- [Instructor] Now that we have an idea
of how the lungs work,
we need to figure out the different volumes
the lungs can contain.
So first off, we have this term called tidal volume,
referred to as TV.
Now this tidal volume is the amount
of a single, normal breath.
So you breathe in,
and you breathe out.
It's not where you're thinking about,
it's where you're simply breathing at a normal pace.
We have what's referred to as dead space volume.
Now every time you breathe in,
the only air that's being utilized
is the air inside the lungs.
Any air that's left in the trachea,
in the bronchi, is not being used.
Therefore, that is referred to as dead space.
The air comes in,
what didn't reach the lungs,
is not being exchanged.
When you breathe that little bit of air back out,
it contains the same exact amount of oxygen.
Nothing's changed.
Then we have vital capacity.
Vital capacity is the maximum amount
of inhalation and exhalation.
So if you breathe in as much as possible,
I mean you take it all the way in (inhales),
all the way until your lungs are fully expanded.
And then you breathe all of that air out,
all the way until you can't breathe out another breath.
That whole volume,
the amount you just exhaled,
is called your vital capacity.
The vital capacity is the maximum amount of air
you can inhale and exhale through your lungs.
We have this inspiratory reserve volume.
When we think of the term reserve, that means extra.
Inspiratory means your breathing in.
Inspiratory reserve volume
means how much area you can inhale
after a normal breath.
So after a tidal volume,
you're trying to figure out
how much more air you can inhale.
On the flip side, we have expiratory reserve volume.
The volume of air that can be forcibly exhaled
after normal breath.
So if you're breathing in and out, in and out,
in and out normally,
if you're breathing in, out,
and then you keep breathing out,
that extra air you breathe out,
that's your expiratory reserve volume.
And then we have this residual volume.
'Cause no matter what,
there's always air left in your lungs.
Alright, I'm sorry,
there's two exceptions to the rule.
Exception one, you're dead.
Then, no, there's no air left.
Exception two,
you somehow have,
your lungs are punctured, they're deflated.
You've been shot, stabbed,
something happened where a lung has collapsed.
Obviously, not a good scenario.
So in typical, normal functionality,
residual volume is the amount left
after you've exhaled everything out.
Because no matter what,
you can never get every last drop of air out
consciously trying to.
And all these volumes
get measured by what's called a spirometer.
A spirometer is meant to measure how much air
is leaving your mouth.
Therefore, how much air is leaving the lungs.
So here's a recording
of a person going through some lung tests.
You can see the green is normal,
the orange has emphysema.
Well, the case of the normal, that's what we're looking at.
You can see how between the 2,500 and the 3,000,
it's going up and down, kind of bouncing back and forth.
That bouncing back and forth is your tidal volume.
Normal, typical breathing.
But then that green line takes a huge jump up.
From 3,000 up to 6,000.
That's your inspiratory reserve.
How much extra air you could inhale
after a normal breath.
And that dives all the way down
to about 1100.
That massive dive from 6,000 down to 1100,
that's your vital capacity.
The maximum amount of air you can move out of your lungs.
But then if you notice from that maximum out of the lungs
back up to normal tidal volume,
the increase from 1100 to 2500.
That's your expiratory reserve volume.
How much air you could exhale after a normal tidal volume.
In the very bottom, that gray,
that's your residual volume.
The gray residual volume is something that can never
move out of your lungs consciously.
So as long as your lungs are inflated and working,
that residual volume must be there.
Now if you notice the person with emphysema,
when they take that deep inhalation
going all the way up to 6,000,
well, A, they never reach 6,000,
B, the line doesn't increase quite as quickly.
That tells you the lungs are not as pliable.
The lungs cannot expand as quickly and easily.
You can also see it when they exhale fully.
Their exhalation is much slower.
The lungs just cannot be compressed quickly enough
to get the air out.
So in this case, that's not the healthiest in the world,
because now your lungs are not functioning properly.
They're slower and not as efficient.
But, we're looking at the typical, normal person.
Inspiratory reserve,
after normal breath to maximum.
Expiratory reserve,
after a normal breath out, keep breathing out.
And normal breath itself,
that's your tidal volume.
So inspiratory reserve, tidal volume,
expiratory reserve, all three together,
are your vital capacity.