Section 1
Section 1
Nonspecific Defenses
Focus
Overview
Before beginning this section
review with your students the
objectives listed in the Student
Edition. This section introduces
students to the nonspecific defenses
of the human body, including skin
and mucous membranes. Students
will then learn that pathogens that
make it past the first line of defense
face the inflammatory and temperature responses that can be very
effective in killing the invader.
Bellringer
Ask students to make a list of the
many ways the body prevents
infectious organisms from entering.
(skin, mucous membranes, nose
hairs, etc.) When they are finished,
have them share their lists. Ask
them if the barriers on their lists
can distinguish between the types
of infections and can prevent specific ones. (no) TAKS 2 Bio 10A
Two Lines of Nonspecific Defenses
Objectives
Some animals, including turtles, clams, and armadillos, defend
themselves with their hard armor shells. However, even armor will
not protect against the most dangerous enemies that they or the
human body faces—harmful bacteria, viruses, fungi, and protists.
● Compare the inflammatory
You, as well as most animals, survive because your body’s immune
response with the temperature response.
10A 10B TAKS 2 system defends against these pathogens. A pathogen is a diseasecausing agent. The immune system consists of cells and
● Identify proteins that kill or
tissues found throughout the body. The body uses both nonspecific
inhibit pathogens.
10A 10B
TAKS 2
and specific defense mechanisms to detect and destroy pathogens,
● Analyze the roles of white
thereby preventing or reducing the severity of infection.
● Describe how skin and
mucous membranes defend
the body.
10A 10B TAKS 2
blood cells in combating
pathogens.
10A 10B TAKS 2
First Line of Nonspecific Defenses
Key Terms
pathogen
mucous membrane
inflammatory response
histamine
complement system
interferon
neutrophil
macrophage
natural killer cell
Motivate
Discussion
Ask students what happens when
they get a wood splinter in their
finger and they don’t get it out
within the first day or so. (The area
turns red, becomes sore, and may
swell.) What happens after several
more days, if the splinter isn’t
removed? (Pus may form around the
splinter; years ago this was called
“festering.”) Ask them why they
think the pus is whitish in color.
(White blood cells are converging on
the area of the wood splinter and it
is being digested.) LS Verbal
TAKS 2 Bio 10A; Bio 11B
pp. 924–925
Student Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TAKS Obj 3 Bio 4D
TEKS Bio 4B, 4D, 10A, 10B
Teacher Edition
TAKS Obj 2 Bio 10A, 10B
TEKS Bio 4B, 4D, 10A, 10B, 11B, 11D
924
The body’s surface defenses are nonspecific, meaning they do not
target specific pathogens. Your skin is the first of your immune
system’s nonspecific defenses against pathogens. Skin acts as a
nearly impenetrable barrier to invading pathogens, keeping them
outside the body. This barrier is reinforced with chemical weapons.
Oil and sweat make the skin’s surface acidic, inhibiting the growth
of many pathogens. Sweat also contains the enzyme lysozyme,
which digests bacterial cell walls.
Mucous membranes cover some body surfaces that come into contact with pathogens. Mucous (MYOO kuhs) membranes are layers of
epithelial tissue that produce a sticky, viscous fluid called mucus.
Mucous membranes line the digestive system, nasal passages, lungs,
respiratory passages, and the reproductive tract. Like the skin,
mucous membranes serve as a barrier to pathogens and produce
chemical defenses. Cells lining the bronchi and bronchioles in the respiratory tract secrete a layer of mucus that traps pathogens before
they can reach the warm, moist lungs, which are an ideal breeding
ground for microorganisms. Cilia on cells of the respiratory tract continually sweep mucus toward the opening of the esophagus. Mucus
then can be swallowed, sending pathogens to the stomach, where they
are digested by acids and enzymes.
Skin and mucous membranes work to prevent any pathogens
from entering the body. Occasionally these defenses are penetrated.
You take pathogens into your body when you breathe, because
many microbes and microbial spores are suspended in the air.
Other pathogens may be present in the food you eat. Pathogens can
also enter through wounds or open sores. When invaders reach
deeper tissue, a second line of nonspecific defenses takes over.
924
Chapter Resource File
• Lesson Plan GENERAL
• Directed Reading
• Active Reading GENERAL
Planner CD-ROM
• Reading Organizers
• Reading Strategies
• Occupational Application Worksheet
Sanitarian GENERAL
Chapter 40 • The Body’s Defenses
SCID To illustrate our dependence on a functional immune system, show students a picture
of David, the “boy in the bubble.” David was
born with severe combined immune deficiency
(SCID), a disease characterized by the inability
to produce B cells and T cells, which play key
roles in the immune system. SCID patients
must live in a protected environment because
the slightest infection can lead to death. David
died at the age of 12 after an unsuccessful
bone marrow transplant.
TAKS 2 Bio 10A, 10B (grade 11 only)
Second Line of Nonspecific Defenses
What happens when pathogens break through your body’s first line
of defense? When the body is invaded, four important nonspecific
defenses take action: the inflammatory response; the temperature
response; special proteins that kill or inhibit pathogens; and white
blood cells, which attack and kill pathogens.
www.scilinks.org
Topic: Immune Systems
Keyword: HX4103
Teach
READING
Inflammatory response Injury or local infection, such as a cut or a
scrape, causes an inflammatory response. An inflammatory
response is a series of events that suppress infection and speed
SKILL
BUILDER
Interactive Reading Assign
Chapter 40 of the Holt Biology
Guided Audio CD Program to help
students achieve greater success in
reading the chapter. LS Auditory
recovery. Imagine that a splinter has punctured your finger, creating an entrance for pathogens, as shown in Figure 1. Infected or
injured cells in your finger release chemicals, including histamine.
Histamine (HIHST uh meen) causes local blood vessels to dilate,
increasing blood flow to the area. Increased blood flow brings
white blood cells to the infection site, where they can attack
pathogens. This also causes swelling and redness in the infected
area. The whitish liquid, or pus, associated with some infections
contains white blood cells, dead cells, and dead pathogens.
Teaching Tip
Mosquito Bites Ask students why
they think mosquito bites turn red,
swell, and itch if a mosquito is
simply sucking up blood? (The
mosquito injects a small amount of
saliva, which contains an anticoagulant. The anticoagulant initiates the
inflammatory response, making the
bite site swell, turn red, and itch.)
Temperature response When the body begins its fight against
pathogens, body temperature increases several degrees above the
normal value of about 37°C (98.6°F). This higher temperature is
called a fever, and it is a common symptom of illness that shows the
body is responding to an infection. Fever is helpful because many
disease-causing bacteria do not grow well at high temperatures.
Although fever may slow the growth of bacteria, very high fever is
dangerous because extreme heat can destroy important cellular
proteins. Temperatures greater than 39°C (103°F) are considered
dangerous, and those greater than 41°C (105°F) can be fatal.
LS Logical
Group Activity
Figure 1 Inflammatory response
When pathogens penetrate your body, an inflammatory response is triggered.
Pathogens
White
blood cells
Capillary
1. When the skin is punctured,
pathogens enter the body.
2. Blood flow to the area increases,
causing swelling and redness.
3. White blood cells attack and
destroy the pathogens.
925
IPC Benchmark Mini-Lesson
IPC Skills TAKS 4 IPC 8A
Distinguish between physical and chemical changes
in matter.
Activity Ask students to list all the changes that take
place in the body as part of the body's nonspecific
defenses against infection. Have students make a
table with two columns and classify these changes
as physical or chemical changes.
did you know?
