[Instructor] Hi, everybody,
and welcome to DPT 406, Exercise Science.
And today's talk is about bioenergetics.
So if you think of yourself as a living organism,
which you are,
you have the ability to produce, store, and transfer energy.
And basically that's how we survive.
that's how we use foods for fuel for our body.
Energy originates as life from the sun
and it's converted into energy forms
that we utilize for our fuel,
such as carbohydrates, proteins, and fats.
And we get these carbs, proteins, and fats
from animals and plants.
We consume these energy sources,
and through our digestive process,
we break them down
and then we break down these substrates
and our body absorbs them,
assimilating them into our system
for fuel.
We can use this fuel immediately
if we're working out or if our system's been depleted,
or we can store it for later use.
And the form of energy used by our body
is called adenosine triphosphate or ATP.
Some terms that you need to know,
metabolism is the total of all cellular reactions.
So you've probably heard this in regards to yourself
or someone else that they have a slow metabolism
or a fast metabolism.
Anyway, the metabolism is the process
of this cellular reactions
of ingesting and not digesting food,
and then breaking it down into usable fuel sources.
So technically, it's inclusive of the chemical pathways
that result in the synthesis of molecules,
these anabolic reactions,
and we'll talk about some of these pathways in a bit.
So the synthesis is anabolic, building up,
and the breakdown is catabolic.
And bioenergetics is the chemical pathways in the body
that the body uses to convert food
into a biological, usable form of energy.
In our body, there are four different elements
that compose over 90% of us as living beings,
and the majority is oxygen at 65%,
carbon at 18%, hydrogen at 10%, and nitrogen at 3%.
There's also additional elements
that are found in small amounts in our body,
so, like, sodium or iron, zinc, potassium,
magnesium, chloride, and calcium.
And we do need these to have our bodies run efficiently.
These elements are linked by chemical bonds
to form molecules or compounds.
Compounds with carbon are organic,
and compounds without carbon are non-organic.
Again, bioenergetics is the transfer of energy
from the foods we eat into a biologically usable form.
And this process converts chemical energy
to mechanical energy.
And there's a series
of very well-controlled chemical reactions that occur.
So an enderdonic reaction
or sometimes called an endothermic reaction,
requires energy to be added to the reactant
before the reactant can proceed.
So nothing's gonna happen
with an enderdonic or endothermic reaction
until energy or ATP is utilized
to cause that reactant to start.
So it's kinda like putting gas in the car.
The car won't run unless you put some gas in,
and then it can run.
Exergonic reactions or exothermic reactions,
same thing, after these reactions occur,
they give off energy as a result of a chemical process.
So exergonic does not require energy to be added initially.
So an exergonic reaction
doesn't use energy and produces energy.
Five key elements of bioenergetics
are coupled reactions, enzymes,
oxidation-reduction reactions,
understanding substrates and products,
and shuttles and transporters.
So all of these elements are required to produce energy.
So a coupled reaction is a reaction
that releases energy
required for another reaction to occur.
And as we said on the prior slide,
an exergonic reaction releases energy.
And so
this reaction will produce ATP
for an endergonic reaction to occur.
So sometimes you need the energy-producing reaction
to fuel the next reaction
where you're gonna get a bigger bang for your buck.
Enzymes are the catalysts that enhance
the rate of chemical reactions.
So we need these enzymes to kind of get reactions,
to move them along or speed them up.
They facilitate the reaction.
Oxidation and reduction reactions,
we'll talk a little bit more about this
on an upcoming slide,
but these reactions always occur together.
Substrates are molecules that are acted upon by enzymes,
and products are molecules
that are manufactured from the substrates.
There are also different shuttles or transporters
that assist molecules and the molecular movement
across surfaces or membranes from different substrates.
So just some terms, and the book has all of these
and has some pictures too to help show.
But here as an example from the book,
about a coupled reaction.
So as we talked about earlier,
these coupled reactions occur,
so energy is released from one exergonic reaction
to fuel another endergonic reaction.
Oxidation-reduction reaction.
So oxidation is when an electron
is removed from an atom or a molecule,
and reduction is the addition of an electron
to an atom or molecule.
And oxidation and reduction are always coupled reactions,
because a molecule can't be oxidized
or removed an electron
unless it can donate that electron to another atom.
So that reaction won't occur unless there's a place
where that electron can go to.
So basic chemistry.
So this picture is basically showing a bioenergetic process
of nicotinamide adenine dinucleotide turning into NADH,
so having a hydrogen molecule added.
And to do this,
there will be a reductive process.
So NAD is just sitting here
and when it reacts with two hydrogen atoms,
it's going to then receive two electrons.
So remember the oxidative state
is where it can give up electrons,
and the reducted state is when it's receiving electrons.
Whoops.
Okay, so enzymes are, again, technical definition,
proteins that regulate the metabolic pathways.
So as I said,
they control the rate and the speed of a reaction.
So enzymes are really necessary to get reactions going.
They lower the energy of activation
or the energy required to achieve the reaction.
And so having enzymes present increases the probability
that the reaction is going to occur.
So this is a little schematic that kind of shows that.
So you wanna have this reaction occur.
However, there's this barrier here.
Perhaps it's a cell membrane
and there's energy that needs to be utilized
to get this reactant in.
But with an enzyme present,
the energy of activation is lower
and so the reaction has a higher likelihood
that it's going to happen.
So in further breaking down the processes,
we're going to be looking particularly at molecules
that are acted upon by these enzymes.
And so those are termed substrates.
So in the prior picture,
we were looking at a reaction that was utilizing enzymes.
So for those enzymes to work,
they need to act on a molecule or a substrate.
