growth and development...growth and development “in my work what i try to say is that as human...

Growth andDevelopment

“In my work

what I try to

say is that

as human beings

we are more

alike than we

are unalike.”

—Maya Angelou,American novelist

and poet

Talented TeensDiscuss Many children now have opportunities to learn new skillsat an earlier age than ever before. But some argue that pushing achild to excel can be harmful. Research two or three talented teens(for example, Olympic athletes, musicians, or actors). Were theiropportunities positive or negative, or a combination of both? Discussyour findings with your class as part of an oral report.

TEST YOUR GROWTH IQTrue or False?

1. Heart disease can begin todevelop during childhood.

TRUE: Although the symptoms ofheart disease do not usually appearuntil middle age or older, one in sixteenagers has well-developedplaque deposits in their arteries.

2. Shaking a baby is a good way to stop him or her from crying.

FALSE: A baby’s neck and brain are fragile and damage easily.Because neck muscles are weak,shaking a baby can result in blind-ness, brain damage, or even death.

3. People with learning disabilitiescannot be successful.

FALSE: There have been many suc-cessful people who have had learn-ing disabilities. For instance, ThomasEdison had dyslexia. He and manyothers had significant accomplish-ments despite their disabilities.

206 UNIT 4 • Growth and Development

LESSON 19Keeping Your Body Healthy

LESSON 20Learning About the

Reproductive Systems

LESSON 21Learning About Pregnancy

and Childbirth

Christopher Felver/CORBIS

Visit www.glencoe.com to find regularly updated statistics on U.S. lifeexpectancy. Using the information provided, determine the answer to thisquestion: How has U.S. life expectancy changed in the last 50 years?

Visit www.glencoe.com to use , an inter-active tool that helps you determine your health status.

LESSON 22Caring for Infants and Children

LESSON 23Developing Learning and

Planning Styles

LESSON 24Aging Healthfully

UNIT 4 • Growth and Development 207

WHAT’S YOUR VERDICT?To evaluate this advertisement, use the criteria for analyzing and evaluating healthmessages delivered through media and technology that you learned in Unit 1.

EVALUATING MEDIA MESSAGES

CORBIS

http://www.glencoe.comhttp://www.glencoe.com

Keeping Your Body Healthy

• I will keep my body systems healthy.

Your body is made of cells, tissues, and organs that form body systems. A cell is the smallest living part of the body. An organ is abody part consisting of several kinds of tissue that do particularjobs. A body system is a group oforgans that work together to performa main body function. This lessonwill help you review informationabout body systems and whatyou can do to keep thesebody systems healthy.

What You’ll Learn1. Identify behaviors to keep your

cardiovascular, nervous, andimmune systems healthy.(pp. 210, 213, 214)

2. List behaviors important to thehealth of your respiratory,skeletal, and muscular systems.(pp. 215, 216, 217)

3. Identify behaviors important tothe health of your endocrineand digestive systems. (pp. 219,221)

4. List behaviors important to thehealth of your integumentaryand urinary systems. (pp. 223,224)

Why It’s ImportantThink about a car. Many partsneed to work together to keep itrunning well. Your body also hasmany parts that make up yourbody systems, which need towork together to keep you well.

Key Terms• cardiovascular system• nervous system• immune system• respiratory system• skeletal system• muscular system• endocrine system• digestive system• integumentary system• urinary system

MAK 1

Writing About Stretching Suppose one of your friends says she isnot going to warm up and stretch before the big track meet. She saysthat warming up wastes valuable energy that she could use for running.After you read the information on the muscular system on page 217,write a response to this situation in your health journal.


19

LESSON 19 • Keeping Your Body Healthy 209

Blood Your blood carries nutrients,oxygen, carbon dioxide, and cellularwaste products to and from your bodycells. The average-sized adult body hasabout ten pints of blood. Blood is com-posed of plasma and blood cells.Plasma is the liquid component ofblood that carries blood cells and dis-solved materials. It is about 95 percentwater. Plasma contains two majortypes of blood cells—red blood cellsand white blood cells. Plasma also con-sists of particles called platelets. Aplatelet is a particle that helps theblood clot. Blood clots stop the bleedingwhen blood vessels are injured.

A red blood cell transports oxy-gen to body cells and removes carbondioxide from body cells. Red bloodcells contain hemoglobin. Hemoglo-bin is an iron-rich protein that helpstransport oxygen and carbon dioxidein the blood. New red blood cells areconstantly produced in bone marrow,which is the spongy material insidesome bones.

A white blood cell is a blood cellthat attacks, surrounds, and destroyspathogens that enter the body andprevents them from causing infection.

A pathogen is a germ that causesdisease. The number of white bloodcells in your blood increases whenyou have an infection.

Blood vessels There arethree major types of bloodvessels—arteries, veins,and capillaries. An arteryis a blood vessel that car-ries blood away from theheart. Arteries havethick muscular wallsthat move blood be-tween heartbeats.A coronary ar-tery supplies nu-trients and oxygento the heart mus-cle. A pulmonaryartery carries bloodfrom the heart to thelungs, where it absorbsoxygen and releases car-bon dioxide.

StudiOhio

The body system that transports nutrients, gases, hormones, and cellular waste products

throughout the body is the The cardiovascular system consists

of the blood, blood vessels, and the heart.

What to Know About theCardiovascular System

cardiovascular system.

The cardiovascularsystem consists of

blood, arteries, veins,and the heart.

A vein is a blood vessel that returnsblood to the heart. Veins have thinnerwalls than arteries. A capillary is atiny blood vessel that connects arter-ies and veins. Capillaries have thinwalls that allow the transfer of nutri-ents, oxygen, carbon dioxide, and cel-lular waste between the blood andthe body cells.