Symbiotic Bacteria Some of the body’s protection from pathogens comes from symbiotic
bacteria. For example, in the vagina, beneficial
bacteria inhibit the growth of harmful bacteria
and fungi. Use of antibiotics to kill pathogens
often kills the body’s beneficial bacteria as
well, which can lead to vaginal and urinary
tract infections. TAKS 3 Bio 4D; Bio 11D
GENERAL
Sequencing Lines of Defense
Work in groups of three or four.
On index cards, have each group
write the name of each defensive
protector the body has which is
considered a first line of defense.
Do the same with the second line
of defense. On the back of each
card write the function that each
particular defense has in the body.
Have the groups shuffle the cards
and then try to organize them into
first and second lines of defense.
They should check their answers in
this section, then reshuffle the
cards and try again until they get
them right several times in a row.
Next, they should turn the cards
over and try to do the same thing
with the functions of each defense.
Finally, they should use the cards
as flash cards to quiz each other on
the various components of the first
and second lines of defense and
how they function. LS Kinesthetic
Co-op Learning
TAKS 2 Bio 10A, 10B
(grade 11 only)
Transparencies
TT Bellringer
TT Inflammatory Response
Chapter 40 • The Body’s Defenses
925
Magnification: 2,280ⴛ
about 20 different proteins. Complement proteins circulate in the
blood and become active when they encounter certain pathogens.
Then some of these proteins form a membrane attack complex
(MAC), a ring-shaped structure. The MAC punches a hole in the cell
membrane, causing the cell to leak and die. Another nonspecific
defense is interferon (in tuhr FEER ahn), a protein released by cells
infected with viruses. Interferon causes nearby cells to produce an
enzyme that prevents viruses from making proteins and RNA.
Close
Reteaching
Assign students to cooperative
groups of three. Have each group
write a comic sketch or draw cartoons to show how the first line of
defense operates in protecting the
body against pathogens. (Sketches
and drawings may depict the skin
keeping out invaders, pathogens
sticking to mucous membranes,
phagocytes engulfing bacteria,
and aspects of the
inflammatory
English Language
Learners
response.)
White blood cells The most important counterattacks in the second
Figure 2 Macrophage.
Cytoplasmic extensions of this
macrophage (yellow) are capturing bacteria (blue).
Magnification: 14,250ⴛ
GENERAL
True or False:
1. The inflammatory response
targets specific pathogens.
(false; it is nonspecific)
2. Fever can be helpful because
many disease-causing bacteria
do not grow well at high temperatures. (true)
3. The first lines of nonspecific
defense help to keep pathogens
out of the body. (true)
line of nonspecific defenses are carried out by three kinds of white
blood cells: neutrophils, macrophages, and natural killer cells.
These cells patrol the bloodstream, wait within the tissues for
pathogens, and then attack the pathogens. Each kind of cell uses a
different mechanism to kill pathogens.
1. Neutrophils. A neutrophil (NOO truh fihl) is a white blood cell that
engulfs and destroys pathogens. The most abundant type of white
blood cell, neutrophils engulf bacteria and then release chemicals
that kill the bacteria—and themselves. Neutrophils can also
squeeze between cells in the walls of capillaries to attack pathogens
at the site of an infection.
TAKS 2 Bio 10A
Quiz
Proteins Various proteins also provide nonspecific defenses. One
defense mechanism, called the complement system , consists of
Figure 3 Natural killer cell.
This natural killer cell (yellow) is
attacking a cancer cell (pink).
2. Macrophages. White blood cells called macrophages (MA kroh
fay jez), shown in Figure 2, ingest and kill pathogens they
encounter. They also clear dead cells and other debris from the
body. Most macrophages travel through the body in blood,
lymph, and fluid between cells. Macrophages are concentrated
in particular organs, especially the spleen and lungs.
3. Natural killer cells. A natural killer cell is a large white blood
cell that attacks cells infected with pathogens. Natural killer cells
destroy an infected cell by puncturing its cell membrane. Water
then rushes into the infected cell, causing the cell to swell and
burst. One of the body’s best defenses against cancer, natural
killer cells can detect and kill cancer cells, as shown in Figure 3,
before a tumor can develop.
TAKS 2 Bio 10A; TAKS 3 Bio 4D; Bio 11D
Alternative
Assessment
Section 1 Review
GENERAL
Have students make up one test
question for each subsection in this
lesson. Have students supply the
answer for their questions. Then
collect all the papers with the questions and read them to students,
skipping over redundant questions.
Number the questions as you go
through them. Have each student
answer the questions on a piece of
paper as you read them. When finished, go through each question
and discuss the answers.
pp. 926–927
Student Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 10A, 10B
Teacher Edition
TAKS Obj 2 Bio 4B, 10A, 10B
TAKS Obj 3 Bio 4C, 4D
TEKS Bio 4B, 4C, 4D, 10A, 10B, 11D
926
TAKS Test Prep In the inflammatory response,
local blood vessels dilate when infected or injured
10A
cells release
A interferon.
B histamine.
C mucus.
D complement proteins.
Describe how the inflammatory and temperature
10A 10B
responses help defend against infection.
Identify the role of white blood cells in the second
line of nonspecific defenses.
10A 10B
Critical Thinking Relating Concepts
Explain why taking a drug that reduces fever
might delay rather than speed up your recovery
10A 10B
from an infection.
926
Answers to Section Review
1. The inflammatory response increases blood
flow; this brings white blood cells to an injury
site. The temperature defense raises tissue temperature; this kills or inhibits some pathogens.
TAKS 2 Bio 10A; TAKS 2 Bio 10B (grade 11 only)
4.
A. Incorrect. Interferon causes
cells to make an enzyme that prevents viruses
from making proteins and RNA. B. Correct.
Histamine increases blood flow; this brings
white blood cells to the infected area, where
they can attack pathogens. C. Incorrect.
Mucus does not cause blood vessels to dilate.
D. Incorrect. Complement proteins move in
the blood and are activated by pathogens.
2. Neutrophils engulf pathogens. Macrophages
ingest and kill them and rid the body of dead
cells. Natural killer cells puncture membranes
of infected cells. TAKS 2 Bio 10A; TAKS 2 Bio 10B (grade 11 only)
TAKS 2 Bio 10A
3. The drug inhibits the temperature response.
Reducing body temperature may allow
pathogens to thrive. TAKS 2 Bio 10A; TAKS 2 Bio 10B (grade 11 only)
Chapter 40 • The Body’s Defenses
Immune Response
Section 2
Section 2
Focus
Specific Defenses
Objectives
Overview
What happens when pathogens occasionally overwhelm your body’s
nonspecific defenses? Pathogens that have survived the first and second lines of nonspecific defenses still face a third line of specific
defenses—the immune response. The immune response consists of
an army of individual cells that rush throughout the body to combat
specific invading pathogens. The immune response is not localized
in the body, nor is it controlled by a single organ. It is more difficult
to evade than the nonspecific defenses.
● List four kinds of immunesystem cells, and describe
their functions.
10A TAKS 2
Cells Involved in the Immune Response
● Compare the role of T cells
with that of B cells in the
immune response.
10A
White blood cells are produced in bone marrow and circulate in
blood and lymph. Of the 100 trillion or so cells in your body, about
2 trillion are white blood cells. Four main kinds of white blood cells
participate in the immune response: macrophages, cytotoxic T
cells, B cells, and helper T cells. Each kind of cell has a different
function. Macrophages consume pathogens and infected cells.
