Development

Question 1

At what week in development have the alveoli developed enough to support life?

Answer 1

Week 26-28

Question 2

What will be the diagnosis of an infant who is born before his/her alveoli have developed enough to support life?

Answer 2

Respiratory Distress Syndrome

Question 3

Alveoli continue to develop until what age?

Answer 3

8 years

Question 4

What does the diaphragm develop from?

Answer 4

Septum Transversum –> (Forms central tendon)
Pleural Peritoneal Folds –> (Attaches to esophagus and septum transversum)
Mesoesophagus –> (Mesentery covering esophagus-splanchnic mesoderm)
Body Wall

Question 5

What embryological layer do the Type I Pneumocytes develop from?

Answer 5

Endoderm

Question 6

What embryological layer do the Pulmonary Capillaries develop from?

Answer 6

Mesoderm

Question 7

What embryological layer does the Cartilage of Bronchi develop from?

Answer 7

Mesoderm

Question 8

What embryological layer does the Epithelial Lining of Bronchi develop from?

Answer 8

Endoderm

Question 9

What embryological layer does the Pleura develop from?

• parietal layer?
• visceral layer?

Answer 9

Mesoderm

• Parietal from somatic mesoderm
• Visceral from splanchnic mesoderm

Question 10

When during development do the respiratory bronchi form?

Answer 10

Weeks 17-26

This is also the time of intense growth of pulmonary blood vessels

Question 11

What is the pseudoglandular phase?

Answer 11

Weeks 8-16
Development of pulmonary arteries
(All of the body’s glands develop from the GI tract)

Question 12

What are 3 important things for lung development?

Answer 12

Adequate space in thoracic cavity
Fetal breathing mvmts
Adequate volume of amniotic fluid

Question 13

What is the role of Type II Pneumocytes?

Answer 13

To secrete surfactant

• acts like a detergent
• decreases surface tension
• allows alveoli to open up

Question 14

What produces amniotic fluid and why is it important?

Answer 14

Fetal kidneys produce amniotic fluid.

• “breathed” in by fetus
• helps expand lungs
• helps strengthen resp muscles

Question 15

What is the condition characterized by insufficient amniotic fluid?

What are the complications/consequences?

Answer 15

Oligohydramnios

Causes lungs to be underdeveloped (hypoplastic).

Question 16

How does the fluid in the alveoli get cleared after birth?

Answer 16

It gets reabsorbed into the lymphatics.

Question 17

List and briefly describe some common congenital abnormalities.

Answer 17

Tracheoesophageal Fistula - trachea still attached to esophagus
Hypoplastic Lungs - failure of lungs to expand
Congenital Lung Cysts - dilation of bronchi; may lead to pneumothorax

Question 18

What is the main problem associated with diaphragm development?
Describe it.

Answer 18

Failure of all germ layers to fuse.

• causes diaphragmatic hernia
• contents of abdomen enter thorax
• hypoplastic lungs (don’t expand)

Question 19

If the pleuroperitoneal membranes fail to fuse with the septum transversum and the esophageal mesentery, what results?

Answer 19

Foramen of Bochdalek, most commonly seen on the left side.