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Investigating Digestion and Motion

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Tab 2: Unit Overview and Goals i

CONTENTS

Investigating Digestion and Motion Unit Overview ................ 2

Concept Storyline: Investigating Digestion and Motion.......... 5

Suggested Pacing Guide: Investigating Digestion and Motion .. 6

Investigating Digestion and Motion Unit Goals ...................... 7

UNIT OVERVIEW AND GOALS

2 STC Unit: Investigating Digestion and Motion

INVESTIGATING DIGESTION AND MOTION UNIT OVERVIEWStudents of all ages, but particularly those in secondary school, have a natural curiosity about their bodies and how they work. Investigating Digestion and Motion taps this curiosity by helping students clarify what they already know about their bodies and giving them an opportunity to perform a series of engaging hands-on activities through which they extend and enrich this knowledge.

Investigating Digestion and Motion is divided into two parts: The Digestive System and The Musculoskeletal System. In the first half of the unit, students discover how the organs of the digestive system work together, each organ performing a specific task. Students learn that energy enters the body in the form of food, which must be broken down by the digestive system into a form that can be absorbed into the bloodstream and transported to the body’s cells. As the unit proceeds, students learn that the energy released by the digestive system fuels the movement enabled by the musculoskeletal system. Students’ classroom investigations, coupled with readings about health and medicine, help them recognize the roles these two body systems play in maintaining wellness. As they study how the digestive system and the musculoskeletal system interact, students come to appreciate the flow of energy in living systems.

This unit gives students opportunities to build on skills and concepts presented in previous lessons. As students progress through the unit, they take greater responsibility for their own learning, eventually planning and conducting their own procedures, devising their own data tables, and analyzing the results they obtain.

LESSON-BY-LESSON SUMMARY

PART 1 THE DIGESTIVE SYSTEMLesson 1 is a pre-assessment for the unit. It gives students an opportunity to share what they already know about human body systems and the organs of which they are composed.

Students begin by constructing a human body systems poster that they will revisit in subsequent lessons. Based on their current knowledge, students construct definitions of “organ” and “body system.” As the unit proceeds, students continue to revise their posters to reflect the new information they learn in each lesson.

Lesson 2 serves as an introduction to the digestive system. Students measure and mark the length of the organs of the digestive tract on a long piece of polyvinyl tubing. Working in groups of four, they then simulate peristalsis by squeezing an oiled tennis ball through the tubing. (The tennis ball represents food traveling through the digestive tract.) At the end of the lesson, a reading selection introduces students to “Spies,” a serial reading selection featuring two miniature aliens sent to planet Earth by a group of scientists in another galaxy. Throughout the unit, the two aliens, named Peppi and Bollo, lead students on a narrated tour of the body systems covered in this unit.

In Lesson 3, students use Benedict’s solution and Lugol solution to perform chemical tests for sugar and starch, an activity that prepares them for exploring chemical digestion in the mouth. A reading selection explains how students need to eat appropriate amounts of the right kinds of six types of food nutrients to stay healthy.

Lessons 4 through 7 cover in detail the digestive processes that occur in the mouth, stomach, and intestines. During this sequence of lessons, students explore the digestion of carbohydrates, proteins, and fats and examine how the structure of the inner layer of the small intestine facilitates the absorption of digested nutrients into the bloodstream. Students also explore two mechanisms of absorption—diffusion and active transport. Lesson 4 marks the beginning of a “weaning” process that moves students from a point where they are provided with all the components of a scientific inquiry to one where they must design part or all of an inquiry themselves.

Tab 2: Unit Overview and Goals 3

Lesson 8, the first of two formal assessments, has two parts. The first part is a performance assessment in which students are presented with a problem that involves chemical testing of foods and are challenged to design and conduct an inquiry to solve it. Working in pairs, students choose their materials, design a procedure and data table, conduct the inquiry, record their results, and state their conclusions. In the second part of the assessment, students work individually to complete a series of selected-response items, many of which involve analyzing illustrations of processes or concepts introduced in Lessons 1 through 7. Students also update and revise their human body systems posters.

PART 2 THE MUSCULOSKELETAL SYSTEMPart 2 of Investigating Digestion and Motion, The Musculoskeletal System, deals with how the body uses the energy released by the breakdown of food. Lesson 9 introduces the Exploration Activity, Food Choices and Energy. The Exploration Activity is a research project during which students work in pairs to interpret a Nutrition Facts food label and then design a menu for a balanced meal. Students organize their findings and display them in poster form. When their work is complete, each pair shares its poster with the class in a brief oral presentation. Students are encouraged to use a variety of print, audiovisual, and online resources to research the food items they have selected for their Exploration Activity. A reading selection at the end of the Exploration Activity explores the factors that affect food choices at mealtimes.

Lesson 10, during which students dissect a chicken wing, serves as an overview of the musculoskeletal system. In Lesson 11, students explore the nature of joints, with an emphasis on how muscles, bones, and nerves work together to produce movement. Students examine the relationship between muscle size and strength in Lesson 12, and in Lesson 13, they focus on muscle fatigue. In the culminating inquiry in Lesson 14, students investigate homeostasis as they try to maintain a small quantity of water at average human body temperature for a short period of time.

Following Lesson 14, students present their Exploration Activity to the class. They can also use this time to review for their final assessment.

Lesson 15 is a comprehensive, two-part unit assessment. In the first part, students design and carry out an inquiry to determine how practice affects their reaction time to a visual stimulus. The second part contains selected-response questions that cover the entire unit.