Cytotoxic (sie toh TAHKS ihk) T cells attack and kill infected cells.
B cells label invaders for later destruction by macrophages.
Helper T cells activate both cytotoxic T cells and B cells. Macrophages
can attack any pathogen. B cells and T cells, however, respond only to
pathogens for which they have a genetically programmed match.
These four kinds of white blood cells interact to remove pathogens
from the body.
Recognizing Invaders
To understand how the third line of defenses works,
imagine that you have just come down with
influenza—the flu. You have inhaled influenza virus
particles, but they were not all trapped by mucus in
the respiratory tract. The virus has begun to infect
and kill your cells. At this point, macrophages begin
to engulf and destroy the virus.
An infected body cell will display antigens of an
invader on its surface. An antigen (AN tih jihn) is a
substance that triggers an immune response. Antigens typically include proteins and other parts of
viruses or pathogen cells. Antigens are present on the
surface of the infected body cell. White blood cells of
the immune system are covered with receptor proteins that respond to infection by binding to specific
antigens on the surfaces of the infecting microbes.
These receptors recognize and bind to antigens that
match their particular shape, as shown in Figure 4.
● Describe how white
blood cells recognize
pathogens.
10A 10B TAKS 2
● Identify the role of helper
T cells in the immune
response.
10A TAKS 2
TAKS 2
Key Terms
• Lesson Plan GENERAL
• Directed Reading
• Active Reading GENERAL
Planner CD-ROM
• Reading Organizers
• Reading Strategies
Bellringer
Show the class an artist’s rendering
of viruses bursting out of an infected
cell. Ask students what they think is
happening in the picture. (Ideas will
vary, but some students should identify the cell and the many particles
spilling out of it.) Discuss student
ideas, and then point out the
infected cell and viruses. Explain
that viruses must infect other cells
to reproduce. LS Verbal TAKS 3 Bio 4C
cytotoxic T cell
B cell
helper T cell
antigen
plasma cell
antibody
Antigens
Virus
Motivate
Demonstration
Receptor
proteins
Cytotoxic T cell
Figure 4 Antigens. Some cells of the
immune system have receptor proteins that
bind to specific antigens.
927
Chapter Resource File
Before beginning this section
review with your students the
objectives listed in the Student
Edition. This section introduces
students to the body’s third line of
defense, the immune response.
Students will learn that in order to
destroy pathogens, the third line of
defense must be able to recognize
an invader as foreign.
INCLUSION
Strategies
• Attention Deficit Disorder • Gifted and Talented
White blood cells attack particles that
invade the body that can cause diseases or
infections. Have students diagram the way a
white blood cell would eliminate pathogens
that invade the body. Also, have the students
call a local clinic to determine how white
blood cell counts are used to identify different kinds of infections. Students may present
their findings to the class in an oral or a tape
recorded report. TAKS 2 Bio 4B, 10A
GENERAL
To show that microorganisms are
ubiquitous, gather five sterile Petri
dishes filled with sterile nutrient
agar. Collect microorganisms from
five different areas in the room by
sweeping them with sterile swabs
moistened with sterile distilled
water. Label each dish and place all
five upside down in a warm, dark
place or in an incubator for several
days. At the end of this period,
show students the colonies of
microorganisms that have grown
on the agar. Explain that most of
the microorganisms in the dishes
probably are harmless but that
some may be pathogens. Dispose
of swabs and Petri dishes after
sterilizing them in an autoclave or
soaking them for 30 minutes in
chlorine bleach. LS Visual
TAKS 3 Bio 4D; Bio 11D
Transparencies
TT Bellringer
TT Immune Response
Chapter 40 • The Body’s Defenses
927
The Immune Response Has Two Main Parts
Two distinct processes work together in an immune response. One
is the B cell response, a defense that aids the removal of extracellular pathogens from the body. The other is the T cell response,
a defense that involves the destruction of intracellular pathogens by
cytotoxic T cells. Both the T cell response and the B cell response
are regulated by helper T cells. Both responses, which happen
simultaneously, are summarized in Figure 5.
Teach
Teaching Tip
GENERAL
Immune Cells Have students create a Graphic Organizer similar to
the one at the bottom of this page.
Along the top of the table they
should list the following categories:
Type of cell, Function, and
Location in the body. In the first
column, they should list all the
types of cells that play a role in
the body’s defenses. (macrophage,
neutrophil, natural killer cell, helper
T cell, cytotoxic T cell, B cell, plasma
cell, and memory cell) Then ask students to complete the information
in the second and third columns.
IO
B
graphic
Figure 5
Immune Response
The immune response involves several kinds of white blood cells.
2
1
A virus infects body cells, which
display the viral antigen.
Virus
Viral
antigen
Viral
antigen
LS Visual TAKS 2 Bio 10A; Bio 3E
Using the Figure
Once you have discussed Figure 5,
have students answer the following
questions: What types of white
blood cells are involved in the
immune response? (helper T, cytotoxic T, and B cells) What type of
cell is involved in a passive,
humoral defense? (B cell) What
type of cell is active and destroys
pathogens? (cytotoxic T cell) What
is the role of helper T cells? (They
regulate the T- and B-cell actions.)
Receptor
proteins
Cytotoxic
T cell
Macrophage
Helper
T cell
4
3
Virus-containing macrophages
activate helper T cells.
B cell
Helper T cells activate
cytotoxic T cells
and B cells.
Plasma
cell
8
5
B cells form
plasma cells.
Cytotoxic T cells destroy
infected body cells.
6
Infected
body cell
LS Verbal TAKS 2 Bio 10A
Plasma cells release antibodies,
which bind to the viral antigen.
7
IPC Benchmark
Fact
Explain to students that when antibodies bind to antigens, a chemical change
occurs due to a chemical reaction
between the two biological molecules.
As a result of this chemical change, the
invading antigen is altered so as to
incapacitate it or ultimately make it
more susceptible to destruction or elimination by the body’s immune system.
TAKS 4 IPC 8A
Macrophages engulf the
virus and display the
viral antigens.
The binding of antibodies cause
viruses to stick together, thus they
are marked for destruction.
Key
Antibodies
Viral antigen
Antibody
Receptor
protein
Virus
928
Graphic Organizer
Use this graphic organizer with Teaching Tip on this page.
Type of cell
pp. 928–929
Student Edition
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TAKS Obj 3 Bio 4C
TEKS Bio 4C, 10A, 10B
Teacher Edition
TAKS Obj 2 Bio 4B, 10A, 10B
TAKS Obj 4 IPC 8A
TEKS Bio 3E, 4B, 10A, 10B, 11A
928
Function
Location in the body
Macrophage
Neutrophil
Natural killer cell
Helper T cell
Cytotoxic T cell
B cell
Ingests and kills pathogens
Engulfs and destroys pathogens
Punctures infected cells
Activates cytotoxic T and B cells
Punctures infected cells
Labels invaders for destruction
by macrophages
Spleen, lungs, blood, lymph, interstitial fluids
Bloodstream, infection sites
Infected cells
Bloodstream, infection sites
Infection sites
Infection sites
Plasma cell
Memory cell
Releases antibodies
Protects against defeated pathogens
Bloodstream
Bloodstream
Chapter 40 • The Body’s Defenses
Step
When a virus infects body cells, the infected cells display
the viral antigen on their surfaces.
Step
Macrophages engulf the virus and display the viral antigens
on their surfaces.
