Chapter
20
Section
Chapter Organizer
Nervous and Endocrine Systems
Objectives
Activities/Features
Explore Activity: Observe Objects, p. 545
Chapter Opener
Standards
Reproducible Resources
Technology
Test Practice Workbooks are available for
use with each chapter.
English and Spanish audiocassettes are
available for use with each section.
National
State/Local
National Content
Standards: UCP4,
A1, A2, C1, C3,
F1, F4
California Science
Content Standards:
5a, 5b, 7a, 7b, 7c
Activity Worksheets, pp. 109–110
Enrichment, p. 55
Laboratory Manual, pp. 117–120
Multicultural Connections, pp. 39–40
Reinforcement, p. 55
Study Guide, pp. 77-78
Section Focus Transparency 55
Teaching Transparency 39
Glencoe Science Voyages
Interactive CD-ROM
Internet Connection, p. 551
20-1
The Nervous System
3 Sessions
11⁄2 Blocks
1. Describe the basic structure of a neuron
and how an impulse moves.
2. Compare the central and peripheral nervous
systems.
3. Explain how drugs affect the body.
Physics Integration, p. 549
Using Math, p. 550
Skill Builder: Concept Mapping, p. 552
Using Computers, p. 552
Activity 20-1: Reaction Time, p. 553
20-2
The Senses
3 Sessions
11⁄2 Blocks
4. List the sensory receptors in each sense
organ.
5. Explain what type of stimulus each sense
organ responds to and how.
6. Explain the need for healthy senses.
MiniLab: Observing Balance Control, p. 555
Using Math, p. 556
MiniLab: Comparing Sense of Smell, p. 558
Skill Builder: Observing and Inferring, p. 559
Science Journal, p. 559
Activity 20-2: Investigating Skin Sensitivity,
pp. 560–561
National Content
Standards: UCP4,
UCP5, A1, A2, B3,
C1, C3, E2, F1, F5
California Science
Content Standards:
5a, 5b, 5g, 6c, 6d,
6e, 7a, 7c, 7e
Activity Worksheets, pp. 111–114
Enrichment, p. 56
Home Involvement, p. 28
Laboratory Manual, pp. 121–124
Reinforcement, p. 56
Study Guide, p. 78
Section Focus Transparency 56
Science Integration Transparency 20
Glencoe Science Voyages
Interactive CD-ROM
Glencoe Science Voyages
Interactive Videodisc—Life
20-3
The Endocrine System
1 Session
1⁄2 Block
7. Explain the function of hormones.
8. Name three endocrine glands and explain
the effects of their hormones.
9. Explain how a feedback system works.
Problem Solving: Interpreting Blood Sugar
Levels, p. 563
Skill Builder: Comparing and Contrasting,
p. 564
Science Journal, p. 564
How It Works: A Hearing Aid, p. 565
National Content
Standards: UCP2,
A1, C1
California Science
Content Standards:
5a, 5b, 7b, 7c
Critical Thinking/Problem Solving, p. 20
Enrichment, p. 57
Reinforcement, p. 57
Study Guide, pp. 79–80
Section Focus Transparency 57
Teaching Transparency 40
Internet Connection, p. 563
The number of recommended single-period sessions
The number of recommended blocks
One session and one-half block are allowed for chapter review and assessment.
Key to Teaching Strategies
Activity Materials
Explore
Activities
MiniLabs
p. 545
metric ruler
p. 553
metric ruler
p. 555
paper, masking tape
pp. 560–561
3 5 index cards, toothpicks, glue or tape,
metric ruler
p. 558
different types of food, colognes,
or household products, cotton
balls
The following designations will help you decide
which activities are appropriate for your students.
L1 Level 1 activities should be appropriate for students with learning difficulties.
L2 Level 2 activities should be within the ability range of all students.
L3 Level 3 activities are designed for above-average students.
ELL ELL activities should be within the ability range of English Language
Learners.
COOP LEARN Cooperative Learning activities are designed for small group work.
Assessment Resources
Chapter Review, pp. 39–40
Assessment, pp. 77–80
Performance Assessment in the Science
Classroom (PASC)
MindJogger Videoquiz
Alternate Assessment in the Science
Classroom
Performance Assessment, p. 20
Chapter Review Software
Computer Test Bank
P These strategies represent student products that can be placed into a best-
work portfolio.
Need Materials? Contact Science Kit at 1-800-828-7777 or at www.sciencekit.com on the Internet.
For alternate materials, see the activity on the listed page.
544A
CHAPTER 20
NERVOUS
AND
ENDOCRINE SYSTEMS
Multiple Learning Styles logos, as described on page 63T, are used throughout
to indicate strategies that address different learning styles.
544B
20
Chapter
Resource Manager
Nervous and Endocrine Systems
This is a representation of key blackline masters available in the Teacher Classroom Resources.
See Resource Manager boxes within the chapter for additional information.
Transparencies
Hands-on Activities
Section Focus Transparencies
Activity Worksheets
NAME
55
Section 20-1
Section 20-2
56
SECTION FOCUS TRANSPARENCY
SECTION FOCUS TRANSPARENCY
57
DATE
Lab Manual
CLASS
NAME
SECTION FOCUS TRANSPARENCY
Chapter 22
Chapter 22
ACTIVITY 22-1
EXTENDING THE SENSES
LIVING WITH DIABETES
How often do you speak with your friends on the telephone? The telephone provides people with a way to communicate with others over both
short and long distances. Your body also has a communication system. This
system allows different parts of your body to interact with each other. It also
allows you to respond to changes that take place outside your body.
People use many tools and instruments that help to extend their senses. For
example, some people with hearing impairments wear hearing aids that
amplify sounds, or make them louder. Scientists also use many tools and
instruments to help extend their senses. Some of these tools are shown
below. Perhaps you’ve used some of these tools in your study of science or
in other activities.
Diabetes is a disease of the endocrine system. It results when the pancreas
does not produce insulin in proper amounts. Insulin is a hormone that
enables the cells of the body to take in sugar in the form of glucose. If not
enough insulin is produced by the pancreas, sugar accumulates in the
bloodstream or is excreted from the body in urine.
LABORATORY MANUAL
Reaction Time
Lab Preview
1. What are two major divisions of the human nervous system? central (CNS) and
peripheral (PNS)
2. Which system is used when the body reacts to a stimulus? Both are used.
How can reaction time be improved?
You will check to see how many activities you do using your left hand or your right hand.
You will check how many activities you do using your left foot or your right foot.
You will find out if you draw or see objects more to the right side or the left side.
You will find out if the left side or the right side of your brain is dominant.
Materials
paper
red pencil
Procedure
1. Place a check mark in the proper column in Table 1 to show which hand you usually use to do the
following tasks. Note: If you use either hand just as often, then check both columns.
Tell which hand you use to
a. write your name.
b. wave “hello.”
c. bat while playing baseball.
d. place on top when folding your hands.
e. hold your spoon or fork while eating.
4. Your partner must let go of the ruler without warning you.
Goals
• Observe reflexes.
• Identify stimuli and responses.
5. Try to catch the ruler by bringing your
thumb and finger together quickly.
Materials
6. Repeat this activity several times and
record where the ruler was caught in a
data table.
• metric ruler
Procedure
2. Place a check mark in the proper column in Table 1 to show which foot you usually use to do the
following tasks. Note: If you use either foot just as often, check both columns.
Tell which foot you use to
a. start down a flight of stairs.
b. start up a flight of stairs.
c. catch yourself from falling as you lean forward.
d. start skipping.
e. place most weight on when you are standing.
f. start to run.
g. kick a ball.
7. Repeat this activity with your left hand.
Record your results.
1. Review the data table below.
2. Have a partner hold the ruler at the top
end.
Sample Data for left-handed person
3. Draw, in the space provided, a simple side view of a dog. Place a check mark in the column in
Table 1 that shows the direction the nose faces.
Where the Ruler Was Caught
Trial
1. Which of the tools or instruments shown have you used?
1. Why would a person with diabetes need to take insulin in pills or by
injection?
2. What sense do the tools and instruments extend?
3. How do the tools and instruments shown magnify objects? Why is this
useful?
2. Why is maintaining a healthful diet important to a diabetic?
Which brain side is
dominant? 43
Strategy
3. Hold the thumb and finger of your right
hand apart at the bottom of the ruler. Do
not touch the ruler.
What You’ll Investigate
3. Why is it important for different parts of your body to communicate with
each other? What body system is responsible for carrying out this task?
Spanish Resources
CLASS
The human brain is divided into a left and a right side. Many things that you do with the right
side of your body are controlled by your brain’s left side. Many things that you do with the left
side of your body are controlled by your brain’s right side. If much of what you do is done by
your body’s right side, your dominant brain side is the left side. If much of what you do is done
by your body’s left side, your dominant brain side is the right side.
Your body responds quickly to some kinds of stimuli, and reflexes
allow you to react quickly, without even thinking. Sometimes you can
improve how quickly you react. Complete this activity to see if you
can improve your reaction time.
2. Why is communication important?
DATE
Section 20-3
MESSAGE CENTER
1. What are some ways in which people communicate with each other?
Accessibility
Right Hand
Left Hand
1
30
20
2
20
10
3
15
10
4. Draw a circle in the space provided with your right hand. Note the direction in which you made
this circle. Now draw a circle with your left hand. Note the direction in which you made this circle.
If both circles were drawn clockwise, mark the right column in Table 1. If both circles were drawn
counterclockwise, mark the left column in Table 1. If you drew one circle in each direction, check
both columns.
3. Why is it important for a diabetic to get exercise regularly?
L2
L2
55
Copyright©Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
L2
56
Copyright©Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
L2
57
Copyright©Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Science Integration
Transparencies
L2
121
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Teaching Transparencies
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Assessment
20
L2
123
Extending Content
SCIENCE INTEGRATION TRANSPARENCY
The Eye’s Built-in Optics
Hot
pizza
Spinal cord
Receptor in skin
Muscle contracts
Sensory neuron
Interneuron
Motor neuron
39. THE REFLEX
How Do These Lenses Refract Light?
L2
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
40. ENDOCRINE GLANDS
Correction
Concave lens focuses
image directly on retina.
DATE
CLASS
Optical Illusions
DATE
CHAPTER REVIEW
Optical illusions are mistaken ideas based on the sense of vision. What you see and what you think
you see are not always the same. In an optical illusion, your brain “tells” you that you see something
that is not present.
CLASS
The Nervous
and Endocrine Systems
NAME
1. connects brain to spinal cord
2. conducts messages to neuron cell body
2. Examine the figure below. Do you think the
lines could meet? Do they?
3. Examine the figure below. Which horizontal
line appears longer? Measure the lines with a
ruler.
CRITICAL THINKING
4. Stare at the number 1 in the figure below for at
least one minute. What happens to corner 1
when you gaze at it steadily?
2/22:1
brain stem
______________________________
motor
1/22:1
______________________________
4. functioning unit of nervous system
neuron
1/22:1
______________________________
5. brain part maintaining muscle tone
2/22:1
cerebellum
______________________________
6. eye tissue made up of rods and cones
retina
4/22:2
______________________________
7. fluid-filled structure in inner ear
cochlea
4/22:2
______________________________
8. brain part divided into hemispheres
2/22:1
cerebrum
______________________________
9. cells that aid in the sense of smell
4/22:2
olfactory
______________________________
7/22:3
hormones
______________________________
11. move messages away from neuron cell body
1/22:1
axons
______________________________
12. neurons that move impulses to the brain
1/22:2
sensory
______________________________
Complete the following sentences using the correct terms.
1
synapse
1/22:1
13. The space between one neuron and the next is a __________________________.
B
central nervous system
14. The system made up of the brain and spinal cord is the___________________________.
2/22:1
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
peripheral nervous system
15. The ______________________________has
two systems using cranial and spinal nerves. 2/22:1
Interneurons
16. ___________________________are
nerve cells throughout the brain and spinal cord that relay
impulses from sensory neurons to motor neurons. 1/22:1
5. Examine the figures below. What do you see? When you look a
second time, do you see anything different? Can you see both
L2
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
target tissues
7/22:3
17. Hormones affect specific tissues called ______________________________.
L2
CLASS
The Nervous
and Endocrine Systems
Diseases of the Endocrine System
1/22:1
dendrites
______________________________
3. neurons that move impulses from the brain
10. endocrine secretions
DATE
Chapter 22
Part A. Vocabulary Review
Write the correct term in the space beside each definition.
1. Examine the figure below. What do you see?
Is a triangle present?
A
Critical Thinking/
Problem Solving
Chapter Review
NAME
Chapter 22
SKILL ASSESSMENT
Direction of
impulse
Convex Lens
NAME
Chapter 22
Concave Lens
Farsightedness
Image forms beyond retina.
Nearsightedness
Image forms in front of retina.
Correction
Convex lens focuses
image directly on retina.
Performance Assessment
When working properly, your endocrine
glands secrete hormones into your blood. The
hormones are then carried throughout your
body. When the correct amount of a hormone
reaches its target tissue, it causes certain reactions in that organ or tissue. But sometimes,
too much or too little hormone is released.
Some congenital defects can cause low hormone levels. Congenital means “at birth.”
When some babies are born, they have a problem with enzymes that produce hormones.
Unless this is noticed and treated early, such
birth defects can cause severe brain damage.
