If you went to inhale and the pressure of air in the atmosphere was equal to the pressure in your lungs, what would happen to air flow into your lungs?

Question

Our ability to breathe is determined by the pressure of the air in the atmosphere, relative to the air in our lungs. If you went to inhale and the pressure of air in the atmosphere was equal to the pressure in your lungs, what would happen to air flow into your lungs? Explain why you would expect this outcome.

Answer 1

From an anatomical perspective, your diaphragm contracts downward when you inhale to expand the lungs. This larger volume creates larger airspace and the negative pressure sucks in air. If you are in an environment with negative pressure, you will not be able to breathe in and effectively intake any air, unless you found a way to make the negative pressure in your lungs even lower than the environment (breathing deeper). However, you would still be able to exhale. You would experience rapid shortness of breath and hypoxia, and as you would not be able to intake as much oxygen as necessary, still being able to exhale carbon dioxide, you would enter respiratory alkalosis.

Answer 2

You need a pressure difference to push a fluid from one area to another. Gases can diffuse from higher concentration to lower so oxygen would make its way into your lungs where the concentration is less, but it is a much slower process and would be insufficient for breathing. You breathe by lowering your diaphragm and expanding your chest so that the pressure lowers in your lungs (Boyle's Law if n is constant) - That allows the difference between atmospheric pressure and your lungs (about .2 atmospheres) to push air into you.(Equilibrium is reached because P is kept constant by the moles of air increasing in proportion to your volume increase(Avogadro's Principle).