PROFESSOR MARIAN
DIAMOND: All right,
let's go on with our
respiratory system
and look at the alveolar wall.
So what does oxygen have to
go through to reach the RBC?
And what does CO2 have
to go through to get out?
Let's start with the first
layer in our alveolar wall.
It will be surfactant.
Remember, we had that
layer of surfactant?
And after surfactant, we'll have
the simple squamous epithelial
cell of the alveolus.
Simple squamous epithelial cell.
And all epithelium has
a basement membrane,
so then we'll have
the basement membrane.
And then, what they call
an interstitial space.
Interstitial space.
And then we'll encounter
the basement membrane
of the endothelial
cells of the capillary.
So we have another
basement membrane.
I'll just leave that
off and just put
the endothelial cell in next.
So then we have the endothelial
cell of the capillary.
So it's now in the
lumen, and then it
has the membrane of
our RBC to go through.
Membrane of RBC.
So it lets you know.
Quite a lot to transport
to get that in.
Isn't that amazing,
both ways, constantly?
Now let's look at the base gross
anatomy of the lung, briefly.
Put in a few landmarks.
What is that?
Diaphragm.
Isn't it wonderful how we
can interpret modern art now?
And then we'll just
have our bones up here.
What would they be?
Clavicles, right.
And so we have these
two conical shaped lungs
that extend just slightly
above the clavicle.
We can make him a
little bigger here.
So superiorly, slightly
above clavicle.
That's our apex.
And inferiorly, the base,
is on the diaphragm.
We have two surfaces.
We have the costal surface.
And the costal surface then
will be against the ribs
and the intercostal muscles.
And we have the
mediastinal surface.
So we remembered, I'm just
going to do it with Xs here.
Because the mediastinum is the
area between the two lungs.
So we have the
mediastinal surface.
And we want to develop
what's called a hilum here.
It's an indentation on
the mediastinal surface.
So this will be the hilum.
We'll find three structures here
that are entering and exiting
the hilum.
First, we'll have the
bronchi, because we've
got the trachea coming down
and giving off bronchi.
So one will be bronchi.
Two will be the
pulmonary vessels.
I can't put them in
because there's not room,
so we'll just put
pulmonary artery and vein.
And third will be the nerves.
These three structures,
one, two, and three,
make up what's called
the root of the lung.
This is the root of the lung.
And interestingly,
the root of the lung
is the only place that the
lungs are attached to the body.
Otherwise, they're suspended
in the thoracic cavity.
So the root, only place
lung attached to body.
The lung is going to
have its coverings, just
like we had with the heart.
We're going to have the pleura.
So we'll have a parietal
pleura, and it will
be lining the thoracic cavity.
Lines thoracic cavity.
And what are we going
to call the pleura that
covers the lungs?
Visceral, sure.
Visceral pleura covers lungs.
So then we have, between the
parietal and the visceral,
the pleural cavity.
And there will be fluid secreted
by the pleura between these two
layers of pleura.
There is fluid in cavity.
Why do we need fluid there?
Yes, reduce friction, right.
You can figure these
things out now very easily.
So if we get inflammation of
the pleura, what do we call it?
Pleurisy.
Why don't we call it pleuritus?
[INAUDIBLE]
Pardon?
[INAUDIBLE]
You bet it is inflammation.
I don't know, I didn't name it.
But just to be consistent,
wouldn't it have been nice?
It's called pleurisy.
Inflammation of pleura.
Do you know anybody who's
had inflammation of pleura,
when the two stick together?
They say it's
excruciatingly painful.
This gives us just a
brief picture of our--
maybe I should put in the
lobes while we're at it.
The right lung has three
lobes, roughly one, two, three.
And the left lobe has two.
And we can see why,
because the heart
is taking up a
good deal of space
there on the medial surface.
Now let's just look at some
abnormalities of the lungs.
Abnormalities.
First, lung cancer.
In what part of this whole
unit does lung cancer begin?
Begins in the bronchi.
Those going into oncology
of the lung, why bronchi?
Lung cancer is 20
times more prevalent
in smokers than nonsmokers.
And yet people still smoke.
How many in class still smoke?
Do they dare raise their hands?
You just look out and you
want to say something.
Why do you dare?
So lung cancer, 20 times
more prevalent in smokers.
And evidently, lung cancer
moves pretty rapidly
once it's diagnosed.
So stay away from cigarettes,
firsthand or secondhand.
All right, how about emphysema?
We've talked about
emphysema, but again,
since it's caused
primarily by smoking
and you know your
structures now,
emphysema will be
swollen alveoli.
And the elastic fibers
have lost their elasticity.
So how will you recognize
somebody who has emphysema?
Other than the fact they
have trouble breathing,
what will their thoracic
cavity look like?