Step
Receptor proteins on helper T cells bind to the viral antigen
displayed by the macrophages. The macrophages release a
protein called interleukin-1 (ihn tuhr LOO kihn).
Step
Interleukin-1 activates helper T cells, but helper T cells do
not attack pathogens directly. Instead, helper T cells activate
cytotoxic T cells and B cells. Stimulation by interleukin-1
causes helper T cells to release interleukin-2. Interleukin-2
stimulates further division of helper T cells and cytotoxic T
cells, amplifying the body’s response to the infection.
Step
Interleukin-2 released by helper T cells also activates B cells.
Activated B cells divide and develop into plasma cells.
Plasma cells are cells that release Y-shaped antibodies
into the blood. An antibody is a defensive protein produced
upon exposure to a specific antigen, which can bind to
that antigen.
Step
Real Life
How often do you wash
your hands?
Hand washing is an effective way to prevent the
spread of disease. A
recent study found that
only 68 percent of adults
wash their hands after
using public restrooms.
Inferring Relationships
Why is it crucial that food
preparers wash their
hands after using
a restroom?
The binding of antibodies cause viruses and antigens to
stick together, forming clumps that can be easily identified
and destroyed by macrophages.
Step
Activated cytotoxic T cells destroy infected cells by puncturing their cell membranes. Your body makes millions of
different T cells, each with receptor proteins that bind to a
specific antigen. Receptor proteins on cytotoxic T cells
bind to the viral antigen displayed by infected cells. For
example, any of your body’s cells that bear traces of an
influenza virus will be destroyed by cytotoxic T cells with
receptor proteins that bind to the antigen of that virus.
Close
Reteaching
Reading Effectively
Antigens trigger an immune
response. Remember that
an antigen is an antibodygenerating substance.
List the different kinds of white blood cells
Critical Thinking Predicting Outcomes
involved in the immune response.
How would an enzyme that destroys interleukins
10A 10B
affect the immune response?
10A 10B
Describe how white blood cells recognize and
10A 10B
bind to pathogens.
Compare the roles of B cells and T cells in the
10A
TAKS Test
Test Prep
Prep Which cells produce antibodTAKS
ies and release them into the blood?
10A 10B
A cytotoxic T cells
C plasma cells
B helper T cells
D macrophages
Recognizing Relationships Explain the role of
helper T cells in the immune response.
Answers to Section Review
Have students review the function
of T cells in the immune response.
Have them make index cards with
sequential words and drawings
depicting T-cell function. Have students pair off. One student should
shuffle the cards, and the other
student should put them in the
correct order. Students should then
switch roles.
English Language
LS Interpersonal
Learners
TAKS 2 Bio 4B, 10A
Quiz
Section 2 Review
immune response.
Negative Feedback Interleuken-2
released by helper T cells stimulates the division of another type of
T cell, the suppressor T cell. These
cells divide slowly and become
common a week or more after
infection. They gradually shut down
the immune response by inhibiting
the production of B cells and cytotoxic T cells. Ask students what
kind of feedback system this would
be. (a negative feedback system)
LS Logical TAKS 2 Bio 4B; Bio 11A
Plasma cells divide repeatedly and make large numbers of
antibodies. Plasma cells release antibodies into the bloodstream where they attach to the viruses. Antibodies bind
to the viral antigen and mark the virus for destruction.
Step
Teaching Tip
10A
GENERAL
True or False:
1. The immune response of the
body is a defense that is nonspecific. (false; it is specific)
2. Antigens trigger the immune
response. (true)
3. Plasma cells make antibodies.
(true)
TAKS 2 Bio 10A
929
Alternative
Assessment
GENERAL
1. macrophages, cytotoxic T cells, B cells, helper
release of interleukin-1 by macrophages.
Make copies of Figure 5, but withT cells TAKS 2 Bio 10A, Bio 10B (grade 11 only)
Helper T cells also activate B cells and cytoout the explanations at each step.
toxic T cells. TAKS 2 Bio 10A
2. White blood cells recognize invaders because
Have students, without using their
infected cells display surface antigens. White
5. Destroying interleukens would short-circuit the
book, fill in the explanations of
blood cells have receptors that bind to these
immune response.
what is happening at each of the
antigens. TAKS 2 Bio 10A, Bio 10B (grade 11 only)
TAKS 2 Bio 10A, Bio 10B (grade 11 only)
eight steps. LS Visual Bio 3E
3. B cells become plasma cells that release anti6.
A. Incorrect. Cytotoxic T cells
bodies that bind to antigens to mark them for
are white blood cells that attack and kill
destruction by macrophages. T cells are stimuinfected cells. B. Incorrect. Helper T cells
lated by interleuken-1 to produce interleuken-2,
function to activate both cytotoxic T cells
which activates helper T cells and cytotoxic T
and B cells. C. Correct. Plasma cells release
cells that puncture cell membranes. TAKS 2 Bio 10A
specialized, Y-shaped proteins called antibodies into the blood. D. Incorrect. Macrophages
4. Helper T cells bind to viral antigens on
ingest and kill pathogens. TAKS 2 Bio 10A, Bio 10B (grade 11 only)
macrophage surfaces, which stimulates the
Chapter 40 • The Body’s Defenses
929
Section 3
Disease Transmission
and Prevention
Section 3
Focus
Overview
Before beginning this section
review with your students the
objectives listed in the Student
Edition. This section introduces
students to the modes in which
diseases are transmitted and how
transmission can be prevented.
Students will also delve into the history of pathology and immunology.
Bellringer
Have students make a list of all the
infections they have had. (Lists will
include such things as colds,
influenza, infected cuts or scrapes,
chicken pox, etc.) For those who
have had chicken pox, ask them if
they have had it more than once.
(Except in rare situations, most will
answer “no.”) Tell students they
can develop immunity to certain
diseases and this will be discussed
in this section. TAKS 3 Bio 4C, 4D
Motivate
Identifying
Preconceptions
GENERAL
Make photocopies or a transparency of a vaccination record.
Give students the copies of the
vaccination record. Ask students
why it is important to maintain
such records. (If vaccinations are not
kept up-to-date, a person is at risk of
contracting a disease.) Ask students
if they know about other less common vaccinations such as those
that protect against typhoid fever,
yellow fever, and so on. (Answers
will vary.) LS Intrapersonal
● List five ways diseases
can be transmitted to
humans.
4C 4D TAKS 3
● Summarize Koch’s
postulates for identifying
pathogens.
3F 4C 4D TAKS 3
● Analyze how the body
produces immunity to
pathogens.
4C 4D TAKS 3
● Describe how vaccines
produce immunity to
pathogens.
4C 4D TAKS 3
Key Terms
Koch’s postulates
immunity
vaccination
vaccine
antigen shifting
Figure 6 Disease
transmission. When a
person sneezes, pathogens
are expelled from the mouth
and nose.
In general, you can get infectious diseases in any of five different
ways: through person-to-person contact, air, food, water, and animal
bites. Diseases transferred from person to person are considered
contagious, or communicable. For example, when a person sneezes,
droplets of saliva and mucus carrying pathogens are expelled from
the mouth and nose, as shown in Figure 6. If another person
breathes these droplets, the pathogens can infect that person. People directly transmit some diseases by kissing, shaking hands,
touching sores, or having sexual contact. People can also transmit
diseases indirectly through objects contaminated with pathogens,
such as drinking glasses, toys, plumbing, and needles used to inject
drugs or in tatooing.
