Name: Discovery of Gases and Respiration
Uploaded: 2019-07-19
Duration: 6 min 24 s
Description: We all know we breathe in oxygen and breathe out carbon dioxide. But how was this discovered? Watch this experiment to learn more about it in detail.

Question

What is the percentage of oxygen and carbon dioxide in alveolar air and expired air? Is there any difference, why?

Accepted Answer

The amount of air that is present in the respiratory part of the lungs and takes part in a gaseous exchange with the blood of pulmonary capillaries is known as alveolar air. The percentage of oxygen in alveolar air is 13.2% and carbon dioxide is 5.3%.

During expiration, the air given out by the lungs is called expired air. It is formed by the combination of dead space air and alveoli. In comparison with alveolar air, it contains more oxygen and less carbon dioxide. The percentage of oxygen in expired air is 15.3% and carbon dioxide is 3.6%.

During respiration oxygen from alveolar air diffuses into the blood of pulmonary capillaries and at the same time water vapour and mainly carbon dioxide diffuses out from the blood into the alveoli. Thus, the percentage of oxygen is less and carbon dioxide is more in alveolar air compared to expired air.

What is the percentage of oxygen and carbon dioxide in alveolar air and expired air? Is there any difference, why?

Important Questions on Breathing and Respiration

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