It's barreled, a
barrel thoracic cavity.
Because they keep
trying to bring in air.
A barrel chest, it's called.
And again smoking can
take away that elasticity
from your alveoli.
Have you ever known
anybody with emphysema?
You ever tried to walk
with them anywhere?
I innocently did that once.
I said, come on let's go
for a walk around the block.
We got a fourth of the
way around the block
and she couldn't move.
I wasn't sure I'd
get her back again.
So profit from my
experience, but also
stay away from cigarettes.
Now tuberculosis is another
disease, abnormality.
This will be caused by bacteria.
It's a bacterial infection.
And it will destroy the
alveoli and replaces them
with scar tissue, with CT scar.
So that's why they can pick
it up easily when they use
a scan to observe the lungs.
Now what about the innervation?
What's responsible for
you to sit there and be
able to rhythmically breathe
without ever thinking about it?
The rhythmicity, that's
just neural innervation.
The controlled rhythm breathing.
Where in the brain
is it coming from?
It's coming from what's called
the pons and the medulla.
From pons and medulla.
We'll see those when we
develop the brain, for those
who haven't studied it.
So the message
from these centers
will go down to the spinal
cord to the cervical level,
specifically, mainly to
C4, some C3, some C5.
But the main input
is coming from C4,
and it goes down
to the diaphragm
to rhythmically contract,
to allow you to breathe.
So if you're going to cut
your cord in any accident,
cut it below C4.
That gets us briefly through
your respiratory system.
Now we come to the
nervous system.
How many millions of years
has it taken to evolve?
We give it a little
different introduction.
Who would ever imagine that
little masses of protoplasm
could compose a Mozart sonata?
You ever seen little masses
of protoplasm in a Petri dish?
Who would ever imagine that
little masses of protoplasm
could design
despicable landmines?
Think about it.
The human brain has
no peer on this earth
and who knows what lies beyond?
They still haven't
told us, have they?
It's the most complex mass
of protoplasm ever evolved.
As we talk about it, just
think how masses of protoplasm
can think, create,
display consciousness.
Doesn't it literally
blow your mind
if you really stop
to think about it?
And the main thing, it's
thinking about itself.
How is our nervous
system organized
to begin this journey through
this system of the body?
So we're now starting
the nervous system.
You can see why I was attracted
to it when I was your age.
I couldn't believe it.
You only had 100
years on this earth,
study the most complex mass
that's ever been developed.
See if you can
make some headway.
And it's quite
satisfying when you can.
It really feels good.
We divide it for
its organization.
We divide it into a
central nervous system.
Very briefly here, very
simplistically for those
who haven't had any study
of the nervous system.
Central nervous system,
we just abbreviate CNS.
It's going to consist of
the central nervous system,
the brain, the spinal cord.
So important that it gets its
own bony protection, completely
surrounded.
Spinal cord gets vertebrae.
Then we have the
peripheral nervous system.
Peripheral nervous system.
This PNS.
What does the PNS consist of?
It consists of cranial
and spinal nerves.
Cranial nerves, spinal nerves.
How many cranial
nerves do you have?
[INAUDIBLE]
You only have 12?
Only 12?
12 pairs of cranial nerves.
You have to be specific.
How many spinal
nerves do you have?
Never counted them?
[INAUDIBLE]
Well, it's a good
guess, but not quite.
31 pairs of spinal nerves.
They're going to be
bringing in information
to the central nervous
system for processing,
and then taking
it back out again.
So with our spinal
nerves, we're going
to have both sensory and
motor components in a nerve.
We call these afferent,
that will be sensory.
And efferent, these
will be motor.
And so all spinal nerves
have an afferent and efferent
component.
Cranial nerves, some
of them we'll see
will be strictly afferent.
Some will be efferent.
And some will be both
afferent and efferent.
But we'll see those as
we develop the system.
And then the third division is
our autonomic nervous system,
the ANS.
Or also called visceral
nervous system.
It will be involuntary.
It will be going to hollow
organs or viscera, that's
why visceral nervous system.
Viscera or hollow organs.
So it will chiefly be supplying,
it supplies smooth muscle.
What other kind of muscle?
You only have three kinds.
STUDENT: Cardiac.
PROFESSOR MARIAN
DIAMOND: Cardiac, right,
because all the
others over there
were all the skeletal muscles.
So cardiac muscle.
And what else?
Glands.
We've talked about these
divisions previously,
the sympathetic,
parasympathetic divisions.
When you get into
your cranial nerves,
you get various components
coming in from the ANS.
So we have divisions of ANS,
will be the sympathetic.
They called this originally
because they thought
it had to do with feelings.
That's why it was
called sympathetic.
And parasympathetic.
Para means next
to, so sympathetic.
