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Meet the lungs

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    Let's say that this is you. You're enjoying a nice sunny day
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    and you decided to take a nice long deep breath of air.
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    And of course when I say air the part that you
    probably care the most about is just the oxygen,
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    part of that air, that's the part that
    we as humans need to survive.
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    So you take a deep breath.
    Let's say you take it through your mouth,
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    you take a deep breath through your mouth.
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    And then lets say you take one more deep breath,
    a second deep breath,
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    and then you take that one through your nose.
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    And you might think, "Well, these are two totally
    different ways of getting in air."
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    That's certainly how it looks when
    you look at the mouth and nose.
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    They don't look like they have much in common.
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    But the truth is that actually if you follow the air,
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    it almost follows an identical path.
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    The air is gonna go into the back of the throat
    really regardless of how you took it in.
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    So here we have air coming in from the nose,
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    in here yet air coming in from the mouth
    and they meet up in the back of throat.
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    And then they go down down down,
    they go towards this thing that we call the Adam's apple.
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    I'm gonna bring it up a little bit, you can see it more easily.
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    But basically you bring up this, you see
    this Adam's apple right there.
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    And actually you can go ahead and
    take a feel of you own Adam's apple.
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    It's a pretty cool structure in the middle of your throat
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    and everybody has it, that's the first thing I want to tell you,
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    that everybody has it, not just men, women have it too.
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    And the reason it's called an Adam's apple
    is because "Adam" is generally a boy's name.
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    And so it's to remind us that usually men or boys
    have larger Adam's apples than girls.
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    And if you're trying to find it,
    I also want to point that it's a notch here.
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    And you if you can feel the notch with your fingers,
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    in that case you have a nice clue as to where it is located.
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    This is Adam's apple and what it does is,
    it helps you control your voice.
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    And actually there's another name for Adam's apple.
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    Another name for it, sometimes
    people call it the voice box. The voice box.
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    And of course air is passing through the voice box
    in this kind of the entry way into the trachea.
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    And so it actually allows me to make my voice
    very high or make my voice very low,
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    depending on how you change
    the muscles around in that Adam's apple.
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    So that's actually kind of a first cool thing I want to point out to you, that you can actually control your voice.
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    I'm sure you knew this already but what you're using
    is the Adam's apple, your voice box.
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    Now air keeps going, air is just gonna
    keeps making its journey down and
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    specifically of course the part of air I said,
    you know, we care about is the oxygen.
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    It's gonna keep making its journey
    down into the lung areas,
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    now the lung areas, it's gone down the trachea and it goes into the two lungs, the right and left lungs.
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    This is the left lung, I'm gonna put L for left
    and this is the right lung, I'll put R for right.
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    And immediately you'll think,
    "Wait a second, aren't they switched?"
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    Now I want you to remember that this is from the perspective of the person who owns the lungs.
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    So that's why I put it in left where I put it,
    in right where I put it.
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    Now we should probably go ahead and
    start labelling some of these.
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    You can see that the lungs actually
    don't look identical, right?
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    They look slightly different, for example,
    this one has three lobes.
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    The right side has three lobes called
    the upper lobe, middle lobe and lower lobe.
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    And the left one only has two lobes,
    that's the first kind of a big difference.
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    And the other difference is that you actually have
    this thing in the middle that we call a cardiac notch.
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    This thing right here, this is called the cardiac notch.
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    And the reason we call it that is that
    it's a little spot that gets formed
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    because the heart is literally kind of peeking out here.
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    And as a result it's kind of makes a notch
    in the lung where it develops.
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    So the heart takes a little space here, this is the heart.
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    And as a result, it takes or makes that notch.
    So this is our heart space there.
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    So on the other side you've got of course
    your two lobes, your upper and lower lobes.
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    And these are exclusive, you see a lung
    that's kind of sitting by itself.
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    And you want to figure out whether
    it's the left lung or the right lung,
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    you can look for the lobes, the number of lobes,
    or you can look for that cardiac notch.
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    Now around here, around these lungs, you've got ribs.
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    You've got ribs here and between the ribs
