Meet the skin! (Overview) | Integumentary system physiology | NCLEX-RN | Khan Academy

Meet the skin! (Overview) | Integumentary system physiology | NCLEX-RN | Khan Academy


– In this next set of
videos, we’re going to talk about something called
the integumentary system. “And what does that mean? “I mean, I can understand what
the cardiovascular system is, “or the pulmonic system
or the renal system, “but what is your integument?” What comprises the integumentary system? And there are actually
two things we talk about. The integumentary system
is comprised of your skin as well as your appendages. Now, “appendage,” what does
that sound like to you? An appendage could be
something that hangs off, or something that’s a part
of, like your arm is a part of your torso. Well, the appendages of your integumentary system
involve things like your nails on your fingers and on your
toes, your hair on the top of your head or on your arm or elsewhere, and also things like your sweat glands. Glands in general kinda fall
under this classification, and we’ll talk in detail
about these appendages later, but I wanna focus on the skin right now and do a bit of an overview. Because whether you recognize it or not, the skin is actually the largest
organ in, or on, your body. It’s 21 pounds. That’s far heavier than
your liver or your lungs, and yet, many of us can go an
entire day without thinking about the functions of our skin. But what are the functions of our skin? If I told you this was
your arm right here, and this is you giving a little thumbs up, and then your fist, and
then this going back here, what is it that the skin on
your arm enables you to do? Well, one thing you may have noticed is that when it’s raining outside, and you’ve got raindrops
dropping on your head, one thing your skin enables
you to do is be impermeable to the water. It’s impermeable to water
and other things that try and breach its layers
and go into your organs or your bloodstream. It’s impermeable, it cannot
be passed, and that’s as true for water and other molecules
like this virus right here, which I’m drawing. Here’s this little capsid
and its little legs. It wants to come and infect
the cells of your body, but thankfully your skin
says no to this virus, and it’s not allowed to
enter or breach this barrier, because it’s impermeable. But it’s not just a structural barrier, it also has an immunologic
function as well. Your skin can secrete
things like antibodies, or even enzymes like lysozymes. These are the guys that’ll
go and take on these viruses. Or say if there’s a
bacterium that’s present that has intentions of
also getting you sick, the antibodies can coat
this sucker right here, and the lysozyme can assist in breaking down the cell wall to
help protect your skin. And so, your skin also functions as part of the immune system. So immunity is also in
play here, not just what this antibody or this lysozyme… Perhaps you can imagine a
scenario where the bacterium even penetrates a few layers of your skin, and thinks that it has an
opportunity to set up shop, or make an infection or
an abscess somewhere. But you have cells that
are within your top layers of skin, like your Langerhans
cells, like we’ll talk about, that’ll eat these bacteria
up and prevent them from setting up shop or making you sicker than you should be. Other than immunity, your
skin can also perceive things in the environment. If I have this little
pin from a pin cushion that I can prick right here, and it really hurts right there, your skin will tell your brain, “Hey, maybe we shouldn’t
put our hand so close to this sharp object.” So, your skin also has the responsibility of perceiving your environment, and so it conducts sensation. It’s able to tell when there’s a stimulus that’s either painful,
so it perceives pain. It can tell different temperatures, whether something is hot or it’s cold. And also, it can
differentiate types of touch that are present, and
discriminate between textures, whether something is
just grazing your hand or something is poking you deeply. And finally, when you’re
outside and it’s really hot, just kind of as I was already
alluding to with the ability to perceive temperature,
your skin has the ability to respond in a process
that’s called sweating, as we know it. We sweat because of our skin,
and the glands in our skin, and it’s all part of an
overall process known as thermoregulation,
because our sweat allows us to cool off by a process
known as evaporative cooling. But there are also processes
that involve our blood vessels. Here’s a blood vessel
in your arm right here that can help us conduct
heat out of the body. Let’s get rid of that heat, because we notice it’s
already hot outside. So the skin is so much
more than just a barrier, there’s a lot that it does for us. And in the next few videos,
we’ll go into detail about how all of these
functions are achieved.

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