Some of these defects can be detected before
the newborn leaves the hospital. A screening
test is usually done by drawing a small
amount of blood from the baby’s heel.
Congenital hypothyroidism is one birth defect
commonly screened for. Congenital hypothyroidism is a disease of the thyroid gland. The
thyroid gland does not secrete enough thyroid
hormones. This condition affects growth and
brain development. An infant with this condi-
tion will have dry, wrinkled skin, an enlarged
tongue, a broad face, and a slow heartbeat
rate. Children are short for their age and are
mentally retarded. Adults with hypothyroidism are dwarfs. If the condition is found
early enough, these defects may be prevented.
An infant known to have a thyroid deficiency
is treated with hormones.
Many diseases of endocrine glands are
caused by tumors. The tumors may cause the
gland to either produce too much or not
enough of a hormone. Gigantism, or
acromegaly, is caused by a tumor on the pituitary gland. In this case, the tumor causes the
gland to produce too much growth hormone
(GH). GH controls the growth of bones. If a
person has a tumor on the pituitary gland
during childhood, he or she may grow
extremely tall (up to 7 to 9 feet). If treated
early, gigantism can be controlled by slowing
the release of GH by the pituitary with radiation treatment. Sometimes, the tumor can be
removed surgically.
Applying Critical Thinking Skills
1. Why is it important for pregnant women to know about congenital defects?
2. Why do excess amounts of growth hormone cause people to grow extremely tall?
3. Which endocrine gland of “André the Giant,” the professional wrestler, was probably not
functioning properly?
Study the following diagram, and label the parts of the brain shown. 2/22:1
18. cortex
19. cerebrum
22. medulla
things at the same time?
Meeting Different Ability Levels
Study Guide
for Content Mastery
Name
CHAPTER
22
Reinforcement
Date
NAME
Study Guide for Content Mastery
DATE
Chapter 22
Define each term and then label the figure below.
Directions: Use the following terms to complete the concept map below:
brain
brain stem
cerebellum
cerebrum
neuron
the nerve cell or the working unit of the nervous system
1. ______________________________________________________________________
dendrite
the branch of the neuron cell body that receives messages and
2. ______________________________________________________________________
sends them to the cell body
Central nervous
system
axon
the branch of the neuron that sends messages from the cell body
3. ______________________________________________________________________
synapse
the small space between one neuron and the next
4. ______________________________________________________________________
to the next neuron
is made up of
5.
spinal cord
DATE
neuron
brain
Use with Section 1
6.
7.
dendrite
wad of paper
glass door or window
f
_____
a
_____
2. conducts messages away from neuron cell body 1/22:1
Procedure
c
_____
3. consists of the brain and a spinal cord 2/22:1
j
_____
4. made up of nerves that connect the brain and
spinal cord to other parts of body 2/22:1
b
_____
5. brain part coordinating involuntary muscles 2/22:1
k
_____
6. involuntary, automatic response to a stimulus 2/22:1
l
_____
7. eye tissue composed of rods and cones 5/22:2
e
_____
8. fluid-filled structure in inner ear shaped like a
snail’s shell 5/22:2
g
_____
9. control activities in the body; move through the
bloodstream 7/22:3
1. Wad up a piece of paper into a ball. Stand
in front of a friend or relative and gently
toss the paper ball at his or her face.
Observe their eyelids as you throw the
paper.
2. Have your partner stand behind a glass
door or window and again throw the
paper ball at the person. Observe the person’s eyelids as you throw the paper at the
glass.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
cerebrum
cerebellum
brain stem
synapse
The person blinked.
3. What was the response of your partner in step 2?_________________________________________
Name the three kinds of neurons and describe the function of each.
Sensory neurons pick up information from receptors and send messages to
9. ____________________________________________________________________________________
the brain.
which
which
which
interprets senses
and stores
memory
coordinates
voluntary
muscles
coordinates
involuntary
muscles
Motor neurons conduct messages from the brain to the muscles and glands.
10. ____________________________________________________________________________________
Interneurons are nerve cells throughout the brain and spinal cord that transmit
11. ____________________________________________________________________________________
impulses from the sensory neurons to the motor neurons.
no, because the glass is there to protect the eyes
4. Was there a reason for the response? ____________________________________________________
from harm
5. Since there was no logical way that the paper could hurt the person, what explains the reaction?
Blinking is a reflex action.
1. conducts messages to neuron cell body 1/22:1
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Multicultural Connections
NAME
DATE
Chapter 22
The Nervous and
Endocrine Systems
MULTICULTURAL CONNECTIONS
In medical school, Alexa Canady fell in love
with the nervous system because “it’s so neat
and logical and precise.” She set her sights on
becoming a neurosurgeon and was the first
African American woman in the United States to
become one. Canady is now the chief neurosurgeon at Children’s Hospital of Michigan in
Detroit. She is also an associate professor at
Wayne State University. Canady specializes in
neurosurgery for children—an extremely challenging field.
Match the description in the first column with the item in the second column by writing the correct letter in the space
provided. Some items in the second column may not be used.
Materials
yes, to protect the eyes from harm
2. Was there a reason for the response? ____________________________________________________
8.
Chapter 22
Test Practice Workbook
CLASS
I. Testing Concepts
The Eyes Have It
The person blinked.
1. What was the response of your partner in step 1?_________________________________________
axon
DATE
CHAPTER TEST
The Nervous System
Conclude and Apply
contains
43
L2
Assessment
NAME
CLASS
Chapter 22
ENRICHMENT
The Nervous System
L2
22
NAME
Use with Section 1
REINFORCEMENT
Overview The Nervous and Endocrine Systems
25. spinal cord
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Enrichment Worksheets
CLASS
21. brain stem
L2
36
23. pons
24. cerebellum
20. midbrain
6. Name some jobs people have in which they must be aware of
optical illusions.
a. axon
b. brain stem
c. central nervous system
d. cerebrum
e. cochlea
f. dendrite
g. hormones
h. motor neurons
i. olfactory cells
j. peripheral nervous system
k. reflex
l. retina
For each of the following, write the letter of the term or phrase that best completes each sentence.
b
_____
10. ________ conduct impulses from the brain to muscles or glands throughout the body.
a. Interneurons
b. Motor neurons
c. Sensory neurons d. Synapses 1/22:1
a
_____
12. The spinal cord is an extension of the ________. 2/22:1
a. brain stem
b. cerebellum
c. cerebrum
6. From the information in the textbook, what do you suppose the nerve pathway was during
d. spinal disk
A nerve impulse went directly to an interneuron in the spinal cord and
this reaction? ________________________________________________________________________
then to the motor neurons that control the muscles of the eyelids.
Delicate Tissue
d
_____
14. Reflex responses are controlled in your ________. 2/22:1
a. cerebellum
b. cerebrum
c. midbrain
d. spinal cord
a
_____
15. In vision, light rays first pass through the ________. 4/22:2
a. cornea
b. lens
c. optic nerve
d. retina
_____
16. The ________ controls your sense of balance. 5/22:2
d
a. anvil
b. hammer
c. middle ear
d. inner ear
b
_____
17. Olfactory cells aid in the sense of ________. 5/22:2
a. hearing
b. smell
c. touch
d. vision
The human brain and nervous system are very
complex, and their health problems are varied.
Some patients treated by neurosurgeons have
had brain injuries. These can occur because of
such things as an injury during birth, falls, or
bike or car accidents. Other patients have diseases of the nervous system, such as epilepsy or
cancer. Any problem that affects the brain is
serious, because the brain controls the functions
of the rest of the body.
L1
AT LEVEL
85
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544C
CHAPTER 20
NERVOUS
AND
ENDOCRINE SYSTEMS
L2
59
CHALLENGE
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
L2
L3
59
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
97
L2
Canady also studies and treats brain injuries
and tumors in children. Both of these can also
damage brain cells and neurons through pressure on the brain. Tumors are enlarged masses
of tissue resulting from uncontrolled cell division. Some tumors are cancerous, or malignant.
Others are benign. Benign tumors grow more
slowly, do not affect surrounding tissues, and do
not spread to other parts of the body. They usually do not grow back after removal. In the
brain, however, benign tumors can be very dangerous. Brain injuries are more localized than
the damage from hydrocephalus. What makes
the conditions so serious is the fact that they can
sever nerves. The body cannot grow new brain
cells or neurons, and broken neurons do not
heal. The damage is permanent. However, in
minor injuries, the brain can often “reprogram”
itself so that other parts of the brain can take
over for the cells that are lost. Intensive physical
therapy can teach new skills to uninjured parts
of the brain.
Tools for Healing
Hydrocephalus
BASIC
Fluid accumulates in the brain, causing the brain
and head to become enlarged. As the amount of
fluid increases, pressure increases inside the
skull, pressing down on the delicate brain tissue.
If you have ever caught your finger in a drawer,
you have seen the damage that pressure can do
to tissues. Bruises are a sign of broken blood
vessels and cells. In the brain, pressure can
break blood vessels and destroy nerves and
brain cells. If a nerve is damaged, it can no
longer function. That means either that a message from the body may never reach the brain or
that a message from the brain to the body may
never be sent. In severe cases, high pressure in
the brain can result in death.
Canady is involved in research about the cause
for hydrocephalus, but so far the answer has
been difficult to find. Treatment is possible,
however. During the procedure, Canady inserts
a tube into a specific area of the brain. The other
end of the tube extends down the neck and into
the abdomen. There, the fluid drains and is
eliminated from the body, relieving the pressure
and preventing further injury.
Injuries and Tumors
b
_____
11. The large part of the brain divided into two sections is the ________. 2/22:1
a. cerebellum
b. cerebrum
c. midbrain
d. pons
a
_____
13. The releasing of saliva is an example of the ________ at work. 2/22:1
a. autonomic nervous system
c. cerebrum
b. cerebellum
d. somatic nervous system
Make a simple drawing of the brain and label its three main parts.
CLASS
Alexa Canady,
Neurosurgeon
One condition that Canady treats is called
hydrocephalus. This condition occurs in infants.
Technology has provided Canady with many
marvelous tools. Special X rays and imaging
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
L2
43
544D
Chapter
20
The Nervous and Endocrine Systems
C ontent
Helping You Prepare
Receptor Cells
Background
(Section 20-1)
Specialized receptor cells respond to specific stimuli from various parts of the body. The stimulus
produces a self-propagating wave of negative
charges that are transmitted to the central nervous
system via peripheral nerves. The nerve impulse
travels at a rate of approximately 120 m/s. The
brain and spinal cord of the central nervous system interpret the stimuli information.
Appropriate responses are sent via nerves to
various body parts, which react to the stimulus.
The response is a coordinated, integrated action
that maintains homeostasis within the body.
Sensory Receptors
(Section 20-2)
Sensory receptors of the body respond to environmental changes. Voluntary movement of
head, limbs, and body is caused by nerve impulses arising in the motor area of the brain and
carried by nerves to connect with skeletal muscles. The reaction involves both excitation of
nerve cells stimulating the muscles involved
and inhibition of the cells that stimulate opposing muscles.
Movements also may occur in direct response
to outside stimuli and are called reflexes. These
classes of receptors constantly send impulses
into the central nervous system. Some receptors
are sensitive to pain, temperature, touch, and
pressure. Others react to changes in the internal
environment, and a third type responds to
CD-ROM
Glencoe Science Voyages Interactive CD-ROM
Chapter Summaries
Use the Chapter Summary to introduce, teach,
or review chapter material.
The Pituitary Gland
variations in movement, position, and tension.
These impulses end in special areas of the brain,
as do those of special receptors concerned with
sight, hearing, smell, and taste.
Olfactory receptors, primarily in the nose, respond to gas molecules that become dissolved
in the watery fluids of the nasal passages.
Taste buds located on small projections called
papillae of the tongue, the soft palate, and the
walls of the pharynx are sensitive to substances
dissolved in liquids. Specialized taste cells
within the taste buds function as receptors.
Auditory sensory organs are present in the
ears. Vibrations in the air with frequencies between about 16 000 and 20 000 cycles per second can be detected as a sound by the ear. Hairlike projections of the organ of Corti within the
inner ear respond to the vibrations and transmit
nerve impulses to the brain.
Teacher’s
Corner
Products Available from Glencoe
To order the following products for use with this chapter, call Glencoe at 1-800-334-7344:
CD-ROM
NGS PictureShow: Human Body 1
Curriculum Kit
GeoKit: Human Body 2
Transparency Set
NGS PicturePack: Human Body 1
Videodisc
STV: Human Body
544E
CHAPTER 20
THE NERVOUS
AND
ENDOCRINE SYSTEMS
A complex arrangement of light-sensitive
cells within the retina of the eye reacts to light
energy with wavelengths between 380 and 760
millimicrons. The brain interprets the impulses
from the optic nerve.
The body’s sense of motion and equilibrium
structures are located within the inner ear. Sensory hair cells respond to movements of liquids
and of the tiny bits of calcium carbonate called
otoliths in the labyrinth canals.
Products Available from National
Geographic Society
(Section 20-3)
The secretions of the pituitary gland are a good
example of endocrine function. Its hormones
produce a variety of actions and reactions. The
pituitary gland has three parts; the anterior lobe;
the intermediate lobe, which is generally
thought to be nonfunctional; and the posterior
lobe. The anterior lobe is considered the master
gland of the endocrine system. It produces six
hormones that cause stimulation of the growth of
body cells, production of milk after birth, regulation of thyroid gland secretions, regulation of
adrenal cortex secretions, stimulation of egg and
sperm production, and regulations of egg release.
