Download pdf - Chapter 35: The Digestive and Endocrine Systems Text...Digestive System (Human Body Series) Our Immune System Teacher’s Corner 946B The Digestive and Endocrine Systems The Digestive

Chapter 35 OrganizerChapter 35 Organizer

Activities/FeaturesObjectivesSection

MATERIALS LIST

BioLabp. 966 blue pencil, red pencil, graphpaper, ruler

MiniLabsp. 957 paper, pencilp. 964 microscope, prepared slide ofthyroid and parathyroid tissue, paper,pencil

Alternative Labp. 950 Lactaid solution, glucose testpaper, glucose solution, milk, gradu-ated cylinder (2), test tubes (4), dropper

Quick Demosp. 948 barium X ray of digestive tractp. 950 dialysis bag (2), starch solution,pancreatic enzyme solution, beaker,distilled water, Benedict’s solutionp. 955 paper grocery bags, assortedfood samples, waterp. 960 human skullp. 961 microprojector, prepared slideof pancreasp. 963 preserved whole kidney

Need Materials? Contact Carolina Biological Supply Company at 1-800-334-5551or at http://www.carolina.com

946A

Teacher Classroom Resources

Assessment Resources Additional Resources

Products Available FromGlencoeTo order the following products,call Glencoe at 1-800-334-7344:CD-ROMsNGS PictureShow: Human Body 1NGS PictureShow: Human Body 2Curriculum KitGeoKit: Human Body 1Transparency SetNGS PicturePack: Human Body 1NGS PicturePack: Human Body 2VideodiscSTV: Human Body

Products Available FromNational Geographic SocietyTo order the following products,call National Geographic Societyat 1-800-368-2728:VideosDigestive System (Human BodySeries)Our Immune System

Teacher’s Corner

946B

The Digestive andEndocrine SystemsThe Digestive and Endocrine Systems

TransparenciesReproducible MastersSection

FollowingDigestion of a Meal

Nutrition

The EndocrineSystem

Section 35.1

Section 35.2

Section 35.3

Teacher Classroom Resources

Reinforcement and Study Guide, pp. 155-156Content Mastery, pp. 173-174, 176Tech Prep Applications, pp. 45-46

Reinforcement and Study Guide, p. 157Concept Mapping, p. 35BioLab and MiniLab Worksheets, p. 155Laboratory Manual, pp. 255-260Content Mastery, pp. 173, 175-176

Reinforcement and Study Guide, p. 158Critical Thinking/Problem Solving, p. 35BioLab and MiniLab Worksheets, pp. 156-158Content Mastery, pp. 173, 175-176 L1

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Section Focus Transparency 84Reteaching Skills Transparency 50

Section Focus Transparency 85Reteaching Skills Transparency 51

Section Focus Transparency 86Basic Concepts Transparency 65

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Assessment Resources Additional ResourcesSpanish ResourcesEnglish/Spanish AudiocassettesCooperative Learning in the Science ClassroomLesson Plans/Block Scheduling

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Chapter Assessment, pp. 205-210MindJogger VideoquizzesPerformance Assessment in the Biology ClassroomAlternate Assessment in the Science ClassroomComputer Test BankBDOL Interactive CD-ROM, Chapter 35 quiz

Refer to pages 4T-5T of the Teacher Guide for an explanation of the National Science Education Standards correlations.

Following Digestionof a MealNational Science EducationStandards UCP.1-3, UCP.5;B.3; C.5; F.1; G.1 (1 session,1/2 block)

NutritionNational Science EducationStandards UCP.2, UCP.3;A.1, A.2; B.2, B.3, B.6; C.5,C.6; F.1 (1/2 session)

The Endocrine SystemNational Science EducationStandards UCP.1-3, UCP.5;A.1, A.2; B.2, B.3, B.6; C.1,C.5, C.6; F.1; G.1 (21/2 ses-sions, 1 block)

1. Recognize the different functions of theorgans of the digestive system organs.

2. Outline the pathway food followsthrough the digestive tract.

3. Interpret the role of enzymes in chemical digestion.

4. Summarize the contribution of the sixclasses of nutrients to body nutrition.

5. Identify the role of the liver in foodstorage.

6. Relate caloric intake to weight loss orgain.

7. Identify the functions of some of thehormones secreted by endocrine glands.

8. Summarize the negative feedbackmechanism controlling hormone levels in the body.

9. Contrast the actions of steroid andamino acid hormones.

Inside Story: Your Mouth, p. 949Problem-Solving Lab 35-1, p. 952

MiniLab 35-1: Evaluate a Bowl of Soup, p. 957Problem-Solving Lab 35-2, p. 958Biology & Society: The Promise of WeightLoss, p. 968

Problem-Solving Lab 35-3, p. 962MiniLab 35-2: Compare Thyroid andParathyroid Tissue, p. 964Investigate BioLab: Average Growth Rate inHumans, p. 966

Section 35.2

Section 35.1

Section 35.3

Key to Teaching StrategiesKey to Teaching Strategies

Level 1 activities should be appropriatefor students with learning difficulties.Level 2 activities should be within theability range of all students.Level 3 activities are designed for above-average students.ELL activities should be within the abilityrange of English Language Learners.

Cooperative Learning activitiesare designed for small group work.These strategies represent student prod-ucts that can be placed into a best-workportfolio.These strategies are useful in a blockscheduling format.

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The following multimedia resources are available from Glencoe.

Biology: The Dynamics of LifeCD-ROM

Video: X-Ray of SwallowingBioQuest: Body SystemsExploration: Nutrition

Videodisc ProgramX-Ray of Swallowing

The Infinite VoyageA Taste of Health

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http://www.carolina.com

Section

Functions of theDigestive System

The main function of the digestivesystem is to disassemble the food youeat into its component molecules sothat it can be used as energy for yourbody. In this sense, your digestivesystem can be thought of as a sort ofdisassembly line.

Digestion is accomplished througha number of steps. First, the systemtakes ingested food and begins mov-ing it through the digestive tract. Asit does so, it digests—or breaks downmechanically and chemically—thecomplex food molecules. Then, thesystem absorbs the digested food anddistributes it to your cells. Finally, iteliminates undigested materials fromyour body. As you read about eachdigestive organ, use Figure 35.1 tolocate its position within the system.

35.1 FOLLOWING DIGESTION OF A MEAL 947

Eating is something you probablyspend a lot of time thinkingabout—what you will eat,

when you will eat, and who you willeat with. Your digestive system helpsturn food into energy for your body.As in many animals you havestudied, the human digestivesystem is essentially a special-ized tube that has evolvedover millions of years to formdigestive organs, each of whichperforms a unique function.

SECTION PREVIEW

ObjectivesRecognize the differ-ent functions of thedigestive system organs.Outline the pathwayfood follows throughthe digestive tract.Interpret the role ofenzymes in chemicaldigestion.

Vocabularyamylaseesophagusperistalsisepiglottisstomachpepsinsmall intestinepancreasliverbilegallbladdervilluslarge intestinerectum

35.1 Following Digestion of a Meal

Salivaryglands

Mouth

Teeth

TonguePharynx

Esophagus

Pancreas

Stomach

Diaphragm

Smallintestine

RectumAnus

Largeintestine

Appendix

Liver

Gallbladder

Figure 35.1All the digestive organswork together to breakdown food into simplercompounds that can beabsorbed by the body.

These gastric pits in thestomach secrete acidneeded for digestion.

Magnification: 55�

947

Section 35.1

BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES

Use with Chapter 35,Section 35.1

What parts of the digestive system perform functions similar tothe devices shown?

What do you think is the overall function of the digestive system?

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PrepareKey ConceptsThe structures and functions ofthe organs of the digestive systemare presented as students follow ameal through the digestive tract.

Planning■ Acquire old barium X rays for

the first Quick Demo.■ Prepare materials for the sec-

ond Quick Demo.■ Purchase milk and Lactaid for

the Alternative Lab.

1 FocusBellringer Before presenting the lesson,display Section Focus Trans-parency 84 on the overhead pro-jector and have students answerthe accompanying questions.

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Assessment PlannerAssessment PlannerPortfolio Assessment

Portfolio, TWE, pp. 949, 964Alternative Lab, TWE, pp. 950-951Problem-Solving Lab, TWE, p. 958Assessment, TWE, p. 957BioLab, TWE, pp. 966-967

Performance AssessmentMiniLab, SE, p. 964Alternative Lab, TWE, pp. 950-951

Problem-Solving Lab, TWE, p. 952MiniLab, TWE, pp. 956, 964

Knowledge AssessmentSection Assessment, SE, pp. 953, 958, 965Chapter Assessment, SE, pp. 969-971Assessment, TWE, pp. 956, 965Problem-Solving Lab, TWE, p. 962

Skill AssessmentAssessment, TWE, pp. 951, 953, 961

The Digestive andEndocrine Systems

What You’ll Learn■ You will trace the journey of

a meal through the digestivesystem.

■ You will recognize differentnutrients and their uses inthe body.

■ You will outline howendocrine hormones controlinternal body processes.

Why It’s ImportantBy examining the functions ofyour digestive and endocrinesystems, you will understandhow your body obtains energyfrom food and how it controlsyour behavior and development.

Initiating DigestionBite into a cracker. What is hap-pening to the cracker in yourmouth as you chew? Can youdescribe the movement of thecracker through your digestivesystem?

To find outmore about

digestion and the endocrinesystem, visit the GlencoeScience Web Site. www.glencoe.com/sec/science

35

GETTING STARTEDGETTING STARTED

ChapterChapter

These projections, called villi,line the walls of your smallintestine, absorbing food parti-cles as they pass by.

946

Magnification:70�

946

Theme DevelopmentThe theme of systems andinteractions is developed bylooking at the role of the diges-tive and endocrine systems inregulating body functions.

Chapter 35Chapter 35

MultipleLearningStyles

Look for the following logos for strategies that emphasize different learning modalities.

Kinesthetic Meeting IndividualNeeds, p. 948; Quick Demo,

pp. 950, 955Visual-Spatial Getting StartedDemo, p. 946; Quick Demo,

pp. 948, 960, 961; Portfolio, p. 949;Meeting Individual Needs, pp. 954,960; Reteach, p. 957

Interpersonal Check forUnderstanding, p. 953;

Enrichment, p. 955; Biology Journal,p. 956

Intrapersonal Project, p. 952;Cultural Diversity, p. 955; Tech

Prep, p. 962; Portfolio, p. 964Linguistic Biology Journal, pp. 955, 961, 963; Tech Prep,

p. 956; Extension, p. 957Logical-Mathematical Project,p. 957

GETTING STARTED DEMOGETTING STARTED DEMO

Visual-Spatial Test acracker for starch by

adding a few drops of iodine to the ground crumbs. A darkbrown/purple indicates thepresence of starch. To demon-strate the effects of saliva onstarch, add about 1 g of groundcrackers to 1-2 ml of water. Add a small amount of amylase(available from biological sup-ply companies) and let sit for afew minutes. You can test forthe breakdown of starch byperiodically using the iodinetest.

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If time does not permit teach-ing the entire chapter, use theBioDigest at the end of theunit as an overview.

http://www.glencoe.com/sec/science

Incisors

Gums

Soft palate

Cheek

Opening of salivary gland duct

Cuspids orcanines

Bicuspidsor premolars

Molars

Uvula

Hard palate

Your Mouth

Your mouth houses many structures involved inother functions besides digestion. Some of these

structures protect against foreign materials invadingyour body; others help you taste the food you eat.

Critical Thinking Why do your teeth come in variousshapes?


The tongue is covered by projectionsthat contain numerous taste receptor cells

like the one shown here.

