Hyperventilation

Chemistry Level 2

When a person is hyperventilating, they are breathing faster than normal. The result is that more carbon dioxide $(\ce{CO_2})$ is being released from the body. When a person first starts to hyperventilate, what would you expect to happen to the pH of the blood?

Nothing: the buffer system will compensate Nothing: carbon dioxide does not affect pH The pH would increase The pH would decrease

1 solution

Jordan Calmes
Feb 11, 2016

$\ce{CO2 +H2O <-> H2CO3 <-> HCO3^- + H+}$

If carbon dioxide is removed from the system, it will drive the chemical reaction to produce more carbon dioxide and water to maintain chemical equilibrium. The relative amounts of both carbonic acid and bicarbonate will change, in order to maintain blood pH in the optimal range of 7.35-7.45. Removing carbon dioxide will eventually lead to a raise in pH, if the system is overwhelmed and there is not enough carbonic acid or bicarbonate to compensate. So when a person starts to hyperventilate, their blood pH remains normal and bicarbonate concentrations decrease. If they hyperventilate for a longer period of time, they could develop a condition called respiratory alkalosis where the blood pH rises above 7.45 due to abnormal breathing.

The answer should be $\color{#D61F06}{\text{the blood pH would increase}}$ . See the reference below, extracts from Hyperventilation :

Hyperventilation occurs when the rate and quantity of alveolar ventilation of carbon dioxide exceeds the body's production of carbon dioxide.[1][2] Hyperventilation can be voluntary or involuntary.

When alveolar ventilation is excessive, more carbon dioxide will be removed from the blood stream than the body can produce. This causes the concentration of carbon dioxide in the blood stream to fall and produces a state known as hypocapnia. The body normally attempts to compensate for this metabolically. If excess ventilation cannot be compensated metabolically, $\color{#D61F06}{\text{it will lead to a rise in blood pH}}$ . This rise in blood pH is known as respiratory alkalosis. When hyperventilation leads to respiratory alkalosis, it may cause a number of physical symptoms: dizziness, tingling in the lips, hands or feet, headache, weakness, fainting and seizures. In extreme cases it can cause carpopedal spasms (flapping and contraction of the hands and feet).

Chew-Seong Cheong - 5 years, 4 months ago

Thanks for the comment. In the information you've quoted, it says "If excess ventilation cannot be compensated metabolically, it will lead to a rise in blood pH." That metabolic compensation is the buffer system. Hyperventilation can occur for a number of reasons, including anxiety or exercise. People rarely experience symptoms though, because their blood pH doesn't change provided there is enough bicarbonate to compensate. We've tried to make the question a little more clear by highlighting that it's asking about when a person first starts to hyperventilate.

Jordan Calmes - 5 years, 3 months ago

Thanks, the challenge master has explained it. I didn't notice the "first starts". Perhaps, it should be clearer. Only 19% was able to answer it.

Chew-Seong Cheong - 5 years, 3 months ago

Hyperventilation

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