Heart A four-chambered muscle thatcontinually pumps blood throughoutthe body is called the heart. Thetwo upper chambers are atria. The

two lower chambers are ventricles.The heart is divided into the rightatrium and ventricle and the leftatrium and ventricle. Blood that ispoor in oxygen, returning from thebody, flows constantly into the rightatrium and ventricle.

From the right ventricle, blood ispumped through the pulmonaryartery to the lungs. Carbon dioxide isreleased and oxygen is absorbed asthe blood circulates in capillariesaround the air sacs in the lungs. Thisoxygen-rich blood flows into the leftatrium and ventricle. Contractions ofthe left ventricle pump the bloodthrough the aorta to the body. Theaorta is the main artery in the body.The aorta branches into smallerarteries through which blood flows toall parts of the body.

Heart rate is the number of timesthe heart contracts each minute.Pulse is the surge of blood thatresults from the contractions of theheart. Blood pressure is the force ofblood against the artery walls.

How to Keep Your Cardiovascular System Healthy The following are some of the ways you can keep your cardiovascularsystem healthy:

• Reduce the amount of fat inyour diet.

• Reduce the amount of salt inyour diet.

• Exercise regularly to strengthenyour heart muscles.

• Avoid using tobacco productsbecause they increase blood pressure.

• Maintain a healthful weight.

• Practice stress-managementskills


Blood is pumpedfrom the right

ventricle of theheart through thepulmonary artery

to the lungs.

Pulmonary artery

Left ventricle

Left atrium

Pulmonary veins

Right atrium

Right ventricle

Aorta

Vena cava

Coronary arteries

1. Name and describethe parts of thecardiovascularsystem.

2. What is bloodpressure?


The most common type of heart diseas

e is coronary

heart disease, also referred to as coron

ary artery dis-

ease (CAD). There are two coronary art

eries that

branch from either side of the ascendin

g aorta at the

top of the heart. The coronary arteries

are the vessels

that supply the heart muscle with oxyg

enated blood.

With age, these arteries, which are nor

mally elastic,

harden and lose their elasticity. This con

dition is

known as arteriosclerosis (ar TEER ee

o skluh ROH

suhs). A form of arteriosclerosis, called

atherosclerosis

(a thuh roh skluh ROH suhs), involves

the buildup of

deposits within the coronary arteries.

As these deposits accumulate on the in

terior

walls of these vessels, the diameter of t

he arteries

decreases, restricting and blocking the

flow of blood to

the heart muscle. The effects of atheros

clerosis on the

coronary arteries results in CAD.

Cholesterol Excess cholesterol, whic

h comes from

foods we ingest, also is deposited in a

rteries. Although

some cholesterol is needed by the bod

y to make cell

membranes and some hormones, it is

needed only in

small amounts.

As the flow of blood to the heart is res

tricted, the

heart’s ability to pump effectively is re

duced. This can

lead to a condition called angina (an J

I nuh), in which

a person may feel pain in the chest, lef

t shoulder, and

left arm. Angina also can result in a he

art attack, in

which some of the heart muscle tissue

actually dies

from a lack of proper blood supply.

Symptoms of CAD These can range

from not hav-

ing any symptoms or discomfort at all

to shortness of

breath and fatigue,or to mild or severe

chest pain.

Risk factors Can the development of

CAD be

avoided? The risk factors for CAD includ

e: age, family

history of heart disease, high blood cho

lesterol, smok-

ing, high blood pressure, diabetes, ove

rweight/obesity,

and physical inactivity. Some of these f

actors, such as

age and family history, are not in your

control. Many

of the others can be controlled throug

h diet, regular

exercise, and controlling diabetes or ot

her relevant

medical conditions.

CAD is the leading cause of death for

both men

and women in America today. More th

an 13 million

Americans suffer from CAD. Practicing

positive health

behaviors, such as following a well-ba

lanced diet and

exercising regularly, can help reduce yo

ur risk of devel-

oping CAD later in life.

HEARTDISEASE

An electrocardiogram (ECG) is a graph

ic

representation of electrical impulses t

hat

reflect the action of the heart.

Visit www.glencoe.com to resear

ch more

information about coronary artery d

isease.

• How can risk factors, such as bloo

d choles-

terol levels, blood pressure, and weig

ht, be

controlled?

• What effect does stress have on th

e develop-

ment of CAD?

• What role, if any, does gender pla

y in the risk

of developing CAD?

Create a presentation that outlines he

alth behav-

iors that everyone in your family can

follow to

reduce the risk of CAD. In your present

ation, be

sure to address risk factors such as sm

oking,

physical inactivity,and high blood pre

ssure.

Mehau Kulyk/Science Photo Library www.glencoe.com

http://www.glencoe.comhttp://www.glencoe.com


The body system that carries messages to and from the brain and spinal cord and all

other parts of the body is the . The nervous system is composed of two

divisions—the central nervous system and the peripheral nervous system.

What to Know About the Nervous System

nervous system

The consistsof the brain and spinal cord. The

is made

up of nerves that branch out from thecentral nervous system to muscles,skin, internal organs, and glands. Yoursense organs continually send mes-sages, such as odors, sights, or tastes,to your brain through the peripheralnervous system. Your central nervoussystem, in turn, relays responses tothese messages to your muscles andglands as your body responds tochanges in your environment.

Brain The mass of nerve tissue thatacts as the control center of the bodyis called the brain. The human brainweighs about three pounds and canstore more information than all thelibraries in the world put together.Your brain creates ideas and controlsthinking, reasoning, movement, andemotions. The brain has three majorparts—the cerebrum, the cerebellum,and the brain stem.

