MARIAN DIAMOND: Good morning.
It's nice to see some of
you here this morning.
How many of you leave town
as soon as class is over?
A fair number.
The others are going
to stay in town?
Yes.
Well, we wish you all
a Happy Thanksgiving.
So let's begin then.
And this morning, we start
with, of all things, the rectum.
So the end of our
digestive tract,
we've followed this all
the way down and now we're
just at the last portion--
the rectum and they anus.
The rectum we'll be straight.
That's rectum straight to
in contrast to what we've
seen for the colon as it
has it's ascending transfers
descending sigmoid portions.
It will have a simple
columnar epithelium.
So what can you say about
the digestive system
from the esophagus
to the rectum?
What kind of
epithelium do you have?
Simple columnar throughout.
Right?
Every part.
The stomach had it, the small
intestine, large intestine,
now the rectum has it.
It doesn't have stratified
squamous like the vagina.
It has simple
columnar epithelium.
And it will have the
smooth muscle walls
as you saw in the other
part of the digestive system
except the colon where
we had the taeniae coli.
So we'll say there are no
taeniae coli in rectum.
We have two layers inner
circular outer longitudinal.
So that you'd have the strength
in eliminating the feces--
have the longitudinal
muscle surrounding.
Need strength in
eliminating feces.
And then we come
down to the anus.
The end of our digestive tract.
And here we're going to
have stratified squamous.
And we'll have two layers of
muscles forming sphincters.
Let's just put two
sphincters of muscle.
The first will be smooth muscle.
And the second will be skeletal
muscle for voluntary control.
So that gives us
our very brief trip
through the digestive system.
But I do like to tell
my little stories.
Once I was called, do you know
that a little yellow school
bus that goes through
the body the children.
Did you ever follow that
little yellow school bus
when you were a little?
Well, I was called
and asked if I
would consult for them from New
York on the digestive system.
And I said sure.
And so we started.
And I said well, we go down
the esophagus, the stomach.
And I can I was just
describing it to them briefly.
And we get to the large
intestine, we go to the rectum.
We can't do that on television.
So did anybody ever
see what happened
to the little yellow school bus
and the digestive system on TV?
They get it down
to the beginning
of the large intestine and
the child has a big hiccup,
and the little bus
comes out the mouth.
So I hope when you
go into the media
that you give you the facts.
And let people get adjusted.
They've got an anus.
They've got a rectum.
We've got it all.
Everybody has it.
Why are they so hung up?
Isn't that strange?
Boy, the thought of it.
All right.
So let's go on now.
And I'm putting
the tongue in next
because we are coming
back to the mouth
to do the salivary glands.
And I just wanted to review
the innervation of the tongue
with you.
Because very few structures
have the amount of innervation
that both the eye
and the tongue have.
We said how many of our cranial
nerves innervate the eye?
Six.
And now, how many
innervate the tongue?
So let's just review.
Tongue innervation.
We're only doing
this because we're
coming back up to the mouth for
the salivary glands as I said.
So what's general
sensory to the tongue?
It's good we had a review.
Five.
Yes.
General sensory-- remember
five took care of nasal cavity,
and oral cavity, and the
general sensory to the face--
will be five.
So what is a motor
to the tongue?
Everybody knows that one.
12.
Never forget it.
That's the last cranial nerve.
Remember the story
I told you how
the lady save the
autistic girl's life
by knowing her cranial nerves.
Stick out your tongue.
She knew she came that far
down the brain stem she'd be
at the end of the brain stem.
Then she could work back up.
And saved the little girl's
life from being autistic.
She said if you understand
me stick out your tongue.
And she did.
She hadn't spoken in 12 years.
That's why we drill,
and drill, and drill.
You never know when you
can use this information.
So this is 12.
What supplies the anterior
2/3 of tongues taste buds?
That one you do know.
So that's seven.
How about the posterior 1/3
of the tongue's taste buds?
What supplies that?
Nine.
How many of you have had a
thorough neurological exam?
Anybody?
One.
Did they test your taste buds?
Yes.
Could you answer or was
that before you had it?