SCIENCE NOTEBOOKS

Students should have a science notebook in which to record their observations, data, conclusions, and answers to questions as well as their own ideas and thoughts as they progress through the inquiries in the unit. Students should come to view their notebook as a resource that they can use throughout the unit. Reviewing observations, data, and information will help them refine their understanding of key concepts and conceptual models. Teachers will find the science notebook to be a valuable assessment tool in tracking student progress in both content knowledge and inquiry skills.

READING SELECTIONS

The STC Program™ incorporates two types of reading selections into each unit to enhance and extend the lesson material. The first type is embedded directly into the procedure of the lesson. Called “Building Your Understanding,” these reading selections provide background information or further explanation of concepts that are critical to a student’s understanding of the inquiry at hand. A second type, “Extending Your Knowledge,” appears at the end of the lessons, extending the concepts of the lesson to the real world, highlighting the application of the concepts in such contexts as science and technology careers, current events, and the history of science and technology. Each of these reading selections is followed by two open-ended questions designed to help students apply the information from the text and extend their thinking.



USING THE ANNOTATED TEACHER EDITION FOR STC–SECONDARY

The Teacher’s Edition for STC–Secondary was developed to support the teacher in every aspect of the unit. Imagine having everything right at your fingertips, yet in an organized and intuitive design. In each lesson, you will find two types of content—pages that support the teacher, and pages that help the teacher support the students.

Teacher-only Content Pages: These pages have no student guide correlation, and appear at the beginning and end of each lesson. Here you will find overview and background information, planning and preparation, common misconceptions, homework and extension activities, and assessment guidelines. These pages guide teachers to obtain and prepare materials and highlight the concepts of the lesson.

Annotated Student Pages: These pages include inset full-color Student Guide pages right in the Teacher’s Edition. This way, you’ll always have the student instructions and reading selections right in front of you. The step numbers for each inquiry correspond one-to-one between the Student Guide step and the annotated wrap of the Teacher’s Edition. The notes in the wrap provide anticipated or best responses, guide teachers in informal assessment, and offer classroom management tips. It is important to remember that the Student Guide explains the procedure while the annotation in the Teacher’s Edition wrap-around support what is presented there.

TEACHER’S TOOLS CD

The CD included with your kit includes PDF files of all the reproducible sheets needed to teach this unit. Blackline masters are grouped by lesson, so finding exactly what you need is fast and simple. If your unit uses chemicals, you’ll also find PDFs of all the MSDS to print and have

on hand in your classroom or the main office. Additional items include English and Spanish versions of the safety contract and any images or diagrams that need to be printed for use with overhead projectors or document cameras.

GLOSSARY

A glossary is included at the back of the Student Guide. It expresses scientific terms and concepts in a more formal language than students may initially use when they talk about or reflect on the inquiries and their observations. Before you introduce students to and have them use the more formal scientific terms, allow them to develop explanations and express their understanding in their own words.


GRADE-LEVEL CONCEPTSUNIT CONCEPTSUNIFYING THEME

SUBCONCEPT 1Body systems are made of organs that work together.

Lesson 1: Human Body Systems—A Pre-assessmentStudents assemble a poster showing the positions and names of several major organs of the body.

SUBCONCEPT 2Digestion begins in the mouth, then continues as food travels through the digestive tract.

Lesson 2: Moving Through the Digestive TractStudents make a model that simulates peristalsis in the digestive tract.

Lesson 3: Exploring CarbohydratesStudents perform chemical tests for sugar and starch.

Lesson 4: Digestion in the MouthStudents explore the role of chewing in the process of digestion.

Lesson 5: Digestion in the StomachStudents discover the actions of hydrochloric acid and pepsin in chemical digestion in the stomach.

SUBCONCEPT 3Digestion ultimately breaks foods down into a form that can be absorbed into the bloodstream and transported to the cells of the body.

Lesson 6: Diffusion and Active TransportStudents investigate how substances move through a membrane by diffusion.

Lesson 7: Surface Area and AbsorptionStudents learn the relationship between surface area and absorption. Students make a model of the small intestine.

Lesson 8: Digestive System—An AssessmentStudents conduct an inquiry that requires them to demonstrate their ability to test for sugar and starch.

SUBCONCEPT 4Choosing the right foods helps the body function more efficiently.

Lesson 9: Exploration Activity—Food Choices and Energy

Students research a Nutrition Facts food label and create a menu for a balanced meal.

SUBCONCEPT 5Muscles and bones, with the help of nerves, use the energy from food to produce movement.

Lesson 10: The Musculoskeletal SystemStudents learn how muscles, tendons, ligaments, and bones work together.

Lesson 11: Joints and MovementStudents discover how joints work to allow varying degrees of movement.

Lesson 12: Muscle Size and StrengthStudents predict and test the relative strengths of three muscle groups of the arm. They assemble and use models to learn about the structure and function of the human arm and spinal column.

Lesson 13: Exploring Muscle FatigueStudents measure the rate at which muscles fatigue during exercise.

SUBCONCEPT 6Each body system plays a role in maintaining a relatively stable internal environment.

Lesson 14: The Body in BalanceStudents perform an activity in which they try to maintain a small quantity of water at a constant temperature for an extended period of time.

Lesson 15: Digestive and Musculoskeletal Systems—Final Assessment

Students design an inquiry that will determine the effect of practice on reaction time. They also answer a series of selected-response items to demonstrate their knowledge of the concepts of the unit.

Concept Storyline: Investigating Digestion and Motion

• The human body contains organs and systems that work together and depend on one another. The structure of each organ enables it to perform its function.

• The digestive system breaks down food that provides energy for life.• The musculoskeletal system uses this energy to enable the body to move.

• Each organ in the digestive system plays a specific role in the breakdown and absorption of foods. • Food provides the energy for movement. • Muscle, bones, and nerves work together to produce movement.


