Download Human Body - Jackson School District

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ISBN-13: 978-0-15-364950-9
ISBN-10: 0-15-364950-X
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VOCABULARY
tissue
organ
diaphragm
capillary
artery
vein
esophagus
stomach
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A tissue is a body part that
is made up of many tiny
cells. Your skin is a tissue. It
VocabDescription
covers
all of you!
VocabDescription
VocabDescription
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An organ is many tissues
working together. Each
organ in your body has
VocabDescription
a specific job to do. Your
VocabDescription
heart is an organ. So is
VocabDescription
your stomach.
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The diaphragm is a
muscle in your chest. It
pulls air in and pushes it
out. It helps you breathe.
A capillary is a tiny tube
that moves blood. Air
can pass through the thin
walls.
VocabDescription
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An artery is a tube that
moves blood. It is like a
one-way street. It only
carries blood from your
heart.
A vein is another kind of
tube that carries blood.
It is like a one-way street
too. It only carries blood
to your heart.
Your esophagus
is a
VocabDescription
musclar tube connecting
your mouth and stomach.
The stomach is an organ,
shaped like a bag, where
food is digested.
3
READING FOCUS SKILL
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When you sequence things, you put them in order.
Look for the sequence of how your body gets
oxygen and nutrients.
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Have you ever made a model out of blocks? Blocks are
like bricks. They are used to make buildings. The cells in
your body are like building blocks. They make up different
parts of your body.
A tissue is a group of cells that work together. There are
four kinds of tissue. Skin tissue protects your body. Muscle
tissue helps you move. Nerve tissue sends messages
through your body. Connective tissue holds your body
together.
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Tissues work together, too. An organ is a body part. It
is made of different kinds of tissues. They work together
to do a job. Each organ has its own job to do. Skin is the
body’s biggest organ. It protects your insides.
Groups of organs also work together. They make body
systems. Bones make the skeletal system. When you eat,
you use organs in your digestive system.
Tell how cells are organized from a single cell to
a body system.
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The cells in your body need energy. They get it from
nutrients in food you eat. The digestive system breaks
down the food so your body can use it. Here’s how it
works.
You chew food. Your teeth grind it up. Saliva in your
mouth softens it. Then you swallow it. It goes down a
tube, called the esophagus, to your stomach. There,
muscles squeeze and mix the food with other substances.
The food becomes almost liquid.
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Next, the food moves into the small intestine. There
digestive juices break down the food even more. Then,
the nutrients in the food pass into your blood. The blood
carries the nutrients to every cell in your body.
Tell how nutrients in food you eat get to your
body’s cells.
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How does your body get the oxygen it needs? You
breathe it in. The diaphragm is a muscle right under your
lungs. It helps move air into and out of your body.
The air comes through your nose and mouth. Then it
goes down a tube to your lungs. There it goes through
tiny air sacs into your blood. The blood takes the oxygen
to your heart.
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Your heart pumps the oxygen-rich blood through
your body. Cells in the body make a waste called carbon
dioxide. Your body needs to get rid of it. Carbon dioxide is
carried by the blood to the lungs. Carbon dioxide leaves
your body when you exhale.
Tell how oxygen gets into the blood.
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What does the circulatory system do? It carries oxygen,
carbon dioxide, and nutrients to your body’s cells. So it
works with your respiratory and digestive systems. The
heart, blood, and blood vessels make up your circulatory
system.
An artery is a blood vessel. It carries blood away from
the heart. A vein is a blood vessel. It carries blood back
to the heart. A capillary is a blood vessel. It has very thin
walls to let gases through.
Capillaries let carbon dioxide pass into blood. The blood
flows to the heart and then the lungs. It flows through
capillaries in the lungs. Carbon dioxide is released into the
lungs. It leaves your body when you breathe out.
Tell how the circulatory system moves oxygen
in and carbon dioxide out of your body.
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What is blood? It’s tissue. Blood is the body’s only liquid
tissue.
Blood has different kinds of cells. They all move in a
liquid called plasma. The red blood cells carry the oxygen
and carbon dioxide. The white blood cells protect you
from illness. Suppose germs get into your body. Your
white blood cells get to work and try to kill them.
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CXENL09ALR4X_BL04.indd 12
First Pass
12/7/09 12:28:09 PM
Blood also has sticky parts. They are called platelets.
Their job is to stop bleeding. If you get cut, platelets rush
to the spot. They stick together to help stop bleeding.
Tell what happens if someone gets cut.
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Review
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1. After you chew food, it travels through a tube
.
to your
2. Air travels to your lungs through a long tube
.
called the
3. Blood carries away a waste called
.
