Embryology

Question 1

6th arch gives off what endodermic structure?

Answer 1

primitive pharynx

Question 2

This structure develops from a groove in the primitive pharynx.

Answer 2

larynogotracheal diverticulum

Question 3

Diverticulum invaginates and merges to form what structure dividing what structures?

Answer 3

tracheoesophageal septum, trachea, esophagus

Question 4

The trachea is made up of what two germ layers? Give examples for each.

Answer 4

endoderm- epithelium in trachea and lungs, glands, and lungssplanchnic mesenchyme- cartilage, connective tissue, smooth muscles

Question 5

At 5 weeks the trachea gives of what two structures which will give rise to what?

Answer 5

lung buds, main bronchi

Question 6

At 6 weeks lung buds give off what? these will give rise to what in the adult?

Answer 6

bronchial buds, lobar bronchi

Question 7

At 7 weeks what happens to the bronchial buds?

Answer 7

branching into tertiary bronchi or segmental bronchi 10 on right, 9 on left

Question 8

At 24 weeks what structure is now defined in the lungs?

Answer 8

terminal bronchioles and primitive alveoli off of them

Question 9

What is the first phase of lung development called? What weeks does it occur?

Answer 9

Pseudoglandular, 5-16weeks

Question 10

What is the second phase of lung development called? What weeks does it occur?

Answer 10

Canalicular, 16-24 weeks

Question 11

What is the third phase of lung development called? What weeks does it occur?

Answer 11

Terminal sac, 24 weeks - birth

Question 12

What is the fourth phase of lung development called? What weeks does it occur?

Answer 12

Alceovlar, 32 weeks to 8 years

Question 13

What structures are present in the functional unit of the lung during the pseudoglandular stage? What is survival rate and why?

Answer 13

connective tissue starting to develop, some capillaries are present far from developing terminal sac of bronchioles; cant survive, not set up or gas exchange

Question 14

What structures are present in the functional unit of the lung during the Canalicular stage? What is survival rate and why?

Answer 14

developing superior to inferior; vasculature close to end of branches, have respiratory bronchioles off of the terminal bronchioles and terminal sacs too with primitive alveoli; can survive with medical intervention

Question 15

What structures are present in the functional unit of the lung during the Terminal sac stage? What is survival rate and why?

Answer 15

squamous epithelium in terminal sac, it is thinner and in contact with blood vessels ( gas exchange can occur), have lymphatics and secretory epithelial cells- secreting surfactant, will survive

Question 16

What is surfactant, its function and what cell secrets it?

Answer 16

a lipoprotein, coats lungs, gets rid of surface tension and prevent collapse; type II pneumocytes

Question 17

What can surfactant be used for clinically?

Answer 17

Given to preemies to help with lung development, can cause a pneumothorax

Question 18

What structures are present in the functional unit of the lung during the alveolar stage? What is survival rate and why?

Answer 18

alveolocapillary membrane, form more primitive alveoli, mature alveoli 95% develop postnatally up to 3 years of age

Question 19

What race and what gender develop lungs faster?

Answer 19

girls, and African American over caucasian