1 Getting Started

Inquiry 1.1 Reading Selection

2 Inquiry 1.1 continued

Reflecting on What You’ve Done Reading Selection

3 Getting Started

Inquiry 2.1



5 Getting Started

Inquiry 3.1 Reading Selection



7 Getting Started

Inquiry 4.1 Reflecting on

What You’ve Done

8 Getting Started

Inquiry 5.1


Reflecting on What You’ve Done

Reading Selections

10 Getting Started

Inquiry 6.1



Reading Selections

12 Getting Started

Inquiry 7.1

13 Inquiry 7.2


Reading Selections

14 Getting Started

Assessment Part 1: Inquiry 8.1

15 Assessment Part 2:

Written Assessment Reading Selection

16 EXPLORATION

ACTIVITY Getting Started

Reading Selection

17 EXPLORATION

ACTIVITY Part 1

(Planning Your Research)

18 Assessment Results


19 Getting Started

Inquiry 10.1



Reading Selections

21 Getting Started

Inquiry 11.1


Reflecting On What You’ve Done

Reading Selections

23 Getting Started

Inquiry 12.1



25 EXPLORATION

ACTIVITY Part 2 (Conducting Your

Research)

26 Getting Started


What You’ve Done

27 EXPLORATION

ACTIVITY Part 3 (In-class work on posters/presentations)

28 Getting Started


What You’ve Done Reading Selection

29 EXPLORATION

ACTIVITY Part 3 (Practice Presentations)

30 EXPLORATION

ACTIVITY Part 3 (Presenting What

You’ve Learned)

31 Getting Started

Assessment Part 1: Designing and

Conducting an Inquiry

32 Assessment Part 2:

Computing Selected-Response Items

33 Assessment Results


34 Open 35 Open

Lesson 12

Lesson 14

Lesson 6

Lesson 7

Lesson 11

Lesson 9

Lesson 13

Lesson 15

Lesson 10

Lesson 8

Lesson 5Lesson 4

Lesson 2 Lesson 3Lesson 1

Suggested Pacing Guide: Investigating Digestion and MotionPacing Guide is based on 40- to 50-minute class periods.




INVESTIGATING DIGESTION AND MOTION UNIT GOALS

The human body is made up of systems, which are made up of organs, which are made up of tissues, which are made up of cells.

Each organ belongs to one or more body systems.

Every human body system contributes to life and health.

Digestion breaks food down into forms that can be absorbed into the bloodstream and transported to the cells of the body.

Food passes through the digestive system by the process of peristalsis.

Food must be broken down mechanically and chemically before it can be delivered to the cells.

The digestive tract is lined with mucus, a slippery secretion that helps food pass through the system and protects the inner walls of the digestive tract.

Carbohydrates, proteins, and fats are the three basic food types.

Carbohydrates are a major source of energy for the body.

Starch and sugar are forms of carbohydrates.

Food can be tested for simple sugar content using Benedict’s solution, which changes color in the presence of simple sugars.

Food can be tested for starch content using Lugol solution, which changes color in the presence of starches.

Mechanical digestion is the process of breaking food into smaller pieces.

Mechanical digestion helps prepare food for chemical digestion.

Chemical digestion is the process of breaking the chemical bonds in nutrients and changing them into simple forms that can be absorbed by the bloodstream.

Enzymes, which are proteins produced by the body, facilitate chemical digestion.

Digestive enzymes are specific; in other words, they act on only one type of nutrient.

Saliva contains salivary amylase, an enzyme that begins the chemical digestion of starch by breaking it into simple sugars.

The chemical digestion of protein begins in the stomach as a result of the action of gastric juice, which is a mixture of pepsin (an enzyme) and hydrochloric acid.

Some enzymes require special conditions to function; for example, the chemical digestion of protein by pepsin can occur only in the acidic environment created by hydrochloric acid.

Digestive enzymes are specific to only one type of nutrient.

Diffusion, or passive transport, is the process by which molecules spread out from places where they are more concentrated to places where they are less concentrated.

Certain substances can pass through a semipermeable membrane by diffusion.

Certain substances pass through a semipermeable membrane only if a living cell supplies the energy, in a process called active transport.

Certain substances cannot pass through a semipermeable membrane.

In this unit, students investigate the digestive and musculosketal systems. Their experiences introduce them to the following concepts, skills, and attitudes:

CONCEPTS




The chemical digestion of food is completed in the small intestine, and nutrients are absorbed.

A calculation of surface area must include all sides of an object.

The amount of nutrients that pass into the bloodstream depends in part on the amount of surface area available for their absorption.

Because humans must absorb large amounts of nutrients to support life activities, their digestive systems have a large surface area.

The small intestine has folds, villi, and microvilli that increase its surface area.

Factors such as time, money, and parental choices play a role in determining the foods we choose to eat.

Eating behaviors, such as eating in the car or while watching television, may influence how much we eat.

A Nutrition Facts label tells consumers the serving size and number of servings per container. It also reveals the number of calories per serving, the Percent Daily Values, and the total amounts of fat, cholesterol, and sodium per serving.

The Percent Daily Value tells consumers how much of the daily recommended amount of each nutrient is contained in each serving of a certain food.

Different foods may contain very different amounts of calories and nutrients.

The serving size on a Nutrition Facts food label may not represent the amount that is typically eaten.

Some foods are too high in some nutrients, and too low in others.

If a meal has too many or too few of certain nutrients, other meals during the day will need to be adjusted.

Some nutrients, such as fats and sugars, are often consumed in excess. Other nutrients, such as certain vitamins, may be underrepresented in many daily diets.

Muscles and bones work together to enable us to stand erect; our eyes assist us in balance.

