Biology 105
Biology of Exercise
Spring 2003

1) How much oxygen (in ml) is delivered to the tissues at rest per 100 ml of blood?

There is 20 ml O2 / 100 ml of arterial blood. It became fully saturated with oxygen at the alveoli. You can see from the graph above that at 100 mmHg, there is 20 ml O2 / 100 ml blood. There is 15 ml O2 / 100 ml of venous blood after it leaves the tissue. You can see from the graph above that at 40 mmHg, there is 15 ml O2 / 100 ml blood.

The amount of blood delivered to the tissue is the amount in arterial blood - the amount in venous blood. 20 - 15 = 5 ml O2 / 100 ml blood.

2) How would this amount be affected if alveolar pO2 is reduced to 80 mmHg?

Not very much, because the blood flowing away from the alveoli would still be almost completely saturated with oxygen at 80 mmHg according to the graph above.

3) How much oxygen (in ml) is delivered to the tissues at during exercise per 100 ml of blood?

During exercise, tissue oxygen may drop to about 20 mmHg, and thus the blood will have about 5 ml O2/ 100 ml blood according to the graph above.

20 - 5 = 15 ml O2 / 100 ml blood delivered to the tissues.