By minimizing exposure to pathogens, you can decrease your
chances of becoming ill. For example, to prevent illnesses caused by
bacteria found in foods that contain animal products, these foods
should always be cooked thoroughly. Utensils and other surfaces
that foods touch should be sanitized.
Detecting Disease
The German physician Robert Koch (1843–1910) established a
procedure for diagnosing causes of infection. Koch determined that
bacteria cause anthrax, a disease that afflicts cattle, sheep, goats,
and humans. Anthrax is a serious disease although it is not passed
from person to person. In an experiment, Koch isolated bacteria
from a cow with anthrax and then infected a healthy cow with the
bacteria. The healthy cow developed anthrax and had the same bacteria that the first cow had. In his research, Koch developed the
following four-step procedure, known as Koch’s postulates , as a
guide for identifying specific pathogens.
1. The pathogen must be found in an animal with the
disease and not in a healthy animal.
2. The pathogen must be isolated from the sick animal
and grown in a laboratory culture.
3. When the isolated pathogen is injected into a healthy
animal, the animal must develop the disease.
4. The pathogen should be taken from the second
animal and grown in a laboratory culture. The cultured pathogen should be the same as the original
pathogen.
930
Chapter Resource File
TAKS 3 Bio 4C, 4D
pp. 930–931
Student Edition
TAKS Obj 2 Bio 10A
TAKS Obj 3 Bio 4C
TAKS Obj 3 Bio 4D
TEKS Bio 3F, 4C, 4D, 10A
Teacher Edition
TAKS Obj 3 Bio 4C, 4D
TEKS Bio 3E, 4C, 4D
930
Disease Transmission
Objectives
• Lesson Plan GENERAL
• Directed Reading
• Active Reading GENERAL
• Data Sheet for Quick Lab
TT Bellringer
TT Primary and Secondary Immune
Responses
GENERAL
Planner CD-ROM
• Reading Organizers
• Reading Strategies
Chapter 40 • The Body’s Defenses
Transparencies
Long-Term Protection
Antibody concentration
The specific immune response is very
Primary and Secondary Immune Responses
powerful, and it can be a long-lasting
defense. After an immune response,
some B cells and T cells become
Subsequent
memory cells that continue to patrol
exposure
to same
your body’s tissues. Some memory
First exposure
Secondary
pathogen
cells provide lifelong protection
to pathogen
immune
response
against previously encountered
pathogens. If a pathogen ever appears
Primary
again, memory cells activate antibody
immune
production against that pathogen. As
response
shown in Figure 7, a second exposure
Time
to the same pathogen causes a sharp
increase in antibody concentration.
This enables macrophages to destroy
Figure 7 Immune
responses. The first time you
the pathogen before you become ill. You are said to be “immune,” or
are exposed to a pathogen,
resistant, to the disease caused by that pathogen.
Resistance to Disease
Resistance to a particular disease is called immunity . It has long
been observed that individuals who recover from an infectious disease develop an immunity to that disease. This knowledge preceded
the development of immunology, a branch of science that deals
with antigens, antibodies, and immunity. Immunologists study the
body’s defenses and ways to help protect against disease.
In 1796, an English doctor named Edward Jenner performed an
experiment that marks the beginning of immunology. Smallpox,
which is caused by a virus, was a common and deadly disease then.
Jenner observed that milkmaids who had contracted cowpox, a
mild form of smallpox, rarely became infected with smallpox. Jenner
hypothesized that cowpox produced protection against smallpox.
To test his hypothesis, Jenner infected healthy people with cowpox.
As Jenner had predicted, many of the people he infected never
developed smallpox, even though they had been exposed to the
virus. We now know that smallpox and cowpox are caused by two
similar viruses. The cowpox infection caused an immune response
that later prevented smallpox infection in Jenner’s patients.
your immune system responds
normally. If you become
exposed to the same
pathogen again, antibody
production increases quickly.
READING
SKILL
BUILDER
Paired Summarizing Pair each
student with a partner. Have each
student read Section 3 silently
while making notes on a piece of
paper. Have students write down
and put a question mark next to
anything he or she does not clearly
understand. After they finish reading, ask one student to summarize
and the second to add anything
omitted. Both readers should then
help each other with any passages
that either (or both) did not understand. Have them create a list
of questions to ask the class.
Discuss each group’s questions
as a class. English Language
LS Verbal
SKILL
Learners
BUILDER
GENERAL
Interpreting Visuals Have students examine Figure 7. Ask them
why the second peak in the line is
so much higher than the first peak.
(Memory cells in the body recognize
the pathogen when it invades a
second time, and they immediately
produce a massive amount of antibodies to destroy the pathogen.)
A person is not even aware of this
tremendous immune response in
the body. LS Visual Bio 3E
Vaccination Jenner’s procedure of injecting the cowpox virus to
produce resistance to smallpox is called vaccination. Vaccination
(vak sih NAY shuhn) is a medical procedure used to produce immunity. You have probably been to the doctor for vaccination to guard
against various diseases. Modern vaccination usually involves an
injection, or “shot,” of a vaccine under the skin. A vaccine (vak
SEEN) is a solution that contains a dead or modified pathogen that
can no longer cause disease.
A vaccine triggers an immune response against the pathogen
without symptoms of infection. For several days after you are
vaccinated, your immune system develops antibodies and memory
Activity
931
Disease Warfare In September 2001, a deadly
strain of bacterial spores (Bacillus anthracis)
was sent by mail to several U.S. locations.
Twenty-two confirmed or suspected cases of
anthrax infection resulted. Five persons died.
The B. anthracis spores were sent in at least 5
letters to Florida, New York City, and
Washington, D.C. Because of these deadly
attacks, the U.S. government stepped up its
efforts to produce new anthrax vaccine. One of
the first cases of the modern use of biological
weapons in the United States occurred in 1984.
Teach
About 3,000 followers of an Indian guru named
Bhagwan Shri Rashneesh settled near the north
central Oregon town of The Dalles. Attempting
to take over the county government, the
Bhagwan’s followers cultured salmonella bacteria and secretly sprinkled it on restaurant salad
bars, doorknobs, and other common locations,
hoping to sicken enough people so they could
not vote in the local election. In all, 751 people
became ill, but the election was not compromised. Some of the Bhagwan’s followers were
prosecuted and jailed. TAKS 3 Bio 4D
Mutating Viruses Changes in the
surface proteins of many viruses,
such as cold and influenza, can
allow them to re-infect individuals
many times. Ask students how this
can be so. (The mutations prevent
the immune system from recognizing
the virus as one that is has encountered before, so they are not able to
immediately destroy the virus.) Have
students create an illustration,
model, or computer animation
illustrating their answer. Students
may want to also include information about why it may be difficult
to create a vaccine for a mutating
virus. LS Kinesthetic TAKS 3 Bio 4C
Chapter 40 • The Body’s Defenses
931
cells against the pathogen. You develop a long-lasting immunity to
the disease. In 1977, smallpox became the first infectious disease to
be eradicated from the public by vaccination. Vaccination has also
reduced the incidence of many other diseases, including measles,
polio, tetanus, and diphtheria.
Real Life
Simulating Antigen
Activity
TAKS 1 Bio/IPC 1A, 2A, 2C; TAKS 2 Bio 10A
Skills Acquired
Inferring, predicting
Teacher’s Notes
Before the lab, review
antigens and antibodies.
Flu can be deadly.
In 1918, an influenza (flu)
epidemic killed more than
20 million people. To prevent this from happening
again, scientists track the
antigen shifting of flu
viruses and target the new
viral antigens for vaccines.