INSIDESSTORTORYY

INSIDE

Teeth The incisors are adapted for cutting food. The cuspids, or canines, tear or shred food. The three sets of molars can crush and grind food. Often, there is not enough room for the third set of molars, called wisdom teeth, which then must be removed.

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Tongue Thetongue is attachedto the floor of themouth. It is madeof numerous skeletal musclescovered with amucous membrane.

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Enamel

Dentin

Nerve

Pulp

Rootcanal

Vascular supplyBone

CROWN

NECK

ROOT

Tonsils A pair oftonsils is located atthe back of themouth. They play arole in preventinginfections in thenose and mouth byhelping to eliminateforeign bacteria.

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Structure of a tooth Teeth are made mainlyof dentin, a bonelike substance that gives atooth its shape and strength. The dentinencloses a space filled with pulp, a tissue thatcontains blood vessels and nerves. The dentin of the crown is covered with an enamel thatconsists mostly of calcium salts. Tooth enamel is the hardest substance in the body.

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IINSIDENSIDESSTORTORYY

INSIDE

Purpose Students examine teeth and otherstructures of the mouth.

Teaching Strategies■ Bring in models of animalskulls, including a human skull,to compare teeth. Ask studentswhether other mammals havebaby or milk teeth. Yes. Some stu-dents may recall their puppies or kit-tens losing baby teeth.

MisconceptionStudents may believe that cavitiesare the greatest threat to teeth.Explain that while cavities dodestroy teeth, periodontal diseaseof the gums is much more seriousand far more prevalent today.

Visual Learning■ Point out the structures of the

mouth shown in the diagram.As each structure is men-tioned, have a volunteer readthe description of the struc-ture.

■ Ask students to name the threetypes of teeth shown. incisors,cuspids, and molars

■ Elicit from students the func-tion of the tonsils and theirlocation. The tonsils are locatedin the back of the mouth andfunction to remove bacteria thatenter the mouth or nose.

Critical ThinkingDifferent teeth perform differentfunctions—incisors are shapedfor cutting, while molars areshaped for crushing and grinding.

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The MouthThe first stop along the digestive

disassembly line is your mouth.Suppose it’s lunchtime and you havejust prepared a bacon, lettuce, andtomato sandwich. The first thing youdo is bite off a piece and chew it.

What happens as you chew?In your mouth, your tongue moves

the food around and helps position itbetween your teeth so that it can be chewed. Chewing is a form ofmechanical digestion, the physicalprocess of breaking food into smal-ler pieces. Mechanical digestion pre-pares food particles for chemicaldigestion. Chemical digestion is the process of changing food on a

molecular level through the action of enzymes. What purpose do thedifferent structures inside yourmouth serve? Find out by reading theInside Story.

Chemical digestion begins in the mouth

Some of the nutrients in yoursandwich are starches, large mole-cules known as polysaccharides. Asyou chew your bite of sandwich, sali-vary glands in your mouth secretesaliva, as shown in Figure 35.2.Saliva contains a digestive enzyme,called amylase, which breaks downstarch into smaller molecules such asdi- or monosaccharides. In the stom-ach, amylase continues to digeststarch in the swallowed food forabout 30 minutes. Table 35.1 listssome digestive enzymes that act tobreak food molecules apart.

Swallowing your foodOnce you’ve thoroughly chewed

your bite of sandwich, your tongueshapes it into a ball and moves it tothe back of your mouth to be swal-lowed. Swallowing forces food fromyour mouth into your esophagus, amuscular tube that connects yourmouth to your stomach. Food moves down the esophagus by way of

948 THE DIGESTIVE AND ENDOCRINE SYSTEMS

Organ Enzyme Molecules digested Product

Salivary glands Salivary amylase Starch Disaccharide

Stomach Pepsin Proteins Peptides

Pancreas Pancreatic amylase Starch Disaccharide Trypsin Proteins PeptidesPancreatic lipase Fats Fatty acids and glycerolNucleases Nucleic acids Sugar and nitrogen bases

Small intestine Maltase Disaccharide MonosaccharideSucrase Disaccharide MonosaccharideLactase Disaccharide MonosaccharidePeptidase Peptides Amino acidsNuclease Nucleic acids Sugar and nitrogen bases

Table 35.1 Digestive enzymes

OriginWORDWORD

peristalsisFrom the Greekword peri, meaning“around,” andstellein, meaning “todraw in.” Peristalsispropels food in onedirection.

Figure 35.2Salivary glands secretesaliva, a watery sub-stance that containsthe enzyme amylase.


948

2 Teach

Visual LearningExplain that the pancreas is 15cm long and produces 1 L ofpancreatic juice each day. Havestudents use Table 35.1 to list thechemicals that compose pancre-atic juice. pancreatic amylase,trypsin, pancreatic lipase, nucleases

ReinforcementHave two students hold a 9-mlong piece of string. Explain thatthe string represents the lengthof the human digestive tract.Briefly discuss how food movesalong the length of the digestivetract and the changes that occurwithin the tract.

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Quick DemoQuick Demo

Visual-Spatial Show stu-dents old barium X rays

of the digestive tract (oftenavailable at hospitals). Use theX rays to discuss and identifyparts of the digestive tract. Xrays of jawbones may also beobtained and used for discus-sions about teeth.

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PortfolioPortfolio

Primary TeethVisual-Spatial Have students inves-tigate how the number and loca-

tion of primary teeth in humans differfrom the secondary teeth. Ask studentsto diagram a mouth that shows only pri-mary teeth. Have students identify thetypes of teeth shown in the diagram.

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Resource ManagerResource Manager

Section Focus Transparency 84and Master

Tech Prep Applications, p. 45L2

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MEETING INDIVIDUAL NEEDS MEETING INDIVIDUAL NEEDS

Learning DisabledKinesthetic Cut a 15-cm length ofstring and lay it fully stretched out

on a desk. Use a second 15-cm piece ofstring to form a zigzag pattern. Have stu-dents observe the total horizontal distancebetween the two ends of each piece ofstring. Compare this to the increased sur-face area created by villi.

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VIDEODISCSTV: The Human Body, Vol. 1Digestive System

Unit 2, Side 2, 2 min. 10 sec.Stomach

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VIDEODISCSTV: The Human Body, Vol. 1Digestive System

Unit 2, Side 2, 2 min. 30 sec.Mouth

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Esophagus

Pancreas

Pancreaticduct

Stomach

Diaphragm

Duodenum

Bile duct

Smallintestine

Liver

Gallbladder

Chemical digestion in the stomach

The inner lining of the stomachcontains millions of glands thatsecrete a mixture of chemicals calledgastric juice. Gastric juice containspepsin and hydrochloric acid. Pepsinis an enzyme that begins the chemi-cal digestion of proteins in food.Pepsin works best in the acidic envi-ronment provided by hydrochloricacid, which increases the acidity ofthe stomach contents to pH 2.

Knowing that the stomach secretesacids and enzymes, you may be won-dering why the stomach doesn’tdigest itself. The stomach lining isprotected by mucus that forms a layerbetween it and the acidic environ-ment of the stomach. The mucus issecreted by the stomach lining itself.

Food remains in your stomach forapproximately two to four hours. Bythe time the food is ready to leave thestomach, it is about the consistencyof tomato soup. At that time, theperistaltic waves gradually becomemore vigorous and begin to forcesmall amounts of liquid out of thelower end of the stomach and intothe small intestine.

The Small IntestineFrom your stomach, the liquid food

moves into your small intestine, amuscular tube about 6 m long. Thissection of the intestine is called smallnot because of its length, but becauseof its narrow diameter—only 2.5 cm.Digestion of your meal is completedwithin the small intestine. Musclecontractions contribute to furthermechanical breakdown of the food; atthe same time, carbohydrates andproteins undergo further chemicaldigestion with the help of enzymesproduced and secreted by the pan-creas and liver.

Chemical actionThe first 25 cm of the small intes-

tine is called the duodenum (doo AHD

un um). Most of the enzymes andchemicals that function in the duode-num enter it through ducts that col-lect juices from the pancreas, liver,and gallbladder. These organs, shownin Figure 35.5, play important rolesin digestion, even though food doesnot pass directly through them.

Secretions of the pancreasThe pancreas is a soft, flattened

gland that secretes both digestiveenzymes and hormones, which youwill learn more about in the last sec-tion of this chapter. The mixture ofenzymes it secretes breaks down car-bohydrates, proteins, and fats. Alkalinepancreatic juices also help to neutral-ize the acidity of the liquid food,stopping any further action of pepsin.

Secretions of the liverThe liver is a large, complex organ

that, among its many functions, produces bile. Bile is a chemical


Figure 35.5Both the pancreasand the liver producechemicals needed fordigestion in the smallintestine.

Skill Have students make aflow chart of the digestive system,listing the secretions at eachstage. L2

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AssessmentAssessment

Analysis1. What did Lactaid do to the lactose in

milk? It broke down the lactose.2. What is the function of test tubes 1, 2, and

4? They are controls.3. How will Lactaid help people who cannot

digest lactose. Lactaid will help breakdown the lactose present in dairy products.

Portfolio Have students write asummary of the lab, including the answersto the Analysis questions, and add them totheir portfolios. Use the Performance TaskAssessment List for Lab Report in PASC,p. 47. PP

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951

Frommouth

Contraction

Contractionof circularmusclesbehindfood mass

Longitudinalmuscle

Food massTo stomach

Contractionin circularmuscle layerforces foodmass forward

Contraction oflongitudinalmuscles aheadof food mass

Circularmuscle

Esophagus

Stomach

Small Intestine

peristalsis (per uh STAHL sus), a series of involuntary smooth musclecontractions along the walls of the digestive tract. Figure 35.3shows how the food is moved alongfrom the mouth to the stomach. Thecontractions occur in waves: first, cir-cular muscles relax and longitud-inal muscles contract; then circularmuscles contract and longitudinalmuscles relax.

Have you ever had food go downthe wrong way? When you swallow,the food enters the esophagus.Usually, a flap of cartilage called theepiglottis (ep uh GLAHT us) closesover the opening to the respiratorytract as you swallow, preventing foodfrom entering. After the food passesinto your esophagus, the epiglottisopens again. But if you talk or laughas you swallow, the epiglottis mayopen, allowing food to enter theupper portion of the respiratorytract. Your response, a reflex, is tochoke and cough, forcing the foodout of the respiratory tube.

The StomachWhen the chewed food reaches

the end of your esophagus, it entersthe stomach. The stomach is a mus-cular, pouchlike enlargement of thedigestive tract. Both physical andchemical digestion take place in thestomach.

Muscular churningThree layers of involuntary mus-

cles, lying across one another, arelocated within the wall of the stom-ach. When these muscles contract, asshown in Figure 35.4, they work tophysically break down the swallowedfood, creating smaller pieces. As themuscles continue to work the foodpieces, they mix them with digestivejuices produced by the stomach.

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Figure 35.3Smooth muscle contractions are responsiblefor moving food through the digestive system.

AA

BB

CC

DD

Figure 35.4Smooth muscle contrac-tions churn the food inthe stomach until itbecomes a thin liquid.

Visual LearningHave students look at Figure35.3. Ask: What type of musclemakes up the walls of the stom-ach? smooth muscle

Alternative LabDigesting Lactose

Purpose Students test whether Lactaid or anotherlactose digestive aid will digest lactose.PreparationDo not use the tablet form of Lactaid; it

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tests positive for glucose. If you useanother liquid lactose digestive aid, test itfor glucose first.MaterialsLactaid or another liquid lactose digestiveaid, glucose test paper, glucose solution,milk, graduated cylinders, droppers, testtubesProcedureGive students the following directions.

