Respiratory Physiology Lecture 4 Part 18: Regional Differences in Ventilation

Question 1

Regional differences in ventilation are due to what?

Answer 1

gravity and posture

Question 2

How can ventilation be measured?

Answer 2

Patient inhales and holds their breath
Amount of radioactivity measures how much are is taken in

Question 3

Where is ventilation lowest/ greatest when standing?

Answer 3

ventilation is always greater closer to ground

Question 4

Why is ventilation greater at the bottom of the lungs

Answer 4

The weight of the lungs increases pressure in regions near bottom (Makes P_IP less negative) therefore less pressure pulling it open than regions at top of lung.

Question 5

How is P_IP generated?

Answer 5

Generated by the balance of the elastic recoil of the lung and the elastic recoil of the chest wall

Question 6

Why do bottom region receive a larger portion of air?

Answer 6

Since alveoli at bottom are starting more deflated, they are able to expand more

• little changes in intrapleural pressure will generate large changes in lung volume