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- [Instructor] Now that we have an idea

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of how the lungs work,

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we need to figure out
the different volumes

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the lungs can contain.

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So first off, we have this
term called tidal volume,

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referred to as TV.

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Now this tidal volume is the amount

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of a single, normal breath.

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So you breathe in,

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and you breathe out.

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It's not where you're thinking about,

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it's where you're simply
breathing at a normal pace.

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We have what's referred
to as dead space volume.

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Now every time you breathe in,

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the only air that's being utilized

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is the air inside the lungs.

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Any air that's left in the trachea,

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in the bronchi, is not being used.

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Therefore, that is
referred to as dead space.

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The air comes in,

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what didn't reach the lungs,

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is not being exchanged.

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When you breathe that
little bit of air back out,

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it contains the same
exact amount of oxygen.

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Nothing's changed.

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Then we have vital capacity.

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Vital capacity is the maximum amount

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of inhalation and exhalation.

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So if you breathe in as much as possible,

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I mean you take it all
the way in (inhales),

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all the way until your
lungs are fully expanded.

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And then you breathe all of that air out,

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all the way until you can't
breathe out another breath.

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That whole volume,

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the amount you just exhaled,

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is called your vital capacity.

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The vital capacity is
the maximum amount of air

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you can inhale and exhale
through your lungs.

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We have this inspiratory reserve volume.

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When we think of the term
reserve, that means extra.

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Inspiratory means your breathing in.

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Inspiratory reserve volume

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means how much area you can inhale

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after a normal breath.

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So after a tidal volume,

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you're trying to figure out

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how much more air you can inhale.

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On the flip side, we have
expiratory reserve volume.

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The volume of air that
can be forcibly exhaled

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after normal breath.

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So if you're breathing
in and out, in and out,

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in and out normally,

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if you're breathing in, out,

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and then you keep breathing out,

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that extra air you breathe out,

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that's your expiratory reserve volume.

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And then we have this residual volume.

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'Cause no matter what,

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there's always air left in your lungs.

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Alright, I'm sorry,

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there's two exceptions to the rule.

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Exception one, you're dead.

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Then, no, there's no air left.

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Exception two,

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you somehow have,

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your lungs are punctured,
they're deflated.

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You've been shot, stabbed,

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something happened where
a lung has collapsed.

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Obviously, not a good scenario.

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So in typical, normal functionality,

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residual volume is the amount left

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after you've exhaled everything out.

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Because no matter what,

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you can never get every
last drop of air out

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consciously trying to.

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And all these volumes

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get measured by what's
called a spirometer.

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A spirometer is meant
to measure how much air

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is leaving your mouth.

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Therefore, how much air
is leaving the lungs.

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So here's a recording

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of a person going through some lung tests.

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You can see the green is normal,

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the orange has emphysema.

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Well, the case of the normal,
that's what we're looking at.

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You can see how between
the 2,500 and the 3,000,

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it's going up and down, kind
of bouncing back and forth.

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That bouncing back and
forth is your tidal volume.

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Normal, typical breathing.

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But then that green line
takes a huge jump up.

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From 3,000 up to 6,000.

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That's your inspiratory reserve.

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How much extra air you could inhale

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after a normal breath.

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And that dives all the way down

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to about 1100.

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That massive dive from 6,000 down to 1100,

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that's your vital capacity.

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The maximum amount of air you
can move out of your lungs.

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But then if you notice from
that maximum out of the lungs

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back up to normal tidal volume,

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the increase from 1100 to 2500.

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That's your expiratory reserve volume.

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How much air you could exhale
after a normal tidal volume.

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In the very bottom, that gray,

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that's your residual volume.

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The gray residual volume
is something that can never

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move out of your lungs consciously.

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So as long as your lungs
are inflated and working,

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that residual volume must be there.

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Now if you notice the
person with emphysema,

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when they take that deep inhalation

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going all the way up to 6,000,

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well, A, they never reach 6,000,

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B, the line doesn't
increase quite as quickly.

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That tells you the lungs
are not as pliable.

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The lungs cannot expand
as quickly and easily.

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You can also see it
when they exhale fully.

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Their exhalation is much slower.

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The lungs just cannot be
compressed quickly enough

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to get the air out.

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So in this case, that's not
the healthiest in the world,

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because now your lungs are
not functioning properly.

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They're slower and not as efficient.

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But, we're looking at the
typical, normal person.

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Inspiratory reserve,

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after normal breath to maximum.

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Expiratory reserve,

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after a normal breath
out, keep breathing out.

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And normal breath itself,

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that's your tidal volume.

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So inspiratory reserve, tidal volume,

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expiratory reserve, all three together,

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are your vital capacity.