Oh.
You could answer.
Good for you
because they testing
if your seventh sensory
nerve is intact.
I mean we've said what
we did for motors seven.
But when you get a thorough
physical for neurology,
you go through all
your cranial nerves.
So I want you to
be knowledgeable.
And so you know that there
are 4 of the 12 cranial nerves
just to your tongue.
All right.
With that, let's move on
to our salivary glands.
We have three pairs
of salivary glands.
So we have the parotid.
We'll take each one separately.
The submaxillary
and the sublingual.
So why do we have
our salivary gland?
They will then produce
and discharge secretions
into oral cavity.
And why?
What's the purpose?
Very simple.
Straightforward.
To moisten the food.
The ease with swallowing.
To moisten the mouth.
Let's put oral cavity.
To assist with speaking.
We all know when we're
scared and we have no saliva,
it's hard to speak.
So moisten the oral cavity.
Assist with speaking.
And to add enzymes
to the saliva.
What's one of the examples
of an enzyme in your saliva?
Amylase.
Everybody knows that one.
Amylase acts on carbohydrates
to begin break down.
How many have ever played
on the DNA molecule
at the Lawrence Hall of Science?
Do you know what that
DNA molecule represents?
Amylase.
We thought it would be fun to
have a DNA molecule of spit
for the kids to play on.
So when they see it
in their textbooks
when they're in college
they won't be afraid of DNA.
We've played on it.
That's why the big
molecule is up there.
All right.
We also have glucagon.
Glucagon will raise blood sugar.
So what is the location
of these glands
so they can secrete saliva?
Let's take parotid first.
It's the largest.
What does para mean?
Near.
Next to.
Let's just say near.
And otid-- what's
that going to be?
Yes.
Ear.
So it's near the ear.
It's going to be
anterior inferior
to your external
auditory meatus.
It's anterior inferior to
your external-- remember it--
auditory meatus.
Does that mean now,
that it's going
to be anterior posterior
to sternocleidomastoid?
[INAUDIBLE] sternocleidomastoid.
Find out where it is.
As it goes up there.
You've got a gland
that's fine to be
anterir inferior to your
external auditory meatus.
And my question is, you've got
a sternocliedomastoid coming
from the sternum and clavicle
up to the mastoid process.
Where's the mastoid process?
Behind.
So is my parotid
anterior posterior
to the sternocleidomastoid?
Anterior.
Sure.
I want to work these out.
I want you to have the
knowledge to play with it.
So this is an then anterior
to sternocleidomastoid.
Students are always
asking, well,
will our next exam
cover the whole class.
Well, sure.
This is part of
what you've learned.
But it's also being brought in
again in a different context
here.
Right?
You know your
sternocleidomastoid.
You should.
Right?
All right.
So this gives us our parotid.
And now, it's
producing secretions.
Where are those
secretions destined?
The oral cavity.
But where?
Do you know where the duct
enters the oral cavity.
The duct for the parotid enters
opposite the second molar
of the upper jaw.
If you use your tongue,
you can count over.
You can feel your canines.
Right?
And get to the second molar.
Not premolars.
Second molars.
So go one, two.
Next one doesn't know
your parotid duct
is going to come in there.
When you get your teeth
cleaned, do you notice sometimes
when they're cleaning
your teeth that they
spend a little more time by
that second molar scraping.
Because frequently you
form more tartar there
as this duct is
pushing in the saliva.
You don't notice that?
I used to notice that.
All right.
So opposite the second molar.
That's the second
molar upper jaw.
Now, we have two other glands.
The submaxillary.
It's said to be walnut sized.
So most of us know
the size of a walnut.
So you get a visual image
of the sub maxillary.
This is our second one.
Sub maxillary.
And we said walnut size.
Where is it?
It's going to be just inferior.
Did I say maxillary?
I should say mandibular.
I'm sorry.
I get so excited with all these.
But it has to be mandibular
because of its location
because it's submandibular.
Submandibular.
I'm sorry.
It is the inferior to
the body of the mandible.
And then we have the smallest
one, which is the sublingual.
So you know where it is.
