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Hello and welcome back to
Fundamentals of
Human Physiology.
This activity is going to be
about membrane potential.
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Membrane potential means
the electrical charge
across the membrane
of a given cell.
Cells that have the
ability to utilize
that electric charge to
send a signal of some sort,
are called excitable cells.
Now, the most obvious one we
might think about is a neuron,
but also muscle cells
are excitable cells,
many cells in our body
are able to carry
and utilize an electrical
charge to send a signal.
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Now, you might remember
from our last lecture,
we were talking about neurons.
Just to get sort of
the basic anatomy
of a neuron out of the way,
and you probably
already know this,
neurons generally
look like this,
but they can come in all
different shapes and sizes.
But for our purposes now,
we'll look at a basic neuron
that looks something like this.
Its job is to carry a signal
from point A to point B.
Now, that signal was received
here at the cell body,
generally travels in from these
dendrites to the cell body.
That signal might come
from another neuron
or it could come
from a hormone, etc.
that's going to cause this
neuron to be activated.
Once activated, it will
fire an action potential,
we'll learn how that happens,
where an electrical signal
travels all the way down
this axon to the
end of the neuron,
where it then communicates
with the next cell.
This next cell could
be another neuron.
It could be a muscle cell,
it could be a gland
where the neuron
could be telling it to
release a hormone, etc.
Now, we'll talk about how all of
that happens in little
bits and pieces.
But what we need to
first figure out is
what do we mean by an
electrical signal?
What is this electrical signal
and how does a neuron,
A, have the potential
to do that,
and B, get it to
travel along the axon?
Membrane potential
means that it has
the potential to generate
an electrical signal,
and membrane potential
specifically is
the charge that we measure
across the membrane.
We'll learn how
all of that works
on our way through
this activity.
But to do that, we're
going to zoom in on
just a little portion
of this cell membrane,
a little cross-section
of the cell membrane,
to start to understand
how this works.