A chicken’s wing is similar to a human arm, containing four types of tissues: muscle, nervous, epithelial, and connective.

Connective tissue includes tendons, ligaments, and bone.

Bones and joints work together to enable the human body to move in many different ways.

Fibrous joints allow for little or no movement.

Synovial joints can move freely; they allow for different types of movement.

Skeletal muscles work together in opposing pairs to move bones in various ways.

The size of a muscle group may be an indicator of its strength.

The force exerted by muscles is a measure of their strength.

Skeletal muscles become fatigued from sustained activity.

Skeletal muscles become fatigued from repetitive activity.

The human body can maintain a stable internal environment.

The human body responds to changes in the external environment by making internal adjustments.

Homeostasis is the ability of an organism to maintain a relatively stable internal environment.

The nervous, excretory, and circulatory systems play major roles in maintaining a constant body temperature in warm-blooded animals.


Developing an interest in investigating processes and structures in the digestive system and the musculoskeletal system.

Recognizing the importance of food nutrients in maintaining good health.

ATTITUDES

Performing experiments that simulate functions of the digestive system.

Performing chemical tests for starch and sugar.

Devising data tables.

Recognizing the relationship between food nutrients and good health.

Designing and performing an inquiry.

Comparing and contrasting digestion in the mouth and digestion in the stomach.

Calculating the surface area of an object.

Building a model of the small intestine.

Recognizing the relationship between surface area and nutrient absorption in the small intestine.

Communicating results through writing and with graphs.

Interpreting Nutrition Facts food labels.

Selecting foods to create a balanced meal.

Performing experiments and using models to learn how bones and muscles work together.

Reflecting on experiences with body systems through writing and discussion.

Sharing the results of research with the class.

Designing and creating a poster to show research results.

Reading to obtain more information about the digestive system and the musculoskeletal system.

SKILLS

STC Life Science Strand: Life on Earth i

PART 1 THE DIGESTIVE SYSTEM

Lesson 1 Human Body Systems—A Pre-assessment

Lesson at a Glance ..................................................................... 1-A

Galen—The Gladiators’ Doctor ...................................................... 4Inquiry 1.1 Human Body Mapping ...................................... 5

Humans—The Problem-Solving Animals ...................................... 8

Lesson 2 Moving Through the Digestive Tract


Inquiry 2.1 Moving Right Along .......................................... 15

Spies: All Systems Go! .................................................................... 18

Lesson 3 Exploring Carbohydrates


Inquiry 3.1 Testing Foods for Sugar and Starch .............. 23

What Is a Water Bath? .................................................................... 23

Nutrients: You Just Can’t Live Without ‘Em .................................... 27

Lesson 4 Digestion in the Mouth


Inquiry 4.1 Exploring Chemical Digestion

in the Mouth ............................................................37

Where’s the Starch? ........................................................................ 40

Spies: Into the System ................................................................... 42

CONTENTS

INVESTIGATING DIGESTION AND MOTION

ii STC Unit: Investigating Digestion and Motion

Lesson 5 Digestion in the Stomach


Inquiry 5.1 Exploring Chemical Digestion

in the Stomach ................................................... 47

Chance of a Lifetime ............................................................................. 50

Spies: Into the Blender .................................................................. 51

Lesson 6 Diffusion and Active Transport


Inquiry 6.1 Spreading Out and Through ........................... 57

Diffusion and Active Transport: Getting From Here to There ....... 62

Making It Simple ........................................................................... 64

Spies: The Long and Winding Tube ............................................... 66

Lesson 7 Surface Area and Absorption


Inquiry 7.1 Increasing the Surface Area

of a Clay Cube ................................................... 71

Inquiry 7.2 Modeling the Inside Surface

of the Small Intestine ....................................... 72

Surface Area: Your Intestine Isn’t Small at All ................................ 75

Spies: Leftovers ............................................................................. 77

Lesson 8 The Digestive System—An Assessment


Inquiry 8.1 Which Solution Has the Enzyme? ................... 82

PART 2 THE MUSCULOSKELETAL SYSTEM

Lesson 9 Exploration Activity—Food Choices and Energy

Lesson at a Glance ..................................................................... 83-C

Part 1: Introducing the Exploration Activity:

Planning Your Research .............................................. 86

STC Life Science Strand: Life on Earth iii

Part 2: Conducting Your Research ........................................... 87

Part 3: Presenting What You’ve Learned ............................... 88

Eating Right ................................................................................... 89

Looking Good, Feeling Better ........................................................ 94

Lesson 10 The Musculoskeletal System—An Overview


Inquiry 10.1 Winging It ......................................................... 101

Life in the Bone Zone ..................................................................... 105

Spies: Two Working as One ............................................................ 109

Lesson 11 Joints and Movement


Inquiry 11.1 Exploring Joints with Models ......................... 115

Skin: Your Body’s Custom-Made Wrap ........................................... 120

Spies: What Kind of Joint Is This? ................................................... 124

Lesson 12 Muscle Size And Strength


Inquiry 12.1 Investigating Muscle Size and Strength .........131

Anabolic Steroids—Not Worth the Risk ........................................ 136

Lesson 13 Exploring Muscle Fatigue


Inquiry 13.1 Working Against Fatigue ............................... 141

Repetitive Stress Injury: Too Much of the Same Old Thing .............. 143

Spies: Who’s In Charge? .........................................................................145

Lesson 14 The Body in Balance


Making Adjustments ..................................................................... 151

Inquiry 14.1 Maintaining a Balance .................................... 152

Lie Detectors: Tracking Reactions ................................................. 155

Spies: Back Home ..................................................................................157

INVESTIGATING DIGESTION AND MOTION

iv STC Unit: Investigating Digestion and Motion

Lesson 15 Final Assessment—Digestive And Musculoskeletal Systems


Part 1 ................................................................................................ 162

Part 2 ................................................................................................ 162-B

Reflex Actions: Ready or Not, Here They Come! ............................ 164

STC Life Science Strand: Life on Earth v

LESSONMOVING THROUGH THE DIGESTIVE TRACT

GETTING STARTED INQUIRY 2.1Moving Right Along

OBJECTIVES Discuss the purpose of the digestive processes.

