So how do we use all of
these different calories,
especially the ones for
basal metabolic rate.
You need to know where the
majority of calories go to.
So a quick graphic here
to help us with that.
First of all our brain,
again we have numbers on here.
You really need to
consider the relativity.
So which organ uses
the most calories?
Right, in our basal metabolic rate, we
consider the liver, which maybe surprising.
But the liver uses almost
the majority of our calories,
but it doesn't
awful lot of stuff.
It's always active,
it's always working for us.
As well as our brain, so that also
has a fairly high caloric usage.
And then the heart and kidneys are
pretty active in using calories.
And then skeletal muscle, well of
course we're using the skeletal muscle
to stand and move
around at all times.
And so it is going to use surprisingly
just about as much as the brain.
So the brain really does have a
high demand on our caloric intake.
All the other organs fit
the other slice of the pie.
So don't go memorizing the numbers,
understand that the major users
of our basal metabolic rate,
the calories attributed to that.
Brain, liver, skeletal
muscle, heart and kidney,
are good enough.
Because again, sources will vary
on the specific percentages.
So any calories that we
consumed above and beyond,
are basal metabolic needs pictured
here, are going to be stored, right.
And we generally
store them as fat.
And they can become an issue if
we have an imbalance in the intake
and output of those calories.
We need to consider for your
exam, what calories come from?
You are familiar with
the major macromolecules,
carbohydrates, proteins, fats.
Those are our sustenance
and then of course alcohol is
an additional consideration
for us when we're
You can see the USDA's
recommendations of portion sizes.
We moved from the pyramid
to this full plate concept,
with all the different
proportions in various places.
There are different arguments as
to what are the ideal proportions
carbohydrates and fats.
But for the purposes of your
exam, the standard here
is probably going to be what
they hit on most heavily.
So keep these numbers in mind,
4 calories and 4 calories.
Sometimes you'll see
carbohydrates noted as 4.5.
Seems from more sources
4 is good enough.
Alcohol 7 calories per gram,
and fat having the most calories per gram
because it is an excellent
calorie storage spot.
So, what you will also want to do is
recall where each of the different fuels
are utilized in cellular
respiration or metabolism.
And I'm certain that you spent
plenty of time examining those
between anatomy and physiology,
between cell and molecular biology
and in biochemistry,
You probably know many of the
intermediates along the pathway.
And what you need to remember
in this census of nutrition
is where each of these sources
enter into the respiratory cycle.
So is it utilized in glycolysis?
Is it utilized in the Krebs cycle?
And where are the intermediaries
coming into there.
And again that has been covered in
the cellular respiration lectures.
So keep those pathways in mind.
The one that we may have not spent as
much time in is alcohol metabolism.
Alcohol metabolism is a
particularly hot topic
in the multi-disciplinary area
of nutrition for the exams.
I think you've seen
the pathway before.
I want to alert you to two key
enzymes, alcohol dehydrogenase,
which is involved in conversion of ethanol
and some other alcohols to acetaldehyde.
And then acetaldehyde dehydrogenase
taking more hydrogens off.
And the formation of acetate which can
easily enter into the Krebs or TCA cycle,
so that it can be metabolized.
Acetate is harmless.
Acetaldehyde on the other
hand is another story.
It turns out to be fairly toxic.
A couple of drugs to consider,
there is Formepizole.
And that is involved in
treatment of alcohol poisoning.
So ethylene glycol or
It's administered to deactivate
And prevent poisoning from the build up
of acetaldehyde and other toxic chemicals.
The next drug that you should be
familiar with is disulfiram or antabuse.
Now you probably heard that the symptoms
of taking this drug and drinking alcohol
are quite formidable in sense of a
really, really bad hangover.
And that is because acetaldehyde
dehydrogenase is inactivated
and that results in a
build up of acetaldehyde.
And excessive acetaldehyde is what causes
the classic symptoms of a hangover.
So usually the hangover results
from having sort of a back log
in the activity
of these enzymes.
So we have a build up of
intermediaries creating a hangover.
Antabuse locks that creating greater
symptoms and ideally prohibiting
the individual from wanting to consume
alcohol cause it feels so awful.
Anyway that's what you
need to know on the basics
of alcohol metabolism as far
as nutrition is concerned.