A Full Journey Through Your Lungs

Ooh, flashing lights, electric impulses traveling at mind-boggling speeds, everything around is aglow. No, it's not a thunderstorm or that burrito you ate. It's you. You just yawned, sending a powerful surge of energy through your body. Um, do it again, please, I'll show you what it looks like. Thanks. First, the air, with me in it – yes, I'm that tiny little thing you see right here – enters the mouth and nostrils. One nostril, in fact, because the other is naturally resting. Hey, are you eating something there? Just don't try to make another breath while swallowing that pizza. Only babies are capable of that and inhaling at the same time. And we reach the pharynx, where air and food come together. The tunnel we're in is about 5 inches long, and it's a kind of sorting stage. Now this flap is epiglottis, and here we say bye to the chewing stuff. Epiglottis makes sure that food goes where it belongs, to the esophagus. And we go to the larynx, which then leads us into the trachea and finally to the two bronchi, one going to each lung. Ah, I see, we're turning left. Get ready for a rough ride. Hey, is that a wall? We're gonna crash! No, not really. We travel down one of the numerous branches, and with a soft bump, we end up in an alveolus of the left lung. It's a tiny air sac, and there are millions of them in the lungs. The air fills the rest of the alveoli, and from here, our journey begins in earnest. Oxygen molecules squeeze through the walls of the alveoli and get into the bloodstream. Woohoo! We're pumped via the pulmonary vein and straight into the left part of the heart. The blood we're in now is rich with oxygen, and it's being pushed into the aorta, the largest artery in your body. At its widest, it might reach a full inch across. The stream here is also very powerful, so it's gonna be a crazy ride! Be prepared! Woohoo! That was something! Okay, now we're in the calmer waters of other arteries. I wonder where we're going? The aorta feeds other arteries, which traverse the whole body. Ah, I feel we're moving up, so it must be the brain! Yes! Oh, wow! You see that too? Those sparks and flashes I told you about earlier, here they are, appearing all along our way through this vital organ. As we feed it with oxygen, it's lighting up our path. These are neural connections, the signals being sent to various organs and body parts. The brain controls your whole body, and it needs lots of oxygen to stay healthy. As we move through the head, the molecules of this gas around us are growing sparse and are being replaced by CO2. The byproduct of breathing. Our movement slows down, and the corridors become narrower with each turn. We're leaving the arteries and entering the capillaries, the smallest blood vessels. They make sure that every little nook of your brain and head overall is supplied with much needed energy. Finally, we reach the end of the road, and there's no oxygen left in the stream around us, only CO2. Slowly but steadily, we turn around and prepare to travel back to the heart. But while we're stuck here, let's check out what's going on in other parts of the body. Yep, I've come prepared and dropped some trackers when we entered the bronchi. Let's see… Okay, one of them is now getting to the stomach lining. It seems the pizza you ate after letting us in made the blood system dilate the vessels around the stomach, so most of the blood rushed there. Ah, look, you're blushing, aren't you? I know, because when you blush, your stomach lining does too, and now it's become redder than usual. Anyway, let's take a look at another tracker. It's now entering the renal artery, the one that leads to the kidneys. Oh, that's gonna be some trip. And yes, see how everything's shaking? It's the stream being cleared of all that doesn't belong there. The kidneys are the cleaning station of the body. They take in the blood from outside, filter it, and let the clean blood go back to the heart, all while the waste gets rid of. Hmm, the shaking is becoming harder. It seems like my tracker has been marked as an intruder. Oh yeah, the stuff all around it is definitely not the clean blood. Oops, the signal's lost. Good thing I didn't go there myself. Alrighty then, we're still moving rather slowly, and the first tracker is moving from the stomach through the intestinal tract on its way to the liver. The liver is, in fact, one of the most astonishing organs. It performs about 500 different functions, most of which aren't even fully understood. It's also the only organ that can regrow itself completely, even when it's been reduced to a quarter of its size. No worries here, though, your liver seems to be in top shape. The tracker enters the organ and goes out. Hey, where's the picture? It seems the liver didn't like my little buddy either. Anyway, we're finally gaining some speed and entering the veins, which carry the CO2-rich blood back to the heart. The flow is going stronger by the second, and hold on to something! That was the last rollercoaster, and we're steadily going up. In a few moments, we're in the heart again, its right part this time. From the right atrium, we're pumped into the right ventricle, and here we wait for a literal heartbeat. The ventricle contracts, and we're pushed down the pulmonary artery. It leads to the lungs again. Gaining a lot of speed, we travel through the blood highway. Slowing down again, and here we are, one of the millions of alveoli again. Hey, there's oxygen here, look! It's squeezing through the wall, and we're being flushed out with the rest of the carbon dioxide. Up the bronchi, collecting the rest of the gas on the way to the windpipe, and… wait, why am I being tucked back again? What's going on? Don't tell me! That's really mean of you! If you wanna know, the speed of a sneeze reaches 100 mph, and that's the speed I'm flying at right now. Oof! I finally stopped. Well, at least I'm outside. Hey! Where are you? Where have you gone? Alright, wanna play hide-and-seek? I'll find you and make you pay for the sneeze, just you wait!