Build a model of the digestive tract.

Investigate how food moves through the digestive tract.

Explore the function of mucus in the digestive tract.

CONCEPTS Digestion breaks food down into forms that can be absorbed into the bloodstream and transported to the cells of the body.

Food passes through the digestive system by the process of peristalsis.

Food must be broken down mechanically and chemically before it can be delivered to the cells.

The digestive tract is lined with mucus, a slippery secretion that helps food pass through the system and protects the inner walls of the digestive tract.

OVERVIEW Students discuss how they think food moves through the digestive tract and what happens to the food as it moves along.

Students measure and mark the length of the organs of the digestive tract on a piece of polyvinyl tubing, then simulate peristalsis by squeezing an oiled tennis ball through the tubing.

KEY TERMS Digestive tract Mucus

Peristalsis

Sphincter

TIME 0.25 period 1.5 periods

CORRELATION TO NATIONAL

SCIENCE STANDARDS

Content Standard A• Understanding about scientific inquiry

Content Standard C• Structure and function in living systems

Content Standard A• Abilities necessary to do scientific inquiry


11-A STC Unit: Investigating Digestion and Motion

LESSON AT A GLANCE

READING SELECTION

Spies: All Systems Go! Students are introduced to Peppi (the teacher) and Bollo (the student), two miniature extraterrestrial visitors who will journey through the human body.

By becoming very small, the imaginary Peppi and Bollo can travel inside the body for a first-hand look at human anatomy and physiology.

“Spies: All Systems Go!” Peppi and Bollo get ready for their trip through the body.

Digestive system

Musculoskeletal system

0.25 period


TEACHER’S NOTES

STC Life Science Strand: Life on Earth 11-B

MOVING THROUGH THE DIGESTIVE TRACTLESSON

OVERVIEW

In Lesson 1, students discussed what they know about human body systems and some of the major organs of the body. In this lesson, they focus on the digestive system. They explore how food moves through the digestive tract by means of peristalsis. This inquiry provides a foundation for the next five lessons, in which students will investigate what happens to food as it moves through the mouth, esophagus, stomach, small intestine, and large intestine.

BACKGROUND

The purpose of digestion is to break food down into forms that can be absorbed into the bloodstream and transported to the cells of the body. Digestion is not a single activity, but a series of processes. These processes are mechanical and chemical.

• Mechanical digestive processes include the tearing and grinding action of the teeth, the mixing and mashing action of the tongue, the churning of food by the muscles that line the walls of the digestive tract, and the breaking down of large fat droplets into smaller ones through the action of bile.

• Chemical digestive processes are a series of actions that break down the chemical bonds in nutrients so that they can be absorbed into the bloodstream. Chemical digestion is accomplished by the digestive enzymes.

The distinction between mechanical and chemical digestion is not always clear-cut. You may simply tell students that mechanical digestion prepares food for the more complex process of chemical digestion.

The human digestive tract (see Figure 2.1) is a single, convoluted tube that is about 8 to 10 meters (m) long. Its walls are composed of an inner layer of circular muscle that is surrounded by a layer of longitudinal muscle. (The stomach has a third layer, composed of diagonal muscle.) These muscular layers are held together by connective tissue and are covered and protected by epithelial tissue.

The circular and longitudinal layers of muscle work together to produce wavelike motions that push food slowly through the digestive tract and help break it down into smaller and smaller particles. This wavelike motion is called peristalsis. Although the force of gravity has a minor role in the passage of food through the digestive tract, peristalsis provides the major push. The peristaltic contractions are so strong that food would continue to move forward through your digestive tract even if you were standing on your head!

Sphincters provide another muscular activity that is essential to digestion. These rings of thickened muscles facilitate the passage of food from one area of the digestive tract to another. They usually ensure that food continues to move in one direction. Sphincter muscles are found at the openings of the digestive system: the lips and anus. Other sphincter muscles are located at points where two digestive organs meet (for example, between the esophagus and the stomach).

11-C STC Unit: Investigating Digestion and Motion

A SIMPLIFIED ILLUSTRATION OF THE HUMAN DIGESTIVE TRACT AND THE DIGESTIVE PROCESSES.FIGURE 2.1

Pharynx (back of mouth)

Food enters mouth

Within two hours, the pyloric sphincter opens to release chyme, a little at a time, into the small intestine.

Appendix

Esophagus. The journey from the mouth to the stomach takes approximately six seconds.

The stomach fills as food is swallowed. Food may remain in the stomach up to 4 ½ hours.

Within 4–12 hours, digested nutrients are being absorbed into the bloodstream.

Within 18 hours, excess water usually passes back into the bloodstream, leaving solid waste (feces).

The solid waste usually takes between 12 and 24 hours to move through the large intestine and to be eliminated through the anus.

STC Life Science Strand: Life on Earth 11-D


The sphincters control the passage of food from one area to another. For example, the pyloric sphincter (see Figure 2.2) helps regulate the passage of food into the small intestine.

Mucus, a slippery secretion that coats the inner walls of the digestive tract, also facilitates the movement of food. In addition, mucus protects the stomach and small intestine from being damaged by acidic gastric juices and other digestive enzymes.