Antigen shifting You can get the flu even if you have already been
infected or vaccinated. Influenza viruses constantly mutate over
time. The viruses produce new antigens that your immune system
does not recognize, a process known as antigen shifting. With subsequent exposure to the virus, your body must make new antibodies.
Answers to Analysis
1. AB
2. Antibodies are bound to
antigens.
3. Type A would clot only with
anti-A serum. Type B would
clot only with anti-B serum.
Simulating Antigen Activity
Using simulated blood, you can see what happens
when antigens encounter specific antibodies.
Materials
TAKS 1, TAKS 2
safety goggles, disposable gloves, lab apron, 2 blood-typing
trays, simulated blood (types AB and O), simulated anti-A and
anti-B blood-typing serums, 4 toothpicks
Procedure
Close
1.
Reteaching
Invite a health professional to
speak to the class about disease
transmission and prevention. Have
students write questions to ask the
speaker. LS Auditory
TAKS 3 Bio 4C, 4D; Bio 11D
Quiz
GENERAL
True or False:
1. Hand-washing after using the
restroom is an important way to
stop the spread of disease. (true)
2. Vaccination can “trick” the
body into producing an immune
response. (true)
Bio 11C
Put on
safety
goggles, disposable gloves,
and a lab apron.
2. Place 3–4 drops of type AB
simulated blood into each well
in a clean blood-typing tray.
CAUTION: Use only simulated blood provided by
your teacher.
3. Add 3–4 drops of anti-A
blood-typing serum to one
well. Stir the mixture for
30 seconds using a
toothpick. Add 3–4 drops of
anti-B blood-typing serum to
the other well. Use a new
toothpick to stir the mixture.
Look for clumps separating
from the mixtures.
4. Repeat steps 2 and 3 using
simulated type O blood.
5.
Dispose of
your materials
according to your teacher’s
directions. Clean up your work
area and wash your hands.
Analysis
1. Determine which blood
type has antigens that are
recognized by the bloodtyping sera.
2. Evaluating Results What
does clumping of the blood
mixtures indicate?
3. Predicting Outcomes
What would happen if you
did the same experiment
using type A blood and
type B blood?
Section 3 Review
List two ways that diseases can be transmitted
Critical Thinking Relating Concepts Explain
between people.
why you cannot get many diseases more
4C 4D
than once.
4C 4D
Summarize Koch’s postulates for identifying
specific pathogens.
3F 4C 4D
Describe how vaccination produces immunity.
4C 4D
TAKS Test Prep Smallpox is caused by a
C fungus.
D protist.
4C
A virus.
B bacterium.
932
pp. 932–933
Student Edition
TAKS Obj 1 Bio/IPC 1A, 2A, 2C
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TAKS Obj 3 Bio 4C
TAKS Obj 3 Bio 4D
TEKS Bio 3F, 4C, 4D, 10A, 10B, 11B
TEKS Bio/IPC 1A, 2A, 2C
Teacher Edition
TAKS Obj 1 Bio/IPC 1A, 2A, 2C, 2D
TAKS Obj 2 Bio 10A
TAKS Obj 3 Bio 4C, 4D
TEKS Bio 3F, 4C, 4D, 10A, 11A, 11B,
11C, 11D
TEKS Bio/IPC 1A, 2A, 2C, 2D
932
Answers to Section Review
1. Answers might include kissing, shaking hands,
sharing eating utensils, engaging in sexual
activity, and so on. TAKS 3 Bio 4C, 4D
2. The pathogen is found in sick, but not in
healthy, animals. The pathogen can be isolated
and grown in the laboratory. Injection of the
pathogen into a healthy animal causes the disease. The pathogen isolated from the second
animal is the same as the one isolated from the
first animal. TAKS 3 Bio 4C, 4D; Bio 3F
3. Vaccination induces the immune system to
develop antibodies and memory cells for a
specific pathogen. TAKS 3 Bio 4C, 4D
Chapter 40 • The Body’s Defenses
4. Memory cells immediately recognize the
pathogen, and the immune system mounts
a response, quickly eliminating the pathogen.
TAKS 3 Bio 4C, 4D
5.
A. Correct. The once-deadly
disease is caused by a virus. B. Incorrect.
Bacteria, unlike smallpox, are cellular organisms. C. Incorrect. A fungus is a cellular
organism. Smallpox, a virus, is not made of
cells. D. Incorrect. Protists are single-celled
eukaryotes. Viruses are not made of cells.
TAKS 3 Bio 4C
Disorders of the
Immune System
Section 4
Section 4
Focus
Overview
Autoimmune Diseases
Objectives
The ability of your immune system to distinguish cells and antigens
of your body from foreign cells and antigens is crucial to the fight
against pathogens. In some people, the immune system cannot distinguish between the body’s antigens and foreign antigens, causing
an autoimmune disease. In an autoimmune disease , the body
launches an immune response against its own cells, attacking body
cells as if they were pathogens. The immune system cannot distinguish between antigens of “self” and “nonself.” This effect may be
caused by the inappropriate production of antibodies specific to the
antigens of body cells.
Autoimmune diseases affect organs and tissues in various areas of
the body. For example, multiple sclerosis (skleh ROH sihs) usually
strikes people between the ages of 20 and 40. Multiple sclerosis (MS)
is generally thought to be an auto-immune disease. In people with
multiple sclerosis, the immune system attacks and gradually destroys
insulating material surrounding nerve cells in the brain, in the spinal
cord, and in the nerves leading from the eyes to the brain. This
impairs and may eventually stop the functioning of these nerve cells.
Multiple sclerosis causes problems with vision, speech, and coordination. Table 1 lists and describes several autoimmune diseases.
● Describe several autoimmune diseases.
10A
TAKS 2
● Summarize how HIV
disables the immune
system.
4C 10A TAKS 2
● List five ways HIV is
transmitted.
4C 10A TAKS 2
● Identify causes of an
allergic reaction.
11B
Key Terms
autoimmune disease
AIDS
HIV
CD4
allergy
Table 1 Autoimmune Diseases
Disease
Areas affected
Symptoms
Graves’ disease
Thyroid gland
Weakness, irritability, heat intolerance, increased
sweating, weight loss, insomnia
Multiple
sclerosis (MS)
Nervous system
Weakness, loss of coordination,
problems with vision and speech
Joints
Severe pain, fatigue, disabling
inflammation of joints
Rheumatoid
arthritis
TAKS 1 Bio/IPC 2D
Activity
Connective tissue,
joints, kidneys
Facial skin rash, painful joints, fever,
fatigue, kidney problems, weight loss
Type I diabetes
Insulin-producing
cells in pancreas
Increased blood glucose level, excessive urine
production, problems with vision, weight loss,
fatigue, irritability
933
• Lesson Plan GENERAL
• Directed Reading
• Active Reading GENERAL
• Data Sheet for Data Lab
GENERAL
Bellringer
Have students make a list of all the
organs they can think of that have
been transplanted from one person
to another. (Answers may include
such organs as skin, heart, kidneys,
and lungs.) Ask them why some
transplants fail even though the
surgery was technically a success.
(Some students should mention
organ rejection, which can lead to a
discussion of immunosuppressant
drugs and their effectiveness.)
Motivate
Systemic lupus
erythematosus (SLE)
Chapter Resource File
Before beginning this section
review with your students the
objectives listed in the Student
Edition. This section introduces
students to disorders of the
immune system. It also describes
situations in which the body’s
immune system launches an attack
on its own cells, including how the
human immunodeficiency virus
(HIV) affects the immune system,
and what causes allergic reactions.