The posterior lobe of the pituitary gland has a
role in regulation of water secretion by the kidneys, the contraction of the muscles of the uterus
in the birth process, and the contraction of milkproducing glands in female breasts.
Disturbances
of Endocrine
Function
(Section 20-3)
For current events or science in the news,
access the Glencoe Science Web Site at
www.glencoe.com/sec/science/ca
Disturbances in function of endocrine production may be classed
as either hyperfunction, which refers to excess activity, or hypofunction, which means insufficient
activity. Hyperfunction of the anterior pituitary
gland with overproduction of the growth hormone may result in gigantism. When excess
adrenal-stimulating hormone is produced by an
overactive anterior pituitary gland, a group of
symptoms known as Cushing’s disease occurs.
Symptoms of Cushing’s disease include hypertension, weakness, plethora, bruising, and an
unusual type of obesity. Deficiency in anterior
pituitary activity that takes place early in life
leads to dwarfism, sexual underdevelopment,
weakness, and occasionally severe gauntness.
Hormone-Producing Bacteria
(Section 20-3)
Researchers have developed techniques for
using genetically altered bacteria to produce insulin for diabetic patients. This procedure is
often referred to as recombinant DNA technology, gene splicing, or genetic engineering. This
allows insulin to now be produced in quantity.
Teacher to Teacher
“To illustrate impulse pathways, students take turns representing
To order the following products for use with this chapter,
call National Geographic Society at 1-800-368-2728:
various parts of a nerve impulse pathway. They stand next to
Videos
Nervous System (The Human Body Series)
Incredible Human Machine
each other in the correct order and pass a message along the
pathway. The ‘interneuron’ student reads the message and decides whether the response is muscular or glandular.”
Rebecca S. Buckingham, Teacher
Lisbon Central School
Lisbon, NY
544F
CHAPTER
CHAPTER
20
20
The Nervous
and Endocrine
Systems
Chapter Preview
CHAPTER OVERVIEW
Section 20-1
Section 20-1 This section
centers on the functions of the
nervous system, the movement of impulses along neurons, and the two major divisions of the system.
Section 20-2 This section describes the sense organs and
how they enable the body to
distinguish changes in its internal and external environments.
Section 20-3 The endocrine
system and its secretions are
studied in this section. The effects of the hormones on tissues are described.
If time does not permit
teaching the entire chapter, use Reviewing Main
Ideas on pp. 566-567.
544
CHAPTER 20
THE NERVOUS
W
ho’s in front of you? What note do we start on? Where’s
the conductor? Am I marching in rhythm? There’s a lot
to be aware of when you’re part of a marching band. You must
be sensitive to your surroundings and aware when changes
take place. All organisms must be able to detect what is happening around them. Sights or sounds can warn of danger.
Odors can help find food. Sensations of hot and cold can protect
from fire or extreme temperatures. In this chapter, you will
learn how your body’s nervous
C
system interprets all of the sensations it receives to produce a
B
picture of its surroundings. In
A
the following activity, find out
whether your eyes can interpret objects correctly.
Section 20-3
The Endocrine
System
Skills Preview
Skill Builders
• Map Concepts
• Make and Use a Table
L2 ELL
Preparation
Collect some additional illustrations of optical illusions, such as inkblot tests,
to extend the learning of this
activity.
Materials
Activities
Observe Objects
Teaching Strategies
• Compare and Contrast
• Design an Experiment
1. Look at the figure at the right of
Have students devise their
own optical illusions in the
form of inkblots.
the page.
2. Estimate the difference in heights
• Interpret Data
ck
ng Che
Readi
between pole A and pole C.
✔
3. Use a metric ruler to measure the
heights of poles A, B, and C.
20-1,
Section
g
in
n
in
g
e
llow
Before b art that will a st
h
c
contra
make a
re and
a
p
m
o
c
system
you to
ervous
n
l
a
us
r
t
n
al nervo d.
the ce
eripher
a
p
e
r
e
h
u
t
yo
and
l it in as
il
F
.
m
e
t
sys
In your Science Journal,
record what you found
out about the height of
the lines. Were your
estimates correct? What
did your eyes tell you?
545
Look for the following logos for strategies that emphasize different learning modalities.
Multiple
Learning
Styles
Linguistic Science Journal, pp. 547,
558; Across the Curriculum, p. 548;
Assessment, pp. 559, 564; Preview, p. 566
Logical-Mathematical Activity, p.
553; Assessment, p. 553
Visual-Spatial Explore Activity, p. 545;
Activity, pp. 547, 563; Visual Learning,
p. 547; Reteach, pp. 551, 557, 563, 566
Auditory-Musical Out of Time,
p. 566
ENDOCRINE SYSTEMS
Students
should
observe
that the heights are the same
but appear to be different.
They should also include a
reference as to whether their
estimates were correct.
Assessment
544
AND
Visual-Spatial Use the
Explore Activity to introduce students to one aspect of
the nervous system—vision.
Inform students that they will
be learning more about the
nervous and endocrine systems as they read the chapter.
metric ruler
MiniLabs
Stability and Change The integrated efforts of the nervous
and endocrine systems bring
about a stable environment
necessary for the healthy
functioning of the body.
?
Explore Activity
The Senses
Theme Connection
TIME
Purpose
Section 20-2
cerebrum
cerebellum
brain stem
reflex
cochlea
retina
olfactory cell
taste bud
hormone
target tissue
OUT OF
Explore Activity
The Nervous
System
Chapter Vocabulary
neuron
dendrite
axon
synapse
central
nervous
system
peripheral
nervous
system
The Nervous
and Endocrine
Systems
Kinesthetic Quick Demo, p. 548;
Making a Model, p. 549; Multiple
Learning Styles, p. 549; MiniLab, pp. 555, 558
Interpersonal Discussion, pp. 550,
551; Enrichment, p. 550; Tying to Previous Knowledge, p. 554; Activity pp.
560–561; Review, p. 566
Intrapersonal Enrichment, p. 548
Assessment Planner
Portfolio
Content Assessment
Refer to p. 567 for suggested items that students might select for their portfolios.
Section Assessment, pp. 552, 559, 564
Chapter Assessment, pp. 568–569
Proficiency Prep, pp. 552, 559, 564
Performance Assessment
Performance Have
students collect other optical illusions and work in small
groups to find how the eyes
can be tricked. Have them
present their findings on a
poster. Use Performance Assessment in the Science
Classroom, p. 73.
See p. 567 for additional Performance Assessment options.
Skill Builder, pp. 552, 564
MiniLab, pp. 555, 558
Activity 20-1, p. 553; 20-2, pp. 560–561
545
SECTION
20 1
20•1
Prepare
It's Important
Background
Vocabulary
Preplanning
Why
What
neuron
dendrite
axon
synapse
central nervous system
peripheral nervous system
cerebrum
cerebellum
brain stem
reflex
Refer to the Chapter Organizer on pp. 544A–B.
1 Motivate
Bellringer
Before presenting the lesson,
display Section Focus
Transparency 55 on the
overhead projector. Use the
accompanying Focus Activity
worksheet. L2 ELL
The scene described above is an example of how your body
responds to changes in its environment and adjusts itself.
Your body makes these adjustments with the help of your
nervous system. Any change inside or outside your body that
brings about a response is called a stimulus. Each day, you’re
bombarded by thousands of stimuli. Noise, light, the smell of
food, and the temperature of the air are all stimuli from outside your body. A growling stomach is an example of an
internal stimulus.
How can your body handle all these stimuli? Your body
has internal control systems that maintain steady conditions,
no matter what’s going on outside the body. This is called
homeostasis. Breathing rate, heartbeat rate, and digestion are
just a few of the activities that are constantly checked and regulated. Your nervous
and the endocrine system, a
It'ssystem
Important
chemical control system described later in this chapter, are
the main ways your body maintains homeostasis.
It's Important
Your body can react to your
environment because of your
You'll Learn
nervous system.
CY
ANSPAREN
FOCUS TR
SECTION
The teletelephone?
er both
CENTER
nds on the
others ov
MESSAGE you speak with your frie
nicate with
tem. This
do
y to commu communication sys
also
with a wa
a
How often
ple
has
h other. It
o
peo
eac
als
y
vides
with
y.
phone pro g distances. Your bod r body to interact
bod
r
lon
outside you
ts of you
ce
par
short and
pla
ent
e
ws differ
es that tak
system allo respond to chang
to
allows you
some
rtant?
ate with
ation impo
communic
r body to
communic
this task?
parts of you
rying out
for different responsible for car
nt
rta
po
is
it im
y system
3. Why is
What bod
each other?
1. What are
Why
You'll Learn
What
Figure 20-1 A neuron is made up of a cell
body, dendrites, and an
axon. How does the
branching of the dendrites
allow for more impulses to
be picked up by the neuron?
h other?
ate with eac
communic
ich people
ways in wh
2. Why is
Dendrites
Cell body
Axon
Direction of impulse
55
cGraw-Hill,
Glencoe/M
Copyright©
CHAPTER 20
THE NERVOUS
AN
EN
2 Teach
Activity
Visual-Spatial In a
school yard or athletic
field, position two students
100 m apart. Use this visual
representation to illustrate
the distance that some nerve
impulses travel in 1 s. L2 ELL
Discussion
B A message is sent to your
brain by way of sensory
neurons.
What would happen if
all your sensory neurons
stopped working? Your brain
would stop receiving stimuli
from inside and outside your
body, making it impossible to
maintain homeostasis.
C Your brain sorts
the information
and determines
a response.
D The response is
sent back along
motor neurons
to your muscles.
Teacher FYI
Neurons
The axons of neurons grow
and branch when used. More
and better connections with
other neurons result in learning. Schoolwork helps neurons make connections.
The working unit of the nervous system is the nerve
cell, or neuron (NOO rahn). The single neuron in
Figure 20-1 is made up of a cell body and branches
called dendrites and axons. Dendrites receive messages
and send them to the cell body. An axon (AK sahn) carries messages away from the cell body. Any message
carried by a neuron is called an impulse. Notice that the
end of the axon branches. This allows the impulses to
move to many other muscles, neurons, or glands.
Caption Answer
Figure 20-1 Each neuron can
receive impulses from several
different sensory receptors because of the increased number of
dendrites.
Types of Neurons
Your skin and other sense organs are equipped with structures called receptors that respond to various stimuli. Three
types of neurons—sensory neurons, motor neurons, and
interneurons—then become involved with transporting
impulses about the stimuli. As illustrated in Figure 20-2,
sensory neurons (B) receive information and send impulses
to the brain or spinal cord. Once the impulses reach your
brain or spinal cord, interneurons relay the impulses from the
sensory to motor neurons. You have more interneurons in
your body than either of the other two types of neurons.
Motor neurons (D) then conduct impulses from the brain or
spinal cord to muscles or glands throughout your body.
E Your heart immediately
starts to pound and your
breathing rate increases.
You throw the book.
Resource Manager
Remind students that coordinated body movements are
accomplished by the nervous
system and the skeletal muscles working together.
The following Teacher Classroom
Resources can be used with Section 20-1:
Reproducible Masters
Activity Worksheets, pp. 109–110
Enrichment, p. 55
THE NERVOUS
AND
ENDOCRINE SYSTEMS
20 1
SYSTEMS
Multicultural Connections, pp. 39–40
Reinforcement, p. 55
L2
Study Guide, pp. 77-78
L2
L3
Laboratory Manual, pp. 117–120
OCRINE
THE NERVOUS SYSTEM
547
V ISUAL
Learning
Tying to Previous
Knowledge
CHAPTER 20
system, impulses travel a pathway.
Together, the three types of neurons act like a relay team, moving
impulses through your body from
stimulus to response.
anies, Inc.
aw-Hill Comp
of The McGr
a division
546
546
Figure 20-2 In your nervous
COOP LEARN
Response to Stimuli
Section 20-1
55
break, sensory receptors in
your ears are stimulated.
After doing the dishes and finishing your homework, you
settle down in your favorite chair and pick up that mystery
novel you’ve been trying to finish. Only three pages to go
. . . Who did it? Why did she do it? Then, “CRASH!” You
scream and throw your book in the air. What made that
unearthly noise? You turn around to find that your dog’s
It's Important
wagging tail just swept
the lamp off the table beside you.
Suddenly, you’re aware that your heart is racing and your
hands are shaking. But, then, after a few minutes, your
You'll Learn
breathing returns to normal
and your heartbeat is back to its
regular rate. What’s going on?
The basic structure of a neuron
and how an impulse moves
Information about the central
and peripheral nervous
systems
How drugs affect the body
Refer to Receptor Cells on p. 544E.
A When you hear the lamp
The Nervous System at Work
You'll Learn
C ontent
The Nervous
System
L1
Transparencies
Teaching Transparency 39
L2
ELL
L2
L2
Nerve Analogy Have students write a
paragraph that explains how a nerve is
similar to a wire going from a controlling
switch (stimulus) to a lightbulb (response). L2 P
Figure 20-2 Have students follow the
sequence of events that occurs as an impulse is initiated and moves through the
body, and a response is generated.
