Ventilation / Perfusion

Question 1

At the apex of the lung, is there more or less intrapleural fluid? What effect does this have on intrapleural pressure? What effect does this have on the size of alveoli?

Answer 1

Less, due to gravity. The intrapleural pressure is more negative (-10 H20). The alveoli are larger.

Question 2

At the base of the lung, is there more or less intrapleural fluid? What effect does this have on intrapleural pressure? What effect does this have on the size of the alveoli?

Answer 2

More, due to gravity. The intrapleural pressure is less negative (-2 to -3). The alveoli are smaller.

Question 3

What is ventilation?

Answer 3

Air that reaches the alveoli

Question 4

What is perfusion?

Answer 4

Blood that reaches the alveoli via the capillaries