1. Label four test tubes 1, 2, 3, and 4.

Remind students to handle test tubeswith care and to dispose of any brokenglass in the designated container.

2. Place 2 mL of glucose in test tube 1, 2mL of milk in test tube 2, 2 mL of milkin test tube 3, and 2 mL of Lactaid intest tube 4.

3. Place 5 drops of Lactaid in test tube 3.4. Allow all tubes to sit for 5 minutes.5. Using the glucose test paper, test each

tube for glucose.950


Kinesthetic To demon-strate both digestion and

diffusion, fill a dialysis bag with1-5% starch solution. In a sec-ond dialysis bag, add 2 mL ofpancreatic enzymes and fill theremainder of the bag withstarch solution. Allow each bagto sit in a beaker of distilledwater for one day. Then, run aBenedict’s test on the fluid ineach beaker. Explain that theenzymes will digest the starchand change it to glucose, whichdiffuses out of the dialysis bag.The glucose will produce a pos-itive Benedict’s test.

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CD-ROMBiology: The Dynamicsof Life

Video: X Ray of SwallowingDisc 5

VIDEODISCBiology: The Dynamicsof Life

X Ray of Swallowing (Ch. 31)Disc 2, Side 1, 35 sec.

!:6Ç"


BioQuest: Body SystemsDiscs 1-5

VIDEODISCSTV: Human Body, Vol. 1Digestive System

Unit 2, Side 2Small Intestine 1, 3 min. 41 sec.

Small Intestine 2, 1 min. 47 sec.

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!9NÇ>a$F"Large Intestine, 1 min. 31 sec.

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Reinforcement and StudyGuide, pp. 155-156

Content Mastery, p. 174Reteaching Skills Trans-

parency 50 and Master

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Fatty acidsAmino acidsMonosaccharides

Columnarepithelium Lymph

vesselBlood vesselnetwork

directly into the cells of the villi, asshown in Figure 35.7. The foodmolecules then diffuse into the bloodvessels of the villus and enter thebloodstream. As you can see, the villiare the link between the digestivesystem and the circulatory system.

As your lunch comes to the end ofits passage through the small intes-tine, only the indigestible materialsremain in the digestive tract.

The Large IntestineThe indigestible material from

your meal now passes into your large intestine, a muscular tube thatis also called the colon. Even thoughthe large intestine is only about 1.5 m long, it is much wider than thesmall intestine—about 6.5 cm indiameter. The appendix, a small,tubelike extension off the large intes-tine, is thought to be an evolutionaryremnant from our herbivorous ances-tors as it seems to serve no functionin human digestion.

Water absorptionAs the indigestible mixture passes

through the large intestine, water isabsorbed by the intestine walls, leav-ing behind a more solid material. Inthis way, the water is not wasted. A secondary function of the large

intestine is vitamin synthesis.Anaerobic bacteria in the large intes-tine synthesize some B vitamins andvitamin K, which are absorbed asneeded by the body.

Elimination of wastesAfter 18 to 24 hours in the large

intestine, the remaining indigestiblematerial, now called feces, reachesthe rectum. The rectum is the lastpart of the digestive system. Fecesare eliminated from the rectumthrough the anus. Your meal’s entirejourney from the beginning of thedigestive tract to the end has takenbetween 24 and 33 hours.


Section AssessmentSection Assessment

Understanding Main Ideas1. Sequence the organs of your digestive system

according to the order in which food passesthrough them.

2. In which sections of the digestive system arestarches digested? Which enzymes break downstarches?

3. How do villi of the small intestine increase therate of nutrient absorption?

4. What role does the pancreas play in digestion?

Thinking Critically5. How would chronic diarrhea affect the balance

of fluids in your body?

6. Making and Using Graphs Prepare a circlegraph representing the time food remains ineach part of the digestive tract. For more help,refer to Organizing Information in the SkillHandbook.

SKILL REVIEWSKILL REVIEW

Figure 35.7Once food has beenfully digested in thesmall intestine, it is in the form of mole-cules small enough toenter the body’sbloodstream.

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3 AssessCheck for Understanding

Interpersonal Play the “Di-gestive System Game.”

Have a student name an organ ofthe digestive system. The nextstudent must name a type ofdigestion that occurs in the organ(chemical or mechanical). Thenext student must further definethis action by listing the enzymesor juices involved or defining themechanical action (chewing orstomach churning). A fourth stu-dent should tell how the digestiveaction is controlled. Repeat theprocess until all organs have beendiscussed.

ReteachVisual-Spatial Have studentsprepare a chart of the diges-

tive organs and the role of eachin digestion.

ExtensionLinguistic Have interestedstudents research and report

on cancers of the digestive tractand their possible causes andtreatments.

Skill Have students label adiagram of the digestive systemand identify the functions of eachpart.

4 CloseDiscussionAsk students how the digestivesystem is like the plumbing sys-tem of a house. Have themexplain where the faucets of thedigestive system are located. L2

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Section AssessmentSection AssessmentSection Assessment1. mouth, esophagus, stomach, small intes-

tine, large intestine, rectum2. mouth, small intestine; salivary amylase,

pancreatic amylase3. By increasing the total surface area, villi

allow for increased absorption rates.4. The pancreas secretes digestive enzymes,

which break down carbohydrates, pro-teins, and fats.

5. Loose stool has an unusually high watercontent. Patients suffering from diarrhealose tremendous amounts of fluids everyday. These fluids must be restored bydrinking water regularly.

6. Students’ graphs should show approxi-mately these percentages: large intestine,75%; small intestine, 13%; stomach, 11%;mouth and esophagus, 1%

Is it possible to live without a gallbladder? Apparentlyyes, as many people have had this organ surgically removedand are still alive.

AnalysisThe following diagrams show the appearance of a nor-

mal liver and gallbladder (diagram A) and the appearancewhen the gallbladder has been removed (diagram B).

Thinking Critically1. Where is bile produced? Where is bile stored?2. Does bile bring about a chemical or physical change to

fat? Explain.3. Sequence the pathway for bile from the liver to the duo-

denum in the person with a gallbladder. 4. Sequence the pathway for bile from the liver to the duo-

denum in the person with no gallbladder. 5. The gallbladder is a muscular sac. It squeezes and dis-

charges a large quantity of bile when fats are present inthe duodenum. Explain why a person without a gallblad-der is unable to digest fats as efficiently as someone whohas a gallbladder.

Problem-Solving Lab 35-1Problem-Solving Lab 35-1 Sequencingsubstance that helps break down fats. Once made in the liver, bile isstored in a small organ called the gallbladder, from which it passesinto the duodenum. Bile causes fur-ther mechanical digestion by break-ing apart large drops of fat intosmaller droplets. If bile becomes tooconcentrated due to high levels ofcholesterol in the diet, or if the gall-bladder becomes inflamed, gallstonescan form, as seen in Figure 35.6.Can a person live without a gallblad-der? Find out in the Problem-SolvingLab on this page.

Absorption of foodLiquid food stays in your small

intestine for three to five hours and isslowly moved along its length byperistalsis. As digested food movesthrough the intestine, it passes overthousands of tiny fingerlike struc-tures called villi. A villus is a singleprojection on the lining of the smallintestine that functions in the absorp-tion of digested food. The villigreatly increase the surface area ofthe small intestine, allowing for agreater absorption rate. Because thedigested food is now in the form ofsmall molecules, it can be absorbed


Figure 35.6Gallstones can form inthe gallbladder or bileduct. They consistmainly of precipitatedbile salts.

AA BB

Gallstones

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Purpose Students compare the path of bilefrom the liver to the duodenumwith and without the gallbladder.

Process Skillsanalyze information, compareand contrast, draw a conclusion,interpret scientific illustrations,sequence, think critically

Teaching Strategies■ Demonstrate the role of bileby adding a small amount of oilto a test tube of water. Shake itand have students note what hap-pens to the oil after waiting a fewminutes. (Oil reforms on top ofthe water.) Repeat the demon-stration using liquid detergent tosimulate bile. (Oil will remain assmall droplets.)■ Point out to students that thegallbladder is under involuntarycontrol—it releases bile whenstimulated by a hormone.

Thinking Critically

1. liver; gallbladder2. Bile physically changes fat

into smaller droplets.3. liver, hepatic duct, gallblad-

der, bile duct, duodenum4. liver, hepatic duct, bile duct,

duodenum5. Only a small, but continuous,

amount of bile reaches theduodenum. Large amountsneeded to break up fats effi-ciently are not available.

Performance Have stu-dents make a poster illustratingwhy gallstones cause discomfort.Advise them that (a) gallstones canblock the bile duct and (b) thegallbladder contracts automaticallywhen fats are in the duodenum.Have them explain what couldcause the considerable discomfortassociated with gallstones. the gall-bladder squeezing and not being ableto empty Use the Performance TaskAssessment List for Poster inPASC, p. 73. L2

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Problem-Solving Lab 35-1Problem-Solving Lab 35-1

P R O J E C TMeat Tenderizers

Intrapersonal Have students conductlibrary research to find out how meat

tenderizer works. Have them use the infor-mation they gather to design a demonstra-tion that can be used to explain the processto others. Encourage students to write out

the procedural steps for their demonstrationand explain the purpose for each step.Finally, have students complete their demon-stration with information that relates thefunction of meat tenderizer to its comple-mentary organ of the digestive system.

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Fluorine (F)Dental cavityreductionFluoridated water

Iodine (I)Formation ofthyroid hormoneSeafood, eggs,iodized salt,milk group

Copper (Cu)Development ofred blood cells,formation of somerespiratoryenzymesGrain group, liver

Iron (Fe)Formation ofhemoglobin(carries oxygen tobody cells) andcytochromes (ATPformation)Liver, egg yolk,grain and meatgroup, leafyvegetables

Sodium (Na)Nerve activity,body pHregulationBacon, butter,table salt,vegetable group

Magnesium (Mg)Muscle and nerveactivity, boneformation,enzyme functionFruit, vegetable and grain groups

Calcium (Ca)Teeth and boneformation, muscleand nerve activity,blood clottingMilk and graingroup

Phosphorus (P)Teeth and boneformation, bloodpH, muscle andnerve activity, partof enzymes andnucleic acidsMilk, grain andvegetable group

Potassium (K)Nerve and muscleactivityVegetable group,bananas

Sulfur (S)Builds hair, nails andskin, componentof insulinGrain and fruitgroup, eggs, cheese

fuel body functions. Some sugar iscarried to the liver where it is storedas glycogen.

Cellulose, another complex carbo-hydrate, is found in all plant cellwalls and is not digestible by humans.However, cellulose (also known asfiber) is still an important item toinclude in the diet as it helps in theelimination of wastes. Sources offiber include bran and spinach.

FatsMany people think that eating fat

means getting fat, yet fats are anessential nutrient. They provideenergy for your body and are alsoused as building materials. Recall thatfats are essential building blocks ofthe cell membrane. They are alsoneeded to synthesize hormones, pro-tect body organs against injury, andinsulate the body from cold.

Sources of fat in the diet includemeats, nuts, and dairy products, aswell as cooking oils. In the digestivesystem, fats are broken down intofatty acids and glycerol and absorbedby the villi of the small intestine.Eventually, some of these fatty acidsend up in the liver. The liver con-verts them to glycogen or storesthem as fat throughout your body.

ProteinsYour body has many uses for pro-

teins. Enzymes, antibodies, manyhormones, and substances that helpthe blood to clot, are all proteins.Proteins form part of muscles andmany cell structures, including thecell membrane.