It will be in the
floor of the mouth.
And these two-- one
and two ducks combine.
Two or three ducks.
Two and three ducks
join, and they
will enter the floor of the
mouth lateral to the frenulum.
How many know what
your frenulum is?
You know when you look
at the inferior surface
of your tongue, you see
this mucous membrane
attaching the tongue to
the floor of your mouth,
officially that you're frenulum.
It prevents you from
swallowing tongue.
Your tongue is attached,
right with the frenulum.
So lateral to the frenulum.
And the frenulum then
is the mucous membrane
that attaches tongue
to floor of mouth.
Have any of you ever
seen your saliva
when you have done something
in your mouth that causes
it to eject your reading?
You've never seen that?
We usually have students
who've had that happen.
You've never had it happen?
Sure.
Some of you are nodding.
I mean I have.
So I know it happens.
But the books tell
you it happens.
Sometimes if you put lemon
or something really very
hard that it constricts
the walls of the ducts
and they eject saliva.
And it gets on your page.
It's rather messy.
But it's kind of interesting.
It lets you know that
you have ducts coming
in to the floor of your mouth.
All right?
You might try it on each other.
We'll see.
If it doesn't work,
don't blame me.
It just doesn't
have a [INAUDIBLE]
that's strong enough.
Anyhow.
Let's go on then.
That tells us a little
about [INAUDIBLE]..
One thing we could
say, of how much
saliva is being formed
each day, since I
like to put these in to
give the dynamics of one
system affecting another, from
700 to 1,000 cc's of saliva
is formed each day.
So again, it lets you
know the importance
of having a healthy
colon that's going
to be absorbing all this
fluid that's being produced.
Now, then let's move
on to another gland.
Let's take the liver.
The liver is the largest
gland in your body.
How much does it weigh?
Three pounds.
Right.
Good for you.
You remembered.
What other major organ in
your body weighs three pounds?
Your brain.
Right.
So now, where do
we find the liver.
We find it inferior
to the diaphragm.
We know that
represents diaphragm.
And we'll have four lobes.
We'll have right, left,
quadrate, quadrate,
and caudate--
caudate.
So you can tell roughly
where they'll be.
The largest lobe is over in our
right abdominal upper quadrant.
So we'll have a large lobe.
This will be right.
And then we'll have
left over here.
And there is a membrane
between the two.
It's called a ligament.
The falciform ligament
separates the two.
And if we look on the inferior
surface of our right lobe,
we'll find the
two smaller lobes.
Posterior-- which one do you
thinks going to be posterior?
The quadrate or the caudate?
Caudate.
Good for you.
Caudate.
So anterior inferior right
lobe will be the quadrate.
So now, the liver is
a very, very richly
supplied with blood organ.
Rich blood supply.
How much it bleeds
when it's injured.
So review.
Where's the arterial blood
coming from for the liver?
I'll give you a hint.
That artery is coming
off of the celiac.
Where's the celiac calling from?
Abdominal aorta.
Remember, three branches
of the abdominal aorta--
celiac, superior mesenteric,
inferior mesenteric.
We've got the celiac, and
it's giving off an artery
that goes to the liver.
What you call it?
Hepatic artery.
Sure.
Hepatic artery.
But we also have a major
blood supply coming in.
What's the second one?
The hepatic portal vein.
Right.
Hepatic-- good for you--
portal vein.
I had a student come back this
morning from Pittsburgh Medical
School who took our class.
She said she just
loves medical school
because she has this grounding.
She knows it.
And she just can't
think of anything
she'd rather be
doing with her life
than back there
in medical school
building on this material.
Anyhow, she came all
the way to say hello.
Hepatic portal.
Where is blood coming from
into the hepatic portal vein?
Well, it's bringing nutrients.
So coming from the stomach,
the small intestine, pancreas,
and spleen.
Because it's a vein it's
not carrying arterial blood.
It's carrying venous
blood rich in nutrients
from stomach, small
intestine, spleen, pancreas.
So with this buildup
now, let's look
at the histology of the liver.
Histology of liver.
Does anybody know the
structural and functional unit
of the liver?