Planner CD-ROM
• Reading Organizers
• Reading Strategies
• Supplemental Reading Guide
Microbe Hunters
GENERAL
Immune System Disorders Have
students work in groups to list as
many allergies and disorders of the
immune system as they can think
of. Students should rank them on a
scale of 1–10, from most critical to
the least critical. (Example, hay
fever might be ranked as an 8,
whereas a food allergy may be a 1
or 2.) Have each group share its
list and discuss why different
groups have different rankings of
different allergies. LS Interpersonal
Co-op Learning
Bio 11A, 11B
Transparencies
TT Bellringer
TT Autoimmune Diseases
TT Number of Helper T Cells Following
HIV Infection
Chapter 40 • The Body’s Defenses
933
HIV Infection
Teach
Teaching Tip
Figure 8 HIV. Small HIV
particles (purple) surround a
helper T cell (orange).
Antibodies to HIV can be detected in blood. Someone whose blood
contains antibodies to HIV is said to be HIV positive. A diagnosis
of AIDS may be made based on several criteria, including a helper
T cell count less than 200 cells/mL of blood. Figure 9 shows how
the number of helper T cells may decline over time in an HIVpositive person.
The time between HIV infection and the onset of AIDS can exceed
10 years, and this time period is increasing as new treatments for
HIV infection are developed. A person with HIV may feel and appear
healthy but can infect other people. In the United States, the number
of deaths caused by AIDS has dropped from more than 51,000 in
1995 to about 38,000 in 1996, and to about 22,000 in 1997. This
decrease does not reflect a decline in HIV infection, but rather more
effective drug therapies, which postpone onset of the disease.
Bio 11A
Using the Figure
GENERAL
Have students study the graph in
Figure 9. Ask them what happens
to the number of helper T cells per
milliliter of blood over time following an HIV infection. (The number
of helper T cells decreases.) Ask students why this happens. (HIV infects
helper T cells and kills them.) Ask
students how the number of helper
T cells per milliliter of blood relates
to AIDS. (When the number falls
below 200 helper T cells per milliliter
of blood, AIDS is diagnosed.)
Testing for HIV
Figure 9 Onset of AIDS.
The graph at right shows
the decline over time in the
number of helper T cells in a
person infected with HIV.
LS Visual TAKS 3 Bio 4C; Bio 11A, 11D
Number of Helper T Cells Following HIV Infection
Number of helper T cells
(per mL of blood)
Organ Rejection Drugs such as
cyclosporine and corticosteroids,
which are immunosuppressants, are
given to recipients of organ transplants. Have students hypothesize
as to why this is necessary and what
precautions transplant recipients
must take. (Immunosuppressive therapy reduces the recipient’s immune
response to antigens found in the
transplanted organ.) Have students
explain why transplant patients are
more likely than others to develop
cancer. (One of the functions of the
immune system is to destroy cancer
cells before they spread.) LS Verbal
Before 1981, AIDS , or acquired immunodeficiency syndrome, was
unknown. Between 1981 and 2001, more than 460,000 Americans
died of AIDS, and since then the total number of AIDS cases
reported in the United States has increased to more than 810,000.
AIDS is a disease caused by HIV , or the human immunodeficiency
virus. Many scientists think HIV evolved from a virus similar to one that infects nonhuman primates in Africa. A
mutation enables HIV to recognize a receptor protein called
CD4 on some human cells. HIV, shown in Figure 8, enters
white blood cells by binding to CD4. HIV usually invades
helper T cells, which begin to produce HIV soon after infection. As helper T cells die, the immune system gradually
weakens and becomes overwhelmed by pathogens that it
would normally detect and destroy. The body becomes susceptible to other diseases, called opportunistic infections,
that generally cause illness only in people with weakened
immune systems.
900
800
700
600
500
400
300
200
100
0
1
Infection
2
3
4
5
6
7
Time since infection (years)
934
Cultural
Awareness
pp. 934–935
Student Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 10A, 10B
Teacher Edition
TAKS Obj 1 Bio/IPC 2C, 2D
TAKS Obj 3 Bio 4C
TAKS Obj 4 IPC 8A
TEKS Bio 4C, 3F, 11A, 11C, 11D
TEKS Bio/IPC 2C, 2D, 3C
TEKS IPC 8A
934
Sir Frank Macfarlane Burnet Sir Frank
Macfarlane Burnet was an Australian scientist who discovered and described acquired
immunological tolerance to transplanted
tissues. He also developed techniques of virus
culture in chick embryos, which have become
standard laboratory practice. Sir Macfarlane
Burnet was elected to the Royal Society in
Chapter 40 • The Body’s Defenses
1942, received the Order of Merit in 1958,
and was awarded the Nobel Prize for
medicine in 1960. His book, Natural History
of Infectious Disease, which was co-authored
with David O. White, was published by
Cambridge University Press in 1972.
Bio/IPC 3C; Bio 3F
Transmission of HIV
You can become infected with HIV if you come in contact with
body fluids—including the blood—of an infected person. The most
common method of HIV transmission is through sexual contact.
Use of a latex condom during sexual contact reduces but does not
eliminate the risk of getting or spreading HIV. Many people infected
with HIV do not know they are infected. The only sure way to prevent HIV infection is through abstinence (the conscious decision to
refrain from sexual activity).
HIV can be passed between drug users who share a hypodermic
needle because HIV-infected blood often remains in the needle or
syringe. Several years ago, many people became infected with HIV
after receiving transfusions of HIV-contaminated blood. This is
very unlikely now because blood made available for transfusion is
tested for HIV. In addition, pregnant or nursing mothers can pass
HIV to their infants through blood and breast milk.
HIV is not transmitted through the air, on toilet seats, by kissing or
handshaking, or by any other medium where HIV-infected white
blood cells could not survive. Although HIV has been found in saliva,
tears, and urine, these body fluids usually contain too few HIV particles to cause an infection. Mosquitoes and ticks do not transmit
HIV because they do not carry HIV-infected white blood cells.
www.scilinks.org
Topic: HIV Transmission
Keyword: HX4098
0100010110
011101010
0010010001001
1100100100010
0000101001001
1101010100100
0101010010010
SKILL
TAKS 1
AIDS Cases in the United States, 1996-2001
Analysis
3. Evaluating Data The graph
indicates that the number of
new AIDS cases reported each
year has decreased since
1996. Suggest a possible
reason for this decline.
(adults and adolescents)
Number of cases (thousands)
2. Inferring Relationships
Is the number of Americans
infected with HIV most likely
greater than or less than the
number of people with AIDS?
Explain why.
Cumulative cases
New cases
Deaths
BUILDER
GENERAL
Math Skills Ask students why
HIV keeps spreading in the population even though there is much
information about how to prevent
it from spreading. (Many people are
infected with HIV and do not know
it, so they continue to spread the disease.) If one person infected 5 other
people in Year One and then died,
and each of those infected 5 people
in one year, and then died (and so
on), how many people would be
infected after just 10 years? (Year
One: 5 infected; Year 2: 25; Year 3:
125; Year 4: 625; Year 5: 3,125;
Year 6: 15,625; Year 7: 78,125; Year
8: 390,625; Year 9: 1,953,125; Year
10: 9,765,625 infected!) LS Logical
The graph below shows the total AIDS cases reported in the
United States between 1996 and 2001. Use the graph to answer
the following questions:
1. Describe how the number of
people with AIDS has changed
since 1996.
