Question

In humans, the urge to breathe results from high concentrations of CO₂ in the blood; there are no direct physiological sensors of blood pO₂. Skin divers often hyperventilate (breath rapidly and deeply for several minutes) just before making a dive in the belief that this will increase the O₂ content of their blood. (a) Does it do so? (b) Use your knowledge of hemoglobin function to evaluate whether this practice is useful.

Short answer

(a) Hyperventilation does not increase the O₂ content in the blood.

(b) The practice of hyperventilation is useful to stay longer without breathing but associated with some risk of unconsciousness.

Step-by-step solution

Hyperventilation before diving

Hyperventilation, that is, breathing rapidly and deeply allows the divers to push out more CO₂ from the lung than they can do with normal breathing. This decreasing CO₂ concentration diminishes their urge to breathe and allows the divers to stay down for a longer period of time.

(a) Whether hyperventilation increases the O2 content of the divers’ blood

Hyperventilation does not increase the blood’s O₂ content. It only decreases the CO₂ content and increases the pH.

(b) Whether hyperventilation is useful

Hyperventilation might be useful for divers to stay longer without the urge to breathe. The blood CO₂ content becomes very low, with a normal O₂ content in the blood. The divers do not feel the urge to breathe until all the blood O₂ is consumed.

However, there are some risks associated with hyperventilation. When all the O₂ from the blood is consumed, the brain cannot function properly. Thus, the divers might lose their consciousness.