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  • Let's say that this is you.

  • You're enjoying a nice sunny day,

  • and you decided to take a nice long, deep breath of air.

  • And of course, when I say air, the part

  • that you probably care the most about

  • is just the oxygen part of that air.

  • That's the part that we, as humans, need to survive.

  • So you take a deep breath, and let's say

  • that you take it through your mouth.

  • You take a deep breath through your mouth.

  • And then let's say you take one more deep breath,

  • a second deep breath.

  • And you take that one through your nose.

  • Now you might think, well, these are two totally different ways

  • of getting in air.

  • That's certainly how it looks when

  • you look at a mouth and a nose.

  • It doesn't look like they have much in common.

  • But the truth is that actually.

  • If you follow the air, it almost follows an identical path.

  • So the air is going to go into the back of the throat,

  • really regardless of how you took it in.

  • So here we have air coming in from the nose.

  • And here you have air coming in from the mouth.

  • And they meet up in the back of the throat.

  • And then they go down, down, down.

  • They go towards this thing that we call the Adam's apple.

  • I'm going to bring up a little bit of the canvas

  • so you can see it more easily.

  • But basically, you see this Adam's apple right here.

  • And actually you can go ahead and take

  • a feel of your own Adam's apple.

  • It's a pretty cool structure in the middle of your throat,

  • and everybody has it.

  • That's the first thing I want to tell

  • you is that everybody has it, not just men.

  • Women have it too.

  • And the reason it's called an Adam's apple,

  • it's called an Adam's apple because Adam is generally

  • a boy's name.

  • And so it's to remind us that usually men or boys have

  • larger Adam's apples than girls.

  • And if you're trying to find it, I just also want to point out

  • there's this notch here.

  • And if you can feel the notch with your fingers,

  • that gives you a nice clue as to where it's located.

  • But this is it.

  • This is the Adam's apple.

  • And what it does is it helps you control your voice.

  • And actually, another name for the Adam's apple, sometimes

  • people call it the voice box.

  • The voice box.

  • And of course, air is passing through the voice box,

  • and it's kind of the entryway into the trachea.

  • And so it actually allows me to (FALSETTO)

  • make my voice really high, (DEEP BARITONE)

  • or make my voice very low, depending

  • on how you change the muscles around in that Adam's apple.

  • So that's actually the kind of first cool thing

  • I want to point out to you is that you can actually

  • control your voice.

  • I'm sure you knew this already, but what you're using

  • is your Adam's apple, or your voice box.

  • Now air keeps going.

  • Air is just going to keep making its journey down--

  • and specifically, of course, the part of air

  • I said we care about is the oxygen.

  • It's going to keep making its journey down

  • into the lung area.

  • So this is now the lung area.

  • It's going down the trachea, and it goes into the two lungs--

  • the right and left lung.

  • This is the left lung.

  • I'm going to put L for left.

  • And this is the right lung.

  • I'll put R for right.

  • And immediately you're thinking, well, wait a second,

  • aren't they switched?

  • I want you to remember that this is

  • from the perspective of the person who owns the lungs,

  • so that's why I'm putting left where I put it

  • and right where I put it.

  • Now we should probably go ahead and start

  • labeling some of this.

  • You can see that the lungs actually don't look identical.

  • They look slightly different.

  • For example, this one has three lobes.

  • The right side has three lobes.

  • We call it the upper lobe, middle lobe and lower lobe.

  • And the left one only has two lobes.

  • So that's the first kind of big difference.

  • And the other difference is that you actually

  • have this thing in the middle that we call a cardiac notch.

  • This thing right here, this is called the cardiac notch.

  • And the reason we call it that is

  • that it's a little spot that gets

  • formed because the heart is literally

  • kind of peeking out here.

  • And as a result, it kind of makes a notch

  • in the lungs when it develops.

  • So the heart takes up a little bit of space here.

  • This is our heart.

  • And as a result, it makes that notch.

  • So this is our heart space here.

  • So on the other side, you've got,

  • of course, your two lobes-- your upper and lower lobe.

  • And these are two clues, so if you ever see a lung just kind

  • of sitting by itself and you want to figure out

  • whether it's the left lung or the right lung,

  • you can look for the number of lobes,

  • or you can look for that cardiac notch.

  • Now around these lungs, you've got ribs.

  • So you've got ribs here, and between the ribs,

  • you've got rib muscles.

  • And they are, of course, on both sides.

  • And below the lungs and below the heart,

  • you've got a big muscle.

  • Actually it's going to come through here.

  • I'm going to just kind of go through the word heart.

  • And it basically becomes the floor.

  • So the heart and the two lungs, they

  • sit on this floor made up of this muscle.

  • And this muscle is the diaphragm muscle.

  • So this diaphragm muscle makes up the floor.

  • The ribs make up the walls.

  • So what do we have?

  • We have basically a room.

  • We have a giant room with walls and a floor.

  • And this entire room we actually call the thorax.

  • So within this room then, you have your two lungs

  • and your heart.

  • So far, so good.

  • But I haven't done a very nice job of actually showing you

  • where the air goes.

  • I've just kind of pointed that it goes through the two lungs,

  • but you don't actually get to see where it goes after that.

  • So I'm going to erase a lot of this.

  • I'm going to reveal to you what it

  • would look like if you could slip on some X-ray glasses

  • and look at your two lungs.

  • This is kind of what it would look like.

  • You've got all this interesting architecture.

  • And the easiest way to think about this, probably

  • the simplest way to think about this, is to imagine a tree.

  • So imagine a tree, and that tree has been flipped upside down.

  • So you've got all these branches off that tree.

  • And they're branching and branching.

  • And if you flip this tree upside down,

  • you start seeing that it looks a lot like what

  • we have in our lungs.

  • Our lungs basically look like a flipped upside down tree.

  • And we even call it that.

  • We even call this entire structure,

  • we call it a bronchial tree.

  • So when you look at the lungs and they

  • look kind of messy or complicated,

  • just think of them as an upside down bronchial tree, and all

  • of a sudden it'll look much simpler.

  • Basically in the middle, you've got this nice trunk.

  • Right?

  • This is our trunk.

  • And then it starts kind of branching from there.

  • So air goes down this main trunk, this trachea, and then

  • it kind of starts splitting up.

  • And each of these colored regions-- the green region

  • or the purple region-- serves a different lobe.

  • So this green region serves the lower lobe down here.

  • The purple serves the upper lobe.

  • And on this side, you've got an upper, a middle, and a lower

  • lobe.

  • Now I know it looks a little bit strange, because you've

  • got some green branches in what should be the middle lobe,

  • like right here.

  • You've got some orange branches in what