And in general, we learned
that the sympathetic speeds
up a reaction and
parasympathetic slows it.
So what was this, the
innervation of the heart
that we gave you,
that slows the heart?
STUDENT: The vagus.
PROFESSOR MARIAN
DIAMOND: The vagus, sure.
So basically, you could
go through all structures
and learn this, but I
think we'll continue on.
This gives a very, very
fundamental division,
but you see they
all play together.
You have your central
nervous system,
your peripherals coming in, your
ANS is coming in, all of them.
This is done for pedantic
reasons, to separate these.
So let's just look at
neurohistology, then.
Two kinds of cells, for
all of the functions
of the nervous system.
All of your behavior,
only two kinds of cells.
Nerve cells and glial cells.
Technical term for
nerve cell is neuron.
For glial cells, neuroglia.
Frequently, the people
who work in the field
just speak of glia.
We're going to take
the nerve cell first.
Obviously, you could have a
whole course on it, at least.
Years of courses.
So what's its function?
My goodness.
Well obviously, it has
sensory motor functions.
It can conduct impulses.
It can store information.
It can retrieve information,
and on and on and on.
We could fill a blackboard when
you ask what the heart does,
and you could fill blackboards
with what these cells do.
Just amazing.
But this gets us started.
What does a cell look like?
Tremendous variation
in shapes and sizes.
Structure.
Well first, we're going
to have a cell body.
We call the cell body the soma.
And the fist makes a perfect
little soma to begin with,
but it stretches out its
membrane and forms processes.
So we have two
kinds of processes.
This will be one, the axon.
In vertebrates, what we
are, there's only one axon.
If we go to invertebrates, they
can have more than one axon.
But we just have one axon.
And then we can have dendrites.
We can have one, or
two, or thousands.
We'll just put many, to bring
in a tremendous amount of input.
The axon conveys the
impulse away from the soma.
The dendrites convey
impulse to the soma.
Different speeds,
different sizes,
all sorts of things about them.
Now the axon, then, let's
just take an example.
Can be micro long or
it can be feet long.
Some of the shortest
axons, we'll
find those in granule cells of
the cerebellum, as an example.
Short axons, granule, I'll
show you pictures of them,
cells in cerebellum.
And in another very
important place,
the dentate gyrus
of the hippocampus.
Granule cells in dentate, it
looks like a row of teeth,
dentate.
Of hippocampus,
which is debatable,
but gave its name because
it looked like a seahorse.
But these places
have short axons,
so if you're going to
try to look for cells
in the nervous system that
can divide in an adult,
you'd go looking in these areas.
There are some
places, only recently,
people working in our lab showed
that the dentate cells could
divide in an adult,
in an animal that was
being stimulated and enriched.
We did that 1989.
Salk did it in 1999,
exactly the same thing.
I just tell you,
for those of you
who go into research, because
ours was sent in to Nature,
they refused it.
Salk sent it in to Nature, the
same thing, 10 years later,
it was published.
Made headlines around the world.
Some people feel good
and some people feel bad.
But not necessarily, because
you know you got it first.
But it's interesting
with science,
the way things can turn out.
These cells have short axons.
They can divide.
You have short axons that
you've already studied.
How about your
olfactory epithelium?
Those little axons that go
through your cribriform plate.
You're getting new cells
there every 40 days.
So there are places that just
normally are turning over.
So your olfactory
epithelium, that's important.
How important smell
was to survival, right?
So olfactory epithelium, new
cells, normally every 40 days.
We've given some
places where you
can get-- these are the
main places that have been
shown to form new nerve cells.
You go to the old
literature, it says
nerve cells don't
divide after birth,
but there are
places where there's
small axons, where they can.
Long axons, where
do we find those?
I gave you an example, I
think, the very first day,
when I talked about a
pseudounipolar cell,
but let's just look
at a long axon.
We can find these, for
example, move your big toe.
Don't look at it, that's
a different pathway.
Just move it down there.
Is it moving?
First neuron is way up in your
cerebral cortex, your brain.
It goes all the way down to
the bottom of your spinal cord.
So there we are.
But then from there, it goes
all the way to your big toe,
for you to move that.
So you could have an axon
that can be several feet long.
So one of the places
here, it could
be a pyramidal cell
in cerebral cortex,
or it can be an anterior
cell, anterior horn
cell in spinal cord.
Does anybody know
anybody who has polio,
or have we eradicated
it completely?
Anybody know anybody
who's ever had polio?
The anterior horn cell is
attacked by the polio virus.
When it attacks that, that's
when you get paralysis.
So these are important.
We'll leave those two.
There are lots of
examples of long axons,
but the difference
between feet and a few
millimeters at most in an axon.
So tremendous variation.
Let's see where our
axon's coming from.
