Question

Alveolar ventilation is increased by breathing 

A. 21 per cent O₂ and 79 per cent N₂. 

B. 17 per cent O₂ and 83 per cent N₂. 

C. 2 per cent CO₂ and 98 per cent O₂. 

D. 10 per cent CO₂ and 90 per cent O₂. 

E. A gas mixture which raises arterial P_CO2 by 10 per cent.

Answer 1

A. False This is the normal composition of air. 

B. False The O₂ level must fall to around 15 per cent before breathing is stimulated. 

C. True The stimulating effect of high P_CO2 is little affected by high P_O2 levels. 

D. False This level of carbon dioxide depresses breathing. 

E. True This is enough to double the volume breathed per minute.