CA Science Content
Standards
Page 546: 5a, 5b
Page 547: 5a, 5b
20-1 THE NERVOUS SYSTEM
547
Figure 20-3 An impulse
Flex Your Brain
moves in only one direction
across a synapse—from an
axon to the dendrites or cell
body of another neuron.
Use the Flex Your Brain
activity to have students
explore SYNAPSES.
Cerebrum
Axon
Motor
V ISUAL
Learning
Tongue
Chewing
Sensory
Direction of impulse
Figure 20-5 Have students describe how the
brain is protected. Hair,
skin, skull bones, and
membranes protect the
brain.
Salivation
Axon
Dendrite
Synapse
Enrichment
Surface of
next neuron
Intrapersonal Have
students research and
report to the rest of the class
on concussions. They should
find out how they occur, what
happens to the brain, symptoms, and treatment. Preventive measures such as wearing seat belts should also be
brought out.
Synapse
Figure 20-4 The brain and
spinal cord (yellow) form the
central nervous system, which
sorts and interprets information
from stimuli. All other nerves
are part of the peripheral nervous system (green).
Spinal
cord
(CNS)
The Infinite Voyage:
Unseen Worlds
Chapter 7 Brain Tumor
Surgery: Made Possible by MRI
2:30
Refer to the Teacher Guide for
bar codes and teaching strategies.
Brain
548
CHAPTER 20
THE NERVOUS
Neurons don’t touch each other. How does an impulse
move from one neuron to another? To get from one neuron to
the next, an impulse moves across a small space called a
synapse (SIHN aps). In Figure 20-3, you can see that when an
impulse reaches the end of an axon, a chemical is released by
the axon. This chemical diffuses across the synapse and starts
an impulse in the dendrite or cell body of the next neuron. In
this way, an impulse moves from one neuron to another.
The Central Nervous System
Spinal cord
Vertebra
548
CHAPTER 20
Spinal nerve
THE NERVOUS
AND
Language Arts Have students look up
synapse in the dictionary. Students will find
that it comes from the Greek roots syn (together) and haptein (unite). Ask students to
think about how the roots of the word reflect
its meaning. L2
AND
ENDOCRINE SYSTEMS
Smell
Hearing
Cerebellum
Figure 20-5 Different
areas of the brain control
specific body activities.
Brain Stem
The Brain
The brain is made up of approximately 100 billion neurons.
You can see in Figure 20-5 that the brain is divided into three
major parts: cerebrum, cerebellum, and brain stem. The
largest part of the brain, the cerebrum (suh REE brum), is
divided into two large sections called hemispheres. Here,
impulses from the senses are interpreted, memory is stored,
and the work of voluntary muscles is controlled. The outer
layer of the cerebrum, the cortex, is marked by many ridges
and grooves. The diagram also shows some of the tasks that
sections of the cortex control.
A second part of the brain, the cerebellum (ser uh BEL um),
is behind and under the cerebrum. It coordinates voluntary
muscle movements and maintains balance and muscle tone.
The brain stem extends from the cerebrum and connects the
brain to the spinal cord. It is made up of the midbrain, the
pons, and the medulla. The brain stem controls your heartbeat, breathing, and blood pressure by coordinating the involuntary muscle movements of these functions.
PHYSICS
I N T EG RATION
Watching the Brain
Scientists use positron emission tomography (PET) to
learn more about the brain.
Brain cells that are active
take up radioactive glucose,
which causes an image to
appear on a color monitor.
Different colors indicate
which areas of the brain are
being stimulated. By comparing different PET images,
researchers have located the
areas of the brain used for
seeing, reading, hearing,
speaking, and thinking.
The Spinal Cord
Your spinal cord is an extension of the brain stem. It is made
up of bundles of neurons that carry impulses from all parts of
the body to the brain and from the brain to all parts of your
body. The spinal cord, illustrated in Figure 20-4, is about as
big around as an adult thumb and it is about 43 cm long.
Guided Reading Strategy
Quickwrites This strategy, sometimes called
freewrites, lets students use spontaneous
writing to discover what they already know.
Have students write a list of ideas about a
topic, then share these ideas with the class.
Next, have students write their ideas freely in
a paragraph without worrying about punctuation, spelling, and grammar. Have students use
a Quickwrite to share ideas during or after a
learning experience in this chapter.
Using Science Words
Have students compare the
use of the word cortex as used
by botanists and physiologists.
L2
The isotope fluorine-18 is used to
provide the radioactivity used in
PET. In addition to detection of
sensory areas, PET has been used
to detect tumors in the brain.
C ontent
Background
20-1
ENDOCRINE SYSTEMS
Across the Curriculum
Kinesthetic Have students make a model of
the vertebral column and
spinal cord by stringing 31
thread spools on a rope. Use
circular pieces of foam rubber
for the disks between the vertebrae. Have students note
how the cord (rope) is protected. L2 ELL COOP LEARN
Swallowing
Figure 20-4 shows how organs of the nervous system are
grouped into two major divisions: the central nervous system
(CNS) and the peripheral nervous system (PNS). The central
nervous system is made up of the brain and spinal cord. The
peripheral (puh RIHF rul) nervous system is made up of all
the nerves outside the CNS, including cranial nerves and
spinal nerves. These nerves connect the brain and spinal cord
to other body parts.
Brain
Skull
The brain coordinates all
your body activities. If someSpinal
one pokes you in the ribs,
nerves
Cerebrum
your whole body reacts. Your
(PNS)
neurons are adapted in such
a way that impulses move in
only one direction. Sensory
Spinal cord
neurons send impulses that
Cerebellum
move from a receptor to the
brain or spinal cord.
Quick Demo
COOP LEARN
Vision
Making a Model
Videodisc
Kinesthetic Have three
students stand side by
side. Their arms and fingers
should be outstretched at
their sides. Starting at one
end of the line, have the students pass a metric ruler from
person to person. Students’
fingers should not touch. Use
this to show students how an
impulse travels from a sensory neuron through an
interneuron to a motor neuron. Have students identify
the axon and dendrites of
each “nerve cell.” L2 ELL
Chemical
THE NERVOUS SYSTEM
549
Multiple Learning Styles
Kinesthetic Have
students
make a model of the brain from
papier-mâché or Styrofoam. Paint
each part a different color and label
the areas of activity. L1 ELL
The adult human
brain weighs about 1.4 kg
and has a volume of approximately 1500 cm3. It
contains over 100 billion
neurons.
CA Science Content
Standards
Page 548: 5a, 5b
Page 549: 5a, 5b
20-1 THE NERVOUS SYSTEM
549
The CNS is protected by a bony cap called the skull, by vertebrae, and by three layers of membranes. Between some of
these membranes is a fluid called cerebrospinal (suh ree broh
SPINE ul) fluid. What purpose might this fluid serve?
Answer to
Text Question
What purpose might this
fluid serve? It cushions the
vertebrae.
The Peripheral Nervous System
Caption Answer
Figure 20-6
system
the autonomic
Discussion
Interpersonal Have
students discuss other
reflex responses to stimuli
that prevent injury to the
body. Examples include: eyelid closing when there is
movement near the eye, rapid
upward foot movement when
stepping on a sharp object.
One of the longest
spinal nerves extends
from the spinal cord
to muscles in the foot.
Estimate the length of
this nerve. If the rate
of travel of a nerve
pulse is approximately
120 m per second,
what is the length of
time for an impulse to
travel from the spinal
cord to the foot?
Estimates will vary. Possible
answers could be from 80 cm
to 1 m. Length of time for
travel will vary from 0.0067 s
to 0.0083 s.
Correcting Misconceptions
Alcohol is often perceived
as a stimulant because it initially makes the person feel
more energetic. However, alcohol actually slows down
the actions of the central nervous system.
Peripheral Nervous System
(cranial and spinal nerves)
Somatic system
Autonomic system
Skeletal muscles
Heartbeat rate
Breathing, digestive,
salivary glands
Figure 20-6 The divisions of
the peripheral nervous system are
shown. What part of the PNS
controls your breathing while
you sleep?
Enrichment
Interpersonal Have
students find out which
motor reflexes a child is born
with. As part of their research, they could interview a
pediatrician.
Your brain and spinal cord are connected to the rest of your
body by the peripheral nervous system. The PNS is made up
of 12 pairs of cranial nerves from your brain and 31 pairs of
spinal nerves from your spinal cord. These nerves link your
central nervous system with all parts of your body. Spinal
nerves are made up of bundles of sensory and motor neurons. For this reason, a single spinal nerve may have impulses
going to and from the brain at the same time.
The peripheral nervous system has two divisions. The
somatic system consists of the cranial and spinal nerves that
go from the central nervous system to your skeletal muscles.
The second division, the autonomic system, controls your
heartbeat rate, breathing, digestion, and gland functions.
When your salivary glands release saliva, your autonomic
system is at work. Use Figure 20-6 to help you remember
these two divisions.
550
CHAPTER 20
THE NERVOUS
AND
Integrating the Sciences
THE NERVOUS
AND
ENDOCRINE SYSTEMS
Figure 20-7 Your response in
Check for Understanding
a reflex is controlled in your spinal
cord, not in your brain.
Discussion
Interpersonal Have
students discuss the
purpose of the extensive folding of the surface of the cerebrum. The folding provides a
greater surface area to be contained within the enclosure of
the skull. Why might a hard
blow to the back of the head
cause a vision disorder? The
primary visual area of the brain
is located at the lower rear side of
the cerebrum.
Sensory neuron
Motor neuron
Muscle contracts
Direction of
impulse
Receptor in skin
Reteach
Reflexes
V ISUALIZING
Have you ever moved quickly from something hot or
sharp? Then you’ve experienced a reflex. A reflex is an involuntary and automatic response to a stimulus. Usually, you
can’t control reflexes because they occur before you know
what has happened. A reflex involves a simple nerve pathway called a reflex arc. Figure 20-7 shows a reflex arc. As you
reach for the pizza, some hot cheese falls on your finger.
Sensory receptors in your finger respond to the hot cheese,
and an impulse is sent to the spinal cord. The impulse passes
to an interneuron in the spinal cord that immediately relays
the impulse to motor neurons. Motor neurons transmit the
impulse to muscles in your arm. Instantly, without thinking,
you pull your arm back in response to the burning food. This
is a withdrawal reflex. A reflex allows the body to respond
without having to think about what action to take. Reflex
responses are controlled in your spinal cord, not in your
brain. Your brain acts after the reflex to help you figure out
what to do to make the pain stop. ✔
Remember in Figure 20-2 how the girl was frightened after
the lamp was broken? What would have happened if her
breathing and heartbeat rate didn’t calm down within a few
minutes? Your body system can’t be kept in a state of continual excitement. The organs of your nervous system control
and coordinate responses to maintain homeostasis within
your body.
Visit the Glencoe
Science Web Site at
www.glencoe.com/
sec/science/ca for
more information about
the nervous system.
Alzheimer’s disease is the result
of the failure of nerve cells in the brain to
communicate. Alzheimer’s patients have
insufficient amounts of acetylcholine, a
chemical that carries impulses from one
nerve to the next.
Visual-Spatial Have
students make flash
cards with the names of the
major parts of the nervous
system. Use the back of the
card to write a brief description of the function. Students
can use the cards to quiz each
other to review section content. L1 COOP LEARN
Extension
✔
k
g Chec
Readin
reflexes
Why are ?
nt
importa
For students who have
mastered this section, use the
Reinforcement and Enrichment masters.
Answer to
heck
Reading C
20-1
Background
Internet Addresses
Spinal cord
G
Interneuron
C ontent
For Internet tips, see Glencoe’s Using the
Internet in the Science Classroom.
CHAPTER 20
3 Assess
ENDOCRINE SYSTEMS
Life Science Have students research
behaviors that are not reflexes but are innate
behaviors in animals. Examples are nest
building by birds and web construction by
spiders. Find out if humans have any innate
behaviors.
550
V ISUALIZING
A Reflex Arc
THE NERVOUS SYSTEM
551
Across the Curriculum
History In the latter part of the eighteenth century, scientists had an interest in
animals that were able to produce an electric
shock, such as the electric eel. These investigations led to research on the effects of electricity on nerves and the muscular contractions that could be produced.
✔
actions
ow quick re
Reflexes all
s withus situation
to dangero
t
to think abou
out having
what to do.
Visual Learning
Figure 20-7 Have students
describe the movement of impulses in the diagram.
CA Science Content
Standards
Page 550: 5a, 5b, 7a
Page 551: 5a, 5b, 7b
20-1 THE NERVOUS SYSTEM
551
Drugs and the Nervous System
4 Close
Proficiency Prep
Use this quiz to check students’ recall of section content.
1. What is the function of
the dendrite? to receive the
messages and send them to
the cell body
2. What are nerve cells that
relay impulses from sensory to motor neurons?
interneurons
3. The peripheral nervous
system consists of what
two types of nerves? cranial, spinal
4. What connects the brain
to the spinal cord? the
brain stem
Figure 20-8 Caffeine, a
substance found in cola, coffee,
and other types of food and
drink, can cause excitability and
sleeplessness.
Section Assessment
1. See Figure 20-1.
2. The central nervous system is made up of the
brain and spinal cord.
The peripheral nervous
system is made up of cranial and spinal nerves.
