Question

1. find the data point in the graph with highest blood oxygen level, and circle it.
2. find the data point in the graph with lowest blood oxygen level, and circle it.

step 2 - reading the lines

1. at rest, what is the o₂ concentration in arterial blood?
2. at rest, what is the o₂ concentration in venous blood?
3. describe the relationship between exercise and the concentration of o₂ in arterial blood.
4. describe the relationship between exercise and the concentration of o₂ in venous blood.

Explanation:

1. Arterial blood is oxygen - rich. At rest, the oxygen concentration in arterial blood is high.
2. Venous blood is oxygen - poor. At rest, the oxygen concentration in venous blood is low.
3. During exercise, the body uses more oxygen. Arterial blood still has relatively high oxygen but the difference between arterial and venous oxygen concentrations may decrease as tissues extract more oxygen.
4. During exercise, venous blood has even lower oxygen concentration as more oxygen is used by the working muscles.

Answer:

1. At rest, the oxygen concentration in arterial blood is high.
2. At rest, the oxygen concentration in venous blood is low.
3. During exercise, the concentration of O₂ in arterial blood decreases slightly while the difference between arterial and venous O₂ concentrations may reduce as tissues consume more oxygen.
4. During exercise, the concentration of O₂ in venous blood is lower compared to rest as muscles extract more oxygen.