3. Cells to Systems.pdf

by Erika Alexander

Scott Foresman Science 5.2

Genre Comprehension Skill Text Features Science Content

Nonfi ction Draw Conclusions Labels

Captions

Diagrams

Glossary

Cells to Systems

ISBN 0-328-13919-X

Vocabularycell membrane

cell wall

chloroplast

cytoplasm

nucleus

organ

organ system

tissue

vacuole

What did you learn?

1. What are some things that cells need that you need too?

2. Why do nerve cells have long, branching shapes?

3. Name three important jobs that your bones do.

4. Every cell in your body needs food. On your own paper, write to explain how the food gets to each of your cells.

5. Draw Conclusions Your bones and muscles work to let you move. What do you think would happen if you didnt have any bones? or if you didnt have any muscles?

Illustrations: Title Page, 5, 7, 9, 12, 15 Leonello CalvettiPhotographs: Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R) Background (Bkgd)Opener: Dr. Fred Hossler/Visuals Unlimited 2 (BR) Dr. Fred Hossler/Visuals Unlimited, (Bkgd) Michael Webb/Visuals Unlimited; 6 (BL) Dr. Dennis Kunkel/Visuals Unlimited, (BC, BR) David Phillips/Visuals Unlimited; 7 (CL) Susumu Nishinaga/Photo Researchers, Inc., (CR) RDF/Visuals Unlimited, (CL) Dr. Dennis Kunkel/Visuals Unlimited; 8 (BL) Quest/Photo Researchers, Inc., (CR) Veronika Burmeister/Visuals Unlimited; 11 (TL) Dr. Fred Hossler/Visuals Unlimited, (CC) Dr. Richard Kessel & Dr. Randy Kardon/Visuals Unlimited, (BL) Dr. Donald Fawcett/Visuals Unlimited

ISBN: 0-328-13919-X

Copyright Pearson Education, Inc.

All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to: Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.

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Cells to Systemsby Erika Alexander

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What is inside a cell? Cells and Their Functions

A cell is the smallest living part of any living thing. Some organisms have only a single cell. Animals and plants may have trillions. Most cells are so small they cant be seen without a microscope.

Cells have the same needs as all life forms, and they contain tiny parts to help them meet their needs. Cells need food to survive, just like you. All cells have parts that move inside of them, and some cells can even move on their own. Cells can respond to changes around them, and can even communicate with other cells to get a job done.

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Cells use materials in food to grow and to repair wounds. Cells also need energy. They mix food with oxygen to get energy. This process is called respiration. Carbon dioxide and water are also made by this process. The energy that cells make is used for growing, moving, and dividing into new cells.

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katyResaltado

katyResaltado

katyResaltado

katyTexto escrito a mquina


katyTexto escrito a mquinalas celulas y sus funciones

katyTexto escrito a mquinapueden

katyTexto escrito a mquinano pueden ser vista sin un microscopio

katyTexto escrito a mquina(aayudarlas a satisfacer sus necesidades)

katyTexto escrito a mquinacomo nosotros

katyTexto escrito a mquinatodas

katyTexto escrito a mquina(moverse por ellas mismas)


katyTexto escrito a mquinaheridas

katyTexto escrito a mquinattambien necesitan energia


katyTexto escrito a mquinason hechos por este proceso

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The Parts of Cells All cells have some of the same parts. Each part has a special

job to do. Many of the jobs are similar to the jobs our larger body parts do. For example, you have skin to protect you, a digestive system to process food, and a system of nerves to control everything.

The cell membrane, which surrounds the cell, acts like a gate. It opens to let food and oxygen in and to let wastes out.

The nucleus of a cell contains chromosomes. Chromosomes are made of DNA, a chemical that is shaped like a twisted ladder. The chromosomes carry the information a cell needs to do its job. Each chromosome has sections called genes that carry units of information. Almost every cell in your body has the same genes. These genes pass from one generation to the next in a process called heredity.

Plant cells have some special parts that animal cells do not have. They have a tough cell wall surrounding their cell membrane. This gives plants extra support. They also have chloroplasts, which plants use to make food. Chloroplasts use sunlight to turn water and carbon dioxide into sugar and oxygen. The plant gets its energy from the sugar.

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The Size of CellsCells must be big enough to hold all their parts, but not too

big. If a cell is too big, food and oxygen are not able to reach the middle of the cell fast enough to keep it alive.

Almost every cell nucleus in your body has 46 chromosomes.

Vacuoles sometimes break down and store material. In plant cells, they may store water.

Mitochondria combine oxygen and food to produce energy in the process of cellular respiration.

The cell membrane can be compared to your skin.

Cytoplasm is all the material of the cell between the cell membrane and the nucleus.

