VQ Relationships

Question 1

At the apex of the lung, the intrapleural pressure is more negative-what does this say about the size of the alveoli at the apex?

Answer 1

At the apex of the lung, the intrapleural pressure is more negative, so the alveoli will be larger (expanded by pressure)
-opposite for the base

Question 2

Would ventilation be higher at the base or the apex?

Answer 2

Ventilation of the lung would higher at the apex

Question 3

The ventilation/perfusion (V/Q) ratio

-Average for the entire lung?

Answer 3

(4 L/min (V)) / (5 L/min (Q))=.8

Question 4

What does a high V/Q ratio mean?

Answer 4

Ventilation is high relative to perfusion

Question 5

Compare and contrast the arterial blood gases that are attained by regions with a high V/Q ratio versus a low V/Q ratio
-High V/Q ratio-PaO2, PaCO2, pHa, volume of blood?

Low would be the opposite

Answer 5

High V/Q ratio
PaO2-High
PaCO2-Low
pHa-High
Volume of blood-Low

Question 6

Compare and contrast the V/Q ratios of the apex, base, and middle regions of the lung in an upright individual

- Apex-High or low V/Q?
          - PaO2, PaCO2, pHa, volume of blood?

Answer 6

Apex-High V/Q (Base is the opposite and middle region represents the normal condition)

• PaO2-High
• PaCO2-Low
• pHa-High
• Volume of blood-Low

Question 7

Middle region

-Normal values-VA/Q, PaO2, PaCO2?

Answer 7

VA/Q=.8
PaO2=100
PaCO2=40

Question 8

Regional ventilation in the lungs

• Intrapleural pressure (like blood flow) is also acted on by gravity
  
  • Compare the intrapleural pressure at the apex of the lung to that of the base of the lung

Answer 8

-At the apex, there is less intrapleural fluid, so the intrapleural pressure is more negative (opposite for the base of the lung)