EXCHANGE OF METABOLIZED GASES

A. Oxygen Uptake (V'-O2)

Consumption at rest (young adult male of average size): 250 ml/min; maximum exercise: 2-4 L/min (==> )

Note:  V' indicates rate of change of volume, usually written with a dot over the V, and pronounced V-dot

V'-O2 is proportional to aerobic work rate

B. Carbon Dioxide Production (V'-CO2)

Production at rest (as above): 200 ml/min; maximum exercise: 2-4 L/min ( ==> )

C. Aspects of Gas Exchange

1.  ventilation: movement of gas into and out of the lungs ( mechanism bulk flow, diffusion too slow)

Note: difference between inspired & expired O2 & CO2 depends on metabolic uptake and production

2.  alveolar gas exchange ( mechanism:  diffusion;  O2 alveoli => blood;  CO2 blood => alveoli )

3.  blood gas transport (dissolved, bound, other chemical form)

4.  alveolar-blood equilibration (diffusion limitation, shunt, ventilation-perfusion mismatch)

5.  cellular gas exchange (diffusion;  O2 blood => cells;  CO2 cells => blood )

6.  regulation of ventilation (Central Nervous System)