You’ve probably heard me talk about the “small airways” in our lungs, but you might be surprised on just how small they actually are.
Here’s a color enhanced photo of the inner surface of our smallest airways taken with a scanning electron microscope. The hollow cavities you see are the alveoli ,this is where the air ends up when you take a breath. We have about 300 million alveoli in each lung. The little squiggly tube thingies are called alveolar capillaries, we have lot’s and lots of those too.
Here we have some red blood cells ( they look like red Cheerios or Lifesavers to me). These guys are great for soaking up oxygen as they pass through those little squiggly tubes that surround the alveoli..
Now, if everything is working as it should, the air that we breath into our alveoli (what we all ventilation), will come in real close contact those circulating red blood cells (what we call perfusion) and presto! ….gas exchange occurs. Oxygen diffuses into the red blood cell where it’s transported to the rest of the body, and carbon dioxide diffuses out from the red blood cells and into the alveoli, where it’s exhaled out of the body.
If you look really closely at the back & white photo, you can actually see a red blood cell as it makes it way through an alveolar capillary, doing it’s thing.
Ventilation and perfusion. Or simply put, the pairing of air with blood in just the right ratio…. That’s what’s it all about. Pretty cool eh?