Name:_______________________________________ Date:________________ Period:_________
Muscular System
By Sharon Fabian
Muscles aren't just for bodybuilders. Each one of us has over 600 muscles
that do everything from running and jumping to smiling and frowning. And
that's just the beginning. Muscles allow us to breathe and digest our food.
Muscles keep our blood pumping.
1
There are three main types of muscles -- smooth muscles, cardiac muscles,
and skeletal muscles. Another way to group muscles is into two groups -voluntary and involuntary. Voluntary muscles are the ones that we move when
we want to. Skeletal muscles are voluntary muscles. They include arm and leg
muscles. Involuntary muscles are the ones that keep working on their own
without our having to do anything. Cardiac muscles, which are the heart muscles, and smooth muscles,
including stomach muscles and tiny muscles in the walls of blood vessels, are involuntary muscles.
2
Tendons connect the muscles in your arms to your arm bones. They make your arm move by pulling
on the bone. Muscles can't push; they can only pull. So you have pairs of muscles in your arms. The
muscle on one side pulls your arm bone to lift up. The muscle on the other side pulls to reach down.
Maybe you will recognize some of these muscle names:
deltoids--in your shoulders
pectorals--in your upper chest
abdominals--near your abdomen ( stomach)
biceps--in your upper arms
quadriceps--in your upper legs
3
You also have strong muscles in your back that are good for lifting and pushing. There are muscles
in your neck that let you rotate your head in different directions. In your face, there are lots of little
muscles. You use these to talk, and to make tiny movements that give you different facial expressions.
The tongue is a group of muscles, too.
4
Heart muscles, also called the myocardium, are strong muscles that tighten up to pump blood out of
the heart, and then relax to let blood flow back into the heart after it has made its trip around the body.
Heart muscles are involuntary. They are controlled by your brain and nerves without any effort on your
part.
5
Involuntary muscles in your stomach move your food around to make the digestive process work.
They push food from your stomach into your intestines, and sometimes when you are sick, they push
food back up into your esophagus and you throw up.
6
Involuntary muscles make your eyes blink. You probably don't even notice that you are blinking
most of the time. Scientists have estimated that eye muscles move about 100,000 times each day.
7
Like other parts of your body, muscles are made of cells. The cells that make up a muscle are called
muscle fibers, and there can be hundreds, or thousands, of them in one muscle. Your six hundred and
some muscles make up a large part of your whole body. In fact, up to about half of your total body
weight may be muscle, so it's no wonder that people say you should exercise every day.
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Copyright © 2007 edHelper
Muscular System
1. Muscles are made of _____.
Water
Cells
Minerals
Skin
2. The myocardium is another name for the
_____ muscle.
Stomach
Heart
Lung
Arm
3. Heart muscles are _____.
Involuntary
Voluntary
4. The muscles in your fingers that you move
when you pick up something are_____.
Involuntary
Voluntary
5. Since they work automatically, you can tell
that the muscles in your lungs are _____.
Involuntary
Voluntary
6. The main idea of this article is _____.
Involuntary muscles
Taking care of your muscles
Parts of the muscular system
Arm muscles
7. Which of the following is true?
8. From the article, you can tell that the stomach
muscles are probably _____.
People have about 360 muscles
Some muscles work automatically
Skeletal muscles
Voluntary muscles move the food around
Cardiac muscles
in your stomach
Smooth muscles
Muscles can push and pull
None of the above
9. The muscular system is the organ system which
functions to ___________________________
Muscular System - Answer Key
1
2
3
4
5
6
7
8
Cells
Heart
Involuntary
Voluntary
Involuntary
Parts of the muscular system
Some muscles work automatically
Smooth muscles