Let’s talk about glucose homeostasis.
The way that this was set us up is that if
you take a look at the picture, on the left
will be that which is going to inhibit the
release of insulin.
On the right, that path is going to promote
the release of insulin.
On your left, low blood glucose means fasting
Just simple things that you want to know for
This is fasting state.
On the right, high blood glucose, this is
the fed state.
So, you already know if you are fasting, you
are not going to be releasing insulin, you
are going to be releasing glucagon.
Where does glucagon come from?
Alpha Islet cell.
What does it do?
It stimulates the liver to do-to bring about
gluconeogenesis so that you can raise your
glucose back to normal in your circulation.
That is the convergent point at the bottom
of the picture, that tube that you are seeing
there is a blood vessel; in other words plasma.
On the right, you have fed state.
So, you had that piece of chocolate, you had
that piece of bread, high blood glucose.
We just got down discussing how glucose passes
through glucose transporter, bring about ATP
blockage of a potassium channel, increase
actual potential, Voltage-gate calcium channel,
there it comes and binds your vesicles to
the membrane, out comes the insulin and that
insulin is going to do what?
It is going to then remove the glucose out
Not only will it do that but if you keep eating
carbohydrates, right, keep eating, what then
Well, you are going to store… you are going
to store some of this in your adipocytes.
Insulin effect, mostly anabolic, increase
glucose uptake by cells, glycogen synthesis
because you want to store it and you are going
to decrease the glycogen effect, break down,
so you are going to have decreased glycogenolysis
and you have inhibition of lipolysis and you
have decreased gluconeogenesis.
In the end, what are you trying to do with
Take a bit of glucose, store it; take a bit
of glucose, store it, take a bit of glucose
and store it.
Overall effect, anabolic, but in order to
do that though, remember, you have to have
glycolysis and such.
The major counter regulatory hormones, so
these are stress hormones.
This then brings us to glucagon.
If you have understood insulin in great detail
then you know about glucagon.
What does glucagon do to glycogen?
Break it down, glycogenolysis.
What type of biochemical pathway?
Gluconeogenesis or glycolysis, it promotes
Along with glucagon, what other peptides,
proteins or hormones behave like it?
Catecholamines, same concept.
Glucocorticoids, which we-we have discussed
extensively with cortisol, decrease glucose
uptake and growth hormone, the 4 major groups
of stress hormones.
Glucagon and cortisol should always be put
You always have epinephrine in here for catecholamine
and growth hormone of course would mean, while
we talked about this earlier, especially as
a child, there is that incredible need, isn’t
there, to make sure that you are able to properly
grow and so, therefore, we need to make sure
that there is proper amounts of glucose in