4. After you get a cut, the sticky parts of the
help stop bleeding.
blood called
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VOCABULARY
spinal cord
bone
joint
muscle
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The spinal cord is a tube
of nerves. It runs through
your backbone. It takes
messages to and from your
brain.
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A bone is a hard organ.
Many bones make up your
skeleton. The bones give
your body its shape.
A joint is where two bones meet. Your
knee has a joint. So you can bend it!
A muscle is a bundle of string-like fibers.
They pull to move body parts.
15
READING FOCUS SKILL
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The main idea is what the text is mostly about.
Details tell more about the main idea.
A main idea is that your body can move. Look for
details that tell more about what makes your body
move.
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Think of your body as a big machine. Your nervous
system is the control center. Your body can’t work
without its help.
Signals from your brain control everything. The brain
is made of billions of nerve cells. It gets messages from
other parts of your body.
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This boy wants to play music. His fingers feel the strings
and send a message to the brain. The messages travel
along the spinal cord. It’s a tube of nerve tissue. It runs
through the backbone to the brain.
The brain gets the message. It goes into action. It sends
a signal back down the spinal cord and tells the boy’s
fingers how to move. He makes music.
Tell the details of how messages get to
the brain.
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A bone is an organ. Its outside is hard and strong. Its
inside has many open spaces.
Bones are really important. Along with your muscles,
bones help hold you up. They give your body a shape.
They help you move. They protect organs inside your
body. Tissue in many bones makes red blood cells.
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A joint is where two bones meet. Most joints can move.
Bones and muscles work together to move a joint. Your
neck has several joints. You can turn your neck. Your
elbow has a joint. It moves like the hinge on a door.
Tell details about what bones do.
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A muscle is a bundle of fibers. Muscles can move parts
of your body. You have three different kinds of muscles.
Skeletal muscles help you move. They work in pairs to
pull bones back and forth. You can control these muscles.
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Cardiac muscle is in your heart. It pumps blood from the
heart by squeezing and relaxing. You don’t control this
muscle. It works on its own.
Smooth muscle is in the walls of organs. These muscles
also work on their own.
Name the three kinds of muscles.
Tell what each does.
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You have many joints in your body. Most joints are
found where bones meet. They help you move from place
to place.
Tough bands of tissue connect the bones at each joint.
These bands are called ligaments. Other tough tissues
connect muscle to a bone. Those tissues are called
tendons.
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Think about what your body does. Bend your elbow.
Turn your head. Write your name. Take a breath. It’s your
wonderful human body in action!
Tell how joints help people move.
Review
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work together to move the
1. Bones and
joints in your body.
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2. Messages travel to your brain along
.
the
3. A
is the place where two bones meet.
4. Cardiac muscles help
heart.
blood from the
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GLOSSARY
artery (ARTsersee) A blood vessel that carries blood away
from the heart
bone (BOHN) A hard organ made of an outer covering tissue
and a softer inside tissue
capillary (KAPsuhslairsee) A blood vessel with very thin walls
that allows oxygen and carbon dioxide to pass through
diaphragm (DYsuhsfram) The muscle in your body that
allows you to inhale and exhale
esophagus (ihsSAHFsuhsguhs) A muscular tube that
connects your mouth with your stomach
joint (JOYNT) A place in the body where two bones meet
muscle (MUHSsuhl) An organ that is made of bundles of long
fibers and works with bones to help you move
organ (AWRsgun) A body part made of different kinds of
tissues that work together to perform a particular job
spinal cord (SPYsnuhl KAWRD) A tube of nerves that runs
through your backbone to your brain
stomach (STUHMsuhk) A baglike organ in which food is
mixed with digestive juices and squeezed by muscles
tissue (TISHsoo) A group of cells of the same type that work
together to perform a certain job
vein (VAYN) A blood vessel that carries blood back to the
heart
24
Think About the Reading
1. Name three body systems. Name the major organs
in each system. Describe what each system does for
the body.
2. Choose two body systems. Explain how they work
together.
Hands-On Activity
Choose one body system. Make a model of an organ found
in the system.
1. Identify the parts of your model. Use it to explain
how the organ works.
2. Explain the importance of the organ and describe
how it helps the body.
School-Home Connection
Tell a family member how the skeletal and muscular
systems help the body move. Identify three types of
muscle and explain where each is found.
GRADE 4
Book 4
WORD COUNT
942
GENRE
Expository NonÞction
LEVEL
See TG or go Online
Harcourt Leveled
Readers Online Database
www.eharcourtschool.com
ISBN-13: 978-0-15-364950-9
ISBN-10: 0-15-364950-X
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