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I]Z =jbVc 7dYn Photo Credits: Cover: Amwell/Getty Images; 5 (bc) Manfred Kage/Peter Arnold, Inc.; 12 (bc) Eye of Science/Photo Researchers, Inc.; 13 (c) Klaus Guldbrandsen/Science Photo Library/Photo Researchers, Inc. If you have received these materials as examination copies free of charge, Harcourt School Publishers retains title to the materials and they may not be resold. Resale of examination copies is strictly prohibited and is illegal. Possession of this publication in print format does not entitle users to convert this publication, or any portion of it, into electronic format. CXENL09ALR4X_BL04_CV.indd 4 1/20/10 9:38:41 AM I]Z=jbVc 7dYn Copyright © by Harcourt, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Requests for permission to make copies of any part of the work should be addressed to School Permissions and Copyrights, Harcourt, Inc., 6277 Sea Harbor Drive, Orlando, Florida 32887-6777. Fax: 407-345-2418. HARCOURT and the Harcourt Logo are trademarks of Harcourt, Inc., registered in the United States of America and/or other jurisdictions. Printed in Mexico ISBN-13: 978-0-15-364950-9 ISBN-10: 0-15-364950-X 2 3 4 5 6 7 8 9 10 805 16 15 14 13 12 11 10 09 08 VOCABULARY tissue organ diaphragm capillary artery vein esophagus stomach =dl9dZh Ndjg7dYn <ZiDmn\Zc VcYCjig^Zcih4 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 2 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. XVe^aaVgn 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 VgiZgn kZ^c 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 H:FJ:C8: When you sequence things, you put them in order. Look for the sequence of how your body gets oxygen and nutrients. I^hhjZhidDg\Vch 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. 7adX`hbV`ZVWj^aY^c\ a^`ZXZaahbV`ZVWdYn# 4 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. BVcnh^b^aVgXZaah[dgbVi^hhjZ# 5 I]Z9^\Zhi^kZHnhiZb 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. I]Zadc\ijWZ i]ViaZVYhidi]Z hidbVX]^hXVaaZY i]ZZhde]V\jh# bdji] Zhde]V\jh hidbVX] hbVaa^ciZhi^cZ EVgihd[i]Z9^\Zhi^kZHnhiZb 6 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. I]Za^c^c\d[i]ZhbVaa ^ciZhi^cZ]VhbVcn [^c\Zga^`Zegd_ZXi^dch! XVaaZYk^aa^#Cjig^ZciheVhh i]gdj\]i]Zi]^clVaahd[ i]Zk^aa^^cidXVe^aaVg^Zh# 7 I]ZGZhe^gVidgnHnhiZb 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. cdhZ bdji] igVX]ZV ajc\h V^ghVXh I]ZijWZi]ViiV`Zh V^gidndjgajc\h^h XVaaZYi]ZigVX]ZV# EVgihd[i]ZGZhe^gVidgnHnhiZb 8 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. I^cnWaddYkZhhZahlgVe VgdjcYi]ZV^ghVXh^ci]Z ajc\h#Dmn\ZcbdkZh[gdb i]ZV^ghVXh^cidi]ZWaddY ^ci]ZhZi^cnkZhhZah# 9 I]Z8^gXjaVidgnHnhiZb 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. idajc\ [gdbajc\ 10 EVgihd[i]Z8^gXjaVidgnHnhiZb XVe^aaVg^Zh ]ZVgi VgiZgn VgiZgn kZ^c kZ^c I]ZgZVgZi]djhVcYhd[ b^aZhd[WaddYkZhhZah ^ch^YZndj 11 7addY 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. l]^iZWaddYXZaa eaViZaZi gZYWaddYXZaa 6h^c\aZYgded[ WaddY]VhbVcnXZaah# 12 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. 7addYXVcWZhZeVgViZY ^cid^iheVgih# Review 8dbeaZiZi]ZhZhZfjZcXZhiViZbZcih# 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 13 VOCABULARY spinal cord bone joint muscle =dl9dZh Ndjg7dYn I]^c`VcY BdkZ4 The spinal cord is a tube of nerves. It runs through your backbone. It takes messages to and from your brain. 14 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 B6>C>9:66C99:I6>AH 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. I]ZCZgkdjhHnhiZb 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. CZgkZXZaah bV`ZjecZgkZh# 16 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. WgV^c he^cVaXdgY cZgkZ 17 H`ZaZiVaHnhiZb 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. WaddYkZhhZah WdcZ 18 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. _d^ci 19 I]ZBjhXjaVgHnhiZb 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. bjhXaZ [^WZg W^XZeh 20 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. NdjgbjhXaZhldg` id\Zi]Zghdi]Vi ndjXVcbdkZ# 21 ?d^cih 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. _d^ci iZcYdc a^\VbZci 22 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 8dbeaZiZi]^hbV^c^YZVhiViZbZci# work together to move the 1. Bones and joints in your body. 8dbeaZiZi]ZhZYZiV^ahiViZbZcih# 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 23 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 > j]Y+6.%3'Z[W