3. Sensory neurons receive
information and send impulses to the spinal cord
or brain. Motor neurons
conduct impulses from
the brain or spinal cord to
muscles or glands throughout the body.
4. Think Critically Cocoa
contains caffeine, which
is a stimulant that can
cause sleeplessness.
Many drugs, such as alcohol and caffeine, have a direct
effect on your nervous system. When swallowed, alcohol
passes directly through the walls of the stomach and small
intestine into the circulatory system. Alcohol is classified as a
depressant drug. A depressant slows down the activities of
the central nervous system. Judgment, reasoning, memory,
and concentration are impaired. Muscle functions also are
affected. Heavy use of alcohol destroys brain and liver cells.
Caffeine is a stimulant, a drug that speeds up the activity of
the central nervous system. Too much caffeine can increase
heartbeat rate and cause restlessness, tremors, and insomnia. It also can stimulate the kidneys to produce more
urine. Caffeine can cause physical dependence.
When people stop taking caffeine, they can have
headaches and nausea. Caffeine is found in coffee, tea, cocoa, and many soft drinks, as seen
in Figure 20-8.
Think again about a scare from the
loud noise. The organs of your nervous system control and coordinate
responses to maintain homeostasis
within your body. This task is more
difficult when your body must cope
with the effects of drugs.
Section Assessment
1. Draw and label the parts of a neuron.
2. Compare the central and peripheral nervous
systems.
3. Compare sensory and motor neurons.
4. Think Critically: During a cold winter
evening, you have several cups of hot cocoa.
Explain why you have trouble falling asleep.
Skill Builder
5.
Concept Mapping Prepare an
events chain concept map of the different kinds
of neurons an impulse moves along from a
stimulus to a response. If you need help, refer
to Concept Mapping in the Skill Handbook on
page 678.
Word Processing Create
a flowchart showing the
reflex pathway of a nerve
impulse when you step
on a sharp object. Label
the body parts involved in
each step of the process.
If you need help, refer to
page 696.
Activity
Using Scientific Methods
20 1
Reaction Time
Flowcharts should show
an impulse moving from
receptor to sensory neuron
to interneuron in the spinal
cord to motor neuron to
muscle in foot.
552
CHAPTER 20
THE NERVOUS
CHAPTER 20
THE NERVOUS
AND
Y
Conclude and Apply
1.
2.
3.
4.
How can reaction time be improved?
Goals
• Observe reflexes.
• Identify stimuli and responses.
Procedure
1. Make a data table in your Science Journal to
record where the ruler is caught during this
activity. Possible column heads are Trial, Right
Hand, and Left Hand.
2. Have a partner hold the ruler at the top end.
3. Hold the thumb and finger of your right hand
apart at the bottom of the ruler. Do not touch
the ruler.
4. Your partner must let go of the ruler without
warning you.
5. Try to catch the ruler by bringing your thumb
and finger together quickly.
6. Repeat this activity several times and record
where the ruler was caught in a data table.
7. Repeat this activity with your left hand. Record
your results.
Identify the stimulus in this activity.
Identify the response in this activity.
Identify the variable in this activity.
Use the table on this page to find your reaction
time.
5. What was your average reaction time for your
right hand? For your left hand?
6. Compare the response of your writing hand
and your other hand for this activity.
7. Draw a conclusion about how practice
relates to stimulus-response time.
Reaction Time (s)
5
10
15
20
25
30
The concept map should include the following: stimulus—sensory neurons—interneurons—
motor neurons—response.
AND
ENDOCRINE SYSTEMS
Time
30 minutes
Materials
metric ruler
Teaching Strategies
Students should keep their
eyes on the ruler as the partner
releases it.
Answers to Questions
1. the ruler falling
2. catching the ruler
3. which hand is used
4. Answers will vary.
5. To find the average, students
should add all reaction times
and divide by the number of
trials.
6. Answers will vary. Generally,
the writing hand reacts faster.
7. With practice, stimulus response time will probably
improve.
Reaction Time
Where Caught (cm)
Process Skills
observing, communicating, using
numbers, recognizing and using
spatial relationships, measuring in
SI, interpreting data
0.10
0.14
0.17
0.20
0.23
0.25
THE NERVOUS SYSTEM
553
ENDOCRINE SYSTEMS
Skill Builder
5.
Purpose
Logical-Mathematical
Students will observe reaction time. L2 ELL COOP LEARN
• Metric ruler
20-1
552
20•1
Materials
our body responds quickly to some kinds of stimuli, and
reflexes allow you to react quickly without even thinking.
Sometimes you can improve how quickly you react. Complete this
activity to see if you can improve your reaction time.
What You’ll Investigate
Activity
Assessment
Portfolio Haves students make models of
two neurons. Have them clearly label the
synapse, axons, dendrites, cell bodies, and
neurotransmitters. Use Performance Assessment in the Science Classroom, p. 51.
Sample data for left-handed person
Assessment
Where the Ruler Was Caught
Trial
Right hand
Left hand
1
30
20
2
20
10
3
15
10
Performance To further assess students’ abilities to measure and improve reaction time, have
them formulate and test a hypothesis about how
long it would take the nonwriting hand to be
trained to respond as the writing hand responds.
Use Performance Assessment in the Science Classroom, p. 21.
CA Science Content
Standards
Page 552: 5a, 5b, 7b
Page 553: 5a, 5b, 7a, 7c
20-1 THE NERVOUS SYSTEM
553
SECTION
20 2
20•2
Prepare
It's Important
Background
Preplanning
Vocabulary
Refer to the Chapter Organizer on pp. 544A–B.
cochlea
retina
Before presenting the lesson,
display Section Focus
Transparency 56 on the
overhead projector. Use the
accompanying Focus Activity
worksheet. L2 ELL
Why
You'll Learn
What
Hearing
Sound energy is to hearing as light energy is to vision. As
illustrated in Figure 20-9, when an object vibrates, it causes
the air around it to vibrate, thus producing energy in the form
of sound waves. When sound waves reach your ears, they
stimulate nerve cells deep in your ear. Impulses are sent to
the brain. The brain responds, and you hear a sound.
Your senses make you aware
of your environment, which
You'll
Learn
helps keep
you safe.
Bellringer
Figure 20-9 A vibrating object
produces sound waves that are heard
by your ears.
It's Important
Why
You'll Learn
What
upward or downward, it
pushes the particles of air
in front of its movement
closer together.
CY
ANSPAREN
FOCUS TR
SECTION
ses. For
their sen
NSES
to extend
t
that help
G THE SE
g aids tha
EXTENDIN ny tools and instrumentspairments wear hearinny tools and
Outer ear
2 Teach
Tying to Previous
Knowledge
ma
g im
ma
ists also use ls are shown
People use e people with hearin
der. Scient
too
som
ence or
ke them lou ses. Some of these
example,
study of sci
nds, or ma
sen
ls in your
end their
amplify sou
too
ext
se
p
hel
the
to
e of
instruments s you’ve used som
hap
below. Per
ivities.
in other act
C As the ruler vibrates up
and down, it creates a
wave-pattern of alternating particles of air that
are compressed and
spread out. This wave
of sound travels to your
eardrum, where the
sound is received.
B At the same time, the air
particles on the opposite
side of the ruler spread
farther apart.
you used?
wn have
ments sho
ls or instru
of the too
end?
1. Which
ments ext
tru
this
ins
s? Why is
tools and
se do the
gnify object
2. What sen
shown ma
truments
ls and ins
too
the
3. How do
useful?
Interpersonal Have
students compare the
sensory system of information processing with that of a
telephone system. Have them
brainstorm similarities and
differences.
Cochlea
(Hearing)
Anvil
Stirrup
Hammer
The cochlea (KOH klee uh) is a fluidfilled structure shaped like a snail’s shell,
in the inner ear. When the stirrup vibrates,
fluids in the cochlea also begin to vibrate.
These vibrations stimulate nerve endings
in the cochlea, and impulses are sent to the
brain by the auditory nerve. Depending on
how the nerve endings are stimulated, you
hear a different type of sound. Highpitched sounds make the endings move
differently than lower, deeper sounds.
Balance also is controlled in the inner ear.
Special structures and fluids in the inner
ear constantly adjust to the position
of your head. This stimulates impulses to
the brain, which interprets the impulses
and helps you make the necessary adjustments to maintain your balance.
Eardrum
Figure 20-10 Your ear responds
to sound waves and to changes in the
position of your head. Why does spinning around make you dizzy?
Figure 20-10 shows that your ear is
divided into three sections: the outer, middle, and inner ear. Your outer ear traps
sound waves and funnels them down the
ear canal to the middle ear. The sound
waves cause the eardrum to vibrate much
like the membrane on a drum. These vibrations then move through three little bones
called the hammer, anvil, and stirrup. The
stirrup bone rests against a second membrane on an opening to the inner ear.
The Inner Ear
Sound waves
A When the ruler vibrates
Section 20-2
56
olfactory cell
taste bud
It's Important
1 Motivate
Middle ear
Semicircular
canals (Balance)
Science fiction stories about space often describe energy
force fields around spaceships. When some form of energy
tries to enter the ship’s force field, the ship is put on alert.
Your body has an alert system as well, in the form of sense
organs. Your senses enable you to see, hear, smell, taste,
touch, and feel whatever comes into your personal territory.
The energy that stimulates your sense organs may be in the
form of light rays, heat, sound waves, chemicals, or pressure.
It's Important
Sense organs are adapted
for capturing and transmitting
these different forms of energy.
The sensory receptors in
each sense organ
What type of stimulus each
sense organ responds to
and how
Why healthy senses are
needed
Refer to Sensory
Receptors on pp. 544E–F.
Inner ear
In Touch with Your Environment
You'll Learn
C ontent
The Senses
Purpose
Kinesthetic Students will
observe and make inferences concerning the factors that
affect their ability to maintain balance. L2 ELL
Observing Balance Control
Procedure
1. Place two narrow strips of paper on the wall to
form two parallel vertical lines. Have a student
stand between them, as still and straight as
possible without leaning on the wall, for three
minutes.
2. Observe how well balance is maintained.
3. Have the student close his or her eyes and
repeat standing within the lines for three
minutes.
Analysis
1. When was balance more difficult to maintain?
Why?
2. What other factors might cause a person to
lose the sense of balance?
56
cGraw-Hill,
Glencoe/M
Copyright©
of The
a division
, Inc.
ill Companies
McGraw-H
554
CHAPTER 20
THE NERVOUS
AND
20 2
ENDOCRINE SYSTEMS
The following Teacher Classroom
Resources can be used with Section 20-2:
CA Science Content
Standards
Page 554: 5a, 5b, 5g
Page 555: 5a, 5b, 7c
554
CHAPTER 20
THE NERVOUS
Reproducible Masters
Activity Worksheets, pp. 111–114 L2
Enrichment, p. 56 L3
Home Involvement, p. 28 L2
Laboratory Manual, pp. 121–124 L2
AND
ENDOCRINE SYSTEMS
THE SENSES
555
Caption Answer
Resource Manager
Reinforcement, p. 56
Figure 20-10 Spinning makes the fluids in the
inner ear send impulses to the brain that conflict
with the actual position of the head. Dizziness
results.
L2
Study Guide, p. 78
Transparencies
Science Integration Transparency 20
L2
For additional help doing this
activity at home, see the corresponding pages in the Home Involvement booklet.
Assessment
Performance To further assess students’ understanding of balance, have them repeat the activity
with feet apart or arms extended sideways. Use
Performance Assessment in the Science
Classroom, p. 25.
Materials
two narrow strips of paper, masking tape
Teaching Strategies
Have students perform this activity with another family member.
Have them take turns standing
and observing. Record whether
the person standing tends to lean
more to one side or the other.
Safety Precautions Some persons may become disoriented. Be
prepared to help any person who
looks as if he or she might fall.
Analysis
1. When the eyes are closed;
when the eyes are open, a
person can focus on a point to
help the body remain balanced.
2. Answers will vary but could
include such conditions as an
inner ear infection or loud,
continuous noise.
20-2
THE
SENSES
555
Vision
Quick Demo
Obtain a double convex
lens to illustrate the refraction
and focusing of light rays
similar to that which occurs
in the eye.
Figure 20-11 Light moves
through several structures—the
cornea and the lens—before
striking the retina.
Retina
Enrichment
Have students research the
phenomenon of afterimage,
where an image is still perceived after its external cause
is gone.
Optic nerve
Have students who wear corrective eyeglasses examine them to
determine whether the lenses are
concave or convex.
PHYSICS
INTEGR ATION
Flex Your Brain
At four years of
age, a young child
can see clearly at a distance as close as 6.3
cm away. As the eye’s
lens hardens with age,
this distance increases.
At 30 years old, the
distance is 15 cm. At
50 years old, the distance has become
40 cm. Estimate how
many times longer the
distance at 30 and 50
years old is compared
to the distance clearly
seen at four years old.
at 30 years old, 15 cm 6.3 cm 2.4 times longer;
at 50 years old, 40 cm 6.3 cm 6.3 times longer
than a four-year-old child
CD-ROM
556
CHAPTER 20
THE NERVOUS
Think about the different kinds of objects you look at every
day. It’s amazing that, at one glance, you can see the words
on this page, the color illustrations, and your classmate
sitting next to you.