The cerebrum is the largest part ofthe brain and controls the ability tomemorize, think, and learn. The cere-brum also determines a person’s intel-ligence and personality. It consists oftwo halves, called hemispheres. Theright hemisphere controls the left sideof the body, and the left hemispherecontrols the right side of the body. Thecerebellum is the part of the brainthat controls and coordinates muscleactivity. It also helps you maintainyour balance.

peripheral nervous system

central nervous system

Aaron Haupt

Spinal cord

Brain

Brain stem

Cerebrum

Cerebellum

Nerves

Concussion A braininjury that sometimesresults in a loss ofconsciousness is aconcussion. An impactcreates a suddenmovement of thebrain within the skull.

The nervous system ismade up of the central

nervous system (thebrain and spinal cord)

and the peripheralnervous system

(nerves).

Your ability to catch a ball is a func-tion of your cerebellum. The brainstem is the part of the brain that con-trols the functions of the internalorgans.

Spinal cord The column of nerve cellsthat extends downward from thebrain is the spinal cord. Your spinalcord carries messages to and fromyour brain and all parts of your body.It keeps your brain informed ofchanges in your body and in yourenvironment. Your spinal cord is pro-tected by your vertebrae.

Nerve cells The nervous system iscomposed of cells called neurons. Aneuron is a nerve cell that is the struc-tural and functional unit of the nerv-ous system. Some neurons in the spinalcord may be several feet long. A neuronconsists of a cell body, an axon, anddendrites.A cell body is the main bodyof the neuron. An axon is an elongatedfiber that carries impulses away fromthe cell body to the dendrites ofanother neuron. Dendrites arebranching fibers that receive impulsesand carry them to the cell body.

Sensory and motor neurons worktogether to help you respond to yourenvironment. Sensory neurons carryimpulses from the sense organs to thespinal cord and brain. Motor neu-rons carry responding impulses tomuscles and glands from the brainand spinal cord. Motor neurons causeresponses in muscles and glands.

Reflex action Have you ever touchedsomething hot and quickly pulledaway from it? You experienced a reflexaction. A reflex action is an involun-tary action in which a message is sentto the spinal cord, is interpreted, and isresponded to immediately.

Sensory neurons carry the mes-sage that you touched a hot surfaceto your spinal cord and brain. Yourbrain interprets the message. Motorneurons carry the message back toyour muscles. You respond by movingyour hand. Reflex actions do notinvolve conscious thought and takeonly a fraction of a second. Reflexactions help keep you safe.

How to Keep Your Nervous System HealthyThe following suggestions will protect your nervous system:

• Wear a protective helmet forsports.

• Avoid diving into shallowwater or water of unknowndepth.

• Use a safety belt.• Follow directions for taking

any medications that affectthe nervous system.

• Avoid drinking alcohol andusing other drugs that impairthe functions of the brain.

• Follow directions for usinghousehold products that con-tain chemicals that may affectthe nervous system.


Sensoryneuron

Motor neuron

Spinal cord

Receptor in skin

Direction ofimpulse

Reaction –muscle contracts

This person’s sensoryneurons sense that abowl that has beenheating in a microwaveis hot. The person’smotor neurons cause theperson’s hand to pullaway from the bowl.

1. What is thedifference betweenthe central nervoussystem and theperipheral nervoussystem?

2. What is a reflexaction?

How to Keep Your Immune System HealthyThe following are ways to keep your immune system healthy:

• Choose foods that are high inprotein and vitamin B.

• Keep accurate records of allimmunizations.

• Get plenty of rest and sleep.• Exercise to keep bones dense

and to protect bone marrow.

The immune system protects yourbody from pathogens. A pathogen is agerm that causes disease. When whiteblood cells attack pathogens, thepathogens are filtered into the lymph.Lymph is a clear liquid that surroundsbody cells and circulates in lymph ves-sels. Lymph carries harmful pathogensand other small particles to lymphnodes. A lymph node is a structurethat filters and destroys pathogens.The spleen is an organ on the left sideof the abdomen that filters foreignmatter from the blood and lymph.

Immunity is the body’s resistance todisease-causing agents. White bloodcells are formed in bone marrow andcirculate in the blood. These whiteblood cells are changed to T cells withinthe thymus gland. A T cell is a whiteblood cell that destroys pathogens. A Bcell is another kind of specializedwhite blood cell that produces antibod-ies. An antibody is a special proteinthat helps fight infection.

The body system that removes harmful organisms from the blood and combats

pathogens is the The immune system is composed of lymph, lymph

nodes, lymph vessels, tonsils, the thymus gland, and the spleen.

What to Know About the Immune System

immune system.

Make theConnection

Immune System Formore information onthe immune system,see page 485 inLesson 44.

214 UNIT 4 • Growth and Development(tt)Photodisc/Getty Images; (cr)Aaron Haupt

Thymus gland

Lymph vessel

Lymph node

Spleen

The immune system protectsyour body from pathogens.

1. What is apathogen?

2. What is immunity?

The body system that provides body cells with oxygen and removes carbon

dioxide that cells produce as waste is the Air enters through your nose or mouth when you

inhale. Mucus in the nasal passages and sinuses warms and moistens the air and traps dust particles and

pathogens. Mucus is a thick secretion that moistens, lubricates, and protects mucous membranes. A mucous membrane

is a type of tissue that lines body cavities and secretes mucus.

What to Know About the Respiratory System

respiratory system.

Air moves from your nose or mouththrough your pharynx to your trachea.The epiglottis is a flap that covers theentrance to the trachea when you swal-low. When you inhale, the epiglottisopens and air flows into the trachea.The trachea is a tube through whichair moves to the bronchi and lungs.Thetrachea is lined with cilia. Cilia arehairlike structures that remove dustand other particles from the air.

The bronchi are two tubesthrough which air moves to the lungs.The lungs are the main organs of therespiratory system. As the bronchienter each lung, they branch to formbronchioles. The bronchioles aresmall tubes that branch to form alve-oli. Alveoli are microscopic air sacs.The walls of the alveoli are so thinthat oxygen and carbon dioxide easilypass through them.