It's the liver lobule.
What's a structural
and functional unit
of compact bone?
Aversion system.
What's a structural
and functional unit
of skeletal muscle?
[INAUDIBLE], sure.
You've got it there.
But it's nice to bring
it out and use it.
So now, we've got the structural
and functional unit of liver
is the lobule--
liver lobule.
So we're going to design
a liver lobule for you
then, so you can see
how it functions.
The main cell here
is going to be
the liver cell the hepatocyte--
hepatocyte.
The hepatocyte is to the
liver that the neuron
is to the nervous system.
And it's going to be arranged
in this lobule, which
is a six sided figure.
This is my lobule.
And it will have in the
center a central vein--
central vein.
And just roughly will
put the basic arrangement
of these liver cells
they say they're
in plates sort of
radiating in this way.
I've left great spaces in
between, which are there.
But giving us our purposes.
These represent
plates of hepatocytes.
And so now, we're bringing
in arterial blood,
and we're bringing
in our portal blood.
So our hepatic
artery with O2 blood.
And our hepatic portal
vein with nutrients
will be found in what
are called triads.
What's a triad?
At the point, we will
have hepatic artery,
hepatic portal vein, and
a branch on the bile duct.
The next one, hepatic
artery, hepatic portal vein,
and a branch of the
bile duct because then,
the hepatic artery and vein
here can liberate their contents
to flow between the hepatocytes
into the central vein.
The channel by which they're
flowing is called a sinusoid.
So a sinusoid is between here.
It's a modified capillary.
You will have phagocytic
cells sitting within it.
We'll put a few little
phagocytic cells in here.
Does anybody know what we
call the phagocytic cells
of the liver?
Phagocytic cell.
It's called a Kupffer cell.
Kupffer cell.
What's an important structure
that it's phagocytizing?
Old RBC's.
Old worn out.
The liver destroys
the old worn out.
So phagocytizes worn out RBC's.
So this gives the oxygenated
blood and the nutrients
to the cells, and then
goes into the central vein.
Where's the central vein going?
Central vein empties
into the hepatic vein.
And the hepatic vein
empties into the main vein
in the abdominal cavity,
which is the what?
Gracious.
Inferior vena cava.
Sure.
Inferior vena cava.
Very, very, basic.
Now, we've got to
worry about what's
coming into that bile duct.
And in order to do that, I want
to make another drawing which
will elaborate on the
hepatocyte and its function.
Let's start with here's our
sinusoid, which is for blood.
And we'll have our
hepatocytes forming a wall.
These are hepatocytes.
And now, we'll have the
other side of the cell.
So we'vve made another channel.
This channel will
be a bile capillary.
To my hepatocytes again.
Same hepatocytes that
we're taking substances
from the blood.
But in my bile capillary, the
hepatocyte is producing bile.
So the bile will be
going down on my bile
capillary and coming
to my bile ducts.
Now, isn't that
a remarkable cell
that it can be producing
bile, absorbing blood,
have two channels for.
Now, this bile that's coming
off here, what does bile do?
We talked about it before?
Emulsifies fats.
So it's got to get
down to the duodenum.
And I'm not going to give you
all a series of bile ducts.
You get that in your
advanced courses.
But it will go down
through bile ducts,
which one will lead to the gall
bladder for storage of bile.
And the other duct will
go to the small intestine,
to the duodenum--
to duodenum.
And will liberate the
bile into the lumen.
Now, one thing.
Where is this gallbladder?
It's on the inferior surface
of the right lobe of the liver.
If we had our liver and we had
our right lobe [INAUDIBLE],,
we'd see peeking out
on the inferior surface
the gallbladder.
So the gall bladder on inferior
surface of right lobe of liver.
So what tells the
gall bladder when
to contract when you've
got fat in your duodenum?
So let's say we
get fat in duodenum
that liberates an enzyme.
What's that enzyme name?
Cholecystokinin.
Cholecystokinin.
Should be up there.
Guess it's not now.
Cholecysto C-Y-S-T-O-K-I-N-I-N.
I And cholecystokinin acts
on the gallbladder.