Light travels in a straight line unless something bends or
refracts it. Your eyes are equipped with structures that bend light. As light enters the
eye, its waves are first bent by the
Iris
cornea and then a lens, as illustrated
in Figure 20-11. The lens directs
the rays onto the retina (RET
Lens
nuh). The retina is a tissue at
the back of the eye that is sensitive to light energy. Two types
Pupil
of cells called rods and cones
are found in the retina. Cones
respond to bright light and color.
Cornea
Rods respond to dim light. They
are used to help you detect shape
and movement. Light energy stimulates impulses in these cells. The
impulses pass to the optic nerve, which carries them to the brain. There, the impulses are interpreted, and you see what you are looking at.
Lenses—Refraction and Focus
Use the Flex Your Brain
activity to have students
explore SENSES.
Glencoe Science Voyages
Interactive CD-ROM
Explorations
Have students do the interactive
exploration How does human
hearing compare with that of
other animals?
Concave lens
Convex lens
556
CHAPTER 20
THE NERVOUS
Light is refracted, or bent, when it passes through a lens.
Just how it bends depends on the type of lens it passes
through. A lens that is thicker in the middle and thinner on
the edges is called a convex lens. The lens in your eye is convex. If you follow the light rays in Figure 20-12, you’ll see that
the lens causes parallel light rays to come together at a focus
point. Convex lenses can be used to magnify objects. The
light rays enter the eyes in such a way through a convex lens
that the object appears enlarged. Magnifying lenses, hand
lenses, microscopes, and telescopes all have convex lenses.
A lens that has thicker edges than the middle is called a
concave lens. Follow the light rays in Figure 20-12 as they
pass through a concave lens. You’ll see that this kind of
lens causes the parallel light to spread out. A concave lens is
used along with convex lenses in telescopes to allow distant
objects to be seen clearly.
Focal
point
Light rays
Light rays
Correcting Vision
In an eye with normal vision, light rays are focused by the
cornea and lens onto the retina. A sharp image is formed
on the retina, and the brain interprets the signal as being
clear. However, if the eyeball is too long from front to back,
light from distant objects is focused in front of the retina.
A blurred image is formed. This condition is called
nearsightedness because near objects are seen clearly. To correct nearsightedness, eyeglasses with concave lenses are
used. Concave lenses focus these images sharply on the
retina. If the eyeball is too short from front to back, light from
nearby objects is focused behind the retina. Again, the image
appears blurred. Convex lenses correct this condition known
as farsightedness. Figure 20-13 shows how lenses are used to
correct these vision problems. ✔
Figure 20-12 Light rays
passing through a convex lens are
bent toward the center and meet
at a focal point. Light rays that
pass through a concave lens are
bent outward. They do not meet.
d by
ness is cause
Nearsighted
from
g
n
lo
at is too
an eyeball th
tant
is
d
g
, causin
front to back
of
t
on
cus in fr
objects to fo
the retina.
Videodisc
k
g Chec
Readin
uses
What ca edness?
ht
nearsig
✔
Figure 20-13 Glasses and contact
lenses use concave or convex lenses to
sharpen your vision.
Farsighted
Nearsighted
✔
Glencoe Science Voyages
Interactive Videodisc—Life
Side 2, Lesson 6 Eyeing
Evolution
!7Å/-2^Ö"
9312
Refer to Videodisc Teacher
Guide for additional bar codes.
3 Assess
Check for Understanding
A A nearsighted person cannot see distant objects
because the image is focused in front of the retina.
C A farsighted person cannot see close objects
because the image is focused behind the retina.
Concave lens
Using an Analogy
Open up a camera and view
the internal components to
compare them to the human
eye.
Reteach
Convex lens
Visual-Spatial Have
students make concept
maps of the sensory organs. L1
Extension
AND
ENDOCRINE SYSTEMS
The term fatigue is sometimes
used to describe a decreased sensitivity of a
receptor, such as the eye, to stimuli. A red
surface seems to become gray when it is
stared at for a long period of time, and
D A convex lens corrects farsightedness.
20-2
THE SENSES
557
For students who have
mastered this section, use the
Reinforcement and Enrichment masters.
Across the Curriculum
Background
ENDOCRINE SYSTEMS
heck
Reading C
B A concave lens corrects nearsightedness.
C ontent
AND
Answer to
the retina is said to be fatigued by long
exposure to the color red. The same is true
of hearing. A sustained noise that is heard
continuously becomes less intense due to
fatigue of the processes of the inner ear.
Reading Find out how Helen Keller was
able to learn to communicate even though
she was deprived of sight and hearing at an
early age. L2
CA Science Content
Standards
Page 556: 5a, 5b, 5g, 6c,
6d, 6e
Page 557: 5a, 5b, 5g, 6c,
6d
20-2
THE
SENSES
557
Smell
Purpose
Kinesthetic Students
will observe the difference
in the sense of smell between
males and females. L2 ELL
Comparing Sense of Smell
Procedure
1. Design an experiment to test your classmates’
abilities to recognize the odors of different
foods, colognes, or household products.
2. Record their responses in a data table according to the gender of the individuals tested.
COOP LEARN P
Materials
small amounts of various spices,
flavor extracts, and other odorous substances; cotton balls
Analysis
1. Compare the numbers of correctly identified
odors for both males and females.
2. What can you conclude about the differences
between males and females in their ability to
recognize odors?
Teaching Strategies
Safety Precautions Students
should not use any substances
with strong, noxious odors (e.g.,
ammonia). Survey students before class to determine whether
any of them might have allergies
that might be affected by the
odors.
Troubleshooting Place a
small amount of the odorous
substance on a cotton ball for
each sniff test. Do not use the
cotton ball for more than one
person.
Figure 20-14 Although your
taste buds distinguish four separate taste sensations (A), scientists
cannot determine differences
among individual taste buds (B).
Taste
B
Analysis
1. Answers may vary, but more
females should correctly
identify specific odors.
2. Generally, females are more
acutely aware of odors than
are males.
A
Bitter
Sour
Assessment
Sour/salty
Performance Have students
conduct a test of identifying
odors while blindfolded. Use
Performance Assessment
in the Science Classroom,
p. 97.
Salty
Sweet
558
CHAPTER 20
A bloodhound is able to track a particular scent through fields and forest.
Even though your ability to detect odors is
not as sharp, your sense of smell is still
important.
You can smell food because it gives off
molecules into the air. Nasal passages
contain sensitive nerve cells called olfactory
cells that are stimulated by gas molecules.
The cells are kept moist by mucous glands.
When gas molecules in the air dissolve in
this moisture, the cells become stimulated. If
enough gas molecules are present, an
impulse starts in these cells and travels to
the brain. The brain interprets the stimulus.
If it is recognized from previous experience,
you can identify the odor. If you can’t recognize a particular odor, it is remembered and
can be identified the next time, especially if
it’s a bad one.
THE NERVOUS
AND
Have you ever tasted a new food
with the tip of your tongue and found
that it tasted sweet? Then when you
swallowed it, you were surprised to
find that it tasted bitter. Taste buds
on your tongue are the major sensory receptors for taste. About 10 000
taste buds are found all over your
tongue, enabling you to tell one taste
from another.
Taste buds respond to chemical stimuli.
When you think of food, your mouth
begins to water with saliva. This adaptation is helpful because in order to taste
something, it has to be dissolved in water.
Saliva begins this process. The solution
washes over the taste buds, and an impulse
is sent to your brain. The brain interprets
the impulse, and you identify the taste.
Most taste buds respond to several taste
sensations. However, certain areas of the
tongue seem more receptive to one taste
ENDOCRINE SYSTEMS
than another. The four basic taste sensations are sweet, salty,
sour, and bitter. Figure 20-14 shows where these tastes are
commonly stimulated on your tongue.
Smell and taste are related. When you have a head cold
with a stuffy nose, food seems tasteless because it is blocked
from contacting the moist membranes in your nasal passages.
Figure 20-15 Many of the
sensations picked up by receptors
in the skin are stimulated by
mechanical energy. Pressure,
motion, and touch are examples.
How important is it to be able to feel pain inside your
body? Several kinds of sensory receptors in your internal
organs, as well as throughout your skin, respond to touch,
pressure, pain, and temperature, as illustrated in Figure 20-15.
These receptors pick up changes in touch, pressure, and temperature and transmit impulses to the brain or spinal cord.
The body responds to protect itself or maintain homeostasis.
Your fingertips have many different types of receptors for
touch. As a result, you can tell whether an object is rough or
smooth, hot or cold, light or heavy. Your lips are sensitive to
heat and prevent you from drinking something so hot that it
would burn you. Pressure-sensitive cells in the skin give
warning of danger to a body part and enable you to move to
avoid injury.
Your senses are adaptations that help you enjoy or avoid
things around you. You constantly react to your environment
because of information received by your senses.
Section Assessment
Section Assessment
5.
Skill Builder
Observing and Inferring How can you
tell the direction of a sound? Do the Chapter 20 Skill
Activity on page 725 to explore how your ears detect
sound.
Proficiency Prep
Use this quiz to check students’ recall of section content.
1. What is the function of
the lens in the eye? to
focus light rays onto the
retina
2. What are the three small
bones in the middle ear?
hammer, anvil, stirrup
3. What are the sensitive
nerve cells in your nasal
passages called? olfactory
cells
4. Where are the major sensory receptors for taste
found? on the tongue
Touch, Pressure, Pain, and Temperature
1. What type of stimulus do your ears respond to?
2. What are the sensory receptors for the eyes and nose?
3. Why is it important to have receptors for pain and pressure in your internal organs?
4. Think Critically: The brain is insensitive to pain. What
is the advantage of this?
4 Close
Write a paragraph in your Science
Journal to describe what
each of the following
objects would feel like.
1. coarse sand from a
beach
2. ice cube
3. silk blouse
4. snake
5. smooth rock
20-2
THE SENSES
1. sound waves
2. eyes: rods and cones;
nose: olfactory cells
3. The body responds to
protect itself or maintain
homeostasis.
4. Think Critically The brain
could continue to function when injured, allowing you to carry out activities for survival.
Entries should reflect
knowledge of the type
of skin receptors involved,
including touch and temperature.
559
Assessment
Senses on the Job Ask students to clip
advertisements in the help wanted section
of the newspaper about jobs that require
keenness of certain senses such as hearing,
vision, balance and coordination, or smell.
558
CHAPTER 20
THE NERVOUS
AND
ENDOCRINE SYSTEMS
They should put these ads, along with
brief descriptions of how and why specific
senses would be involved, in their Science
Journals.
Performance Assess students’ abilities to
make and use tables by having them write a
statement comparing the different types of
energy that stimulate the senses. Use Performance Assessment in the Science Classroom, p. 87.
CA Science Content
Standards
Page 558: 5a, 5b, 7c, 7e
Page 559: 5a, 5b
20-2
THE
SENSES
559
Activity
20•2
Activity 20 2
Design
Your Own
Experiment
Investigating Skin
Sensitivity
Recognize the Problem
Purpose
Interpersonal Students
will design and carry out an
experiment to determine the sensitivity of skin on various parts of the
body by testing for the location of
receptors in the skin. L2 ELL
Possible Materials
• Index card
(3 inches 5 inches)
• Toothpicks
• Tape or glue
• Metric ruler
COOP LEARN P
Process Skills
observing and inferring, forming a
hypothesis, designing an experiment, interpreting data, making
and using tables, comparing and
contrasting
Using Scientific Methods
Y
our body responds to touch, pressure, and temperature.
Not all parts of your body are equally sensitive to stimuli. Some
areas are more sensitive than others. For example, your lips are sensitive to heat. This protects you from burning your mouth. Now think
about touch. How sensitive is the skin on various parts of your body
to touch? Which areas can distinguish the smallest amount of distance between stimuli?
Recognize the Problem
What areas of the body are most sensitive to touch?
Form a Hypothesis
Time
2 class periods
Goals
• Observe the sensitivity to
touch on specific areas of
the body.
Safety Precautions
Caution students not to apply
heavy pressure when using any
contact points device.
• Design an experiment that
tests the effects of a variable,
such as the closeness of contact points, to determine which
body areas can distinguish
between the closest stimuli.
Safety Precautions
Form a Hypothesis
Do not apply
heavy pressure when using
the toothpicks.
Possible Hypotheses
Possible hypotheses could include that the whole body is
equally sensitive, nerve endings
are various distances apart, and
the most sensitive parts of the
body are the fingertips.
Plan
1. As a group, agree upon and write 3. Design a data table to use in
out the hypothesis statement.
your Science Journal.
2. As a group, list the steps you
4. Read over your entire experineed to take to test your hypothment to make sure that all steps
esis. Be specific, describing
are in order.
exactly what you will do at each
5. Identify any constants, variables,
step. Consider the following facand controls of the experiment.
tors as you list the steps. How
will you know that sight is not a
factor? How will you use the card
shown on the right to determine sensitivity to touch? How
will you determine and record
that one or both points of touch
are felt? List your materials.
1. Make sure your teacher
approves your plan and your
data table before you proceed.
2. Carry out the experiment as
planned.
CHAPTER 20
THE NERVOUS
AND
Expected Outcome
The more sensitive areas of the
skin to touch are the fingertips,
palms, and cheeks. Less sensitive
are the back of the hand, forearm,
and back of the neck.
3. While the experiment is going
on, write down any observations that you make and complete the data table in your
Science Journal.