Two exchanges take place in thealveoli. Oxygen passes from the alve-oli into your capillaries and carbondioxide passes from your capillariesinto the alveoli. You exhale carbondioxide. Blood rich in oxygen flowsfrom your lungs to your heart.

How to Keep Your Respiratory System HealthyThe following are ways to keep your respiratory system healthy:

• Do not smoke.• Avoid breathing secondhand

smoke.• Do not inhale harmful drugs.• Avoid breathing polluted air.

• Exercise regularly.• Avoid inhaling harmful

chemicals.• Seek medical help for respira-

tory infections.

LESSON 19 • Keeping Your Body Healthy 215(tt)CORBIS

Nasal cavity

Mouth

PharynxTrachea

Lungs

Larynx

Bronchiole

Alveoli

Epiglottis

The respiratory system providesbody cells with oxygen andremoves carbon dioxide thatcells produce as waste.

Bone is the structural material ofthe skeletal system. Periosteum (peree AHS tee um) is a thin tissue thatcovers bone and contains nerves andblood vessels. Bone marrow is softtissue in the center of most boneswhere both red and white blood cellsare formed.

Cartilage is soft, connective tis-sue on the ends of some bones. It alsoacts as a cushion where bones meet,such as in the knee and hip joint.Cartilage disks between vertebraeserve as shock absorbers. A liga-ment is a tough fiber that connectsbones together. A joint is the pointwhere two bones meet. There are sev-eral types of joints in your body.

The body system that serves as a support framework, protects

vital organs, works with muscles to produce movement, and

produces blood cells is the

What to Know About the Skeletal System

skeletal system.

How to Keep Your Skeletal System HealthyThe following are ways to keep your skeletal system healthy:

• Choose foods rich in calcium,phosphorus and vitamin D.

• Exercise to strengthen joints.• Wear protective equipment

and well-cushioned, properly

fitting shoes and warm upbefore exercising.

• Sit, stand and walk with cor-rect posture. Participate inscreening for scoliosis.

216 UNIT 4 • Growth and Development(tt)Photodisc/Getty Images; (cr)Yoav Levy/Phototake

The skeletalsystem servesas a supportframework foryour body.

1. List three functionsof the skeletalsystem.

2. What connectsbones?

Muscles are divided into two majorgroups: voluntary and involuntary. Avoluntary muscle is a muscle a per-son can control. Muscles in your arms

and legs that help you move are vol-untary muscles. An involuntarymuscle is a muscle that functionswithout a person’s control. Muscles inyour stomach and other internalorgans are involuntary muscles.

There are three types of muscle tis-sue in your body. Smooth muscle isinvoluntary muscle tissue found inmany internal organs. Skeletal mus-cle is voluntary muscle tissue that isattached to bone. Cardiac muscle isspecialized muscle tissue found onlyin the heart. It is unique from othermuscle tissue because of its struc-ture. Contractions in cardiac musclesare generated by nerve stimulation.

A tendon is tough tissue fiber thatattaches muscles to bones. Skeletalmuscles work in pairs to move yourbody. One muscle in the pair con-tracts and shortens, while the otherrelaxes and lengthens.

How to Keep Your Muscular System HealthyThe following are ways to keep your muscular system healthy:

• Discontinue exercise if youhave a muscle injury.

• Warm up and stretch beforeexercise.

• Exercise different musclegroups regularly.

• Maintain your desirableweight.

• Bend at the knees and keepyour back straight when lift-ing heavy objects.

• Select foods and beveragescontaining carbohydrates andproteins for energy and mus-cle development.

• Sleep on a firm mattress.

Frontalis

Pectoralis(chest muscle)

Sternocleidomastoid(neck)

Rectus abdominis(abdominal muscles)

Rectus femoris

Biceps femoris(back of thigh)

Biceps brachiiTriceps brachii

Sartorius

Quadriceps(front ofthe thigh)

Gastrocnemius(calf muscle)

Gluteus maximus

Latissimus dorsi

Deltoid

(The dotted lines are used for musclesthat are on the back side of the figure

and can't be seen from the front.)

Muscles Musclesshorten and lengthenbecause of elasticityin muscle fibers. Thisallows movement atthe joints.

The body system that consists of muscles that provide

motion and maintain posture is the

There are more than 600 muscles in your body.

What to Know About the Muscular System

muscular system.

LESSON 19 • Keeping Your Body Healthy 217(tt)CORBIS; (cl)Lori Adamski Peek/Getty Images

The muscularsystem consistsof muscles thatprovide motionand maintainposture.

Pituitary gland The endocrine glandthat produces hormones, which controlgrowth and other glands is the pitu-itary gland. The pituitary gland islocated below the hypothalamus in thebrain and is about the size of a pea.

Hormones from the pituitary glandinfluence growth, metabolism, devel-opment of the reproductive organs,uterine contractions during child-birth, and many other body functions.

The pituitary gland often is calledthe master gland because it releaseshormones that affect the function ofother glands.

Thyroid gland The endocrine glandthat produces thyroxin is the thy-roid gland. A hormone that controlsmetabolism and calcium balance inthe body is thyroxin. The rate atwhich food is converted into energyin body cells is metabolism. The thy-roid gland is located near the upperportion of the trachea.

Parathyroid glands The endocrineglands that secrete hormones, which control the amount of calcium andphosphorus in the body are theparathyroid glands. There are four parathyroid glands that arelocated on the thyroid gland. Each parathyroid gland is about the size ofa grain of rice.

Parathyroid glands

Thymus

Thyroid gland

Ovaries

Pancreas

Adrenal glands

Pituitary gland

The body system that consists of glands that produce hormones is the

A group of cells that secretes hormones is a gland. A chemical messenger

released into the bloodstream is a hormone. Hormones control many body activities.

