pulmonary surfactant

Question 25

What occurs in premature infants that have too little surfactant?

Answer 25

Respiratory distress syndrome.