Development of cardiovascular and pulmonary systems

Question 1

Pseudoglandular period (6-16 weeks)

Answer 1

Exocrine gland
No gas exchange

Question 2

Canalicular period ( 16-26 weeks)

Answer 2

Lumina of bronchi and bronchioles form
Formation of alveolar ducts and terminal saccules
Well vascularized
Some gas exchange possible

Question 3

Terminal Saccular period (26 weeks to birth)

Answer 3

More terminal saccules develop
Surfactant secreted

Question 4

Alveolar period (32 weeks to 8yrs)

Answer 4

95% of alveoli develop post natally
Tremendous increase in alveoli and capillaries

Question 5

Surfactant

Answer 5

Decrease surface tension between membranes of alveoli