During digestion, proteins are bro-ken down into amino acids. After theamino acids have been absorbed by thesmall intestine, they enter the blood-stream and are carried to the liver. Theliver can convert amino acids to fatsor glucose, both of which can be used

for energy. However, your body usesamino acids for energy only if otherenergy sources are depleted. Mostamino acids are absorbed by cells andused for protein synthesis. Thehuman body needs 20 different aminoacids to carry out protein synthesis,but it can make only 12 of them. Therest must be consumed in the diet andso are called essential amino acids.Sources of essential amino acidsinclude meats, dried beans, wholegrains, eggs and dairy products.

35.2 NUTRITION 955

Figure 35.9Minerals serve manyvital functions.

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2 Teach

Visual LearningRefer to the periodic table onpage A9 of Appendix D as youdiscuss Figure 35.9. Challengestudents to locate the minerals onthe periodic table.

EnrichmentInterpersonal Have studentswork in groups to investi-

gate and prepare a report on onevitamin deficiency, such as scurvy,beriberi, rickets, night blindness,polyneuritis, or pellagra.

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Fat (naturally occurring andadded during cooking)Sugars (added to foods)

Section


The Vital NutrientsSix basic kinds of nutrients can be

found in foods: carbohydrates, fats,proteins, minerals, vitamins, andwater. These substances are essentialto proper body function. You supplyyour body with these nutrients whenyou eat foods from the five main foodgroups shown in Figure 35.8.

CarbohydratesPerhaps your favorite food is pasta,

fresh-baked bread, or corn on thecob. If so, your favorite food containscarbohydrates, important sources ofenergy for your body cells. Recallthat carbohydrates are starches andsugars. Starches are complex carbo-hydrates found in bread, cereal, pota-

toes, rice, corn, beans, andpasta. Sugars are simple car-bohydrates found mainly infruits, such as plums, straw-berries, and oranges.

During digestion, complexcarbohydrates are brokendown into simple sugars suchas glucose, fructose, andgalactose. Absorbed into thebloodstream through the villiof the small intestine, thesesugar molecules circulate to

What’s your favorite food? Howoften do you eat it? Of whatnutritional value is it?

The food pyramid is a diagramthat indicates the number ofservings a person should havedaily from each of the foodgroups. How do your mealsfit into this pyramid?

SECTION PREVIEW

ObjectivesSummarize the contri-bution of the six classesof nutrients to bodynutrition.Identify the role of theliver in food storage.Relate caloric intake toweight loss or gain.

VocabularymineralvitaminCalorie

35.2 Nutrition

Figure 35.8Select foods from thefive food groups andyou’ll have a healthfuldiet that supplies thesix essential nutrientsyour body needs.

Fat (naturally occurring andadded during cooking)Sugars (added to foods)

USE SPARINGLY

2-3 SERVINGS 2-3 SERVINGS

2-4 SERVINGS3-5 SERVINGS

6-11 SERVINGS

Thefood

pyramid

954

Section 35.2

PrepareKey ConceptsStudents become familiar withthe six classes of nutrients. Theyalso relate these nutrients toCalories and metabolism.

Planning■ Purchase a school lunch for

Meeting Individual Needs.■ Acquire foods and brown

paper for the Quick Demo.■ Gather Calorie charts for the

Project.


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What two or three essential nutrients are most abundant in each of the foods shown?

What essential nutrient is available in all the foodsexcept the grapefruit?

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Hearing Impaired/EnglishLanguage Learners

Visual-Spatial Bring in a sampleschool lunch. Ask students to list, on

a sheet of paper, the nutrients found ineach of the foods provided. Next, havethem point out on a diagram of the diges-tive system where each type of nutrient isdigested.

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Kinesthetic Test variousfoods for the presence of

fat using brown paper (fromgrocery sacks). Smear the foodon the brown paper and allowto dry. If the food is dry, grinda small portion with somewater. After the paper has hadsufficient time to dry, hold itup to the light. If the paper istranslucent, the food testedcontains fat.

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Cultural Diversity

Food PreferencesIntrapersonal Populations developfood preferences as they try to

meet their nutritional needs using foodsthat are locally available. Have studentsfind out how different cultures choosecombinations of foods and flavors. Havethem bring in samples of foods from vari-ous cultures.

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BIOLOGY JOURNAL BIOLOGY JOURNAL

Cancer and NutrientsLinguistic Have students researchhow antioxidants destroy free radi-

cals that can damage cells and lead to can-cer. Ask them to find out how vitamins Cand E and beta-carotene destroy thesesubstances.

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Resource ManagerResource ManagerSection Focus Transparency 85 and

MasterConcept Mapping, p. 35

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Exploration: NutritionDisc 5

Evaluate a Bowl of Soup As a consumer, you are bom-barded by advertising that promotes the nutritional benefitsof specific food products. Choosing a food to eat on the basisof such ads may not make nutritional sense. By examining theingredients of processed foods, you can learn about theiractual nutritional content.

Procedure! Examine the information

in the table listing the daily value (DV) of various nutrients. DV expresses what percent of Calories shouldcome from certain nutrients. For instance, in the proposeddiet of 2000 Calories, 60 percent of the Calories shouldcome from carbohydrates.

@ Examine the nutritional information on the soup can labeland compare it with the DV table.

Analysis1. Does your bowl of soup provide more than 30 percent of

any of the daily nutrients? Which ones?2. Evaluate the percentage of calories in soup that are pro-

vided by saturated fat.3. Is soup a nutritious meal? Explain your answer.

MiniLab 35-1MiniLab 35-1 Interpreting the DataWater

Water is the most abundant sub-stance in your body, making up 60percent of red blood cells and 75 per-cent of muscle cells. Water facilitatesthe chemical reactions in your bodyand is necessary for the breakdown offoods during digestion. Water is alsoan excellent solvent; oxygen andnutrients from food could not enteryour cells if they did not first dissolvein water.

Recall that water absorbs andreleases heat slowly. It is this charac-teristic that helps water maintainyour body’s internal temperature. Alarge amount of heat is needed toraise the temperature of water.Because the body contains so muchwater, it takes a lot of added energyto raise its internal temperature. Yourbody loses about 2.5 L of water perday through exhalation, sweat, andurine. As a result, water must bereplaced constantly.

Calories and MetabolismThe energy content of food is

measured in units of heat calledCalories, each of which represents akilocalorie, or 1000 calories (writtenwith a small c). A calorie is theamount of heat required to raise thetemperature of 1 mL of water by1ºC. Some foods, especially thosewith fats, contain more Calories thanothers. In general, 1 g of fat containsnine Calories, while 1 g of carbohy-drate or protein contains fourCalories. To learn more aboutCalories in meals, complete theMiniLab on this page.

The number of Calories neededeach day varies from person to per-son, depending on the person’smetabolism, or the rate at which theyburn energy. Metabolic rate, in turn,is determined by a person’s body

mass, age, sex, and level of physicalactivity. In general, males need moreCalories per day than females,teenagers need more than adults, andactive people need more than inac-tive people. Physicians have deter-mined that many Americans areoverweight. Calculate your BodyMass Index by doing the Problem-Solving Lab on the next page.

35.2 NUTRITION 957

Percentage ofDaily Value (DV)

Carbohydrates 60%

Fat 30% Saturated Fats 10%

Cholesterol 1.5%

Protein 10%

Total Calories 2000

Table 35.3

NUTRITION FACTS

Amount Per ServingCalories 140 Calories from Fat 54

% Daily Value*

Total Fat 8g 12%Saturated Fat 6g 30%

Cholesterol 20mg 7%Sodium 1640 mg 68%Total Carbohydrate 22g 7%

Dietary Fiber 5g 20%Sugars 5g

Protein 6gVitamin A 50% Vitamin C 4%Calcium 2%

Percent Daily Values are based on a 2,000calorie diet. Your daily values may be higher orlower depending on your calorie needs:

Calories 2,000 2,500Total Fat Less than 65g 80g Sat Fat Less than 20g 25gCholesterol Less than 300mg 300mgSodium Less than 2,400mg 2,400mgTotal Carbohydrate 300g 375gFiber 25g 30g

Calories per gram:Fat 9 * Carbohydrates 4 * Protein 4

Iron 2%

Serving Size: 2 cups (452g)Servings Per Container: 1

*

3 AssessCheck for UnderstandingGive the students a sample lunchthat has nutritional deficiencies.Ask them to evaluate the lunch.Ask what nutrients are in excessand what nutrients should beadded. Elicit what foods couldprovide these nutrients.

ReteachVisual-Spatial Have studentsprepare a chart of the six

nutrients. Have them identify thefunctions of these nutrients andidentify foods that contain each.

ExtensionLinguistic Have stu-dents interview a

nutritionist to find out what cri-teria the nutritionist uses whenplanning meals that meet nutri-tional needs.

Portfolio Ask students towrite a summary of which sub-stances need to be included in adaily balanced diet and what eachnutrient does. PP

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Minerals and vitaminsWhen you think of minerals, you

may picture substances that peoplemine, or extract from Earth. Asshown in Figure 35.9 on the previ-ous page, the same minerals can alsobe extracted from foods and put touse by your body.

A mineral is an inorganic sub-stance that serves as a building mate-rial or takes part in a chemical reac-tion in the body. Minerals make upabout four percent of your total bodyweight, most of it in your skeleton.Although they serve many differentfunctions within the body, mineralsare not used as an energy source.

Unlike minerals, vitamins areorganic nutrients that are required in

small amounts to maintain growthand metabolism. The two maingroups of vitamins are fat-soluble andwater-soluble, as shown in Table35.2. Although fat-soluble vitaminscan be stored in the liver, the accu-mulation of excess amounts canprove toxic. Water-soluble vitaminscannot be stored in the body and somust be included regularly in thediet. Table 35.2 lists foods that con-tain fat-soluble and water-soluble vit-amins.

Vitamin D, a fat-soluble vitamin, issynthesized in your skin. Vitamin Kand some B vitamins are made bybacteria in your large intestine. Therest of the vitamins must be con-sumed in your diet.


Vitamin Function Source

Fat-soluble

A maintain health of epithelial cells; formation of liver, broccoli, green and yellow vegetables, light-absorbing pigment; growth of bones and teeth tomatoes, butter, egg yolk

D absorption of calcium and phosphorus in digestive egg yolk, shrimp, yeast, liver, fortified milk; tract produced in the skin upon exposure to

ultraviolet rays in sunlight

E formation of DNA, RNA, and red blood cells leafy vegetables, milk, butter

K blood clotting green vegetables, tomatoes; produced by intestinal bacteria

Water-soluble

B1 sugar metabolism; synthesis of neurotransmitters ham, eggs, green vegetables, chicken, raisins,seafood, soybeans, milk

B2 (riboflavin) sugar and protein metabolism in cells of eyes, skin, green vegetables, meats, yeast, eggsintestines, blood

Niacin energy-releasing reactions; fat metabolism yeast, meats, liver, fish, whole-grain cereals, nuts

B6 fat metabolism salmon, yeast, tomatoes, corn, spinach, liver, yogurt, wheat bran, whole-grain cereals and breads

B12 red blood cell formation; metabolism of amino acids liver, milk, cheese, eggs, meats

Pantothenic acid aerobic respiration; synthesis of hormones milk, liver, yeast, green vegetables, whole- grain cereals and breads

Folic acid synthesis of DNA and RNA; production of red and liver, leafy green vegetables, nuts, orange white blood cells juice

Biotin aerobic respiration; fat metabolism yeast, liver, egg yolk

C protein metabolism; wound healing citrus fruits, tomatoes, leafy green vegetables, broccoli, potatoes, peppers

Table 35.2 Vitamins

OriginWORDWORD

vitaminFrom the Latinword vita, meaning“life.” Vitamins arenecessary for life.

