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Breathlessness isn't caused by lack of oxygen.

The urge to breathe comes mainly from carbon dioxide: chemoreceptors in your brainstem sense how CO2 lowers the pH of your spinal fluid and trigger the breathing drive as levels rise. Oxygen only matters once it has dropped a long way. That is why holding your breath feels unpleasant well before oxygen actually runs short.

Useful: It explains why hyperventilating before a dive is dangerous: it mutes the warning signal, not the oxygen use.

Source: en.wikipedia.org

AtmungGehirn

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Question on this card

What mainly triggers the urge to breathe?

  1. Falling blood oxygen
  2. Rising carbon dioxide
  3. An empty stomach
  4. Fatigue in the diaphragm
Show the answer

Correct: Rising carbon dioxide

Brainstem chemoreceptors respond mainly to CO2 and the falling pH it causes.

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