What to Know About the Endocrine System

system.

endocrine

Hormones Hormonescirculate throughoutthe body in thebloodstream. However,each hormone targetsonly certain organs or tissues.


Testes

The endocrinesystem consists of

glands that producehoromones.

Aaron Haupt

Pancreas The gland that producesboth digestive enzymes and insulin isthe pancreas. The digestiveenzymes produced by the pancreasare essential to the digestion of food.

Insulin is a hormone that regu-lates blood sugar level. If the pan-creas fails to produce enough insulin,a person develops diabetes mellitus.Diabetes mellitus is a disease inwhich the body produces little or noinsulin. Diabetes will be discussedfurther in Lesson 48.

Adrenal glands The endocrine glandsthat secrete several hormones,including adrenaline, are the adre-nal glands. A hormone that pre-pares the body to react during timesof stress, danger, or in an emergencyis adrenaline. When adrenaline issecreted into the bloodstream, bothheart rate and blood pressureincrease.

The adrenal glands also secretehormones that affect the body’s metab-olism. There are two adrenal glands inthe body, located on each kidney.

Ovaries There are two ovaries in thefemale body. The ovaries are femalereproductive glands that produce ovaand estrogen. Ova are egg cells, orfemale reproductive cells.

Estrogen is a hormone producedby the ovaries that stimulates thedevelopment of female secondary sexcharacteristics and affects the men-strual cycle.

Testes There are two testes in themale body. The testes are male repro-ductive glands that produce spermand testosterone. Testosterone is ahormone that produces the male sec-ondary sex characteristics.

How to Keep Your Endocrine System HealthyThe following are important ways to keep your endocrine system healthy:

• Have regular medical checkups.• Perform testicular self-examinations each month.• Keep track of the length and dates of your menstrual cycles.

TestesOvaries

UterusThyroid gland

Kidneys

Adrenal glands

Bones

Pituitary hormones have many functions. They regulate the development of bones andmuscles; affect the reproductive organs; affect the functioning of the kidneys, the adrenalgland and the thyroid glands; and stimulate the uterus to contract during childbirth.

LESSON 19 • Keeping Your Body Healthy 219(l)Aaron Haupt; (r)Aaron Haupt

The body system that breaks down food into nutrients that can be used by the body is the

The digestive system also allows nutrients to be absorbed by body

cells and waste materials to be eliminated from the body. Digestion is the process by

which food is changed so that it can be absorbed by body cells.

What to Know About the Digestive System

digestive system.

Mouth When food is chewed in themouth, teeth break it into smallerpieces. The salivary glands areglands in the mouth that releasesaliva, which contains a chemicalthat begins the digestion of carbohy-drates. Saliva is a fluid that helpssoften food so that it can be swal-lowed more easily.

Approximately 10,000 microscopictaste buds are on the tongue. Eachtaste bud contains 50–100 receptorcells. A tiny hair extends from eachreceptor cell. When the hairs arestimulated by food, they send nerveimpulses to the brain that registerone of four basic flavor sensations:sweet, salty, sour, or bitter.

Esophagus When you swallow food, itmoves into the esophagus. Theesophagus is a tube that connectsthe mouth and the stomach. Foodpasses to your stomach by theprocess of peristalsis. Peristalsis(per uh STAHL suhs) is a series ofinvoluntary muscle contractions.Peristalsis can move food to yourstomach even if you are standing onyour head.

220 UNIT 4 • Growth and Development(tt)Photodisc/Getty Images; Aaron Haupt

The digestive systembreaks down food into

nutrients that can beused by the body.

Stomach The organ that releasesacids and juices that mix with foodand produce a thick paste calledchyme (KIM) is the stomach. Thestomach produces a layer of mucus toprotect its lining from the strongacids released in digestion. Afterabout four hours of churning thefood, muscle contractions force thefood into the small intestine.

Small intestine The coiled tube inwhich the greatest amount of diges-tion and absorption take place is thesmall intestine. The small intestineis about 21 feet long and is lined withvilli. Villi are small folds in the liningof the small intestine that increasethe surface area and allow more foodto be absorbed. Several enzymes areproduced in the lining of the smallintestine. An enzyme is a protein thatregulates chemical reactions.

Liver The gland that secretes bile tohelp break down fats, maintain bloodsugar level, and filter poisonouswastes is the liver. Bile flows to the

small intestine to help in the diges-tion of fats. Bile is stored in the gallbladder, which is a small sac-likeorgan located under the liver.

Pancreas The gland that producesboth digestive enzymes and insulin isthe pancreas. Enzymes from the pancreas break down proteins,starches, and fats from food in thesmall intestine.

Large intestine After food passesthrough the small intestine, it entersthe large intestine, also called thecolon. The large intestine is a tubeextending from the small intestine inwhich undigested food is prepared forelimination from the body. When thelarge intestine is full, it contracts,and solid wastes leave the bodythrough the rectum and anus. Therectum is the lower end of the largeintestine that stores wastes tem-porarily. The anus is the opening tothe outside of the body at the end ofthe rectum.

(t to b)Tony Freeman/PhotoEdit, David Young-Wolff/Getty Images, Terry Sutherland


Make theConnectionHealth BehaviorContracts For moreinformation onmaking a healthbehavior contract to keep your bodysystems healthy, seepage 32 in Lesson 3.

TABLE 19.1 Keep Your Digestive System Healthy

Fiber-rich foods Choose a variety of foods every day and eat plenty of foods that containfiber. Whole-grain breads and cereals, as well as fruits and vegetables, aregood sources of fiber. Fiber stimulates digestive tract muscles.

Enjoyment Chew slowly and enjoy your food. Do not rush to finish a meal. Chew foodwell and avoid indigestion. Avoid arguments when eating.