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Purpose Students evaluate the nutritionalvalue of a food based on its label.

Process Skillsobserve and infer, analyze, inter-pret data

Teaching Strategies■ Explain the concept of dailyvalue (DV) to students.■ You may wish to have studentswork in pairs.

Expected ResultsStudents should discover that thesoup represented is basically ahealthy meal.

Analysis1. Yes, sodium.2. A serving of soup contains

about 39% of its Caloriesfrom saturated fat. (6 g/serv-ing x 9 Cal/g = 54 Calories of saturated fat per serving.54 ÷ 140 = 39%)

3. Basically yes, although thesodium content is high.

Performance Have stu-dents repeat the MiniLab forthree foods found in their homes.Use the Performance Task Ass-essment List for Carrying Out aStrategy and Collecting Data inPASC, p. 25. L2

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MiniLab 35-1MiniLab 35-1

Professional NutritionistLinguistic Students interested innutrition can interview a nutritionist

working for a food company. They mayask what tests are carried out to deter-mine the nutritional content of food pro-duced by the company.

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Nutritional IssuesInterpersonal Divide the class intogroups. Have each group prepare a

presentation on a nutrition issue such ascholesterol, HDLs versus LDLs, anorexia,bulimia, weight gain, junk foods, vegetar-ian diets, or food additives. Have studentsrecord their notes for the group report intheir journals.

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P R O J E C TCalories

Logical-Mathematical Askstudents to list all the foods

they eat during a 24-hour period.Distribute Calorie charts. Have studentsuse the charts to figure out how manyCalories they ate, as well as calculate thegrams of carbohydrates, fats, and proteinsthey consumed.

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Resource ManagerResource ManagerReinforcement and Study Guide,

p. 157BioLab and MiniLab Worksheets,

p. 155Reteaching Skills Transparency 51

and Master

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VIDEODISCThe Infinite Voyage A Taste of Health,

Consequences of a Fatty Diet (Ch. 4) 3 min.

Ancel Keys: Pioneer in Nutrition(Ch. 5) 6 min.

!7KVF"

!7U`H"Assessing Dietary Intake ThroughAnalysis of Garbage (Ch. 8)

4 min.

Understanding How to Eat andLive (Ch. 9) 6 min.

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you eat fewer Calories than yourbody can metabolize, you use someof the energy stored in your body asfat and lose weight.

Millions of people put themselveson diets every year in hopes of losingweight. While many diets are nutri-tionally sound, others prescribe eat-ing habits that are not sensible andusually fail to produce the desiredresult. Read more about fad diets inthe Biology & Society section at theend of this chapter.


What is your BMI? Fifty-five percent of adults in the UnitedStates are considered overweight. How can you tell if you fallinto this category? Use the following equation to find outwhere you rank in relation to the rest of the population.

Analysis Compute your BMI, or Body Mass Index, using the follow-

ing formula:

The federal guidelines are as follows:

A BMI• 25 or below = normal weight• from 25 to 29.9 = overweight • 30 or over = obese

Thinking Critically1. According to federal guidelines, are you normal weight,

overweight, or obese?2. How might a person with a BMI of 27 reduce his or her

BMI? Consider both nutritional intake and physical activity.3. Fred has a BMI of 22. How do you suppose his Calorie

intake compares to his Calorie expenditure? 4. Since 1960, the population of obese individuals in the

United States has risen from 13 to 22 percent. Formulate ahypothesis that may explain this rise.

Problem-Solving Lab 35-2Problem-Solving Lab 35-2 Using Numbers


Understanding Main Ideas1. In what ways are proteins used in the body?2. Why is it important to eat cellulose even

though it has no nutritional value?3. What happens when a person takes in more

food energy than his or her body needs?4. Why are fats needed in the diet?

Thinking Critically5. A person can live several weeks without

food, but can live only days without water. Why is the constant intake of water necessary for the body?

6. Classifying Prepare a chart of food groups,each group showing foods rich in one of the sixnutrients discussed in this section. For more help,refer to Organizing Information in the SkillHandbook.


Figure 35.10When the energy taken in is greater thanthe energy expended, a person gainsweight.

What happens if you eat moreCalories than your body can metabo-lize? As Figure 35.10 shows, youstore the extra energy as body fat andgain weight. On the other hand, if

weight (in pounds)height (in inches )2

� 704.5 = BMI

958

Purpose Students learn how to calculatetheir Body Mass Index and deter-mine whether or not their weightis within accepted values.

Process Skillsthink critically, apply concepts,collect data, interpret data, rec-ognize cause and effect, use num-bers

Teaching Strategies■ Allow students to use calcula-tors.■ Review the technique forsquaring a number.■ You may wish to illustrate theprocess of calculating BMI byworking an example on the boardor overhead projector.

Thinking Critically

1. Student answers will vary.2. The person could reduce his

or her Calorie intake, and/orincrease activity level.

3. His Calorie intake is in bal-ance with his expenditure.

4. Student answers may includethe idea that fatty food intakehas increased even as dailyexercise has decreased.

Portfolio Have studentgroups plan a general long-rangeprogram that will either maintaintheir BMI if below 25 or reducetheir BMI if over 25. Use thePerformance Task AssessmentList for Group Work in PASC,p. 97.

4 CloseDiscussionAsk students to evaluate an aver-age American’s diet comparedwith that of someone living in adeveloping nation. Have studentsconsider differences in protein,mineral, and vitamin content.

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Section AssessmentSection AssessmentSection Assessment1. to form enzymes, antibodies, hormones,

clotting chemicals, and cell structures2. Cellulose provides bulk in the diet, help-

ing with the elimination of wastes.3. That person gains weight.4. Fats provide energy for the body, act as

building materials, protect body organsagainst injury, and insulate the bodyfrom cold.

5. Water is needed for oxygen and nutri-ents to enter cells and to maintain bodytemperature.

6. carbohydrates: bread, pasta, cereal, fruitsand vegetables; fats: dairy, meat, oil, but-ter; protein: meat, dairy, beans; minerals:fruits and vegetables, meat, dairy; vita-mins: fruits and vegetables, grains, dairy,meat; and so on

Problem-Solving Lab 35-2Problem-Solving Lab 35-2Section

Control of the BodyInternal control of the body is

directed by two systems: the nervoussystem, which you will learn moreabout later, and the endocrine sys-tem. The endocrine system is madeup of a series of glands, calledendocrine glands, that releasechemicals directly into the blood-stream. These chemicals act as messengers, relaying information toother parts of the body. Whereas thenervous system produces an immedi-ate response, the endocrine systeminduces gradual change. Let’s takeone of the football players as an

example: While his nervous system isdirecting his legs to run in order tocatch a forward pass, his endocrinesystem is controlling the rate atwhich he grows. The first response isinstant; the second takes years.

Interaction of the nervous system and endocrine system

Although endocrine glands arefound throughout the body, most ofthem are controlled by the action ofthe pituitary gland (puh TEW uh teree), the master endocrine gland. Because there are two control sys-tems within the body—nervous andendocrine—coordination is needed.

35.3 THE ENDOCRINE SYSTEM 959

Imagine yourself as a quarter-back behind these linemen.Could you see over everyone’s

head? Do you wonder how tall youwill end up being? Because youcontinue growing until about age25, you may still be a few inchesshy of your adult height. Whatcontrols your growth? In part,chemical messages within yourbody. They can affecthow long and atwhat rate yougrow.

SECTION PREVIEW

ObjectivesIdentify the functionsof some of the hor-mones secreted byendocrine glands.Summarize the nega-tive feedback mecha-nism controlling hor-mone levels in the body. Contrast the actions ofsteroid and amino acidhormones.

Vocabularyendocrine glandspituitary glandhypothalamustarget tissuesreceptornegative feedback

systemadrenal glandsthyroid glandparathyroid glands

35.3 The Endocrine System

Pituitarygland

The pituitary gland releases chemicalsimportant in controlling the growth ofthese linemen.

OriginWORDWORD

endocrine From the Greekwords endo, mean-ing “within,” andkrinein, meaning“to separate.” Theendocrine glandssecrete hormonesinto the blood.

959

Section 35.3

PrepareKey ConceptsStudents study how the nervoussystem and hormones controlmetabolic processes in the body.

Planning■ Borrow a human skull or a

large animal skull for the firstQuick Demo.

■ Order slides of the pancreasfor the second Quick Demo.

■ Purchase a whole kidney thatstill has the adrenal glandattached for use in the thirdQuick Demo.

■ Order slides of thyroid/para-thyroid tissue for the MiniLab.


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What is the internal result of each of these actions?

Describe the feedback loop involved in each situation.

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Low blood sugaris detected

Pituitary

Hypothalamusstimulates pituitaryto release hGH

hGH stimulates liver to convert glycogen into glucose and release glucose into blood

Increased sugar in blood signals back to hypothalamus to slow stimulation of pituitary

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investigate growth rate in humans by doing the BioLab at the end of this chapter.

Negative Feedback Control

The amount of hormone releasedby an endocrine gland is determinedby your body’s demand for that hor-mone at a given time. In this way, theendocrine system ensures that theappropriate amounts of hormone arepresent in the system at all times.

How do your endocrine glandsknow when you need a certain hor-mone? The endocrine system is con-trolled by a self-regulating systemcalled the negative feedback system.The negative feedback system is asystem in which the hormones, ortheir effects, are fed back to inhibitthe original signal. The thermostat inyour home is controlled by a similarnegative feedback system. It main-tains the room at a set temperature.When the temperature drops, thethermostat senses the lack of thermalenergy and signals the heater toincrease its output. When the ther-mal energy of the room rises again toa certain point, the thermostat nolonger stimulates the heater, whichshuts off. When the temperaturedrops again, the process repeatsitself. In this negative feedback sys-tem, the increase in temperature“feeds back” to signal the thermostatto stop stimulating thermal energyproduction.

Feedback control of hormonesThe majority of endocrine glands

operate under negative feedback sys-tems. A gland synthesizes and secretesits hormone, which travels in theblood to the target tissue where the appropriate response occurs.Information regarding the hormone

level or its effect on the target tissueis fed back, usually to the hypothala-mus or pituitary gland, to regulate thegland’s production of the hormone.

Control of blood water levelsLet’s take a look at an example of a

hormone that is controlled by a neg-ative feedback system. After workingout in the gym and building up asweat, you are thirsty. This is becausethe water content of your blood hasbeen reduced. The hypothalamus,which is able to sense the concentra-tion of water in your blood, deter-mines that your body is dehydrated.In response, it stimulates the pitu-itary gland to release antidiuretic(ANT ih di uh reht ihk) hormone(ADH). ADH reduces the amount of


Figure 35.12 The hypothalamusand pituitary glandcontrol the amountof human growthhormone (hGH) inyour blood.

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Concept DevelopmentInsulin-dependent diabetes is alsocalled Type I, or juvenile, dia-betes. One major complication ofType I diabetes is loss of visiondue to cataracts. The excessiveblood glucose chemically attachesto the lens proteins, clouding thelens. Type I diabetes often causeskidney damage, also. Noninsulin-dependent diabetes is called TypeII diabetes. Because this type ofdiabetes is most common inelderly people, it is sometimescalled late-onset diabetes.

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by nerves and blood vessels. Thehypothalamus sends messages to thepituitary, which then releases its ownchemicals, or stimulates other glandsto release theirs. Other endocrineglands under control of the pituitaryinclude the thyroid gland, the adrenalglands, and glands associated withreproduction.

