Eli5: When we hold our breath, if we fill our mouths too does that give us access to a pocket of air to use to hold out longer or is it completely useless?

Question

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In: Biology

Answer 1

It is a slight increase in the total amount of air in ‘the system’ that your lungs can potentially pull oxygen out of and release CO2 into, but it’s a relatively small amount compared to the capacity of the average person’s lungs, so it’s unlikely to make too much of a difference.