00:01
Extracellular and
intracellular signaling.
00:05
We’ll discuss how cells speak with
each other and deliver communique.
00:10
This could be in close proximity or
those that are far away in the body.
00:15
Also, cells need to communicate
vital information within the cell.
00:20
And how do they do that?
These will be covered within.
00:28
There are many modes
of communication.
00:31
You can come up with a lot
of these on your own.
00:33
Some of them are personal in
nature such as a handshake,
other ones involve things like a
delivered package or envelope,
or even on the internet
you can communicate very
easily with a number of
friends at the same time.
00:48
How do these communique work?
Well, one of the things to
think about with the body
is what modes of
communication does it have.
00:56
One of the more vital ones
are endocrine control.
01:00
Here, you release a signaling molecule or a hormone.
01:04
It travels around in the bloodstream and
is delivered to certain target cells.
01:09
How do you know which cells
will get the communique?
The ones with the
right receptors.
01:15
If you don’t have the
right receptor, you won’t
receive that information
or that signal.
01:22
Neural signals are
also very important.
01:24
Here, a neuron can signal via long projections
of axons going to an axon terminal
and then releasing a packet of information
to the cell it’s trying to signal.
01:39
These neural signals are very powerful
in that they are direct communications
rather than just releasing the
substance into the blood,
letting it travel around
throughout the body.
01:50
Here, it’s more
targeted in nature.
01:54
Now, if we move to some
more local control,
these are signaling molecules that will
signal varying cells right around a cell.
02:05
This involves passive
diffusion in which
a molecule is released
from the signaling cell
and will only be able to diffuse
in the distance around it.
02:16
Which particular cells will
receive the communique?
It’s all based
upon the receptor.
02:22
You need to have a receptor to
catch that signaling molecule.
02:28
Interestingly, there are also
times in which a cell will
want to receive the information
that it is releasing.
02:35
A good example for this, if
you’re releasing signals,
you would want to make sure you knew
how many signals were released.
02:43
You could have a receptor on the
own cell that is sending these out
to get feedback about
that information.
02:53
Now, besides sending a
signaling molecule,
you could also have direct contact
with the cell next to you.
03:02
Some of the direct contacts involve
things called gap junctions.
03:07
Gap junctions are these
specialized tubes
that allow communication between two cells
like it’s not even leaving that cell.
03:17
So these tubes will communicate
electrical information,
sometimes its ionic information,
and this will allow a propagated and coordinated
response between a number of cells.
03:33
Some direct signaling can happen
via paracrine mechanisms.
03:37
For these paracrine mechanisms,
you have to have one cell that can move
around and be able to recognize another.
03:45
So the immune system is
a very good example,
where you might have immune
cells that can travel around
and recognize other cells based upon
what projections they have sticking out.
03:57
Here, it’s like a handshake,
where one cell will get up to
a close proximity to another
and if they can recognize
each other’s projections,
they might be able to bind
and signal each other.