Most digestive activity occurs in the duodenum, the first 25 centimeters (cm) of the small intestine. The entire small intestine is about 6 to 8 m long. Many complaints about stomachaches, as well as the digestive noises we commonly refer to as “stomach growling,” are actually the result of discomfort or movement in the small intestine.

Several accessory organs (see Figure 2.3), including the liver, pancreas, and gall bladder, complement the organs of the digestive tract. The salivary glands, located in the mouth, are also accessory organs of digestion. Although students will not study these organs through inquiry in this unit, they will read about them and learn about their roles in digestion.

By the time food substances reach the large intestine, digestion and absorption of nutrients have already been completed. All that remains is undigested waste. When these waste materials enter the large intestine, they contain a large amount of water and electrolytes (watery solutions of acids, bases, or salts). The major activity that takes place in the large intestine is the absorption of water and electrolytes into the bloodstream.

As more water is absorbed, the undigested waste in the large intestine becomes more concentrated. Dead bacteria make up about one-third of these semisolid remains, or feces. Other, living bacteria feed on the undigested wastes and often produce intestinal gases, called flatus. The feces remain in the rectum until they are eliminated through the anus.

In this lesson, students simulate the peristaltic action of the digestive tract by moving an oiled tennis ball through a 10-m plastic tube. The oil on the tennis ball simulates the effect of the mucus.

Pyloric sphincter

Duodenum Inner layer of diagonal muscles

Esophagus

Outer layer of longitudinal muscles

Middle layer of circular muscles

THE STOMACH HAS THREE LAYERS OF MUSCLE: LONGITUDINAL, CIRCULAR, AND DIAGONAL. THE INSET AT THE LEFT OF THE FIGURE SHOWS A TRANSVERSE VIEW OF THE PYLORIC SPHINCTER.FIGURE 2.2

11-E STC Unit: Investigating Digestion and Motion

Esophagus

Pancreas

Stomach

Small intestine

Liver

Gall bladder

Duodenum

Common bile duct and pancreatic duct empty into the duodenum

THE ACCESSORY ORGANS OF DIGESTIONFIGURE 2.3

READING SELECTION

“Spies: All Systems Go!” is the first episode of a serial reading selection that recounts the adventures of Peppi and Bollo, two imaginary creatures who have been dispatched to planet Earth by scientists in another galaxy. The spies’ job is to learn as much as they can about human anatomy and physiology. As they visit various human body systems, Peppi and Bollo provide students with engaging details about human organs and how they work together to perform tasks.

Peppi and Bollo can shrink or expand in size at will, and they take advantage of this remarkable trait to enter the body of a human. During their journey, they discuss what they see; Peppi is the teacher and Bollo is an eager learner.

Episodes of “Spies” appear periodically throughout this unit. The story reinforces and supplements many of the concepts students will investigate and discuss in class. Please help students understand that although the story reads like science fiction, the information it presents about the human body is factual.

STC Life Science Strand: Life on Earth 11-F

LESSONlesson


How can a snake swallow and digest an egg? Humans aren’t capable of feats like tHis. our jaws aren’t flexible enougH, for one tHing. tHe Human digestive system, However, moves food along witH tHe same kind of muscular contractions tHat tHe snake uses.PHOTOS: Bill Bouton

INTRODUCTION

In Lesson 1, you discussed what you know about human body systems and the organs of the body. For the next several lessons, you will focus on one body system—the digestive system. To begin, your group will perform an inquiry that will help you understand how food moves through the digestive tract. It’s a long trip. Even though you are probably about 1.5 meters (5 feet) tall, your digestive tract is approximately 9 meters (30 feet) long!

After the introduction to the digestive system in this lesson, you’ll be ready to take a closer look at what happens in each organ of the digestive system.

MOVING THROUGH THE DIGESTIVE TRACT

PREPARATION

1. Prepare a transparency of Figure 2.2 in the Student Guide (SG) on page 15. This can be found on the Teacher’s Tools CD. The figure depicts how to mark the plastic tube.

2. Write the following questions on newsprint or a transparency. Leave space under each question to enter students’ responses.

A. How do you think food moves through the digestive tract?

B. What do you think happens to food as it moves along the digestive tract?

C. Why do you think the digestive tract gets narrower at some places?

3. For each group, coat a tennis ball with oil and place it in a small plastic bag with a fold-and-close top. Place one in each plastic box.

NOTE If you choose to use potatoes in this inquiry, they must be baked and

coated with oil as described on page 7-B.

NOTE Lesson 3 requires some advance preparation. Refer to page 17-B for

further information.

NOTE This lesson takes about 90 minutes to complete. Regardless of whether your students will complete it in one 90-minute period or two 45- to

50-minute periods, you should probably not plan any administrative tasks during this lesson. If your class period is 45 to 50 minutes long, choose a cutoff point for the first half of the inquiry. For example, you may find that students will be able to complete “Getting Started” and mark their plastic tubing during a 45- or 50-minute class.


STC Life Science Strand: Life on Earth 13

MATERIALS FOR LESSON 2For your group 1 plastic box 1 long piece of plastic

tubing 1 pair of scissors 1 black marker 1 tennis ball (soaked in oil

and stored in a fold-and-close-top plastic bag)

1 measuring tape 1 large plastic storage bag 1 plastic storage bag with

a fold-and-close top for receiving the tennis ball

OBJECTIVES FOR THIS LESSON

Build a model of the digestive tract.

Investigate how food moves through the digestive tract.

Discuss the purpose of the digestive processes.

Explore the function of mucus in the digestive tract.