We'll have a soma.
Let's just do a
multipolar anterior horn
cell, anterior horn cell.
I'll show pictures so you can
see the variation in cells.
There are so many varieties.
Get these out.
Put in a nucleus.
Here's our soma.
These will be dendrites.
And here's an axon.
The axon is attached
to the soma at what
is called an axon hillock.
A little hill here,
an axon hillock.
And you can tell when you
have an axon coming off
of your soma versus
dendrites coming in,
because the axon hillock
has no Nssl substance
in its cytoplasm.
No Nssl substance
in the axon hillock.
What is Nssl substance?
Well it was named
after a Mr. Nssl,
but then when one has
a higher technology,
you can figure out what it is.
It's rough
endoplasmic reticulum.
Rough endoplasmic
reticulum, which
deals with protein synthesis.
So if we have--
can you see that color?
Can you or not?
It's OK?
So you have Nssl substance
throughout the cytoplasm
of your dendrites and your soma,
so you know where they are.
But when you get to the
axon, there's no Nssl,
and there's none in
the axon hillock.
As the axon comes down, it
decreases its dimensions,
and then becomes uniform.
The area where it's
decreasing its dimensions
is called the initial segment.
Initial segment.
And that has the
lowest threshold
of any part of the neuron
at the initial segment.
The lowest threshold, takes
the least amount of current
to stimulate it here.
Lowest threshold.
Let's just finish
one thing on this.
Add myelin because
we've got our axon,
and dendrites don't have myelin.
Myelin, it's a lipoprotein
sheath on the axon.
And we'll see that the more
myelin you have, the more rapid
the impulse.
What disease commonly has
demyelination going on?
Multiple sclerosis.
We'll look a little
more detail at that,
but I just wanted to
get that because I
wanted to show a picture of it.
Could we have the
slides, please?
And see if anybody
notices anything
different about the slides.
First slide, please.
Notice anything different?
I just wanted you to see
what a vocal cord was,
but do you see anything
new that I'm using?
A green light, yes.
They say because,
with the webcast,
you don't see the red so well.
So they've given us these
really bright torches of green.
Stratified squamous epithelium
on your vocal cords,
terribly important
in your larynx.
And the next one.
Next one, please.
And just the shape of the lung.
We'll just take this one,
conical, and the three lobes.
Next one.
This is our main character
for the next few lectures,
this mass of protoplasm.
We've been talking about
the cerebral cortex up here.
We talked about the
cerebellum, here.
Here's the medulla.
We'll talk more, we're just
getting interested, just
getting introduced.
Next one.
Here's the central
nervous system, the brain,
the spinal cord, the
peripheral, as we go off
with all the peripheral
spinal nerves.
There are peripheral cranial
nerves coming off up here,
and then the autonomic
nerves will be here.
We'll see how they're
related to the spinal nerves.
And the next one.
I just wanted to
show the hippocampus,
is going to be
here in this area.
We've taken what we
call an axial plane here
and cut through, just
to get introduced to it.
It has the dentate gyrus there,
with its short axon neurons.
And the next one.
This just gives you an example
of different sized cells.
We had given you an
anterior horn cell.
Here it is here.
Look at its axon.
And here's an olfactory cell.
Here's its neuron.
Here's its axon.
Here's our pseudounipolar cell.
We know that impulses
have to go in and out.
Pseudounipolar.
But the process is exceedingly--
here's the Purkinje cell
in your cerebellum.
Granule cell of the cerebellum.
Short axon.
Purkinje cell has a long axon.
Next one.
This is the cerebellum,
these are the Purkinje cells
with massive dendritic trees.
They could get
20,000 or more inputs
to be computed by a single cell.
Now these little granules
here are the granule cells
of the cerebellum.
So you see, they're going
to have very short axons.
And the next one.
And here is myelin.
Here's our multipolar
cell with the dendrites,
and here's the axon, and it's
got a myelin sheath on it
that's insulating.
And the more myelin,
the more rapid.
We'll go into it a little
bit more next time.
You begin the myelin
at the initial segment.
You lose the myelin down
as we get to the terminal
branches of the axon.
And the next one.
And this shows you, if we
take an electron micrograph,
look at myelin.
This is the axon
in a cross-section.
Beautiful, the way it's formed.
I was back at MIT when the lady
discovered how that was formed,
how it wraps around the axon.
Betty Geren was her name.
And the next one.
This shows just a multi-picture
of neurons, the somas.
It's a whole different stain,
so all the things in between
are processes, but
you can't see them.
You just see the cell body.
And the little ones
are the glial cells.
Dynamic little cells, which
we'll see as we go along.
But I just thought you'd like
to see a picture of Einstein's
brain, and you can see that
with his nerve cells and glial
cells.
So that's all for now.