Error Analysis
Have students compare their results and their hypotheses and explain any differences that occurred.
Analyze Your Data
Analyze Your Data
1. Compare your results with
those of other groups.
2. Identify which part of the body
tested can distinguish between
the closest stimuli.
1. Results should be consistent.
2. fingertips and usually the
palms
3. back of hand, forearm
4. Answers will vary.
3. Identify which part of the body
is least sensitive.
4. Rank body parts tested from
most to least sensitive. How did
your results compare with your
hypothesis?
Draw Conclusions
Draw Conclusions
1. Based on the results of your
investigation, what can you infer
about the distribution of touch
receptors on the skin?
560
have pairs that are 5 mm and
10 mm apart. With a partner’s
eyes closed, use the part of the
card with toothpicks 1 mm apart
and carefully touch the skin surface. Caution students not to apply
heavy pressure. If the partner feels
two points, record a plus () in
the table. If the partner cannot feel
both points, record a minus () in
the table. Repeat using the other
sides of the card.
Do
Based on your experiences, state a hypothesis about which of the
following five areas of the body you believe to be most sensitive—
fingertip, forearm, back of the neck, palm, and back of the hand.
Rank the areas from 5 (the most sensitive) to 1 (the least sensitive).
Materials
Obtain materials for cooperative
groups. To save time, prepare the
test cards the day before the activity to allow glue to dry.
Test Your Hypothesis
2. What other parts of your body
would you predict to be
less sensitive? Explain your
predictions.
ENDOCRINE SYSTEMS
20-2
THE SENSES
561
Test Your Hypothesis
Possible Procedures
Predict which skin areas are the
most sensitive to touch. Rank the
areas from most (5) to least (1)
sensitive in a data table. Glue the
toothpicks onto the card so that
one side has a pair that are 1 mm
apart; another side has a pair
3 mm apart. The other sides
560
CHAPTER 20
THE NERVOUS
Inclusion Strategies
Physically Challenged Any student
who may not be able to manipulate the testing device may be in charge of formulating the
hypothesis and the design of the experiment.
AND
ENDOCRINE SYSTEMS
Sample Data Table
Body part
tested
1. Touch receptors are closer together in the fingertips and further apart on the back of the
hand and forearm. Receptors
in the palm and back of the
neck vary.
2. Answers may include the
back and the legs because
they are unlikely to be used to
gather new information about
an object.
Assessment
Predictions Felt two points (mm)
1
3
5
10
fingertip
5
palm
4
back of hand
3
forearm
1
back of neck
2
Have students design an experiment to test the
sensitivity of the same body areas to temperature
ranges. Caution students not to use extreme
temperatures. If they carry out the experiment,
be sure their plans are approved first.
Performance To further assess students’
understanding of skin sensitivity, repeat this activity on the lower part of the leg and on the foot.
Use Performance Assessment in the
Science Classroom, p. 17.
CA Science Content
Standards
Page 560: 5a, 5b, 7a, 7c,
7e
Page 561: 5a, 5b, 7a, 7c,
7e
20-2
THE
SENSES
561
SECTION
20 3
20•3
Prepare
It's Important
Functions of the Endocrine System
You'll Learn
C ontent
Background
“The tallest man in the world!” and “the shortest woman
on Earth!” used to be common attractions in circuses. These
people became attractions because of their extraordinary and
unusual height. In most cases, their sizes were the result of a
malfunction in their endocrine systems.
The endocrine system is the second control system of your
It's Important
body. Whereas impulses
are control mechanisms of your nervous system, chemicals are the control mechanisms of your
endocrine system. Endocrine chemicals called hormones are
produced in several You'll
tissuesLearn
called glands throughout your
body. As the hormones are produced, they move directly into
your bloodstream. Hormones affect specific tissues called
target tissues. Target tissues are frequently located in another
part of the body at a distance from the gland that affects
them. Thus, the endocrine system doesn’t react as quickly as
the nervous system. Table 20-1 shows the position of eight
endocrine glands and what they regulate.
How hormones function
Three endocrine glands and
the effects of the hormones
they produce
How a feedback system
works
Refer to The
Pituitary Gland, Disturbances of Endocrine
Function, and HormoneProducing Bacteria on
p. 544F.
Vocabulary
Why
What
hormone
target tissue
Preplanning
It's Important
Refer to the Chapter Organizer on pp. 544A–B.
Endocrine glands control
the chemical mechanisms
You'll Learn
of your body.
1 Motivate
Visit the Glencoe
Science Web Site at
www.glencoe.com/
sec/science/ca for
more information about
endocrine diseases.
A Negative-Feedback System
To control the amount of hormone an endocrine gland
produces, the endocrine system sends chemical information
back and forth to itself. This is a negative-feedback system.
It works much the way a thermostat works. When the temperature in a room drops below a certain level, a thermostat
signals the furnace to turn on. Once the furnace has raised
the temperature to the level set on the thermostat, the
furnace shuts off. It will stay off until the thermostat signals
again. In your body, once a target tissue responds to its
It's Important
Why
Endocrine
You'll Learn glands, which
produce
hormones;
What
milk production;
Gland
Regulates
Pituitary
growth
Section 20-3
CY
ANSPAREN
FOCUS TR
SECTION
pancreas
the
ES
ults when
ITH DIABET endocrine system. It resn is a hormone that t
LIVING W
uli
no
ease of the
ounts. Ins
glucose. If
m of
is a dis
per am
Diabetes
ulin in pro
ar in the for
in the
produce ins body to take in sug sugar accumulates
does not
as,
cells of the
the pancre urine.
enables the n is produced by
in
y
uli
the bod
enough ins or is excreted from
bloodstream
Thyroid
Carbohydrate use
Parathyroids
Calcium
Adrenal
Blood sugar;
salt and water balance;
metabolism
Pancreas
Blood sugar
Ovaries
Egg production;
sex organ development in females
Testes
or by
n in pills
take insuli
es need to
with diabet
uld a person
ic?
1. Why wo
diabet
rtant to a
injection?
diet impo
a healthful
rly?
maintaining
rcise regula
2. Why is
to get exe
a diabetic
for
nt
rta
it impo
3. Why is
cGraw-Hill,
Glencoe/M
Copyright©
562
57
Think Critically
approximately 100 mg/dL; eat
smaller amounts of sugar and
starches; a noon meal
3 Assess
Activity
Visual-Spatial On
a
chart or model of the
human body, have students
locate the endocrine glands
and identify the organs they
control. L2
THE NERVOUS
AND
Diabetes results when the pancreas does not produce
enough insulin. Insulin is a hormone that enables cells
to take in glucose. Glucose is a sugar needed for
energy. Extra glucose is not stored, so the glucose is
carried in the blood unless insulin enables the cells
to take it in. Patients with diabetes have high amounts
of sugar in the blood. Normal levels of sugar in the
morning are between 60 and 100 milligrams per
deciliter (mg/dL). Eating a meal increases glucose in
the blood.
The graph shows the sugar in the blood from morning to afternoon. Notice the difference in blood sugars
between a diabetic and a nondiabetic person.
Think Critically: Approximately how much
difference is there in blood sugar levels between the
two persons first thing in the morning? What might
Key
300
diabetic
non-diabetic
250
200
Reteach
150
Visual-Spatial Using a
chart of the circulatory
system, have students trace
the pathway of a hormone to
its target tissue. L2
100
50
0
1 2
3
4
5
6
Hours After Breakfast
Extension
the diabetic person do to prevent such high readings
one and two hours after breakfast? What might
account for the increased level in blood sugar after
the fourth hour?
20-3
ENDOCRINE SYSTEMS
The following Teacher Classroom
Resources can be used with Section 20-3:
Reproducible Masters
Recall from the first section
in this chapter how the nervous system responds to
changes in environment and
makes adjustments in the
body.
THE NERVOUS
Interpreting Blood Sugar Levels
THE ENDOCRINE SYSTEM
For students who have
mastered this section, use the
Reinforcement and Enrichment masters.
563
Resource Manager
anies, Inc.
aw-Hill Comp
of The McGr
a division
Tying to Previous
Knowledge
CHAPTER 20
CHAPTER 20
Sperm production;
sex organ development in males
Diabetes is caused by the lack
of insulin or the body’s inability to use it. The body is unable to completely metabolize
its sugars, and the kidneys
eliminate this unmetabolized
sugar. Blood sugars sometimes
can be controlled through
food choices.
Check for Understanding
Blood Sugar
(mg Sugar /dL Blood)
Endocrine Glands
Before presenting the lesson,
display Section Focus
Transparency 57 on the
overhead projector. Use the
accompanying Focus Activity
worksheet. L2 ELL
562
2 Teach
The pancreas produces a digestive enzyme. This enzyme is
released into the small intestine through tubelike vessels
called ducts. The pancreas is also part of your endocrine system because other groups of cells in the pancreas secrete hormones. One of these hormones, insulin, enables cells to take
in glucose. Recall that glucose is the main source of energy for
respiration in cells. Normally, insulin enables glucose to pass
from the bloodstream through cell membranes. Persons who
can’t make insulin are diabetic because insulin isn’t there to
enable glucose to get into cells.
Table 20-1
Bellringer
57
The Endocrine
System
The Pancreas—Playing Two Roles
Critical Thinking/Problem Solving, p. 20
L2
Enrichment, p. 57
AND
ENDOCRINE SYSTEMS
L3
Reinforcement, p. 57
L2
Study Guide, pp. 79–80
Internet Addresses
L1
ELL
Transparencies
Teaching Transparency 40
CA Science Content
Standards
L2
For Internet tips, see Glencoe’s Using the
Internet in the Science Classroom.
Page 562: 5a, 5b
Page 563: 5a, 5b, 7b, 7c
20-3 THE ENDOCRINE SYSTEM
563
hormone, the tissue sends a chemical signal back to
the gland. This signal causes the gland to stop or slow
down production of the hormone. When the level of
the hormone in the bloodstream drops below a certain
level, the endocrine gland is signaled to begin secreting the hormone again. In this way, the concentration of the hormone in the bloodstream is
kept at the needed level. Figure 20-16
illustrates how a negative-feedback system works.
Hormones produced by endocrine
glands go directly into the bloodstream and affect target tissues. The
level of the hormone is controlled
ON
by a negative-feedback system.
Hormone
production
In this way, many chemicals in
increases
the blood and body functions are
controlled.
V ISUALIZING
A Feedback System
V ISUAL
Learning
Figure 20-16 Have students describe what is
happening at each point of
the cycle. Have them tell
how this system is like the
thermostat in a home.
Hormone
level
low
ON
Hormone
production
slows down
Use this quiz to check students’ recall of section content.
1. What type of glands do
not have ducts? endocrine
2. What is one of the hormones produced by the
pancreas? insulin
3. What signals a gland to
start secreting its hormone again? when the
level of hormone in the
bloodstream drops
OFF
Students are introduced to a
hearing aid and the different
parts that make it work.
A hearing aid is a small, electronic instrument (left) that makes
sounds louder and easier to understand. A hearing aid fits
around the outside of the ear or inside the ear canal. Some
hearing aids are so small that they are hardly noticeable.
C ontent
Background
PARTS OF A HEARING AID
OFF
1
The tiny microphone built into the hearing aid picks up
sounds. It changes sound waves into electrical signals.
2
The amplifier makes the electrical signals stronger. A hearing
aid user can control the degree to which sounds are amplified, or made stronger.
Sailors invented hearing aids
long ago. They used ear trumpets to communicate over
long distances. By 1900, hearing aids were available. A
hearing aid usually helps
hearing when the outer ear or
middle ear is damaged.
3
Figure 20-16 Many internal
body conditions, such as hormone
level and body temperature, are controlled by negative-feedback systems.
Hormone
level
high
V ISUAL
Learning
Section Assessment
1.
2.
3.
4.
What is the function of hormones?
What is a negative-feedback system?
Choose one hormone and explain how it works.
Think Critically: Glucose passes from the bloodstream through cell membranes and into the cells.
Glucose is required for respiration within cells. How
would lack of insulin affect this process?
Skill Builder
5.
Comparing and Contrasting In what ways
are the nervous system and endocrine system alike? If
you need help, refer to Comparing and Contrasting in the
Skill Handbook on page 684.
564
CHAPTER 20
THE NERVOUS
AND
Both systems send and receive
messages. They also help
maintain homeostasis.
Entries may include that
diabetics are people who
can’t make insulin. This
prevents glucose from entering cells. Diabetes can
be controlled, however.
3
Career
C O N N E C TI O N
Pretend you
are a doctor and
have to explain to a
young patient about
diabetes. What would
you say to him?
An audiologist evaluates and treats
people with hearing loss. He or she
conducts tests to determine specific
hearing problems. Most audiologists have a master’s degree in
audiology (hearing) or speech, language, and pathology (study of
diseases). Pretend that you are an
audiologist. Create an advertisement about services you can
provide and hearing aids that
you recommend for people
who have trouble hearing.
4
Performance Write a paper explaining the
similarities and differences of the nervous
and endocrine systems. Use the Performance Assessment in the Science Classroom, p. 87.
1
The battery is the power
source that makes the hearing aid work. Like batteries
in portable tape or CD players, batteries in a hearing
aid must be changed when
they lose power.
Teaching Strategies
Think Critically
1. Why must a person be able to hear at some level in
order for a hearing aid to work?
