Do you think the person with the greatest vital capacity can hold their breath longer?

Question

 Do you think the person with the greatest vital capacity can hold their breath longer than those with a lower vital capacity? Consider the difference between internal respiration and external respiration and explain why lung capacity may not have a great effect on length of time you can hold your breath.

Answer 1

The length of time you can hold your breath relies more upon your individual cell's need for oxygen and the buildup of acid and CO2 in your blood. The longer individual cells go without new red blood cells delivering oxygen, the more they struggle to make more energy while continuing to release CO2 as a bi-product. Your body has chemoreceptors that detect the amount of CO2 and O2 in the blood. If levels of CO2 rise or the levels of O2 fall (as they would when you are holding your breath), these receptors begin to fire, STRONGLY signaling to your brain to try and force you to breath. Eventually you give in to this drive and you gasp. The amount of air in your lungs at the end of a full inspiration (vital capacity) will likely allow you to deliver slightly more amount of oxygen as you are holding your breath, but you will be unable to get rid of the CO2, which is the primary driver for inspiration.