Embryo

Question 1

How does the ectoderm contribute to the development of the respiratory system?

Answer 1

Neural crest cells form laryngeal cartilage and intramural ganglia

Question 2

How does the mesoderm contribute to the development of the respiratory system?

Answer 2

Lateral Plate: splanchnic mesoderm forms cartilage and smooth muscle of the airways

Paraxial: somitomeres form skeletal muscle of the larynx

Question 3

How does the endoderm contribute to the development of the respiratory system?

Answer 3

Provides epithelial lining and glands

Question 4

How do the larynx and trachea begin to form?

3 steps

Answer 4

• An outgrowth from the ventral wall of the foregut
• two esophagotracheal ridges then separate the airway from the foregut.
• the ridges then fuse together to form the esophagotracheal septum that separates the esophagus from the trachea

Question 5

Source of the cricothryoid muscle and the nerve that innervates it.

Answer 5

Arises from the 4th branchial arch

innervated by the superior laryngeal nerve

Question 6

Source of all the laryngeal muscles and nerve that innervates them EXCEPT for the cricothyroid muscle.

Answer 6

6th branchial arch

innervated by the recurrent laryngeal nerve

Question 7

Describe stage 1 of lung development.

Answer 7

Embryonic Stage: weeks 4-7

• lungs become situated in pleural cavity
• airway divides into primary, secondary, tertiary bronchi

Question 8

Describe stage 2 of lung development

Answer 8

Pseudoglandular Stage: weeks 8-16

• terminal bronchioles form but cannot permit gas exchange
• glands start to form

Question 9

Describe stage 3 of lung development

Answer 9

Canalicular Stage: weeks 16-25

• respiratory bronchioles and alveolar ducts form
• gas exchange becomes possible
• capillaries forming

Question 10

Describe stage 4 of lung development

Answer 10

Terminal Sac Stage: weeks 24-birth

• Type 1 alveolar cells form
• capillaries bulge into alveoli
• Type 2 cells form making surfactant (near the end)

Question 11

Describe Stage 5 of lung development

Answer 11

Alveolar Stage: birth-8 years old

-mature alveoli form and number increases

Question 12

Cause of Respiratory Distress Syndrome.

Answer 12

Inability to produce adequate surfactant. Premature infants are at risk due to birth during early part of stage 4 in lung development

Question 13

Esophageal atresia and Tracheoesophageal fistulas are commonly associated with other birth defects. Explain VACTERL and a common cause.

Answer 13

Vertebral Defects
Anal atresia
Cardiovascular anomalies
TracheoEsophageal fistulas
Renal defects, radial forearm anomalies
Limb defects

-commonly caused by taking oral contraceptives early in pregnancy