Question

15

Part a) Some racers in swimming sprints hyperventilate right before the buzzer initiates the race. (a) How would hyperventilation affect the concentration of O2, HCO3, dissolved CO2, pH and oxygen affinity of hemoglobin?

part b) What are the advantages and disadvantages of the sprinter hyperventilating?  

part c) As the swimmer sprints, the swimmers muscle tissue is actively respiring, how does this affect the concentration of O2, HCO3, dissolved CO2, pH and oxygen affinity of hemoglobin?  

part d) Some racers in swimming sprints do not breath during the sprint, they hold their breath. How would holding your breath affect the concentration of O2, HCO3, dissolved CO2, pH and oxygen affinity of hemoglobin?

part e) What happens when a swimmer hyperventilates before the start of the race and holds his or her breath during the swimming sprint. Does the swimmer gain an advantage or disadvantage by this approach?

Answer 1

In practical terms, all carbon dioxide is eliminated from the body as a gas in exhaled air. When the volumes of air breathed into and out of the lungs increases above what is normal, more carbon dioxide than normal is eliminated from the body. This lowers the pressure of carbon dioxide within the body, whereby carbonic acid changes back to into water and carbon dioxide, eventually resulting in a new equilibrium between bicarbonate ion and carbon dioxide.

CO₂ + H₂O ← H₂CO₃ ← H⁺ + HCO₃^-

But this spontaneous chemical reaction whereby carbonic acid returns to water and carbon dioxide, is not as rapid as the speed with which carbon dioxide is removed from the body by hyperventilation. So when body carbon dioxide pressure is suddenly lowered relative to the bicarbonate concentration, the pH increases above normal because the bicarbonate concentration does not decrease as rapidly. The condition where pH of the body is increased above normal is called “alkalosis”, and all the body fluids and cells become more alkaline than normal. This effect lies at the basis of the mental effects of hyperventilation.

First, there is no benefit to hyperventilation. Hyperventilation, which consists of taking short, quick breaths in rapid succession, seems like a way to get more air in your lungs. However, researchers have shown that (i) you take in a smaller volume of air than when you breath normally, and this leads to (ii) an increase in the concentration of carbon dioxide and decrease in the concentration of oxygen in both your lungs and blood. Certainly hyperventilation before any exercise is counterproductive, and after exercise athletes are encouraged to take as deep of breaths as possible since this will speed the exchange of carbon dioxide for oxygen.

Hyperventilation is accompanied by various symptoms including dizziness/light headedness, anxiety, feeling of suffocation, numbness or tingling in the toes or fingers, feeling of being detached from the body, heart palpitations, chest pains, dry mouth, clammy hands, difficulty swallowing, tremors, sweating, weakness and fatigue. People may also less commonly experience blurring of vision, headaches and sometimes become unconscious.

An attack of hyperventilation may last between 20 and 30 minutes during which time the patient normally seeks help from the nearest doctor or emergency department. Although scary, hyperventilation due to anxiety is seldom dangerous.