Drink at least six to eight glasses of water each day. Water is involved inmany body functions, including digestion and maintaining normal bodytemperature.

Fluids

Healthful Behavior Description of Healthful Behavior

1. What is digestion?

2. What are the four basic flavorsensationsdetected by taste buds?

222 UNIT 4 • Growth and Development(tt)Photodisc/Getty Images

The body system that covers and protects the body and consists of skin, glands

associated with the skin, hair, and nails is the (in TEG yuh MEN

tuh ree) The skin performs several functions that are essential for survival.

What to Know About theIntegumentary System

system.

integumentary

The largest organ in the body is skin.It contains nerve cells that help youdetect pain, pressure, touch, heat,and cold. Skin protects some bodyparts against injury, serves as a pro-tective layer that keeps microorgan-isms from entering the body, andhelps maintain a healthful body tem-perature.

Skin helps with the removal ofwastes from the body and helps yousense the environment. It also helps

protect you from ultraviolet radiationbecause of the presence of melanin.Melanin is a pigment that gives theskin its color.

Two layers Skin is made up of two lay-ers. The epidermis is the outer layerof skin cells. These cells are constantlyshed and replaced. The epidermis doesnot contain blood vessels or nerve end-ings. New skin cells are produced inthe deepest layer of the epidermis.The dermis is a thick layer of cellsbelow the epidermis that containssweat glands, hair follicles, sebaceous(oil) glands, blood vessels, and nerves.

Glands A gland that aids the body ingetting rid of wastes, such as salt, isa sweat gland. Sweat glands alsohelp cool the body by releasing sweatthrough pores to evaporate on thesurface of your skin.

A sebaceous gland is a small oil-producing gland that helps protectthe skin. Sebum is the oil producedby sebaceous glands. Sebaceousglands are usually found togetherwith hair follicles, though some existin hairless areas. Below the dermis isthe subcutaneous layer. The subcu-taneous layer is a layer of fatty

Dermis

Epidermis

Nerves

ArteryVeinHair follicle

Hair

Sweat gland

Sebaceous gland

The integumentarysystem consists of skin,glands associated withthe skin, hair, and nails.

tissue located below the dermis. Alarge portion of the body’s fat is storedin this layer.

Birthmarks and Scars Because skin isthe largest organ in the body, it also isthe most vulnerable organ. There areseveral types of conditions that affectthe skin. Common skin conditionsinclude birthmarks and scars. A birth-mark is an area of discolored skin thatis present at birth. Birthmarks includedifferent types of freckles and molesand may be removed by a physician. Ascar is a mark left on damaged tissueafter the tissue has healed. If a personis cut or has a severe burn, a scar maydevelop. Some people are more likelythan others to develop scars.

Warts Warts and acne are other com-mon skin conditions. A wart is a con-tagious growth that forms on the toplayer of the skin. Warts are caused bya viral infection. They usually grow ingroups and can be spread by contact.Warts can be treated with over-the-counter drugs. However, if wartsspread, they should be treated by aphysician.

Acne A skin disorder in which hair fol-licles or pores in the skin becomeplugged with sebum is acne. Acnemay be prevalent during adolescencebecause hormonal changes stimulatethe sebaceous glands to producesebum. A pustule is a dome-shapedlesion that contains pus consisting ofwhite blood cells, dead skin cells and bacteria. The plug may close thepore, causing it to swell, creating awhitehead. If the pore is open,it is commonly called a blackheadbecause the surface of the plug has a dark appearance. Blackheads are notcaused or colored by dirt.

Acne can last through early adult-hood. Acne may be aggravated byapplication of oil-based makeup, sun-tan oil, or hair products.

Ringworm A skin condition thatcauses small, red, ring-shaped markson the skin is ringworm. Ringwormis caused by a fungal infection and can be spread by physical contact.Physicians usually treat ringwormwith ointments or creams. However,severe cases of ringworm may requiretreatment with antifungal tablets.

Nails and hair Nails and hair also arepart of the integumentary system.Nails are made up of dead cells andkeratin, a tough protein. Hair is athreadlike structure consisting of deadcells filled with keratin. Hair protectsskin from harmful sun rays and helpsmaintain body temperature. Hairvaries in color, texture, and amount foreach person. From 100,000 to 200,000hairs may be on your head. Each hairgrows from a follicle. A hair follicle isa depression on the surface of the der-mis that contains nutrients a hairneeds to grow. The roots of hairs aremade up of living cells.

How to Keep Your Integumentary System HealthyThe following tips will help you keep this body system healthy:

• Wear sunscreen with an SPFof at least 15 when you areexposed to the sun.

• Examine skin monthly for anychanges in moles, warts, orfreckles.

• Follow directions when usingmakeup.

• Shower or bathe each day.• Eat foods containing

vitamin A.• Seek proper medical care for

skin rashes.• Wash hair regularly.• Treat dandruff with appropri-

ate products.


Blisters Blisters arecaused by pressure or friction that causes fluid to collectbetween the layers of the skin.

1. How does skin aidthe body in gettingrid of wastes?

2. What causeswarts?

The body system that removes liquid wastes from the body and maintains the body’s

water balance is the The organs of the urinary system are the kidneys,

ureters, bladder, and urethra.

What to Know About the Urinary System

urinary system.

Kidneys An organ that filters theblood and excretes waste productsand excess water in the form of urineis a kidney. A pale yellow liquid com-posed of water, salts, and other wasteproducts is urine. The body has twokidneys. They lie on either side of thespinal column just above the waist.

Ureters A narrow tube that connectsa kidney to the urinary bladder is aureter (YUR uh tur). Two ureterscarry urine from the kidneys to theurinary bladder.

