The science of skin – Emma Bryce

The science of skin – Emma Bryce


Between you and the rest of the world
lies an interface that makes up 16% of your physical weight. This is your skin, the largest organ
in your body: laid out flat, it would cover close to
1.7 square meters of ground. Its purpose may seem obvious—
to keep our insides in. But a look beyond the surface reveals that it plays a surprising
number of roles in our lives. First, the basics. Skin is the foundation
of the integumentary system, which also incorporates your hair,
nails, and specialized glands and nerves. Made up of three layers, the epidermis, dermis, and hypodermis, skin’s thickness varies
from 0.5 millimeters at its thinnest and up to four millimeters
at its thickest. It also carries out three key functions: protecting, regulating, and sensing the world beyond its limits. On a daily basis, its huge surface
processes hundreds, if not thousands, of physical sensations, relying mostly on large,
pressure-sensitive skin components called Merkel cells. In your fingertips alone, there are 750 Merkel cells
per each square-centimeter of skin, coupled with over 2,500 receptors
that give you your sense of touch. This surface is also the body’s first
major line of defense. Without it, you’d be a soggy mass
of tissue and fluids, fatally exposed to the elements. Skin effectively seals off your insides and also absorbs pressure and shock with flexible collagen
that makes up most of its dermal layer. The epidermis is made up mainly
of skin cells called keratinocytes that are completely replaced
every four weeks. As new cells form at the base of the
epidermis, older ones are pushed up. When these cells move upwards, they’re filled with a hardened protein
called keratin. Once they reach the surface, they form a tightly-overlapping,
waterproof layer that’s difficult for invading
microbes to breach. Any harmful microbes that make it
into the epidermis will encounter Langerhans cells. This group of protective skin cells
detects invaders and communicates their presence
to resident immune system T-cells, which react by launching
an immune response. A crucial feature of this immune defense is the several thousand
species of microorganisms that inhabit the planes, folds, and crevices of your skin. These microbes,
which include bacteria and fungi, thrive in the sebum, an oily substance that’s secreted
onto the skin’s surface by sebaceous glands nestled
inside the dermis. These skin microbes keep the immune system
in a state of constant surveillance, ensuring that it’s ready to react
if the body really is at risk. Beyond this protective role, your skin is also a sensory organ that
helps regulate your body’s temperature, two roles that are closely interlinked. Nerves detect whether your skin
is warm or cold and communicate that
information to your brain. In return, the brain instructs
localized blood vessels to either expand if the body is too warm, releasing heat from
the blood through the skin, or to constrict if the body is cold,
which retains heat. At any given time, up to 25% of the body’s
blood is circulating through the dermis, making this process extremely efficient. Under warm conditions, the skin’s sweat glands will secrete sweat
via ducts onto the surface, transferring heat out of the body. Hair can also be stimulated
to conserve or release body warmth. The average human
has 5 million hair follicles embedded everywhere on the body except the palms of your hands
and soles of your feet. Ninety to 150,000 of those
are on your scalp, where they help shield
the large surface area of your head from physical damage and sunburn. When you’re cold, tiny muscles
called arrector pilli cause hair to stand upright
across the body. That’s the phenomenon known as goosebumps
and it traps body heat close to your skin. Skin’s vast surface isn’t just a shield; it also enables us to interact
and connect with the world. Its multifunctional layer cools us down
and keeps us warm. The integumentary system
may be many things, but it’s certainly more than skin deep.

100 Replies to “The science of skin – Emma Bryce”

  1. Thank you so much to everyone who has started supporting us on patreon.com/teded! We couldn't do this without you! If you want to learn more about how to get involved, check out our Patreon page.

  2. Me 2 years ago: gotta do this biology class project about human skin really quick, I wish there is a video all about it so I can study about skin easier
    Today: great

  3. Just wanted to tell you that
    I am from iraq ( 24 y).. I keep watching your awsome videos.. So does my sister (17y) and her classmates..
    You guys are inspiring and great.. You just make ppl love science more and more .
    I am on my way to be a teacher.. And i'll make sure that my feature students will be watching your videos and hopefully more
    Thank you from the heart.. We DO love you

  4. Umm, I have got a raw deal with my skin right now. Juggling between two dermatalogist and several advisory armchair doctors to sort my epidermises out. Don't be like me and take care of skin before it comes back as vengeful, tyrannical all-father of the underworld out for your soul.

  5. Could you make a video about dermographism? I have it myself and I would love to know more about it!!!

  6. At 3:04 you are showing bacteriophages, which are not harmful to the body itsself, as they only infect bacteria. The are almost always invisible to the immune system.

  7. The quote at the beginning sounds like something a psychopath who makes clothing out of Human skin would say.

  8. Very interesting and informative video.
    We can protect our skin from diseases by covering it with proper dressings and taking regular baths.

  9. Hey it's me subscribe to my channel whoever sees this hey it's me it's back to my channel whoever sees this

  10. How about the myth of "the 5 sun's" and Aztec legend. I've noticed most of the myths are already popular and of Western culture. It would be nice to have a little more diversity

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  12. Can you make a video on why some wounds never seem to heal? Or why minor scratches scar. About 5 months ago I got a cut on my leg from shaving, and it never went away.

  13. could you please make a video about the nervous system it would be perfect. thank you so much we love ted ed and nothing above that.

  14. To the point! Well explained!! Time saving !! Amazing animation!! E everything upto mark!!😊😊😊

  15. Hey .. Ted ed your are doing a good job by educating every one of us through your efforts. Thank you so much .. Can you please make a video on causes dandruff

  16. Will there be Dutch subtitles available anytime soon? That would be great for my Dutch students who need some more English practice. In Dutch there is very few good animations to be found on these topics. If you're having difficulties finding a translator I would volunteer. Groetjes.

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