How your muscular system works - Emma Bryce
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0:07 - 0:09Each time you take a step,
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0:09 - 0:12200 muscles work in unison
to lift your foot, -
0:12 - 0:14propel it forward,
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0:14 - 0:16and set it down.
-
0:16 - 0:21It's just one of the many thousands
of tasks performed by the muscular system. -
0:21 - 0:25This network of over 650 muscles
covers the body -
0:25 - 0:26and is the reason we can blink,
-
0:26 - 0:28smile,
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0:28 - 0:29run,
-
0:29 - 0:30jump,
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0:30 - 0:32and stand upright.
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0:32 - 0:36It's even responsible for
the heart's dependable thump. -
0:36 - 0:40First, what exactly
is the muscular system? -
0:40 - 0:42It's made up of three main muscle types:
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0:42 - 0:46skeletal muscle, which attaches
via tendons to our bones, -
0:46 - 0:50cardiac muscle, which is only
found in the heart, -
0:50 - 0:55and smooth muscle, which lines
the blood vessels and certain organs, -
0:55 - 0:58like the intestine and uterus.
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0:58 - 1:00All three types are
made up of muscle cells, -
1:00 - 1:04also known as fibers,
bundled tightly together. -
1:04 - 1:06These bundles receive signals from
the nervous system -
1:06 - 1:12that contract the fibers, which in turn
generates force and motion. -
1:12 - 1:14This produces almost all
the movements we make. -
1:14 - 1:16Some of the only parts of the body
-
1:16 - 1:19whose motions aren't governed
by the muscular system -
1:19 - 1:21are sperm cells,
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1:21 - 1:23the hair-like cilia in our airways,
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1:23 - 1:25and certain white blood cells.
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1:25 - 1:29Muscle contraction can be split
into three main types. -
1:29 - 1:33The first two, shortening muscle fibers
and lengthening them, -
1:33 - 1:35generate opposing forces.
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1:35 - 1:39So the biceps will shorten
while the triceps will lengthen or relax, -
1:39 - 1:43pulling up the arm and making it
bend at the elbow. -
1:43 - 1:45This allows us to, say, pick up a book,
-
1:45 - 1:49or if the muscle relationship
is reversed, put it down. -
1:49 - 1:54This complementary partnership
exists throughout the muscular system. -
1:54 - 1:58The third type of contraction
creates a stabilizing force. -
1:58 - 2:02In these cases, the muscle fibers
don't change in length, -
2:02 - 2:04but instead keep the muscles rigid.
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2:04 - 2:08This allows us to grip a mug of coffee
or lean against a wall. -
2:08 - 2:13It also maintains our posture
by holding us upright. -
2:13 - 2:17Skeletal muscles form the bulk
of the muscular system, -
2:17 - 2:20make up about 30-40% of the body's weight,
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2:20 - 2:22and generate most of its motion.
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2:22 - 2:26Some muscles are familiar to us,
like the pectorals and the biceps. -
2:26 - 2:29Others may be less so,
like the buccinator, -
2:29 - 2:32a muscle that attaches your cheek
to your teeth, -
2:32 - 2:35or the body's tiniest skeletal muscle,
-
2:35 - 2:38a one-millimeter-long tissue fragment
called the stapedius -
2:38 - 2:41that's nestled deep inside the ear.
-
2:41 - 2:46Wherever they occur, skeletal muscles are
connected to the somatic nervous system, -
2:46 - 2:50which gives us almost complete control
over their movements. -
2:50 - 2:53This muscle group also contains
two types of muscle fibers -
2:53 - 2:59to refine our motions even further,
slow-twitch and fast-twitch. -
2:59 - 3:02Fast-twitch fibers react instantly
when triggered -
3:02 - 3:05but quickly use up their energy
and tire out. -
3:05 - 3:08Slow-twitch fibers, on the other hand,
are endurance cells. -
3:08 - 3:12They react and use energy slowly
so they can work for longer periods. -
3:12 - 3:16A sprinter will accumulate more
fast-twitch muscles in her legs -
3:16 - 3:17through continuous practice,
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3:17 - 3:21enabling her to quickly, if briefly,
pick up the pace, -
3:21 - 3:24whereas back muscles contain
more slow-twitch muscles -
3:24 - 3:28to maintain your posture all day.
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3:28 - 3:31Unlike the skeletal muscles, the body's
cardiac and smooth muscles -
3:31 - 3:34are managed by
the autonomic nervous system -
3:34 - 3:36beyond our direct control.
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3:36 - 3:39That makes your heart thump
roughly 3 billion times -
3:39 - 3:40over the course of your life,
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3:40 - 3:43which supplies the body
with blood and oxygen. -
3:43 - 3:47Autonomic control also contracts
and relaxes smooth muscle -
3:47 - 3:49in a rhythmic cycle.
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3:49 - 3:52That pumps blood through the smooth
internal walls of blood vessels, -
3:52 - 3:56enables the intestine to constrict and
push food through the digestive system, -
3:56 - 4:02and allows the uterus to contract
when a person is giving birth. -
4:02 - 4:07As muscles work, they also use energy
and produce an important byproduct, heat. -
4:07 - 4:11In fact, muscle provides
about 85% of your warmth, -
4:11 - 4:15which the heart and blood vessels
then spread evenly across the body -
4:15 - 4:16via the blood.
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4:16 - 4:19Without that, we couldn't maintain
the temperature necessary -
4:19 - 4:20for our survival.
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4:20 - 4:24The muscular system
may be largely invisible to us, -
4:24 - 4:27but it leaves its mark on almost
everything we do, -
4:27 - 4:30whether it's the blink of an eye
or a race to the finish line.
- Title:
- How your muscular system works - Emma Bryce
- Description:
-
Check out our Patreon page: https://www.patreon.com/teded
View full lesson: https://ed.ted.com/lessons/how-your-muscular-system-works-emma-bryce
Each time you take a step, 200 muscles work in unison to lift your foot, propel it forward, and set it down. It’s just one of the many thousands of tasks performed by the muscular system: this network of over 650 muscles covers the body and is the reason we can blink, smile, run, jump, and stand upright. So how does it work? Emma Bryce takes you into the body to find out.
Lesson by Emma Bryce, directed by Viviane Leezer.
Thank you so much to our patrons for your support! Without you this video would not be possible.
Tony Trapuzzano, Devin Harris, Brandy Jones, John Ess, Jessica James, Barun Padhy, Dale Dualan, Simone Kidner, Shawn Quichocho, Gi Nam Lee, Joy Love Om, Narat Suchartsunthorn, Miloš Stevanović, Ghassan Alhazzaa, Duo Xu, Yankai Liu, Pavel Zalevskiy, André Spencer, Justus Berberich, Claudia Mayfield. - Video Language:
- English
- Team:
closed TED
- Project:
- TED-Ed
- Duration:
- 04:45
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