MATERIALS FOR LESSON 2For the teacher 1 trash bag (large)* 1 container of vegetable

oil 8 plastic storage bags with

fold-and-close tops 8 tennis balls (or baked

potatoes*) 1 piece of newsprint or

transparency* 1 marker* 1 transparency of Student

Guide Figure 2.2*

For each group of 4 students 1 plastic box with lid 1 polyvinyl tubing,

9.3 m 1 pair of scissors* 1 black marker 1 tennis ball (soaked

in vegetable oil and placed in a small plastic storage bag with fold-and-close top)

1 measuring tape, 150 cm

1 plastic resealable storage bag, large, 22.9 × 30.5 cm (9 × 12 in)

1 plastic storage bag with fold-and-close top to receive the tennis ball

*Needed but not supplied


LESSON lesson xx

GETTING STARTED

1

Write the following questions in your science notebook. Leave several lines of space between each question. Then answer the questions.

A. How do you think food moves through the digestive tract?

B. What do you think happens to food as it moves through the digestive tract?

C. Why do you think the digestive tract gets narrower at some places? (See Figure 2.1.)

2

Discuss your answers with your group. Agree on a single answer to each question. Select a spokesperson to present your group’s answers to the class.

3

Listen as each group shares its answers. Add any new ideas that you think are important.

a simplified drawing of tHe Human digestive tract FIgurE 2.1


MoVInG THRoUGH THe DIGesTIVe TRACTlesson 2

GETTING STARTED

1. Direct students’ attention to the questions from the Student Guide that you have recorded on newsprint. Tell students to take a few minutes to brainstorm answers to these questions. They should record their answers in their science notebooks.

2–3. Students should discuss their ideas with their group. Ask a spokesperson from each group to share that group’s ideas with the class. Record all responses on the newsprint or transparency. (The class will take a second look during “Reflecting on What You’ve Done.)


STC Physical Science Strand: Energy in our World 15

INQUIRY 2.1

MOVINg RIgHT ALONg

PROCEDURE

1

Select one person to pick up the plastic box of materials for your group. Listen as your teacher reviews the procedure for the inquiry.

2

Place the plastic tubing on a flat surface. Unroll about 40 cm of the tube.

3

Using Table 2.1 and Figure 2.2 for guidance, measure and mark on the tubing the approximate length of each organ of the digestive tract. Start at the opening of the tube, which represents the opening of the mouth. The mouth is about 11 cm long; therefore, you should place your first mark 11 cm from the opening of the tube. Use that mark as a starting point, then measure 25 cm more, which will represent the esophagus. Continue measuring and marking until you reach the mark for the anus, the opening at the end of the rectum. Double-check your measurements to make sure they are correct. Cut off any extra tubing.

TABLE 2.1 LENgTh OF ThE ORgANS OF ThE DIgESTIvE TRACT

ORgAN LENgTh (CM)

MOUTh 11

ESOPhAgUS 25

STOMACh 22

SMALL INTESTINE 690

LARgE INTESTINE 152

RECTUM 14

How to mark tHe tubing FIgurE 2.2


B. When putting the ball in the tube, students should not touch the ball directly with their fingers. They should manipulate the ball through the bag. If their fingers get greasy, they will find it very hard to squeeze the ball through the tube.

C. Students should keep the tube horizontal at all times.

D. Each student in a group of four should squeeze the ball through approximately 2 m of the tube. This will give everyone an opportunity to participate.

E. The student at the far end of the tube should have an empty plastic bag into which to squeeze the ball.

F. To clean up at the end of a 45- or 50-minute class, have students put the tubing in the large plastic storage bag. Have them write their names on the bag with the marker, give the bag to you, and return their plastic boxes to the materials center.

To clean up at the end of the inquiry, have students dispose of the plastic tubing in the large trash bag and return their other supplies to the materials center.

2–8. Have students start the inquiry. Remind them to discuss the questions in Step 7 as they proceed.

INQUIRY 2.1

PROCEDURE

1. Ask students to collect their materials, and then follow along as you review the procedure for this inquiry in the Student Guide. Emphasize the following points:

A. The numbers in Table 2.1 of their guide indicate the length of each organ, not the cumulative length of the organs. For example, the esophagus is 25 cm long and the

stomach is 22 cm long. Students should place the first mark 11 cm from the opening of the tube; this indicates the approximate length of the mouth. Using that mark as a starting point, they should then measure 25 cm and make a second mark for “Esophagus.” Beginning at the mark they have made for the esophagus, they should then move on to “Stomach.” They should continue this process until they have made the mark for the end of the rectum.


LESSON

4

Using the marker, label each space on the tube with the name of the appropriate organ.

5

Pick up the tube, the plastic bag with the tennis ball, and the empty plastic bag. Move with your group to an uncrowded area of the room. Have all group members space themselves out at equal distances along the length of the tube. The first person in the group should have the bag with the ball, and the last person in the group should have the empty bag.

6

Have the student who is holding the end of the tube that is marked “Mouth” squeeze the tennis ball from the plastic bag into the end of the tubing, as illustrated in Figure 2.3. Squeeze the ball gently into the tube. Be careful not to touch the greasy ball!

How to put tHe ball into tHe tubeFIgurE 2.3

Insert the open end of the plastic bag into the tubing.

Squeeze the tennis ball from the plastic bag into the tubing.

remove the plastic bag from the tubing.

Inquiry 2.1 continued



NOTE Consider displaying one of the tubes on a wall in your classroom. Encourage students to refer to it as they progress through this part of

the unit. Make sure the organs are clearly labeled. The opportunity to see the tube gives students an appreciation of the total length of the digestive tract and the relative size of each organ.

TEACHER’S NOTES


7

Taking turns, move the tennis ball through the tube. Be sure to keep the tube horizontal at all times. Give everyone a chance to squeeze. While you are squeezing, think about the following questions:

A. What does the tennis ball represent?

B. Why do you think the tennis ball was soaked in oil?

8

Continue squeezing until the ball pops out of the tube into the plastic bag.

