-: Now that we understand the basics
for how the mitochondria actually makes energy,
let's look at AMPK, which is essentially the regulator
of whether or not we're going to be feeding
that mitochondria or not, so this essentially
is the gas pedal for your cell.
The mitochondria is like the engine, but AMPK is gonna be
a major driving force on what and how much fuel
we are actually sending to that mitochondria.
If we look at AMPK, it is our master regulator
of cell energy, so it affects two aspects.
It's gonna affect what are we sending to the mitochondria,
and it's also gonna affect what are we actually bringing
into the cell, so it's gonna affect glucose transport
and fatty acids getting into the cell as well as them
getting into the mitochondria, so it's
affecting energy on multiple levels.
It impacts cellular function beyond just providing energy
because what it can also do, is it can actually affect
how we store fuel and what genes
are being turned on as well, so it can improve our ability
to super compensate to an energy demand,
like build up more glycogen than we previously had,
and it can also do things in terms of shifting
which nutrients are being burned at that particular time
versus being stored and things like that.
Under the right conditions, we can look at AMPK as being
anti-catabolic to lean tissue because of the fact
that it is going to bring in nutrients,
so when AMPK goes up, it's in response
to energy being demanded, and it meets those demands
by opening the portals for that cell to take up nutrients,
so AMPK's main mechanism is to control the feeding
of your cell from the outside in, and it works
by communicating with what's going on with the mitochondria,
so it's basically the communication between the mitochondria
and your cell membrane if you wanna think of it that way
in terms of what needs to happen.
Does glucose need to be coming in?
Do fatty acids need to be coming in?
Do we need more, or do we need less?
What is going on?
It kinda works as that gatekeeper there.
When we look at AMPK, we have calcium allocation
as one of the stimuluses.
We talked about contractions, so the nervous system signals
contractions and that works as like a precursor
to the body knowing that okay, we're about to burn
through energy, so that would send signals
to the adrenals and stuff to get blood sugar elevating.
Calcium works the same way within a cell,
so when we contract, contractions cause calcium
to be released, and that calcium being released is a signal,
like a prerequisite signal, that we're
about to burn some fuel, so that in its sense, will start
activating AMPK, which will say, hey, fuel's getting burnt,
let's start actually taking up some nutrients.
That's like the first knock at the door to AMPK,
is that calcium getting released.
The second is actually the usage of the ATP,
so as ATP starts getting burnt up, we get higher amounts
of ADP floating around in the cytosol waiting
to be recycled by the mitochondria.
AMPK can sense that.
Cellular fuel and energy, so when we look at AMPK
in the next thing, you're gonna see that it's
very closely related to glycogen, so the lower
your glycogen levels, the more AMPK will be elevated
because it senses that your reserves are really low
meaning that your threshold to burn
through energy is very small, so if you start burning
some energy, you need to get energy in the cell quick
'cause your reserves are very low, so AMPK
is very closely linked to our actual fuel storage as well,
especially in terms of glycogen,
so look at calcium, telling that story again.
Muscle contractions release the calcium,
that's my precursor, AMPK gets activated as a message
that we are about to burn through a bunch of energy,
so that way I can be preemptive in terms
of getting energy in the cell.
As I burn through energy, what I also need to look at is
the ability to break down ATP even further.
I have ATP to ADP, three to two,
we talked about that already.
There's also the ability to go from ATP all the way down
to AMP, which we will talk about in the metabolic phase.
AMP is the first parts of AMPK.
When I break down energy so much, when I use
even more phosphates than just the one off of the ATP,
I actually signal the demand that energy
is burning at so fast a rate that it's faster
than what the mitochondria can just simply replace.
That is an extremely potent signaler.
That is way more powerful of a signal that ADP itself
is when I've broken two phosphates off of the ATP,
and we'll look at that more in detail
in the metabolic phase, so the ratio in my cell
of how much ATP I have available versus how much AMP
I have, that is a huge stimulus
for how active AMPK will be within that cell.
Let's start to actually work through this.
We talked about it being glycogen sensitive already.
Let's look at some of this stuff in action.
We have some contractile fibers
down here, some muscle tissue.
That's gonna contract, and I'm gonna get some calcium.
That calcium is gonna serve
as a signal for AMPK to be active.
This AMPK is attached to glycogen, so this big long chain
of glucose molecules attached together,
that makes up our glycogen stores.
The AMPK being there is a sensor
for do we have this glycogen as well.
Once it's active, what it'll actually start doing
is cannibalizing that glycogen and breaking off
these glucose chains, so now that glucose can be sent
back over to the mitochondria that are by this muscle cell,
or within that muscle cell to be converted into fuel, so now
this guy can start making ATP because it's burning ATP.
That's very important so the calcium
was a way of signaling some of that glucose
to start being mobilized before we even got to low ATP.
As I keep contracting, I have a certain amount of ATP.
I'm gonna break down that ATP into ADP,
so I break off one phosphate, but then I could break off
another phosphate, which would get me to AMP here,
so if I get done fighting with my screen there,
so we have this process going here.
Once I have AMP, this is an extremely
then potent activator for this guy as well.
When that happens, what I'm also going to do
is not just have this guy breaking off more glucose,
but AMPK is actually gonna send signals to translocate
those glute four receptors that we talked about earlier
to the membrane to allow glucose
from the blood to start coming in and fueling this.
Now, not only am I breaking down glycogen, but I'm also
opening the door for glucose to come in as well, so now
my body's essentially preparing for the chance that like,
okay I don't wanna run out of all this glycogen.
If we run out of that, I have nothing left.
I have to be getting glucose in from elsewhere as well.
We're also gonna open up the door for fatty acids
to come in, and it's gonna start telling that mitochondria
to start revving up faster because it senses
that we're demanding a lot of fuel,
so this is just a snapshot of how AMPK fluctuates.
We're gonna look at it more in detail
and more in context in the metabolic phase.
Just understand that that is a huge signaling component
to where energy is coming from and how much energy
is being burned, so when we look at improving metabolism,
we look at improving glucose sensitivity,
insulin sensitivity, we're really gonna be focused
on how can we train, how can we eat
to influence the signaling of AMPK.