I know that the primary way that CO2 leaves a healthy human’s body from the blood is by diffusing into the lungs during gas exchange and then being exhaled. Is there any other way in which CO2 from the blood leaves the body? Since CO2 is a gas, it only leaves the body when gas is expelled. As far as I know, gases are only stored in the lungs, stomach, and intestines, and they can only expelled by breathing, burping, and farting. Is the CO2 released during burps and farts from the blood? Is there any other way that I didn't account for by which CO2 leaves the body?

This link states that an average person exhales about 500 liters of carbon dioxide every day. How do the numbers from burps and farts compare to that?

This might be useful in identifying hypercapnia or hypocapnia unrelated to respiratory function.

Edit: Bicarbonate is a form of carbon dioxide, and it is excreted in urine.

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    $\begingroup$ The help center says "You should only ask practical, answerable questions based on actual problems that you face". We usually interpret that fairly broadly, but there really should be some motivation for a question besides mere trivia. $\endgroup$
    – Bryan Krause
    Dec 25, 2022 at 19:38
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    $\begingroup$ Here's a situation where that might matter: A doctor wants to measure rates of CO2 production in the body to very high accuracy by measuring average CO2 expulsion over a day by putting sensors on the patient's body, but if he didn't account for all the places in the body where CO2 is expelled, he'd underestimate the CO2 production rate. $\endgroup$
    – user73773
    Dec 25, 2022 at 19:51
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    $\begingroup$ Great, that seems like a good motivation to me. Ideally you could edit that into the original question, as it will help frame answers. $\endgroup$
    – Bryan Krause
    Dec 25, 2022 at 23:57
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    $\begingroup$ humans do uptake tiny amounts of oxygen through skin so it should be worth looking to see if they do the same with co2. ncbi.nlm.nih.gov/pmc/articles/PMC2290093 $\endgroup$
    – John
    Dec 26, 2022 at 1:16
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    $\begingroup$ It would seem (to me) only to be important if a person had hypercarbia unrelated to pulmonary function. Air in the upper GI tract is usually swallowed air; air in the lower GI tract is both swallowed air and gasses produced by bacterial fermentation of contents, so don't really represent CO2 produced by the body anyway. $\endgroup$ Dec 26, 2022 at 16:01


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