9

Follow your teacher’s instructions for cleanup.

ReFleCTInG ON WHAT YOu’VE DONE

1

2

3

With your group, revisit the questions you answered in “getting Started” and the questions in Step 7 of the Procedure. Make revisions if necessary. Share your thoughts with the class.

In what way is the tennis ball different from food as it moves through the digestive tract?

What would you like to know about your digestive system? About nutrition or diet? Make a list in your science notebook. You’ll revisit these questions at the end of this part of the unit.


9. Direct students to follow the clean-up procedures you outlined in the beginning of class.

REFLECTING ON WHAT YOU’VE DONE1. Discuss the answers to the questions that appear in “Getting Started” and in Procedure Step 7 of the Student Guide.

“Getting Started”A. Food moves through the digestive tract by the squeezing action of circular and longitudinal muscles (peristalsis). Students may suggest that they simulated this squeezing action because their

help make sure that food moves through the system in only one direction. Sphincter muscles are found between organs. They are also found at the two openings of the digestive tract, the lips and the anus.

Procedure Step 7A. The tennis ball represents swallowed food.

B. The vegetable oil simulates mucus, a slippery substance that coats the lining of the walls of the digestive tract. Mucus permits food to move more easily and protects the lining of the digestive tract from the digestive enzymes.

2. Students may suggest such differences as, the ball stays the same size, food particles would get smaller, or the chemical composition of food would change.

3. Ask students to think about what they would like to learn about digestive processes, the organs of digestion, and food and nutrition. Have them write the questions in their science notebooks. Note that you will revisit the lists at the end of this part of the unit.

hands squeezed not only down the tube but also around it.

B. The food is broken down into smaller and smaller particles. The breakdown is caused by digestive juices as well as by the squeezing action of the muscles.

C. These narrow places are called sphincters. They are muscles that control the passage of food through the digestive system. They also



Period 1Ask students to read “Spies: All Systems Go!” on pages 18–19 and be prepared to discuss the questions.

Period 2Ask students to read the section on carbohydrates in “Nutrients: You Just Can’t Live Without ’Em,” on pages 27–33.

EXTENSIONS

Language Arts1. Have students research the derivations and meanings of the names of the digestive organs. For example, the word “esophagus” comes from the Greek words osein (meaning “to be going to carry”) and phagein (meaning “to eat”). Then have them try to find other words in English that contain the root words.

Science2. Have students find out why snakes can ingest and swallow objects whose diameter greatly exceeds their own. Have students compile their findings, and include images where possible.

Health/Science3. Ask students to research how laxatives and antidiarrhetics work.

Science4. Ask students to devise a means of adding simulated sphincters to the model of the digestive tract that they used during Inquiry 2.1. What common household or office objects could they use to narrow the passages between organs?

HOMEWORK

17-A STC Unit: Investigating Digestion and Motion

ASSESSMENT

Because this is an introductory lesson, it is recommended that you grade students based on how well they contributed to the class discussion, how they cooperated in their groups, and how much effort they made to answer the written questions.

PREPARATION FOR LESSON 3

Directions for preparing and distributing chemicals can be found in the materials kit. Check the Materials List and Preparation section for Lesson 3 and prepare the containers of foods and chemicals you will need. Label any containers that are not already marked.

TEACHER’S NOTES

STC Life Science Strand: Life on Earth 17-B

LESSON

READING SELECTION exTenDInG yoUR knowleDGe

In this unit, you’re going to explore something that’s very familiar to you: the human body. You will be learning about the digestive system and the musculoskeletal system.

Even though you already know a good deal about your body, you are probably in for a few surprises. Learning about your body and how it functions is important, because it can give you the information you need to take good care of your health.

In class, you’ll be doing investigations to help you understand how the body functions. For example, you’ve already begun to explore how food moves through the digestive tract.

SpieS: All Systems Go!

peppi and bollo take a look at tHeir destination: planet eartH.




exTenDInG yoUR knowleDGe

bollo won’t Have time to play soccer or listen to cds on His mission. but He will need some scientific equipment (and maybe a tootHbrusH).

SCIENCE FICTION ThAT’S LOADED WITh FACTSYou will also be reading about the organs and systems of the body. Some of the reading selections in this unit are part of a series entitled “Spies.” In this series, you’ll follow the adventures of Peppi and Bollo, two creatures who have been sent to planet Earth by scientists in another galaxy. Peppi is in charge. Bollo is her pupil at the Intergalactic University of Saganova. His main job is to ask questions and take good notes.

Once they’ve completed their mission, Peppi and Bollo will return to mission control. The scientists who hired them want to learn everything they can about the human body. Then, the scientists hope to use all their data to design a perfect human body.

Peppi and Bollo have the ability to make themselves (and anything they are wearing or carrying) very small—so small that they can travel through a human body without being detected! They’re well-equipped for the journey. In their backpacks are powerful magnifying lenses and other scientific equipment. They are also carrying a famous textbook called Gray’s Anatomy (just in case Peppi has a lapse of memory).

Peppi and Bollo have a little more work to do to prepare for their journey. You’ll see them again in Lesson 4. Until then, enjoy these introductory lessons that will prepare you for your own journey through the human body. n

1. What might be some advantages and disadvantages of exploring the human body from the inside, as Peppi and Bollo are doing?

2. Hundreds of thousands, if not millions, of experiments on human body function have already been done by very smart and careful scientists. Why is it useful for you to conduct more experiments during this unit rather than just read about the experiments that were already done?

DIsCUssIon QUesTIons

to be continued...



investigating digestion and motion proteins, and fats and examine how the structure of the inner...

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