Lung

Question 1

What are the two phases of the mucociliary escalator?

Answer 1

Hypophase - lower layer of serous watery secretion, cilia propels mucus hypophase in upward direction.
Epiphase - upper mucus (viscous) secretion - traps & immobilises dust particles & bactera.

Question 2

What is the role of;
Terminal and respiratory bronchioles
Alveolar ducts and sacs?

Answer 2

• Particle removal / airflow regulation / limited GE.

- GE / o.2-0.4 uM wall thickness –> efficient gas exchange.

Question 3

How do type I and type II penumocytes differ?

Answer 3

TI - squamous, share common BM with blood vessel (40% but 90% of SA)
TII - cuboidal, secrete surfactant and stem cells (60 but represent only 10%).