    you've got rib muscles and of course on both sides.
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    And below the lungs and below the heart,
    you've got a muscle, a big muscle.
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    Actually it's gonna come through here,
    I'm just gonna kind of go through the word heart,
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    and it basically becomes the floor.
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    So the heart and the two lungs sit on this floor
    that made up of this muscle
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    and this muscle is the diaphragm muscle.
    So this diaphragm muscle makes up the floor;
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    the ribs make up the walls. So what do we have?
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    We have basically a room, we have a giant room
    with walls and the floor.
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    And this entire room we actually call the thorax.
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    So within this room then you have
    your two lungs and your heart.
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    So, so far so good, but I haven't done a very nice job
    of actually showing you where the air goes.
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    I just kind of pointed that it goes to the two lungs,
    we don't have to get to see where it goes after that.
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    So let me actually, I'm gonna erase a lot of these.
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    I’m gonna reveal to you what it would look like.
    If you could slip on some X-ray glasses
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    and look into your two lungs,
    this is kind of what it would look like.
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    You've got all these interesting architecture and
    the easiest way to kind of think about this,
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    probably the simplest way to think about this,
    is to imagine a tree,
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    to imagine a tree, and that tree
    has been flipped upside down,
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    so you've got all these branches of that tree
    and they are branching and branching.
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    And if you flip this tree upside down, you start seeing that it looks a lot like what we have in our lungs.
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    Our lungs basically look like a flipped up or
    a flipped upside down tree and we even call that,
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    we even call this entire structure,
    we call it a bronchial tree.
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    So when you look at the lungs and
    they look kind of messier and complicated.
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    Just think of them as an upside down bronchial tree
    and all of a sudden
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    it'll look much simpler with basically
    in the middle you've got this nice trunk,
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    this is our trunk, and then it's kind of
    branching from there.
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    So air goes down this main trunk, this trachea,
    and they kind of start splitting up.
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    And each of this kind of colored regions, the green region and the purple region serve a different lobe.
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    So this green region serves the lower lobe down here,
    the purple serves the upper lobe.
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    And on this side, you've got an upper,
    a middle and a lower lobe.
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    Now I know it looks a little bit strange because
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    you’ve got some green branches in what should be
    the middle lobe like right here;
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    you've got some orange branches in what
    looks like the upper lobe like right there.
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    But what you have to remember, this is kind of tricky,
    just try to play it in you head,
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    what you have to remember is that, what you have
    is basically a three dimensional lung.
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    So you have to imagine that we are literally
    looking at the front side,
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    but of course that middle lobe does go back.
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    And if you went back then you'd make perfect sense
    why the orange branches are where they are at.
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    Now let me continue the air journey because
    I wanna make sure we finish it off.
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    So let's say we take a little branch like that, we expand it.
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    We keep zooming into it, zooming into it, zooming into it,
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    until it's microscopic, you cant see it
    with your eyes any more;
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    but you could see it under a microscope.
    It would look like this.
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    It would basically in a microscope,
    it would look like a bunch of little sacs like these.
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    And these sacs, we call these alveoli. Alveoli.
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    And the air, it actually kind of runs into the alveoli.
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    It has a dead end and then it comes back around.
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    And then you breathe it out. So that's how breathing works.
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    The air goes all the way from the mouth down
    to the alveoli, takes a U-turn and it goes back out.
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    But before it does that, before it leaves-
    Very close to the alveoli is blood.
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    Let's say blood is coming this way and going that way,
    and what will happen is that,
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    actually out of the or into the blood, let's do that first.
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    We've got oxygen, oxygen will actually go into the blood, and out of the blood will be waste.
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    So you'll have some carbon dioxide waste
    that your cells have been making.
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    And that waste actually then
    gets thrown back into the alveoli.
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    So now you can see how oxygen
    gets from the outside world,
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    gets breathed into the lungs when you inhale,
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    gets down into the alveoli, exchanges with the blood;
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    and then you exhale and let all that carbon dioxide out.
Title:
Meet the lungs
Description:

Every time you take a breath, oxygen makes it way into your lungs. Follow along on that journey! Rishi is a pediatric infectious disease physician and works at Khan Academy.

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Video Language:
English
Duration:
09:36

English subtitles

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