2. How might background noise cause problems for people
with hearing aids?
20-3
Assessment
Have students cup their
hands behind their ears
and have another student
make a sound. Compare
the sound with normal
hearing. Cupping your
hand behind your ear amplifies the sound like a
hearing aid.
4
The receiver changes the
amplified electrical signals
back into sound signals
and sends them to the
eardrum.
ENDOCRINE SYSTEMS
Skill Builder
5.
THE NERVOUS
Purpose
V ISUALIZING
1. They are endocrine secretions that control activities in parts of the body
not near the gland.
2. a system that uses the
level of hormone in the
blood to signal when a
gland should secrete the
hormone again
3. Refer to Table 20-1 for
possible answers.
4. Think Critically Insulin
enables glucose to pass
from the bloodstream
into cells. Cells need glucose for respiration. Without insulin, cells can’t
respire.
CHAPTER 20
A Hearing Aid
2
Section Assessment
564
How it Works
G
4 Close
Proficiency Prep
How it Works
Thinking Critically
1. A hearing aid is an amplification device
only.
2. The hearing aids also would amplify
background noise, the person might
have trouble distinguishing conversation or sounds from the radio or TV if
background noise also is loud.
THE ENDOCRINE SYSTEM
565
Career
C O N N E C TI O N
Audiologists need to complete a two-year
postgraduate training course before they
can work. They need to have an undergraduate degree such as a Bachelor of Arts or Science before they can apply for the course.
Have students design their
own speaking tubes that will
amplify their voices. Compare the different voices
when the tube is coiled and
when it is straightened. Students can make the speaking
tube by using a cardboard
paper-towel holder, tape, and
a funnel. Tape the funnel to
one end of the tube. Discuss
how the amplification of the
tube is like the amplification
of a hearing aid.
CA Science Content
Standards
Page 564: 5a, 5b
Page 565: 5a, 5b
AND
ENDOCRINE SYSTEMS
20-3 THE ENDOCRINE SYSTEM
565
20
The Glencoe
MindJogger,
Audiocassettes,
and CD-ROM
provide additional
opportunities for review.
Linguistic Have students try to answer the
questions in their Science
Journals. Use student answers as a source for discussion throughout the chapter.
ectio
20-1 BODY REGULATION
Your body is constantly
receiving a variety of stimuli from
inside and outside the body. The
nervous and endocrine systems
respond to these stimuli to maintain homeostasis. What are some
body functions that are constantly being checked and
regulated?
✔
genor three
List two s about the
ion
eralizat nd endocrine
a
nervous xchange lists
E
.
s
they
system
rmine if
e
t
e
and d
urate.
are acc
ectio
n
Preview
Readin
n
or a preview of this
chapter, study this
Reviewing Main Ideas
before you read the chapter.
After you have studied this
chapter, you can use the
Reviewing Main Ideas to
review the chapter.
F
Reviewing Main Ideas can
be used to preview, review,
reteach, and condense chapter content.
k
g Chec
Reviewing Main Ideas
S
20
Chapter
Reviewing
Main Ideas
S
Chapter
20-2 THE SENSES
Your senses respond to energy. The eyes respond
to light, and the ears respond to sound waves. The
olfactory cells of the nose and the taste buds
of the tongue are stimulated by chemicals.
What senses are involved as you
pick up and eat a freshly baked
chocolate chip cookie?
Answers to Questions
Section 20-1
Body Regulation Some of
the body functions that are
constantly being checked are
heartbeat, breathing, and hormone levels in the bloodstream.
Nervous System The two
major divisions of the nervous system are the central
nervous system (CNS) and
the peripheral nervous system (PNS).
Review
Reteach
Visual-Spatial Have
students look at the illustrations on these pages.
Ask them to describe details
that support the main ideas of
the chapter found in the statement for each illustration.
OUT OF
TIME
?
Auditory-Musical If
time does not permit
teaching the entire chapter, use the information on
these pages along with the
chapter Audiocassettes to
present the material in a
condensed format.
566
CHAPTER 20
THE NERVOUS
AND
Arrow-Poison Frogs Skin glands of
arrow-poison frogs secrete a powerful
venom that results in muscular paralysis. An
amount as small as 0.000 01 g can kill a
human. Have students find out how the native peoples of Central and South America
extract the venom and how they use it to
hunt. L2
566
CHAPTER 20
THE NERVOUS
AND
ENDOCRINE SYSTEMS
ectio
20-3 THE ENDOCRINE SYSTEM
Endocrine glands secrete
hormones directly into your bloodstream.
Hormones affect specific tissues throughout the body and regulate their activities.
A feedback system regulates the hormone
levels in your blood. How can a gland
that is near your head control the
rate of chemical activities throughout
your entire body?
CHAPTER 20 REVIEWING MAIN IDEAS
ENDOCRINE SYSTEMS
Cultural Diversity
Section 20-3
Endocrine System The gland
releases its secretion into the
bloodstream, which carries it
to a specific site anywhere in
the body.
n
NERVOUS SYSTEM
The basic unit of the nervous
system is the neuron. Stimuli are
detected by sensory neurons, and the
impulse is carried to an interneuron
and then transmitted to a motor neuron. The result is the movement of a
body part. Some responses are automatic and are called reflexes. What
are the two major divisions of the
nervous system?
Section 20-2
Senses The senses involved
are sight, smell, touch, and
taste.
S
Interpersonal Have
students answer the
questions on separate pieces
of paper and compare their
answers with those of other
students in the class.
CD-ROM
Glencoe Science Voyages
Interactive CD-ROM
Chapter Summaries and Quizzes
Have students read the
Chapter Summary then take the
Chapter Quiz to determine
whether they have mastered
chapter content.
567
Assessment
Portfolio Encourage students to place in
their portfolios one or two items of what
they consider to be their best work. Examples include:
• Science Journal, p. 547
• MiniLab, p. 558
• Activity 20-2, pp. 560–561 P
Performance Additional performance assessments may be found in Performance
Assessment and Science Integration Activities. Performance Task Assessment Lists
and rubrics for evaluating these activities
can be found in Glencoe’s Performance Assessment in the Science Classroom.
CHAPTER 20 REVIEWING MAIN IDEAS
567
Chapter
20
Chapter
Assessment
a. axon
b. brain stem
c. central nervous
1. n
2. i
3. c
4. l
5. d
d.
e.
f.
g.
h.
To reinforce
chapter vocabulary, use the Study Guide
for Content Mastery booklet.
Also available are activities for
Glencoe Science Voyages on
the Glencoe Science Web Site.
www.glencoe.com/sec/
science/ca
1.
2.
3.
4.
5.
l.
m.
n.
o.
p.
nervous system
reflex
retina
synapse
target tissue
taste bud
a small space between neurons
basic unit of nervous system
division containing brain and spinal cord
an automatic response to stimuli
center for coordination of voluntary
muscle action
Checking Concepts
11. C
12. A
13. C
14. C
15. D
Choose the word or phrase that best answers
the question.
6. How do impulses cross synapses?
A) by osmosis
B) through interneurons
C) through a cell body
D) by a chemical
Thinking Critically
16. Accept all reasonable
responses; so messages
do not get mixed; so that
responses can be coordinated.
17. Reflexes are automatic
acts that occur without
our thinking about them.
Therefore, they happen
quickly and can shield our
bodies from danger such
as sharp or hot objects.
18. The doctor might check to
see if the pancreas was
producing enough insulin.
19. Examples include giantism, dwarfism, or diabetes.
CHAPTER 20
system
cerebellum
cerebrum
cochlea
dendrite
hormone
i. neuron
j. olfactory cell
k. peripheral
Match each phrase with the correct term from
the list of Vocabulary words.
Checking Concepts
568
10. What part of the brain controls voluntary
muscle?
A) cerebellum
C) cerebrum
B) brain stem
D) pons
Using Vocabulary
Using Vocabulary
6. D
7. B
8. C
9. C
10. A
20 Assessment
THE NERVOUS
CHAPTER 20
THE NERVOUS
AND
ENDOCRINE SYSTEMS
21. Classifying: Classify the types of
neurons as to their location and
direction of impulse.
12. What is controlled by the somatic division of the PNS?
A) skeletal muscles
B) heart
C) glands
D) salivary glands
13. Which of the following are endocrine
chemicals produced in glands?
A) enzymes
C) hormones
B) target tissues
D) saliva
23. Concept Mapping: Prepare a concept
map showing the correct sequence of the
structures through which light passes in
the eye.
14. Which gland controls many other
endocrine glands throughout the body?
A) adrenal
C) pituitary
B) thyroid
D) pancreas
24. Interpreting Scientific Illustrations:
Using the following diagram of the
synapse, explain how an impulse moves
from one neuron to another.
15. Which of the following does the inner
ear contain?
A) anvil
C) eardrum
B) hammer
D) cochlea
18. You have had your blood tested for
sugar, and the doctor says you have a
problem. How might your doctor determine which gland is responsible for this
regulation problem?
19. Describe an example of a problem that
results from improper gland functioning.
25. Observing and Inferring: If an impulse
traveled down one neuron, but failed to
move on to the next neuron, what might
you infer about the first neuron?
26. Predicting: Refer to the Try at Home
MiniLab in Section 20-2 and predict
ways to improve your balance. Test your
prediction.
20. If a fly were to land on your face and
another one on your back, which might
you feel first? Explain how you would
test your choice.
What does the test expect of me?
Find out what concepts, objectives, or
standards are being tested before the
test. Keep those concepts in mind as you
answer the questions.
21. Sensory neurons are located in the sense
organs and spinal cord and carry impulses to the brain. Interneurons are located in the central nervous system and
carry impulses from the central nervous
system to motor neurons. Motor neurons are in muscles and glands and
carry impulses from brain to muscles
and glands.
22. cerebrum—memory,
senses, thinking; cerebellum—voluntary muscles,
balance, muscle tone;
brain stem—coordinating
involuntary muscle movements, controlling heartbeat, breathing, and blood
pressure
23. Concept map should include the following steps:
cornea—lens—retina—
optic nerve—brain.
24. A n e r v e - t r a n s m i t t i n g
chemical is released from
the axon of one neuron,
diffuses across the
synapse, and starts an impulse in the next neuron.
25. It may be lacking the
nerve-transmitting chemical released by the axon.
26. Ways to improve balance
could include practicing,
exercising, and taking
dance lessons.
Test Practice
Use these questions to test your Science
Proficiency.
1. What happens to an endocrine gland
when the blood level of its hormone is
increased?
A) The gland stops producing hormones
until the hormone level in the blood
falls below a certain point.
B) The gland continues producing hormones until the blood can’t hold any
more hormones.
C) All endocrine glands keep producing
their hormones until all hormone levels in the blood are equal.
D) All endocrine glands stop producing
hormones until all hormone levels in
the blood are balanced.
2. Which statement below is the correct
pathway from the stimulus to the
response in a reflex response?
A) receptor—interneuron—brain—motor
neuron—muscle
B) sensory neuron—brain—spinal
cord—motor neuron
C) muscle—receptor—sensory neuron—
interneuron—motor neuron
D) receptor—sensory neuron—interneuron—motor neuron—muscle
Bonus Question
TEST-TAKING
How is your endocrine
CHAPTER 20 ASSESSMENT
Developing Skills
The Test-Taking Tip was
written by The Princeton Review, the nation’s leader in
test preparation.
1. A
2. D
Test-Taking Tip
22. Comparing and Contrasting: Compare
and contrast the structures and functions
of the cerebrum, cerebellum, and brain
stem. Include in your discussion
the following functions: balance, involuntary muscle movements, muscle
tone, memory, voluntary muscles,
thinking, and senses.
17. How are reflexes protective?
Test Practice
ENDOCRINE SYSTEMS
20. The skin on your face has more neurons
or more closely arranged neurons than
the skin on your back. The sense of
touch is more pronounced on the face.
You could check this out with a series of
tests using something lightweight, such
as a feather or paintbrush hair to test
sensitivity of the face and neck.
AND
If you need help, refer to the Skill Handbook.
16. Why is it helpful to have impulses move
in only one direction in a neuron?
8. What are neurons detecting stimuli in
the skin and eyes called?
A) interneurons
C) sensory neurons
B) motor neurons D) synapses
568
Developing Skills
Thinking Critically
7. What are the neuron structures that
carry impulses to the cell body?
A) axons
C) synapses
B) dendrites
D) nuclei
9. What is the largest part of the brain?
A) cerebellum
C) cerebrum
B) brain stem
D) pons
11. What is the part of the brain that is
divided into two hemispheres?
A) pons
C) cerebrum
B) brain stem
D) spinal cord
Assessment
Assessment Resources
The Test Practice Workbook provides students
with practice in the format, concepts, and critical-thinking skills tested in standardized exams.
Glencoe Technology
Chapter Review Software
Computer Test Bank
Reproducible Masters
Chapter Review, pp. 39–40 L2
Performance Assessment, p. 20
Assessment, pp. 77–80 L2
569
system like the thermostat in
a house? According to the level
of hormone in the blood, target
tissue sends a chemical message
back to the gland to stop or start
hormone secretion. Likewise, the
thermostat in a house signals the
heating or air conditioning unit
to start or stop according to the
temperature in the house.
MindJogger Videoquiz
L2
CHAPTER 20 ASSESSMENT
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