How does the lungs know which is O2 and CO2? We breathe a ton of different gasses daily but what happens to the other gases other than O2 and CO2 when inhaled?
In: 729
Well, we really _don’t_ breathe that many different gasses. Air is composed of 78% nitrogen, 21% oxygen and 1% trace gasses (everything else). When you take a breath, it is pretty much entirely nitrogen and oxygen.
Our bodies don’t “know” which gas is which. Instead, our red blood cells have chemical receptors which carry both oxygen and carbon dioxide. One of the laws of chemistry is that high-concentration solutions will diffuse into lower-concentration solutions until equilibrium is reached. When our high CO2 concentration blood is exposed to the low CO2 concentration air, the oxygen and CO2 will naturally exchange, trying to reach equilibrium. This is how our lungs exchange gasses.
The other gasses are dissolved in our blood using the same mechanism, but since concentrations (aside from nitrogen) are so low, they have very little impact. Nitrogen is dissolved in our blood in higher quantities, but since it is a very inert gas it doesn’t really affect anything either.
Note that these rules only apply at normal air pressures – I’m a SCUBA diver and one of the things we are _very_ concerned about is the build-up of dissolved nitrogen from spending time at depth.
Latest Answers