Urinary bladder The muscular sacthat stores urine is the urinarybladder. As the urinary bladder fillswith urine, it expands. During urina-tion, urine is forced out of the bladderinto the urethra.

Urethra The narrow tube extendingfrom the urinary bladder to the out-side of the body, through which urinepasses out of the body is the urethra(yu REE thruh).

Urinarybladder

UreterArtery

Urethra

Kidney

Vein

How to Keep Your Urinary System HealthyThese two tips will help you keep this body system healthy:

• Drink plenty of water a day,especially in hot weather orwhen doing physical activity.

• Maintain a healthful bloodpressure, as high blood pres-sure damages the kidneys.

224 UNIT 4 • Growth and Development(l)Aaron Haupt, (r)Gen Nishino/Photodisc/Getty Images

The urinary systemconsists of the kidneys,

the ureters, thebladder, and the

urethra.

To keep your urinary system healthy, make sure youstay hydrated.

1. Name twofunctions of theurinary system.

2. How can highblood pressureaffect the urinarysystem?

19STUD

Y

GUIDE

Key Terms ReviewMatch the following definitions with the lesson Key Terms on the left. Do not write in this book.

Recalling the Facts

1. produces a hormone that controls growth

2. includes ligaments and joints

3. contains cells that transmit messages tobody parts

4. includes plasma and hemoglobin

5. helps the body remove liquid wastes

6. the main organs are the lungs

7. helps provide motion and maintain posture

8. covers and protects the body

9. includes antibodies that fight infection

10. produces enzymes that break down proteins and starchescardiovascular

systemcentral nervous

systemdigestive systemendocrine systemimmune systemintegumentary

systemmuscular systemnervous systemperipheral nervous

systemrespiratory systemskeletal systemurinary system

11. What is the function of white blood cells?

12. List three ways to keep your integumentarysystem healthy.

13. What is the difference between pulse andblood pressure?

14. What are three types of muscle? How arethey different?

15. Describe the exchange that occurs in thealveoli.

16. What is the function of the urinary system?

17. Why is it important to eat foods that con-tain fiber?

18. Name and describe the five functions ofthe brain.

Critical Thinking

LESSON 19 • Study Guide 225MAK 1

ActivitiesSharpen Your Life Skills28. Analyze Influences on Health Set

up six or eight stations. Choose an activity(such as push-ups or jumping jacks) for eachstation. Circulate through the stations.Record your heart rate before and after eachactivity. Allow two minutes at each station.A rest station is last. Evaluate your results.Did your heart rate differ? Discuss how theheart reacts to activity and then recovers.

Responsible Decision Making27. Journaling You are going to a midday

baseball game with a friend. The weatheris going to be hot and sunny. Your friendtells you that you should protect yourselffrom the sun so that you don’t get sun-burned. What should you do? Write aresponse to this situation in your journal.Refer to the Responsible Decision-MakingModel on page 61 for help.

19. How are sensory and motor neurons simi-lar? How are they different? How do theywork together?

20. How are the cardiovascular and immunesystems related?

21. Explain the relationship between the mus-cular and the skeletal systems in the waythey function.

22. Explain how the integumentary and urinarysystems have a common function.

Real-Life Applications23. Why would having a hyperventilating per-

son breathe into a paper bag be helpful?

24. Investigate what options are available to youif you injure the cartilage in your knee joint.

25. How might eating too fast affect yourdigestive system?

26. Explain why physical activity might be beneficial to a person recovering fromcoronary artery disease.

Visit www.glencoe.com for more Health & Wellness quizzes.

http://www.glencoe.com

Health & WellnessTable of ContentsUNIT 1 Health SkillsLesson 1 Taking Responsibility for HealthLesson 2 Accessing Valid Health Information, Products, and ServicesLesson 3 Practicing Healthful BehaviorsLesson 4 Analyzing Influences on HealthLesson 5 Using Communication SkillsLesson 6 Setting Health Goals and Making Responsible DecisionsLesson 7 Being a Health Advocate

UNIT 2 Mental and Emotional HealthLesson 8 Developing Good CharacterLesson 9 Developing a Healthy MindLesson 10 Expressing Emotions and Managing StressLesson 11 Dealing with DepressionLesson 12 Dealing with Loss and Grief

UNIT 3 Family and Social HealthLesson 13 Developing Healthful Family RelationshipsLesson 14 Adjusting to Family ChangesLesson 15 Examining Dating and FriendshipsLesson 16 Practicing Abstinence From SexLesson 17 Recognizing Harmful RelationshipsLesson 18 Preparing for Marriage and Parenthood

UNIT 4 Growth and DevelopmentLesson 19 Keeping Your Body HealthyLesson 20 Learning About the Reproductive SystemsLesson 21 Learning About Pregnancy and ChildbirthLesson 22 Caring for Infants and ChildrenLesson 23 Developing Learning and Planning StylesLesson 24 Aging Healthfully

UNIT 5 NutritionLesson 25 Choosing Healthful FoodsLesson 26 Following Dietary GuidelinesLesson 27 Using Diet to Guard Against DiseaseLesson 28 Developing Healthful Eating HabitsLesson 29 Maintaining a Healthful Weight

UNIT 6 Personal Health and Physical ActivityLesson 30 Having Regular Physical ExamsLesson 31 Being Well-GroomedLesson 32 Getting Adequate Rest and SleepLesson 33 Participating in Physical ActivityLesson 34 Practicing FitnessLesson 35 Exercising Safely

UNIT 7 Alcohol, Tobacco, and Other DrugsLesson 36 Using Prescription and OTC Drugs SafelyLesson 37 Choosing an Alcohol-Free LifestyleLesson 38 Choosing a Tobacco-Free LifestyleLesson 39 Avoiding Illegal Drug UseLesson 40 Avoiding Drug DependenceLesson 41 Resisting Pressure to Abuse DrugsLesson 42 Reducing Risk by Being Drug FreeLesson 43 Assessing Treatment Options