So you can see here, here's a little enzyme molecule
and it's going to attach itself
to these two substrate molecules,
and it becomes a new complex, right here.
So this is a product of the enzyme and the substrates.
It's like a lock and a key.
And so these two substrates are gonna fit
into the shape of the enzyme's active site,
so it's very site specific, forming this product.
The enzyme then, it catalyzes the chemical reaction
to form this new product here.
These reactions
can produce a product,
but then they can be broken back down
into their substrate components
or produce a new product.
So here, were two substrates alone and enzyme acts on them,
it forms a new product,
and then the enzyme can break away
and it has this resultant new product
that's different than the sum of the substrate parts,
if that makes sense.
Enzymes are released from our body.
They're controlled by different processes.
When there's cell damage or disease,
enzymes are released to kind of start
the inflammatory process or the cleanup process.
Often, some laboratory tests will be used
to identify whether enzymes are present or not.
So when someone has a heart attack, for example,
these cardiac enzymes will be released into the system
because there's been a damage to the system.
And if those enzymes are found,
it's indicative that there was in fact,
myocardial infarction.
Enzymes all end in an ase.
So dehydrogenase is an enzyme that removes hydrogen.
So anytime you see an ase at the end of a word,
it is an enzyme.
Enzyme activity is affected by temperature,
so hot and cold, as well as pH levels,
so something's more acidic or alkaline,
and that can either the temperature and acidity,
or pH level can either facilitate or restrict a reaction.
So here's just a schematic,
looking at how body temperature
can affect enzymatic activity.
So the optimal range
is right at about
body temperature.
So anything too hot,
the enzymatic activities going to decrease,
anything too cold, it's going to decrease.
Same thing, the optimal range for the pH
is right around that neutral level,
so, like, a 7.4.
And so anything greater than an 8,
if it's too
alkaline or too acidic, the other direction,
then the enzymatic activity will not be optimal.
So we just talked about some different terminology
necessary to understand bioenergetic processes.
And now let's talk a little bit about the fuels
that are used within these processes.
For any type of physical activity or just existence alone,
our body needs fuel.
And our body uses carbohydrates, fats,
and protein nutrients.
And so these nutrients
provide the energy needed
to maintain all of our cellular functions,
both at rest and during exercise.
So even when you're sitting doing nothing,
your body needs fuel just to maintain
the homeostasis of your body,
your basal metabolic rate
or your resting metabolic rate.
You know, your digestive processes, your heart.
So all of that needs fuel
even when you're not moving.
During exercise or physical activity,
you need even more fuel.
And the primary nutrients for this fuel
are fats and carbohydrates.
Proteins contribute a small amount to the total energy use,
it's mostly fats and carbs.
Carbohydrates, as they're sounding,
are composed of carbon, hydrogen, and oxygen atoms,
and stored carbs within our muscle, or tissues,
or in our blood,
provide the body with a rapid available form of energy.
So carbs are kind of the first thing that we can use.
One gram of carbohydrate
yields about 4 kilo calories of energy or kcals.
It's kind of the equivalent of a calorie.
So this'll be important later on
when we get into determining how much fuel or carbs
someone needs to eat
to do a certain amount of physical activity or output,
or how many carbs they need to not eat
if they're trying to lose weight.
So 1 gram of carbohydrate yields
approximately 4 kcals.
Fats, carbon and oxygen ratio in the fats
is greater than in the carbohydrate.
So there's more energy
in a fat nutrient.
And so 1 gram of fat contains about 9 kcals of energy.
And fatty acids are the primary type of fat used by muscles,
you know, kind of for long endurance-type activities.
Proteins on the other hand,
1 gram contains about 4 kilo cals of energy as well,
but they are not the first choice of fuel
to be used in our body.
So a calorie, just a technical definition,
is the amount of heat or the quantity of heat
required to raise the temperature of 1 kilogram of water
by 1 degree Celsius,
or from 58 degrees Fahrenheit to 60 degrees Fahrenheit.
And so the amount of work that is performed by a human
can be quantified through calories.
And so these calories are abbreviated
as I mentioned, on the other slide, as a kcal.
Or they can also be
defined by kilojoules as well,
but kcals is more familiar or calories,
and you see it on all of our food labels now.
How many calories are embedded
in that fuel if you eat them.
So for our bodies to be able to use
our food fuel sources of carbs and fats,
we need energy to break that down.
And the immediate source of energy for a muscle contraction
is the high-energy phosphate compound
of adenosine triphosphate or ATP and it's
the most important
energy-carrying molecule in the cell.
And without sufficient amounts of ATP, most cells die.
So it's not the only energy-carrying molecule,
but it's the most important one.
So ATP consists of three components,
adenine, which is a nucleobase,
ribose, which is a sugar,
and three phosphate molecules,
so triphosphate 3.
And the two outermost phosphates represent high-energy bonds
that are storing potential energy within this ATP molecule.
So when those bonds are broken,
that's when the energy is released.
So ATP is essential for repeated muscle contraction
and must be rapidly regenerated when work is performed,
because the body only stores small amounts of ATP.
So we need to constantly be reproducing that.
Formation of ATP occurs
by combining adenine diphosphate or two phosphates, ADP.
So it's combining ADP and an inorganic, no carbon phosphate,
so another P.
So you add a P to the ADP,
and you get a TP, triphosphate.
So some of this energy is stored in the chemical bond
that's joining ADP and a P.
This bond is called a high-energy bond.
That's the one that I was talking about in the prior slide.
And when ATPase, if you recall, ase is an enzyme,
breaks that bond,
that two phosphate bond,
energy is released and the energy can be used to do work.
So we need that ATPase,
the enzyme to break the chemical bond
between the adenosine diphosphate
and the inorganic phosphate.