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Muscles are a necessity of living. Without them, we
would never |
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be able to do things like run, play sports, or even
chew our food! |
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But what are muscles, and how do they make you able
to do |
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these things? |
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Your muscles are made basically of a substance called
myofibril, |
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a thread-like structure composed of complex proteins.
Each |
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muscle cell or fiber is made of many myofibrillae.
The myofibril are |
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composed of two kinds of myofiliments, thick and
thin. Each thick |
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myofiliment can contain several hundred myosin
proteins. Each |
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thick myofiliment contains two strands of the protein
actin. The |
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myofibrillae are made of alternating rows of thick
and thin |
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myofiliments with their ends interleaved. During
muscular |
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contraction these nterdigitated rows of filaments
slide along each |
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other by means of cross bridges that act as ratchets.
The energy |
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to preform this tack is generated by densley packed |
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mitochondria that surrounds myofibrillae. |
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Different Types of
Muscles |
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There are two basic types of muscles: voluntary and
involuntary. |
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There are also cardiac muscles, the muscles of the
heart. The |
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involuntary muscles move on their own. For innstance,
your |
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eye lids automaticlly blind when they get dried out,
and your |
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heart pumps blood without you telling it to. You
don't even |
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need tothink about it, it just happens. Voluntary
muscles on |
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the otherhand require some thinking. When you move
your |
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arm to pick up a glass of water, your brain sends
signals to |
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your muscles tellingthem to reach out and grab the
glass. |
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Why Do You Have
Muscles? |
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Why do you have muscles? Your muscles are needed to
move |
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your bones around. In order to move your bones, two
muscles |
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are needed. One rests while one pulls. There are
actually twice |
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as many muscles as bones. When you do a sit up, you
are using |
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several muscles at one time to lift you upward. The
way that your |
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body does that is the muscles in your stomach and
back rest and |
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pull to pull you up. |
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