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?
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The lungs don’t really know, but your blood knows. At an atomic level, it wants to grab onto oxygen more than anything else, so as it passes through the lungs, it grabs as much oxygen as it can and loses the co2 and other waste products it picked up throughout the body.
I think you could compare it to a conveyor belt running buy a load of scrap metal with magnets. anything with iron in it is going to catch while the rest will be left there.
So your lungs bring in everything, O2 CO2, smoke, dust, germs, etc. Then they provide a massive amount of surface area for your blood to interface with what they bring in. This is one reason it’s important to be careful about what you’re breathing in. If they get stuck in the lungs, you can end up with scar tissue or otherwise damaged tissue which reduces the surface area your blood can take oxygen from, which makes it harder to get O2 from the atmosphere into your bloodstream.
Chemoreceptors, they tell your body when there’s too much CO2 in your body. They are why you feel like you’re dying when you hold your breath but you die in your sleep when your furnace emits CO into your house.
CO2 and O2 attach to a thing in your blood called hemoglobin. In your lungs the pH is different and the hemoglobin changes shape causing more O2 to attach. When that oxygenated hemoglobin reaches tissues the pH is different causing the hemoglobin to change to a shape that picks up CO2 better.
With respect to “what happens to the other gases” part of your question, those are absorbed by your blood also. That can be helpful (it’s a common way of administering anesthetics ) or bad (Carbon Monoxide poisoning) or neutral (there’s a lot of nitrogen in your blood which, as long as you don’t have significant changes in pressure, just stays there doing not-that-much.)
Some good explanation here already, but the real oversimplified ELI5 version is that it’s the same as throwing some nails and some wood chips in a fire and asking how the fire knows which one to burn. It doesn’t, but the flammable stuff you put in the fire burns and the other stuff doesn’t.
How does Velcro know the difference between the other side of the velcro and a rock?
It doesn’t “know” anything, but when you rub the velcro against the rock, nothing really happens. When you rub it against other-velcro, it sticks.
That’s fundamentally what’s happening in your lungs. You breath in a mix of gasses, and the “Velcro” in your lungs grabs the oxygen, while letting the carbon dioxide (and nitrogen and whatever else) just exit when you breath out.
This is why breathing in helium (making funny balloon voices) can potentially be dangerous. Your lungs are breathing in and out, like normal, so your body thinks everything is alright. But no oxygen is being delivered, so the “Velcro” in your lungs has nothing to grab onto. If you take too many helium breaths without a normal oxygen breath in there, you can pass out.
The human body does not monitor CO2 directly. It measures pH, which CO2 affects. It doesn’t monitor oxygen levels at all, which is why nitrogen gas is so dangerous: as long as you are breathing out CO2, you’ll feel fine – even if you aren’t getting any oxygen. There are many stories of people walking into a room filled with nitrogen and working happily for 4 minutes until they pass out and die.
Burrowing animals like rabbits and rats do actually monitor oxygen directly.
Imagine the Oxygen is square and the CO2 is Rectangular. Your lungs only have Square and rectangle holes other gases are the wrong shape, generally.
There are some gases that are the same shape.. those are toxic/poisonous to us.
There’s a lot of CO2 inside, there’s a lot of O2 outside, both go from were there is much to were there is little.
The lungs and their blood it’s the place where they can meet and go from the inside, to the outside, or backwards, they just move from where there is a lot to where there is little.
You also have a shit ton of nitrogen dissolved in your blood. Doesn’t much matter until you go scuba diving, though.
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