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katyTexto escrito a mquinatodas las celulas tienen algunas similares partes


katyTexto escrito a mquinaque hacen las partes mas grandes de nuestro cuerpos

katyTexto escrito a mquinapiel

katyTexto escrito a mquinatodo

katyTexto escrito a mquinaoracion sustantiva / cubre o envuelve a la celula

katyTexto escrito a mquinapuerta

katyTexto escrito a mquinase abre para dejar comida y oxigeno y dejar hechar los desperdicios


katyTexto escrito a mquinadoblado

katyTexto escrito a mquinaescalera

katyTexto escrito a mquinallevar


katyTexto escrito a mquinasu

katyTexto escrito a mquinamyyourhisheritsourtheir

katyTexto escrito a mquinacesi

katyTexto escrito a mquinalos mismos genes

katyTexto escrito a mquinaestos genes pasan de una generacion a la siguientes en un proceso se llama herencia





katyTexto escrito a mquinaellas tiens una pared celular envolviendo su membrana celulsa esto le da a las plantas mas soporte

katyTexto escrito a mquinaellas tienes cloroplastos que las plantas usan para hacer comida

katyTexto escrito a mquinalos cloroplastos usan la luz solar para transformar el ahgua y y dioxido de carbono



katyTexto escrito a mquinala membrana celular es comparado con nuestra piel

katyTexto escrito a mquinacasi todas las celulas de nuestro cuerpotienen 46 cromosomas


katyTexto escrito a mquinala mitocondria combina el oxigeno y la comida par producri energia en el proceso que se llama re respiracion celular


katyTexto escrito a mquinal citoplasma es un material de la celula que puede entrar a la membrana celular y al nucleo



katyTexto escrito a mquinalas vaualas son como una reserva de materiales


katyNota adhesivapoder

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How do cells work together? Types of Cells and Their Work

The shapes of cells help them do different jobs. Some cells have special parts to help them do their job.

Very long cells are called branching cells. Nerve cells have branching shapes to help them send messages through the body. Their great length allows signals to be sent very quickly between different parts of the body.

Cells that have a smooth round shape are called round cells. Red blood cells are round. They act like saucers to pick up and carry oxygen. Their smooth shape helps them move through blood vessels.

A third kind of cell is called a flat cell. These cells join together to cover a surface. A layer of flat cells is very strong yet flexible. Your skin is made of flat cells.

This nerve cell is a branching cell.

This red blood cell is a round cell.

This skin cell is a flat cell.

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Special Cell Structures

Cilia are some other tiny hairlike structures. Cilia wave back and forth to sweep dirt and germs out of your airways.

There are hairlike structures in your ears that bend when sound waves make vibrations. When they bend, nerve signals travel to your brain.

Muscle cells contain long fibers. These fibers can move to make the cell shorter. The fibers are not very strong by themselves. But they work together in each cell. Then many cells work together to make the muscle strong.

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katyNota adhesivajuntas

katyNota adhesivaforma

katyNota adhesivanervio

katyNota adhesivarama


katyNota adhesivaa traves

katyNota adhesivalongitud

katyNota adhesivaentre

katyNota adhesiva

katyNota adhesivarapido


katyNota adhesivaredondo

katyNota adhesivasangre

katyNota adhesivasuave

katyNota adhesivacapa

katyTexto escrito a mquinanuestra piel esta hecha por una cpapa plana de celulas

katyTexto escrito a mquinalos globulos rojos son cellulas redondas


katyTexto escrito a mquinalos nervios son ramas de las celulas


katyTexto escrito a mquinalas celulas de nuestra piel son planas

katyNota adhesivapelos , sensores



katyTexto escrito a mquinalas ondas hacen vibraciones en nuestro cerebro las cuales


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Cells Form TissuesOften the same kind of cells work together to do the same

job. When cells work together, they form a tissue. Nerve cells work together to form nerve tissue. A group of bone cells make up bone tissue.

Tissues Form OrgansTissues join with other tissues to form organs. Your bodys

organs do many important jobs. Your heart, eyes, ears, and stomach are all organs. Your skin is the largest organ you have. Plants have tissues and organs too. Plant organs include stems, roots, leaves, and flowers.

Hair follicleHair forms inside cells in hair follicles. As new cells form, old ones are pushed out. The hair you see is dead tissue.

Sweat gland poreSweat leaves your skin through pores. It then evaporates from your skin, helping to keep you cool.

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Skin Cell TissueSkin cells form in

many layers. The top section alone has about 25 layers! New cells form in the bottom layer and push the other cells outward and away from the blood supply. Cells are dead when they reach the surface. Dead cells simply fall off, but they are always being replaced by new cells from below. It takes about one month for skin cells to be pushed to the surface.

Other Tissues in the SkinYour skin is more than just layers of flat skin cells. Skin has

many tissues working together to do many jobs. Your skin prevents germs from entering your body. It also keeps too much water from leaving. Nerve tissue allows your skin to sense touch, pressure, and temperature. Oil glands make oil that keeps your skin soft. The hair on your skin stands up when you get cold, trapping air next to the skin to keep you warm. This is what we call goosebumps. It is caused by muscles in the skin pulling the hair upright.