UNIT 8 Communicable and Chronic DiseasesLesson 44 Avoiding Communicable Diseases.Lesson 45 Dealing with Respiratory Diseases, Asthma, and AllergiesLesson 46 Reducing the Risk of STDs and HIVLesson 47 Reducing the Risk of Cardiovascular DiseasesLesson 48 Managing Chronic Health ConditionsLesson 49 Reducing the Risk of Cancer

UNIT 9 Consumer and Community HealthLesson 50 Acquiring Knowledge of Health LawsLesson 51 Managing Time and MoneyLesson 52 Analyzing Media MessagesLesson 53 Accessing Reliable Health CareLesson 54 Investigating Health CareersLesson 55 Learning About Public Health

UNIT 10 Environmental HealthLesson 56 Learning About Environmental IssuesLesson 57 Preventing Air and Water PollutionLesson 58 Preventing Noise and Visual PollutionLesson 59 Practicing Recycling and ConservationLesson 60 Protecting the Environment

UNIT 11 Injury Prevention and Personal SafetyLesson 61 Reducing Unintentional InjuriesLesson 62 Staying Safe During Severe Weather and Natural DisastersLesson 63 Reducing the Risk of ViolenceLesson 64 Respecting Authority and Obeying LawsLesson 65 Protecting Yourself From Physical ViolenceLesson 66 Protecting Yourself From Sexual ViolenceLesson 67 Staying Away From GangsLesson 68 Reducing Weapon InjuriesLesson 69 Performing Common First Aid ProceduresLesson 70 Performing Emergency First Aid Procedures

Health ResourcesEnglish/Spanish GlossaryIndexCredits

Feature ContentsActivity: Using Life SkillsSpeaking OutHealth NewsFacts AboutJust the Facts

Student WorkbooksReading EssentialsTo the StudentUnit 1: Health SkillsLesson 1: Taking Responsibility for HealthLesson 2: Accessing Valid Health Information, Products, and ServicesLesson 3: Practicing Healthful BehaviorsLesson 4: Analyzing Influences on HealthLesson 5: Using Communication SkillsLesson 6: Setting Health Goals and Making Responsible DecisionsLesson 7: Being a Health Advocate

Unit 2: Mental and Emotional HealthLesson 8: Developing Good CharacterLesson 9: Developing a Healthy MindLesson 10: Expressing Emotions and Managing StressLesson 11: Dealing with DepressionLesson 12: Dealing with Loss and Grief

Unit 3: Family and Social HealthLesson 13: Developing Healthful Family RelationshipsLesson 14: Adjusting to Family ChangesLesson 15: Examining Dating and FriendshipsLesson 16: Practicing Abstinence From SexLesson 17: Recognizing Harmful RelationshipsLesson 18: Preparing for Marriage and Parenthood

Unit 4: Growth and DevelopmentLesson 19: Keeping Your Body HealthyLesson 20: Learning About the Reproductive SystemsLesson 21: Learning About Pregnancy and ChildbirthLesson 22: Caring for Infants and ChildrenLesson 23: Developing Learning and Planning StylesLesson 24: Aging Healthfully

Unit 5: NutritionLesson 25: Choosing Healthful FoodsLesson 26: Following Dietary GuidelinesLesson 27: Using Diet to Guard Against DiseaseLesson 28: Developing Healthful Eating HabitsLesson 29: Maintaining a Healthful Weight

Unit 6: Personal Health and Physical ActivityLesson 30: Having Regular Physical ExamsLesson 31: Being Well-GroomedLesson 32: Getting Adequate Rest and SleepLesson 33: Participating in Physical ActivityLesson 34: Practicing FitnessLesson 35: Exercising Safely

Unit 7: Alcohol, Tobacco, and Other DrugsLesson 36: Using Prescription and OTC Drugs SafelyLesson 37: Choosing an Alcohol-Free LifestyleLesson 38: Choosing a Tobacco-Free LifestyleLesson 39: Avoiding Illegal Drug UseLesson 40: Avoiding Drug DependenceLesson 41: Resisting Pressure to Abuse DrugsLesson 42: Reducing Risk by Being Drug FreeLesson 43: Assessing Treatment Options

Unit 8: Communicable and Chronic DiseasesLesson 44: Avoiding Communicable DiseasesLesson 45: Dealing with Respiratory Diseases, Asthma, and AllergiesLesson 46: Reducing the Risk of STDs and HIVLesson 47: Reducing the Risk of Cardiovascular DiseasesLesson 48: Managing Chronic Health ConditionsLesson 49: Reducing the Risk of Cancer

Unit 9: Consumer and Community HealthLesson 50: Acquiring Knowledge of Health LawsLesson 51: Managing Time and MoneyLesson 52: Analyzing Media MessagesLesson 53: Accessing Reliable Health CareLesson 54: Investigating Health CareersLesson 55: Learning About Public Health

Unit 10: Environmental HealthLesson 56: Learning About Environmental IssuesLesson 57: Preventing Air and Water PollutionLesson 58: Preventing Noise and Visual PollutionLesson 59: Practicing Recycling and ConservationLesson 60: Protecting the Environment

Unit 11: Injury Prevention and Personal SafetyLesson 61: Reducing Unintentional InjuriesLesson 62: Staying Safe During Severe Weather and Natural DisastersLesson 63: Reducing the Risk of ViolenceLesson 64: Respecting Authority and Obeying LawsLesson 65: Protecting Yourself From Physical ViolenceLesson 66: Protecting Yourself From Sexual ViolenceLesson 67: Staying Away From GangsLesson 68: Reducing Weapon InjuriesLesson 69: Performing Common First Aid ProceduresLesson 70: Performing Emergency First Aid Procedures

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