Endocrine control of the bodyThe chemicals secreted by en-

docrine glands into the bloodstreamare called hormones. Recall that ahormone is a chemical released inone part of an organism that affectsanother part. Hormones conveyinformation to other cells in yourbody, giving them instructionsregarding your growth, development,and behavior. Once released by theglands, the hormones travel in thebloodstream and then attach to spe-cific binding sites found on theplasma membranes, or in the nuclei,of target tissue cells. These bindingsites on cells are called receptors.Figure 35.11 summarizes the actionof endocrine hormones.

Example of endocrine control Human growth hormone (hGH) is

a good example of an endocrine sys-tem hormone. When your body isactively growing, blood glucose lev-els are slightly lowered as the grow-ing cells use up the sugar. This lowblood glucose level is detected by thehypothalamus, which stimulates theproduction and release of hGH fromthe pituitary into the bloodstream.hGH binds to receptors on theplasma membranes of liver cells,stimulating the liver cells to releaseglucose into your blood. Your cellsneed the glucose in order to con-tinue growing. Figure 35.12 sum-marizes the control of hGH by thepituitary gland. You can further


PituitaryAmino acidhormonesControls adrenalgland, thyroidgland, ovaries,testis, mammaryglands, storeshypothalamushormones, andsecretesgrowth hormone

ParathyroidGlandAmino acidhormonesSecretes para-thyroid hormone

AdrenalMedullaAmino acidhormonesSecretesepinephrine andnorepinephrine

Adrenal CortexSteroid hormonesSecretes gluco-corticoid andaldosterone

HypothalamusAmino acidhormonesControls pituitaryand synthesizesantidiuretichormone andoxytocin for uteruscontraction duringbirth

Thyroid glandAmino acidhormonesSecretes thyroxinto stimulategrowth andmetabolism andsecretes calcitonin

OvarySteroid hormonesSecretes femalesex hormones

TestisSteroid hormonesSecretes malesex hormones

Figure 35.11 This diagram shows the principal human endocrine glands. The toplabel indicates the name of the gland, the middle label indicatesthe type of hormone(s) secreted, and the bottom label tells theaction of the gland/hormone.

The hypothalamus is the portion ofthe brain that controls the pituitarygland. The pituitary gland is locatedin the skull just beneath the hypo-thalamus, and the two are connected

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2 TeachUsing Science TermsExplain the meaning of the fol-lowing terms: Endo is Greek for“within” and crine (krinein) isGreek for “to separate.” Insulingets its name from the Latininsula, meaning “island.” Insulinis made in the small islands orislets of beta cells in the pancreas.Hypo is Greek for “under” andthalamus is Greek for “the innerroom.” The thalamus was aninner room in a Greek ship.


Visual-Spatial Use ahuman skull or large

animal skull to demonstratewhere the pituitary gland sitsinside the cranium.

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English Language LearnersVisual-Spatial Have students whoare having difficulty keeping track of

hormones and glands prepare a table withthe columns Gland, Hormone, Action, andTarget tissue. Beneath the Gland head, havestudents list the names of the glands pre-sented in this section and then completethe table for each gland.

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Visual-Spatial Using aprojection microscope

viewer, show a section of thepancreas. Point out the islets(small islands) containing thehormone-producing cells.These cells are surrounded byother cells that produce diges-tive enzymes.

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Hormone ActionsLinguistic Have students write aparagraph describing what happens

to insulin and glucagon levels in theirbodies while they sleep.

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The BioLab at theend of the chaptercan be used at thispoint in the lesson.

INVESTIGATEINVESTIGATE


Section Focus Transparency 86and Master

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VIDEODISCThe Secret of LifeEndocrine System / Circulation

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Ions

Ion channel

Enzyme(inactive)

Enzyme(active)

Cellmembrane

Nucleus

Amino acidhormone

Hormonereceptor

11

22

33

Ribosome

Nucleus

Steroidhormone

Cell membrane

Hormone-receptorcomplex

mRNA

mRNA

DNA

New proteinmolecule

11

22

33

of amino acids and others are largechains. These amino acid hormones,once secreted into the bloodstream,bind to receptors embedded in theplasma membrane of the target cell,as shown in Figure 35.14. Fromthere, they open ion channels in themembrane, or route signals downfrom the surface of the membrane toactivate enzymes inside the cell. Theenzymes, in turn, alter the behaviorof other molecules inside the cell. In both of these ways, the hormone isable to control what goes on insidethe target cell.

Adrenal Hormones and Stress

You are sitting in math class andthe teacher is about to hand out thesemester test. Because this test is animportant one, you have spent manyhours studying for it. Like most ofyour classmates, you are a little ner-vous as the test is being passed downthe row. Your heart is beating fastand your hands are a little sweaty. Asyou review the first problem, how-ever, you begin to calm down becauseyou know how to solve it.

The adrenal glands play an impor-tant role in preparing your body forstressful situations. The adrenalglands, located on top of the kidneys,consist of two parts—an inner portionand an outer portion. The outer por-tion secretes steroid hormones,including glucocorticoids (glew ko KOR tuh koydz) and aldosterone(ahl duh STEER ohn). These steroid


Figure 35.14 When an amino acidhormone binds to thereceptor on the cellmembrane (1), it canopen ion channels(2), or activateenzymes (3).

Figure 35.13 Steroid hormonesenter a cell (1), bindto a receptor (2),which in turn bindsto DNA (3).

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EnrichmentHave students identify causes ofstress in their lives and bodilyresponses they notice as a result.increase in breathing rate, heartrate, alertness, a churning feeling inthe stomach, or an increase in bloodpressure List the stresses andresponses on the chalkboard.Point out to students that suchresponses are under the controlof the nervous system and hor-mones. L1

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What are the effects of glucagon and insulin duringexercise? Exercise represents a special example of rapid fuelmobilization in the body. The body must gear up to supplygreat amounts of glucose and oxygen for muscle metabolism.The glucose use in a resting muscle is generally low butchanges dramatically with exercise. Within ten minutes ofbeginning exercise, glucose uptake from the blood mayincrease by fifteenfold; within 60 minutes, it may increase bythirtyfold.

AnalysisThe graph here shows the effects of prolonged exercise

on blood insulin and glucagon levels in humans.

Thinking CriticallyExplain why glucagon concentration goes up and insulin

concentration goes down during exercise, and how theseactions help get glucose to the body cells.

Problem-Solving Lab 35-3Problem-Solving Lab 35-3 Interpreting Data

water in your urine. It does so bybinding to receptors in kidney cells,promoting their absorption of waterand reducing the amount of waterexcreted in urine. Informationregarding blood water levels is con-stantly fed back to the hypothalamusso it can regulate the pituitary’srelease of ADH. If the body becomesoverhydrated, the hypothalamusstops stimulating release of ADH.

Control of blood glucose levelsAnother example of a negative

feedback system involves the regula-tion of blood glucose levels. Unlikemost other endocrine glands, the

pancreas is not controlled by thepituitary gland. When you have justeaten and your blood glucose levelsare high, your pancreas releases thehormone insulin. Insulin signals liverand muscle cells to take in glucose,thus lowering blood glucose levels.When blood glucose levels becometoo low, another pancreatic hormone,glucagon, is released. Glucagon bindsto liver cells, signaling them torelease stored glycogen as glucose.Learn more about glucose storageand release by doing the Problem-Solving Lab on this page.

Hormone ActionOnce hormones are released by an

endocrine gland, they travel to thetarget tissue and cause a change.Hormones can be grouped into twobasic types according to how they acton their target cells: steroid hor-mones and amino acid hormones.

Action of steroid hormones Hormones that are made from

lipids are called steroid hormones.Steroid hormones are lipid-solubleand therefore diffuse freely into cellsthrough their plasma membranes, asshown in Figure 35.13. There theybind to a hormone receptor insidethe cell. The hormone-receptorcomplex then travels to the nucleuswhere it activates the synthesis ofspecific messenger RNA molecules.The mRNA molecules move out tothe cytoplasm where they activate thesynthesis of the required proteins.

Action of amino acid hormonesThe second group of hormones is

made from amino acids. Recall thatamino acids can be strung together inchains and that proteins are madefrom long chains of amino acids.Some hormones are short chains


Insu

lin (µ

U/m

L)

Glu

cago

n (p

g/m

L)

Hours

Insulin

Glucagon

10

5

450

300

150

0 1 2 3 4

Levels of Insulin and Glucagon During Exercise

OriginWORDWORD

adrenal From the Latinwords ad, meaning“attached to,” andren, meaning “thekidneys.” Theadrenal glands arelocated on top ofthe kidneys.

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Purpose Students relate changes in bloodinsulin and glucagon levels duringprolonged exercise to the body’sneed to get glucose to its cells.

Process Skillsrecognize cause and effect, inter-pret data, analyze

Teaching Strategies■ Ask students to list on thechalkboard the changes that occurin the body during exercise.Identify the changes that requireincreased glucose inside cells.

Thinking CriticallyGlucagon causes blood glucoselevels to rise by increasing theconversion of glycogen into glu-cose. The body needs more glu-cose during exercise. Insulin actsto lower blood glucose levels byconverting glucose to glycogen.Consequently, its levels are re-duced during exercise.

Knowledge Ask studentsto summarize in their journals theeffects of prolonged exercise onblood insulin and glucagon. Havethem explain how the actions ofexercise help get glucose to bodycells. Use the Performance TaskAssessment List for Writing inScience in PASC, p. 87. L2

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Problem-Solving Lab 35-3Problem-Solving Lab 35-3

Juvenile DiabetesIntrapersonal Have students inter-ested in diabetes search the Internet

or interview a doctor to find out the mostrecent treatments for juvenile diabetes.

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Using a whole kidney withadrenal gland attached, pointout the gland and relate itsposition to the word origin of“adrenal” (attached to thekidneys).

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Hormone ReleaseLinguistic Have students write astory that describes how and when

stress hormones are released in their bod-ies and the effects of these hormones.

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VIDEODISCThe Secret of LifeControl of Blood

Glucose

!7;LjE"Resource ManagerResource Manager

Basic Concepts Transparency 65 andMaster

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Blood calciumlevels decreased

PTHIntestine

Ca2+ absorbedto blood

Ca2+ releasedto blood

Blood calciumlevels increased

Calcitonin

Parathyroids Thyroid

Kidney

Ca2+ absorbedto blood

Ca2+

absorbed

Bone

Ca2+ excreted

of kidney cells and causes an increasein calcium excretion. Calcitonin alsobinds to bone-forming cells, causingthem to increase calcium absorptionand synthesize new bone.

Another hormone involved in min-eral regulation, the parathyroid hor-mone (PTH), is produced by theparathyroid glands, which areclosely associated with the thyroidgland. It increases the rate of calcium,phosphate, and magnesium absorp-tion in the intestines and causes therelease of calcium and phosphatefrom bone tissue. It also increases therate at which the kidneys remove cal-cium and magnesium from urine andreturn them to the blood.

The overall effect of parathyroidhormone and calcitonin hormoneinteraction in the body is shown inFigure 35.15. Take a closer look atthyroid and parathyroid tissue bycompleting the MiniLab on the previ-ous page.

As you can see, hormones associ-ated with the endocrine system areresponsible for controlling many dif-ferent functions in your body.Different hormones may play moreimportant roles during some periodsin your life than others. In any case,they remain the principal biologicalinfluence on your behavior anddevelopment.



Understanding Main Ideas1. How does a steroid hormone affect its target

cell? How does this action differ from how anamino acid hormone affects its target cell?

2. Explain how the nervous system helps to controlthe endocrine system.

3. How does the negative feedback system work tocontrol hormone levels in the blood?

4. What glands and hormones are involved in stressreactions?

Thinking Critically5. Hormones continually make adjustments in

blood glucose levels. Why must blood glucoselevels be kept fairly constant?

