The science of skin - Emma Bryce
-
0:07 - 0:10Between you and the rest of the world
lies an interface -
0:10 - 0:13that makes up 16% of your physical weight.
-
0:13 - 0:17This is your skin, the largest organ
in your body: -
0:17 - 0:22laid out flat, it would cover close to
1.7 square meters of ground. -
0:22 - 0:27Its purpose may seem obvious—
to keep our insides in. -
0:27 - 0:28But a look beyond the surface
-
0:28 - 0:32reveals that it plays a surprising
number of roles in our lives. -
0:32 - 0:34First, the basics.
-
0:34 - 0:38Skin is the foundation
of the integumentary system, -
0:38 - 0:44which also incorporates your hair,
nails, and specialized glands and nerves. -
0:44 - 0:46Made up of three layers,
-
0:46 - 0:47the epidermis,
-
0:47 - 0:48dermis,
-
0:48 - 0:49and hypodermis,
-
0:49 - 0:54skin’s thickness varies
from 0.5 millimeters at its thinnest -
0:54 - 0:57and up to four millimeters
at its thickest. -
0:57 - 1:00It also carries out three key functions:
-
1:00 - 1:01protecting,
-
1:01 - 1:02regulating,
-
1:02 - 1:05and sensing the world beyond its limits.
-
1:05 - 1:10On a daily basis, its huge surface
processes hundreds, if not thousands, -
1:10 - 1:12of physical sensations,
-
1:12 - 1:16relying mostly on large,
pressure-sensitive skin components -
1:16 - 1:18called Merkel cells.
-
1:18 - 1:20In your fingertips alone,
-
1:20 - 1:25there are 750 Merkel cells
per each square-centimeter of skin, -
1:25 - 1:30coupled with over 2,500 receptors
that give you your sense of touch. -
1:30 - 1:34This surface is also the body’s first
major line of defense. -
1:34 - 1:38Without it, you’d be a soggy mass
of tissue and fluids, -
1:38 - 1:41fatally exposed to the elements.
-
1:41 - 1:44Skin effectively seals off your insides
-
1:44 - 1:47and also absorbs pressure and shock
-
1:47 - 1:51with flexible collagen
that makes up most of its dermal layer. -
1:51 - 1:56The epidermis is made up mainly
of skin cells called keratinocytes -
1:56 - 1:59that are completely replaced
every four weeks. -
1:59 - 2:04As new cells form at the base of the
epidermis, older ones are pushed up. -
2:04 - 2:06When these cells move upwards,
-
2:06 - 2:10they’re filled with a hardened protein
called keratin. -
2:10 - 2:12Once they reach the surface,
-
2:12 - 2:15they form a tightly-overlapping,
waterproof layer -
2:15 - 2:19that’s difficult for invading
microbes to breach. -
2:19 - 2:22Any harmful microbes that make it
into the epidermis -
2:22 - 2:24will encounter Langerhans cells.
-
2:24 - 2:28This group of protective skin cells
detects invaders -
2:28 - 2:33and communicates their presence
to resident immune system T-cells, -
2:33 - 2:36which react by launching
an immune response. -
2:36 - 2:39A crucial feature of this immune defense
-
2:39 - 2:42is the several thousand
species of microorganisms -
2:42 - 2:44that inhabit the planes,
-
2:44 - 2:45folds,
-
2:45 - 2:47and crevices of your skin.
-
2:47 - 2:50These microbes,
which include bacteria and fungi, -
2:50 - 2:52thrive in the sebum,
-
2:52 - 2:55an oily substance that’s secreted
onto the skin’s surface -
2:55 - 2:59by sebaceous glands nestled
inside the dermis. -
2:59 - 3:04These skin microbes keep the immune system
in a state of constant surveillance, -
3:04 - 3:09ensuring that it’s ready to react
if the body really is at risk. -
3:09 - 3:10Beyond this protective role,
-
3:10 - 3:15your skin is also a sensory organ that
helps regulate your body’s temperature, -
3:15 - 3:18two roles that are closely interlinked.
-
3:18 - 3:21Nerves detect whether your skin
is warm or cold -
3:21 - 3:24and communicate that
information to your brain. -
3:24 - 3:27In return, the brain instructs
localized blood vessels -
3:27 - 3:30to either expand if the body is too warm,
-
3:30 - 3:32releasing heat from
the blood through the skin, -
3:32 - 3:37or to constrict if the body is cold,
which retains heat. -
3:37 - 3:42At any given time, up to 25% of the body's
blood is circulating through the dermis, -
3:42 - 3:45making this process extremely efficient.
-
3:45 - 3:47Under warm conditions,
-
3:47 - 3:51the skin’s sweat glands will secrete sweat
via ducts onto the surface, -
3:51 - 3:53transferring heat out of the body.
-
3:53 - 3:58Hair can also be stimulated
to conserve or release body warmth. -
3:58 - 4:01The average human
has 5 million hair follicles -
4:01 - 4:03embedded everywhere on the body
-
4:03 - 4:07except the palms of your hands
and soles of your feet. -
4:07 - 4:10Ninety to 150,000 of those
are on your scalp, -
4:10 - 4:14where they help shield
the large surface area of your head -
4:14 - 4:16from physical damage and sunburn.
-
4:16 - 4:20When you're cold, tiny muscles
called arrector pilli -
4:20 - 4:23cause hair to stand upright
across the body. -
4:23 - 4:29That’s the phenomenon known as goosebumps
and it traps body heat close to your skin. -
4:29 - 4:32Skin’s vast surface isn’t just a shield;
-
4:32 - 4:35it also enables us to interact
and connect with the world. -
4:35 - 4:39Its multifunctional layer cools us down
and keeps us warm. -
4:39 - 4:42The integumentary system
may be many things, -
4:42 - 4:45but it’s certainly more than skin deep.
- Title:
- The science of skin - Emma Bryce
- Description:
-
View full lesson: https://ed.ted.com/lessons/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. But besides keeping your organs in, what is its purpose? Emma Bryce takes us into the integumentary system to find out.
Lesson by Emma Bryce, animation by Augenblick Studios.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 05:11
Michelle Mehrtens edited English subtitles for The science of skin - Emma Bryce | ||
Michelle Mehrtens edited English subtitles for The science of skin - Emma Bryce | ||
Elizabeth Cox approved English subtitles for The science of skin - Emma Bryce | ||
Elizabeth Cox accepted English subtitles for The science of skin - Emma Bryce | ||
Michelle Mehrtens edited English subtitles for The science of skin - Emma Bryce | ||
Michelle Mehrtens edited English subtitles for The science of skin - Emma Bryce |