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  • - 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.

- In this next set of videos, we're going to talk

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認識皮膚(概述)| Integumentary system physiology|NCLEX-RN|可汗學院。 (Meet the skin! (Overview) | Integumentary system physiology | NCLEX-RN | Khan Academy)

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    Amy.Lin 發佈於 2021 年 01 月 14 日
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