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How do organs work together? Organ Systems

In your body, many cells work together in tissues. Many tissues work together in organs. An organ system is a group of organs that work together to perform important jobs for your body.

Bones Form a SystemEach of your bones is an organ. About two hundred

bones work together in your skeletal system. This system supports your body. It also protects other organs from being damaged.

Muscles Work as a SystemYour muscles are part of a system too. The job

of your muscles is to move your body. Your body has about 640 muscles in it. Different muscles work together when your brain tells them you want to run or jump. Sometimes muscles work without your brain telling them to. For example, if you are cold, your muscles might shiver, helping to keep you warm. You shiver without even thinking about it.

Bones work together.This is a cutaway view of where the bone in your leg meets the bone in your hip.

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Bone cellsBetween the bone cells is a hard material that has lots of calcium. This material makes bones hard. Other parts of the body, such as muscles, also use calcium from blood to do their work. Bones store calcium until the level of calcium in the blood is low.

Muscles work together.Squeeze your fist tight. Several muscles work together to make your fingers form a fist. Can you feel the muscles get tight in your lower arm?

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Organ Systems Work TogetherSometimes organ systems need to work together to do more

difficult jobs. Your skeletal system and muscle system need to work together so you can move. Your bones provide support, and your muscles move your bones. You need both systems to move your arm or any other part of your body.

Two or more muscles have the job of moving a bone in opposite directions. Muscles move bones by pulling on them. They never push.

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Other Systems Work TogetherIn your body, many systems must work together. For

example, you know that your muscles work with your bones to make you move. But the muscles would not work if they didnt receive messages telling them what to do. Your nervous system carries these messages from the brain and spinal cord.

Some organs might belong to two organ systems. Your heart pumps your blood, so it is part of the circulatory system. But it is also a muscle, so it is also part of your muscle system. Your bones make up your skeletal system, but they also do an important job for the circulatory system. A soft material called marrow is found inside some of your bones. Marrow makes red and white blood cells for the circulatory system.

Bone marrow

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Muscles Flex and ExtendWhen you bend your elbow, your biceps muscle pulls your

arm up. When you straighten your arm again, your triceps muscles are pulling. Muscles work in pairs to bend your wrist and rotate your arm too.

Triceps

Biceps

Triceps

Biceps

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It is amazing to think about all the work that cells do in your body. Tiny cells work together to form tissues. Tissues team up and make organs. Your organs work with each other and form organ systems. This teamwork is what makes it possible for your body to do all the things you need it to do.

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Glossarycell membrane surrounds the cell and allows things to pass

in and out

cell wall strong wall provides support and protection for plant cells

chloroplast green part of a plant cell that uses energy from sunlight to turn water and carbon dioxide into oxygen and sugar

cytoplasm everything between the cell membrane and the nucleus

nucleus the part of a cell that contains DNA

organ a group of different tissues that join together to do a main job in the body

organ system a group of organs that work together to do an important job

tissue a group of the same kind of cells working together doing the same job

vacuole a cell part that stores and breaks down materials

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Vocabularycell membrane

cell wall

chloroplast

cytoplasm

nucleus

organ

organ system

tissue

vacuole

What did you learn?

1. What are some things that cells need that you need too?

2. Why do nerve cells have long, branching shapes?

3. Name three important jobs that your bones do.

4. Every cell in your body needs food. On your own paper, write to explain how the food gets to each of your cells.

5. Draw Conclusions Your bones and muscles work to let you move. What do you think would happen if you didnt have any bones? or if you didnt have any muscles?

Illustrations: Title Page, 5, 7, 9, 12, 15 Leonello CalvettiPhotographs: Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R) Background (Bkgd)Opener: Dr. Fred Hossler/Visuals Unlimited 2 (BR) Dr. Fred Hossler/Visuals Unlimited, (Bkgd) Michael Webb/Visuals Unlimited; 6 (BL) Dr. Dennis Kunkel/Visuals Unlimited, (BC, BR) David Phillips/Visuals Unlimited; 7 (CL) Susumu Nishinaga/Photo Researchers, Inc., (CR) RDF/Visuals Unlimited, (CL) Dr. Dennis Kunkel/Visuals Unlimited; 8 (BL) Quest/Photo Researchers, Inc., (CR) Veronika Burmeister/Visuals Unlimited; 11 (TL) Dr. Fred Hossler/Visuals Unlimited, (CC) Dr. Richard Kessel & Dr. Randy Kardon/Visuals Unlimited, (BL) Dr. Donald Fawcett/Visuals Unlimited

ISBN: 0-328-13919-X

Copyright Pearson Education, Inc.

All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to: Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.

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