6. Comparing and Contrasting What effects docalcitonin and parathyroid hormone have onblood calcium levels? For more information, referto Thinking Critically in the Skill Handbook.


Figure 35.15 Calcitonin and parathyroid hormone (PTH) haveopposite effects on blood calcium levels.

3 AssessCheck for UnderstandingHave students make a diagramthat summarizes the control of cal-cium levels in the body.

ReteachHave students go around theroom, with the first student nam-ing a gland, the second naming ahormone, and the third namingthe function of the hormone.

ExtensionHave students look up informationon scientists who have discoveredor synthesized endocrine hor-mones. F. G. Banting and C. H.Best discovered insulin, while E. C.Kendall isolated thyroxine and cor-tisone, and P. S. Hench discoveredthat cortisone had a beneficial effecton inflamed tissues.

Knowledge Ask studentsto summarize hormonal controlof blood sugar levels.

4 CloseDiscussionDiscuss with students what mighthappen if their thyroid glandbecame over- or underactive.

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Compare Thyroid and Parathyroid Tissue Although theirnames seem somewhat similar, the thyroid and parathyroidglands perform rather different functions within the body.

Procedure! Copy the data table.@ Use low-power magnifi-

cation to examine a pre-pared slide of thyroidand parathyroidendocrine gland tissue.Note: Both tissues appearon the same slide. CAUTION: Use cautionwhen working with amicroscope and preparedslides.

# The image on the right isa photograph of thyroidand parathyroid tissue. Useit as a guide in locatingthe two types of endocrinegland tissue under low power and in answering certainanalysis questions.

$ Now locate each type of gland tissue under high-powermagnification. Draw what you see in the data table. Thenuse what you learned in the chapter to identify the namesof the hormones produced by each gland.

Analysis1. Compare the microscopic appearance of parathyroid tis-

sue to that of thyroid tissue.2. a. Which tissue type contains follicles (large liquid

storage areas)? b. What may be present within the follicles? c. Are follicles composed of cells? Could they produce the

hormone associated with this gland tissue? Explainyour answer.

d. Hypothesize what the function may be for the thinlayer of tissue that surrounds each follicle.

3. How might you explain the fact that both thyroid andparathyroid tissue can be seen on the same slide?

MiniLab 35-2MiniLab 35-2 Observinghormones cause an increase in avail-able glucose and raise blood pressure.In this way, they help the body com-bat stresses such as fright, temperatureextremes, bleeding, infection, disease,and even test anxiety.

The inner portion of the adrenalgland secretes two amino acid hor-mones: epinephrine (ep uh NEFrun)—often called adrenaline—andnorepinephrine. Recall the fight-or-flight response discussed in the ani-mal behavior chapter. During such aresponse, the hypothalamus relaysimpulses to the nervous system,which in turn stimulates the adrenalglands to increase their output of epi-nephrine and norepinephrine. Thesehormones increase heart rate, bloodpressure, and rate of respiration;increase efficiency of muscle contrac-tions; and increase blood sugar levels.If you have ever had to perform infront of a large audience, you mayhave experienced these symptoms,often referred to collectively as an“adrenaline rush.” This is how thebody prepares itself to face or flee astressful situation.

Thyroid andParathyroid Hormones

The thyroid gland, located in theneck, regulates metabolism, growth,and development. The main meta-bolic and growth hormone of thethyroid is thyroxine. This hormoneaffects the rate at which the bodyuses energy and determines yourfood intake requirements.

The thyroid gland also secretescalcitonin (kal suh TONE un)—a hor-mone that regulates calcium levels in the blood. Calcium is a mineralthe body needs for blood clotting,formation of bones and teeth, andnormal nerve and muscle function.Calcitonin binds to the membranes


Parathyroid (A) and thyroid (B) tissue

TissueName of hormone(s)producedDrawing

Thyroid

Parathyroid

Data Table

AA

BB

Magnification: 333

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Purpose Students analyze a prepared slideof thyroid and parathyroid tissue.

Process Skillscompare and contrast, observe,apply concepts, hypothesize,interpret scientific illustrations

Teaching Strategies■ Prepared slides of thyroid andparathyroid tissue are availablefrom biological supply houses. Itis cheaper to purchase the com-bined slide of both tissues ratherthan separate slides of each.■ To further reduce costs, pro-ject one prepared slide onto a TVscreen using a video camera.

Expected ResultsStudents will be able to differen-tiate between thyroid andparathyroid tissue.

Analysis1. Student may notice that thy-

roid tissue contains manylarge spaces surrounded by athin band while parathyroidtissue contains no large spacesor follicles.

2. a. thyroidb.stored hormones (thyrox-

ine or calcitonin)c. No. No, cells, not storage

areas, would be needed toproduce the hormone.

d.It makes the hormones.3. Both glands are located in the

same general area of theneck. The parathyroids lie onthe thyroid gland itself.

Performance Ask studentsto research the cause and appear-ance of thyroid goiter. Providestudents with prepared slides ofnormal thyroid tissue and thyroidtissue exhibiting a goiter. Havestudents compare and contrastthe two tissues. Ask them to relatetheir microscopic observations tothe macroscopic appearance of agoiter. Use the Performance TaskAssessment List for MakingObservations and Inferences inPASC, p. 17.


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MiniLab 35-2MiniLab 35-2

Section AssessmentSection AssessmentSection Assessment1. A steroid hormone passes through the

target cell membrane and activatesprotein synthesis. An amino acid hor-mone activates ion channels or enzymepathways in the cell from its positionon the membrane.

2. The hypothalamus, part of the brain(central nervous system), controls the

pituitary, or master, endocrine gland.3. In a negative feedback system, when a

hormone reaches an appropriate level,it or its effects feed back to inhibit therelease of more hormone.

4. The adrenal glands secrete glucocorti-coids and epinephrine, hormonesinvolved in stress reactions.

5. Glucose is the fuel for body cells and aconstant level needs to be maintainedfor normal body functions.

6. Parathyroid hormone raises blood cal-cium levels by increasing the rate ofabsorption in the intestines, while cal-citonin lowers blood calcium levels byincreasing its excretion rate.

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Resource ManagerResource ManagerReinforcement and Study Guide,

p. 158Content Mastery, pp. 173, 175-176BioLab and MiniLab Worksheets,

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PortfolioPortfolio

Parathyroid HormoneIntrapersonal Have studentssequence the pathway of parathy-

roid hormone from the parathyroidglands to its target tissues. Have studentscaption their flowcharts with a summaryof the effects the hormone has on its tar-get tissues.

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Going FurtherGoing Further

Application Determine the height of allthe students in your biology class. Comparethe range of heights in your class to the sta-tistical average.

To find out more abouthuman growth, visit the

Glencoe Science Web Site.www.glencoe.com/sec/science

4. Construct a second graph thatshows height on the vertical axisand age on the horizontal axis.

5. Plot the data for the averagefemale growth in height fromages 8 to 18. Connect the datapoints with a straight red line.

6. Plot the data for the average malegrowth in height from ages 8 to18. Connect these data pointswith a straight blue line.


1. Analyzing Data During whatages do females and malesincrease the most in mass? Inheight?

2. Analyzing Data Interpret thedata to find if the average growthrate is the same in males andfemales.

3. Thinking Critically How can youexplain the differences in growthrates between males and females?

4. Relating Concepts Why do youthink male and female growth

rates increase during the teenyears?

ANALYZE AND CONCLUDEANALYZE AND CONCLUDE

Age Female

8

9

10

11

12

13

14

15

16

17

18

25

28

31

35

40

47

50

54

57

58

58

25

28

31

37

38

43

50

57

62

65

68

123

129

135

140

147

155

159

160

163

163

163

124

130

135

140

145

152

161

167

172

174

178

Male Female Male

Height (cm)Mass (kg)

Data Table: Averages for growth in humans


1. Mass: females, ages 11-13;males, ages 12-14. Height:females, ages 9-14; males,ages 12-15

2. Average growth is the sameuntil puberty. At puberty,females have an earliergrowth spurt than males, buton the average, males growtaller and have greater massthan females.

3. Timing of puberty and theproduction of sex hormonesdiffer between males andfemales. For example, malesproduce more of the hormonetestosterone than females.Testosterone increases growthin muscle and bone mass in males.

4. The reproductive hormonesreleased during the teen yearsincrease the growth rate.

Portfolio Have studentswrite summaries of the BioLaband include them, their graphs,and their answers to the questionsposed in the Analyze and Con-clude section in their portfolios.Use the Performance TaskAssessment List for Lab Reportin PASC, p. 47. L2

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ANALYZE AND CONCLUDEANALYZE AND CONCLUDE

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Going FurtherGoing Further

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INVESTIGATEINVESTIGATEAverage Growth Rate in Humans

Human growth results from more than one hormone. Humangrowth hormone, thyroid hormones, and the reproductive hormones

that are produced during puberty are all important in human growth atvarious ages. Together, these hormones stimulate the growth of bone andcartilage, protein synthesis, and the addition of muscle mass. Because thereproductive hormones are involved in human growth, perhaps there is adifference in the growth rate between males and females.

ProblemIs average growth rate the same in

males and females?

ObjectivesIn this BioLab, you will:■ Graph the average growth rates in

males and females.■ Identify any differences in the aver-

age growth rates of males andfemales.

Materialsblue pencilsgraph paperred pencilsruler

Skill HandbookUse the Skill Handbook if you need

additional help with this lab.

PREPARATIONPREPARATION

2. On the graph, plot the datashown in the table for the averagefemale growth in mass from ages8 to 18. Use a ruler to connectthe data points with a straight redline.

3. On the same graph, plot the datafor the average male growth inmass from ages 8 to 18. Connectthese data points with a straightblue line.

1. Construct a graph for the growthrate data that shows mass on thevertical axis and age on the hori-zontal axis.

PROCEDUREPROCEDURE


Time Allotment One class period

Process Skillsmake and use graphs, interpretdata, analyze

■ Collect two sheets of graphpaper and two different col-ored pencils for each student.

PREPARATIONPREPARATION

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PROCEDUREPROCEDURE

Teaching Strategies■ Have students refer to the Making andUsing Graphs section of the Skill Hand-book for help.

Troubleshooting■ As students connect their data points,they should draw a line closest to the given

set of points. Remind them that not all ofthe points will be on the line.

Data and ObservationsStudents will observe that females have anearlier growth spurt than males, but on theaverage, males grow taller and heavier thanfemales.


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Chapter 35 AssessmentChapter 35 Assessment

SUMMARYSUMMARY

Section 35.1

Section 35.2

Section 35.3

Main Ideas■ Digestion begins in the mouth with both

mechanical and chemical action. The esopha-gus transports food from the mouth to thestomach.

■ Chemical and mechanical digestion continuein the acidic environment of the stomach.

■ In the small intestine, digestion is completedand food is absorbed. The liver and pancreasplay key roles in digestion.

■ The large intestine absorbs water before indi-gestible materials are eliminated.

Vocabularyamylase (p. 948)bile (p. 951)epiglottis (p. 950)esophagus (p. 948)gallbladder (p. 952)large intestine (p. 953)liver (p. 951)pancreas (p. 951)pepsin (p. 951)peristalsis (p. 950)rectum (p. 953)small intestine (p. 951)stomach (p. 950)villus (p. 952)

FollowingDigestion of a Meal

Main Ideas■ Carbohydrates are the body’s main source of

energy. Fats are used to store energy. Proteinsare used as building materials.

■ Minerals serve as structural materials or takepart in chemical reactions. Vitamins areneeded for growth and metabolism.

■ Metabolic rate determines how quickly energyis burned.