It's telling it to contract.
And it contracts, produces bile
that goes into the duodenum,
and begins to emulsify that fat.
Isn't that a nice system?
Like a circular pattern there.
I once sat next to a
man on an airplane,
and we were stuck for an
hour or so for some reason.
And I asked him what he did.
He said he was a lawyer.
And I said oh.
He said but what I'd rather
do is study the liver.
He didn't know me from Adam.
He didn't know I knew
anything about liver.
And I just sort of
looked at him and let
you know that he recognizes
what a phenomenal organ this is.
So as we look at the
functions of this liver, one
type of cell, let's
see what it can do.
We've already shown
that it can absorb blood
they can put out an enzyme.
But let's look at the
functions of the liver.
Have you ever thought
about your liver before?
How many eat liver?
It's good.
Isn't it?
All right.
Very healthy.
And you'll see why.
Functions of liver.
So let's first look at
its dietary functions.
Well, we've just given one.
And that's to form
bile to emulsify fat.
So we can break down
the fat for digestion.
Right?
So form bile to emulsify
fats for digestion.
What does emulsify mean?
Breakdown.
You know that if
you get some butter,
and you put it all
over your hands,
and you put it under the
faucet nothing happens.
Right?
You've got fat there
that's not broken down.
Then you get a
little bit of soap.
And you put some soap in there,
and that breaks up a molecule,
and put it under the
water, and it washes away.
Well, that soap is essentially
representing what bile does.
It breaks up the fat so
that it can be utilized.
So we're forming bile
to emulsify fats.
Then it stores glycogen. It
stores glycogen. Same cells.
And glycogen then is
a source of glucose.
Right?
What does the brain burn?
Where does the brain
get its energy?
From glucose.
So glycogen can
turn into glucose.
We'll just put to
feed the brain.
So what happens if you
become an alcoholic
and you destroy
these hepatocytes?
Severe alcoholism not gentle.
So you destroy hepatocytes.
Replace them with
connective tissue
so you have no
glucose for the brain
So you have a demented brain.
So when people
always ask, what's
the effect of
alcohol on the brain,
it's more serious
than what's the effect
of the alcohol on the liver
knocking it out first.
And it does affect
the brain too.
But here you've
knocked out the liver.
All right?
The hepatocyte stores vitamins.
It stores Vitamin A, Vitamin
D, Vitamin E, Vitamin K,
and B 12 as examples.
So we're always told
to eat our liver
to get Vitamin A. It's very
rich in these vitamins.
Now, what else does it do?
It will modify
carbohydrates, fats,
and proteins for utilization.
So now, what are other
functions of the liver that
aren't necessarily directly
related to digestion?
So [INAUDIBLE] just little.
Here's your little hepatocyte
up here with all its function.
So other functions
let's call it.
What else do we think it can do?
I'm sorry?
It will in the fetus form RBCs.
Your RBCs are forming where?
In your bone marrow.
When you were a fetus, and
fetus, liver, forms RBCs.
What do we call the
formation of RBCs?
Erythropoiesis.
Good.
Begin to use the language.
Again, thank you.
We have mentioned
previously plasma proteins.
And we said certain
plasma proteins
were formed in the liver.
So we have fibrinogen,
fibrinogen and prothrombin.
These are for blood coagulation.
And then we said
just a moment ago
that we have macrophages
called Kupffer cells.
Kupffer cells.
Macrophage they
destroy old RBCs.
So how old is an old RBC?
Anywhere over 120 days.
Right?
So when they ask
you how old you are,
you can ask you mean
my RBCs or my lining
cells for my small intestine?
Do you remember
how old they are?
Four days.
Sure.
All right.
Now, what else do we have here?
We're going to detoxify
nitrogenous wastes.
Detoxify nitrogenous wastes.
And then produce
urea and ammonia.
One little cell,
little type of cell.
How can it possibly do all this?
Isn't that amazing?
So when you think of eating
your Thanksgiving dinner, what's
happening to your liver
and all it's doing for you,
I'm sure the other guests
at your dinner table
will be interested.