VocabularyCalorie (p. 957)mineral (p. 956)vitamin (p. 956)

Nutrition

Main Ideas■ The endocrine glands work with the nervous

system to regulate body functions.■ Blood hormone levels are controlled by a

negative feedback system.■ Steroid hormones bind to receptors inside the

target cells and amino acid hormones bind toplasma membrane receptors.

Vocabularyadrenal glands (p. 963)endocrine glands (p. 959)hypothalamus (p. 960)negative feedback

system (p. 961)parathyroid glands (p. 965)pituitary gland (p. 959)receptor (p. 960)target tissues (p. 960)thyroid gland (p. 964)

The EndocrineSystem

CHAPTER 35 ASSESSMENT 969

1. Which of these is an example of mechanicaldigestion?a. peristalsis c. chewingb. coughing d. epiglottis

UNDERSTANDING MAIN IDEASUNDERSTANDING MAIN IDEAS 2. Which of these is NOT a function of thedigestive system?a. eliminating wastesb. absorbing nutrientsc. digesting foodd. regulating metabolism

969

Main IdeasSummary statements can be used bystudents to review the major con-cepts of the chapter.

Using the VocabularyTo reinforce chapter vocabulary, usethe Content Mastery Booklet andthe activities in the Interactive Tutorfor Biology: The Dynamics of Life onthe Glencoe Science Web Site.www.glencoe.com/sec/science

1. c2. d

UNDERSTANDING MAIN IDEASUNDERSTANDING MAIN IDEAS


All ChapterAssessment

questions and answers have beenvalidated for accuracy and suitabil-ity by The Princeton Review.


Chapter Assessment, pp. 205-210MindJogger VideoquizzesComputer Test BankBDOL Interactive CD-ROM, Chapter 35

quiz

You’ve probably come across statements likethese in magazine and television advertise-

ments. Take a pill, sip a shake, or follow a certaineating plan and those extra pounds will just slipaway—or so the headlines claim.

The appeal of fad diets Many people who areoverweight (or who simply think they are) areoften willing to do almost anything to loseunwanted pounds. Most fad diets look like a fastand easy solution to a weight-loss problem. Butdo fad diets work as advertisements claim theydo? And are they safe?

Types of fad diets Some fad diets involve fast-ing—going without food for a period of time.Some require taking diet pills that depress theappetite, or that cause the body to lose water.Other fad diets revolve around eating only onefood, or a certain kind of food. Then there areliquid diets, in which a special drink replacesbreakfast and lunch, and a dieter eats only onemeal of solid food each day.

A temporary solution Many people who start afad diet shed weight quickly in the first week ortwo. After that, however, weight loss usuallyslows dramatically. This is because the initialweight loss is mostly due to loss of water, not fat.When people quit a fad diet, they usually returnto their old eating habits and rapidly regain thelost weight.

What the advertisements don’t say Nearly allfad diets are based on unhealthy nutritional prin-ciples. People on fad diets usually are not eatinga balanced diet, and, therefore, not gettingproper amounts of vitamins, minerals, and otherimportant compounds their bodies need to growand function properly.

Some fad diets also can cause serious healthproblems. High-protein diets, for example, arevery high in fat and cholesterol, substances thatpromote heart disease and circulatory problems.

Fad diets may help some people lose a fewpounds temporarily. But for safe, long-termweight loss, nutritionists recommend a diet basedon healthy eating habits: balanced, regular mealsrich in fruits, vegetables, whole grains, sufficientprotein, and small amounts of fat.


Analyzing Information Collect advertisementsfor three different fad diets that promise “mira-cle” results. Based on what you know about goodnutrition, would you recommend any of thesediets to a friend who is trying to lose weight?Why or why not?

To find out more about fad diets,visit the Glencoe Science Web

Site.www.glencoe.com/sec/science

INVESTIGATING THE ISSUEINVESTIGATING THE ISSUE

The Promise ofWeight Loss“Lose ten pounds in one week!”“Shed weight without going hungry!” “Burn fat while you sleep!”

968

Purpose Students evaluate diet programsin light of what they know aboutgood nutrition.

BackgroundSeveral years ago, nutritionistsbelonging to the Food and Nu-trition Science Alliance (FANSA)put together a list of “warningsigns” to help consumers evalu-ate various diet programs. Claimsto watch out for include the fol-lowing:■ Recommendations that pro-

mise a quick fix■ Dire warnings of danger from

a single product or regimen■ Claims that sound too good to

be true■ Simplistic conclusions drawn

from a complex study■ Recommendations based on a

single study■ Dramatic statements that are

refuted by reputable scientificorganizations

■ Lists of “good” and “bad” foods■ Recommendations made to

help sell a product■ Recommendations based on

studies published without peerreview

■ Recommendations from stud-ies that ignore differencesamong individuals or groups

Teaching Strategies■ Invite a nutritionist to yourclassroom to talk about the risksof fad diets and to suggest strate-gies for designing healthy eatingplans.■ Divide the class into threegroups. Have each groupresearch a popular fad diet andthen present their findingsregarding the likelihood that thediet will result in safe, long-termweight loss.

P

LS

Going FurtherGoing FurtherGoing Further

Have students check out Internet sitesthat look at the topic of weight loss orother health issues. L2

P

LS

■ Lead the class in a discussion about soci-etal pressures to be thin, and why Americansspend millions of dollars every year trying tolose weight.

Investigating the IssueIn most cases, students will be able to iden-tify serious flaws in the nutritional sound-ness of fad diets, as well as potential healthrisks if the diet is followed for an extendedperiod of time.

VIDEOTAPEMindJogger Videoquizzes

Chapter 35: The Digestive and EndocrineSystems Have students work in groups as they playthe videoquiz game to review key chapterconcepts.




CHAPTER 35 ASSESSMENT 971

22. How could removal of the parathyroid glandsaffect muscle contraction?

23. Recognizing Cause and Effect How is therole of pancreatic hormones in glucose regu-lation important for homeostasis?

24. Interpreting Data The relationship betweenparathyroid hormone secretion and bloodcalcium levels is shown in the graph below.To what level does the blood calcium levelhave to fall in order to get maximum parathy-roid hormone secretion?

25. Concept Mapping Complete the conceptmap by using the following vocabulary terms: liver, bile, small intestine, stomach,esophagus, gallbladder.

THINKING CRITICALLYTHINKING CRITICALLY

ASSESSING KNOWLEDGE & SKILLSASSESSING KNOWLEDGE & SKILLS

The following table contains nutritional infor-mation for a meal of macaroni and cheese.

Interpreting Data Use the data in Table35.5 to answer the following questions.1. How many Calories are there in one

serving of macaroni and cheese?a. 7 c. 280 b. 35 d. 1540

2. Being fond of macaroni and cheese, Juaneats five servings each day. Assuming thisis all he eats, how many Calories doesJuan eat each day?a. 8 c. 300 b. 35 d. 1400

3. What percent of Juan’s Calories arederived from fat?a. less than 1 percentb. approximately 10 percentc. approximately 38 percentd. more than 50 percent

4. Juan should eat only 1800 Calories a day.What proportion of his daily diet isderived from his five servings of maca-roni and cheese?a. 10 percent c. 50 percentb. 38 percent d. 78 percent

5. Interpreting Data The recommendeddaily allowance of sodium is approxi-mately 2.4 g. Make a statement thatdescribes Juan’s sodium intake.

For additional review, use the assessmentoptions for this chapter found on the Biology: TheDynamics of Life Interactive CD-ROM and on theGlencoe Science Web Site.www.glencoe.com/sec/science

CD-ROM

Blood calcium (mg/dL)Max

imun

PTH

secr

etio

n(%

)

100

50

0 5 6 7 8 9 10 11 12 13 14

Relationship Between ParathyroidHormone and Blood Calcium Levels

NutrientGramsper serving

Caloriesper gram

Protein

Carbohydrate

Fat

Sodium

Table 35.5 Macaroni and cheese nutritionServing size: 8 ouncesCalories per serving: 280

1.540

4

4

9

0

7

35

12

4.

5.

6.

passesfood to the

which isstored in the

makes

2.

1.

which passes food to the

which deliversbile to the

3.

971

21. The enzyme pepsin would nothave the proper environment inwhich to function. As a result,proteins would not be digestedin the stomach.

22. The parathyroid glands secretePTH, which increases the cal-cium level in the blood. Calciumis required for muscle contrac-tion. Removal of the glandcould greatly reduce blood cal-cium concentration and inter-fere with muscle contraction.

23. The glucose concentration inthe blood is maintained in avery narrow range. The pan-creas releases insulin to removeglucose from the blood andglucagon to cause the releaseof glucose into the blood.

24. Blood calcium levels must dropbelow 8 mg/dL to get maximumparathyroid hormone secretion.

25. 1. Esophagus; 2. Stomach; 3.Small intestine; 4. Liver; 5. Bile;6. Gallbladder

THINKING CRITICALLYTHINKING CRITICALLY

APPLYING MAIN IDEASAPPLYING MAIN IDEAS


1. c2. d3. c4. d5. George’s diet contains too

much sodium.


3. Even if you were standing on your head, thisprocess would still move food along yourdigestive tract.a. peristalsis c. secretionb. swallowing d. absorption

4. Which of the substances listed in Table 35.4 have a pH near that of your stomach during digestion?

5. Which of these enzymes functions best in theacidic pH of the stomach?a. lipase c. pepsinb. lactase d. amylase

6. What is the primary function of the largeintestine?a. food absorption c. vitamin synthesisb. food digestion d. water absorption

7. Which of the following is under the controlof the hypothalamus?a. pituitary gland c. pancreasb. taste buds d. liver

8. Which of these is NOT a function of thethyroid gland?a. controls growth and developmentb. regulates metabolismc. regulates blood calcium levelsd. responds to stressful situations

9. What unit is used to measure the energy con-tent of food?a. temperature c. Calorieb. grams d. mass

10. What is the most abundant substance in thehuman body?a. carbohydrates c. waterb. vitamins d. proteins

11. Hormones released by ________ glands affectspecific areas known as ________.

12. Salivary glands in your mouth produce________, an enzyme that breaks down________.

13. The ________ prevents swallowed food fromentering the ________.

14. When your body needs energy, it breaksdown ________ in the liver and releases________ into the bloodstream.

15. The pancreas releases the hormone ________,which removes ________ from the blood.

16. A(n) ________ is an inorganic substance thatserves as a building material or takes part in achemical reaction in the body.

17. ________ hormones are made from lipids; theother group of hormones is made from________.

18. A negative feedback system controls the levelof hormones by feeding back information tothe ________ or the ________.

19. The ________ gland is controlled by the________ , tying the endocrine and nervoussystems together.

20. The ________ is a muscular tube of the digestive system that connects the mouth to the ________.

21. Achlorhydria is a condition in which thestomach fails to secrete hydrochloric acid.How would this condition affect digestion?

APPLYING MAIN IDEASAPPLYING MAIN IDEAS

970 CHAPTER 35 ASSESSMENT

TEST–TAKING TIPTEST–TAKING TIP

Where’s the fire? Slow down! Go back over reading passages anddouble-check your math. Remember that doingmost of the questions and getting them right isalways preferable to doing all the questions andgetting lots of them wrong.

Substance pH

black coffee

bleach

lemon juice

baking soda

Table 35.4

5

12

2

9

970

3. a4. (lemon juice)5. c6. d7. a8. d9. c

10. c11. endocrine, target tissues12. amylase, starches13. epiglottis, respiratory tract14. glycogen, glucose15. insulin, glucose16. mineral17. Steroid, amino acids18. hypothalamus, pituitary gland19. pituitary, hypothalamus20. esophagus, stomach