Invite a healthcare professional to
give a presentation to the class
about how HIV is transmitted and
the best ways to protect yourself
from transmission. Encourage
students to take notes throughout
the presentation. Afterwards, have
students make an outline of the
main points made by the speaker.
LS Auditory TAKS 3 Bio 4C
Tracking the Spread of AIDS
Background
Demonstration
400
350
Bio 11C
300
250
200
The Spread of
AIDS
150
TAKS 1 Bio/IPC 2C, 2D
100
0100010110
011101010
0010010001001
1100100100010
0000101001001
1101010100100
0101010010010
50
1996
1997
1998
1999
2000
2001
Skills Acquired
Interpreting, analyzing,
inferring
Year
Estimated data from Centers for Disease Control and Prevention
935
Answers to Analysis
MISCONCEPTION
ALERT
AIDS-related Infections Some students
may think that HIV itself causes the death
of AIDS patients. Actually AIDS is a result
of cancers and infections by opportunistic
pathogens that are unusual in individuals
with healthy immune systems. Infections
and cancers associated with AIDS include
Kaposi’s sarcoma, Pneumocystis carinii
pneumonia, candidiasis, and others. Kaposi’s
sarcoma is a cancer of the skin and mucous
membranes that often spreads through other
Teacher’s Notes
Review with students how to
read a bar graph.
organs. Pneumocystis carinii pneumonia is
the most common of these AIDS-related
diseases. Candidiasis, commonly known as
thrush, is a fungal infection producing a
thick, white coating of the mouth, tongue,
and other components of the digestive system. Other opportunistic pathogens include
cytomegalovirus, which produces inflammation of the retina, colon, and adrenal glands;
and tuberculosis and Salmonella infection,
both caused by bacteria. TAKS 3 Bio 4C
1. AIDS cases have risen sharply,
from less than 50,000 cases to
more than 600,000 cases.
2. Greater; everyone who has
AIDS is infected with HIV, but
not everyone who is infected
with HIV has developed AIDS.
3. New drugs postpone the
onset of AIDS in HIV-infected
individuals.
Chapter 40 • The Body’s Defenses
935
Allergic Reactions
Asthma
Many health problems are caused by inappropriate responses of the
immune system. One example is an allergic reaction. An allergy is the
body’s inappropriate response to a normally harmless antigen. Allergycausing antigens include pollen, the feces of dust mites, fungal spores,
and substances found in some foods and drugs. Most allergic reactions
are merely uncomfortable. Cells exposed to allergy-causing antigens
release histamine. Histamine causes swelling, redness, increased
mucus production, runny nose, itchy eyes, and nasal congestion. Most
allergy medicines contain antihistamines, which are drugs that prevent the action of histamine. Severe allergic reactions, such as asthma,
can be life threatening if they are not treated immediately.
TAKS 2 Bio 10A, Bio 10B
(grade 11 only); Bio 11C
Invite a person who has asthma
to class to share his or her
experiences with this disease.
Discussion
Ask students: Do you agree or
disagree with the reasons given
for high inner-city asthma
rates? (Answers will vary.)
Asthma
Close
A
Reteaching
Have students write and act out a
one-minute commercial about
allergy relief. They should address
what causes allergies, what the
symptoms are, and how allergy
medication works. TAKS 2 Bio 10A
Quiz
GENERAL
True or False:
1. HIV attacks the very immune
system designed to prevent infections. (true)
2. HIV and AIDS is the same thing.
(false; HIV is the virus that can
lead to the condition called AIDS)
TAKS 3 Bio 4C
Asthma Attack
During an asthma attack, the
respiratory passages become inflamed and swollen. Then mucus
collects in the lungs, restricting
airflow. Finally, muscles that surround the bronchial tubes tighten,
causing shortness of breath.
Treating Asthma
Asthma sufferers can take medicines that increase airflow by
relaxing bronchial-tube muscles, but their effects wear
off after a few hours. Other
medicines provide long-lasting
relief by preventing or reducing
inflammation.
Measuring lung capacity
www.scilinks.org
Topic: Asthma
Keyword: HX4015
Section 4 Review
Alternative
Assessment
Describe the cause of autoimmune diseases.
GENERAL
Have each student conduct
research about one of the diseases
discussed in this section. Students
should write a report including the
disease name, its scientific name,
where it is commonly found, how
it is transmitted, what happens to
it when it infects a new host, and
how it can be prevented or treated.
LS Verbal TAKS 3 Bio 4C, 4D
pp. 936–937
Student Edition
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TAKS Obj 3 Bio 4C
TEKS Bio 4C, 10A, 10B, 11B
Teacher Edition
TAKS Obj 2 Bio 10A
TAKS Obj 3 Bio 4C, 4D
TEKS Bio 4C, 4D, 10A, 11B, 11C
936
sthma is an inflammation of
the respiratory tract often
caused by an allergic reaction to
substances in the air. Asthma
affects about 15 million Americans and causes more than
5,000 deaths each year. Innercity residents get asthma three
times as often as people who live
outside cities. In some cities, the
death rate from asthma is eight
times the national average. Some
scientists think increased asthma
rates in inner-city residents is
related to pollution, emotional
stress, and limited access to health
care. One study suggests that
cockroach feces may cause
asthma in many inner-city children.
TAKS 2
10A
4C 10A
TAKS Test Prep One common symptom of
an allergic reaction to airborne antigens is
10A 11B
A a weakened immune response.
B opening nasal passages.
C reduced mucus production.
D itchy eyes.
List two ways that HIV can be transmitted and
two ways that it cannot.
Distinguish between HIV infection and AIDS.
4C 10A
Critical Thinking Recognizing
Relationships Explain why it might take several
weeks after exposure to HIV for a person’s HIV
4C 10A
antibody test to be positive.
936
Answers to Section Review
1. Autoimmune diseases occur because the body
lacks the ability to distinguish between self
and non-self cells. TAKS 2 Bio 10A
2. HIV can be transmitted by sexual contact,
hypodermic needles, tainted blood, breast
milk, and from a mother to a fetus. HIV
cannot be transmitted by shaking hands,
toilet seats, insect bites, or though the air.
TAKS 2 Bio 10A; TAKS 3 Bio 4C
3. The immune system might take several weeks to
build up enough HIV antibodies to be
detected. TAKS 2 Bio 10A; TAKS 3 Bio 4C
Chapter 40 • The Body’s Defenses
4. HIV infection is diagnosed by the presence of
antibodies in the blood. AIDS is diagnosed if
there are less than 200 helper T cells/mL blood.
TAKS 2 Bio 10A; TAKS 3 Bio 4C
5.
A. Incorrect. An airborne antigen, like any antigen, would stimulate a strong
immune response. B. Incorrect. Airborne antigens would likely cause swelling of nasal passages. C. Incorrect. Airborne antigens usually
increase mucus production. D. Correct. A common symptom of an allergic reaction to airborne
antigens is itchy eyes, caused by the release of
histamine from cells exposed to the antigen.
TAKS 2 Bio 10A; Bio 11B
Study
CHAPTER HIGHLIGHTS
ZONE
Key Concepts
Alternative
Assessment
Key Terms
Section 1
1 Nonspecific Defenses
●
Skin and mucous membranes act as barriers to pathogens.
●
The inflammatory response increases blood flow to an
infected area, while the temperature response inhibits
bacterial growth.
●
Complement proteins form a membrane attack complex
(MAC). Interferon stimulates cells and inhibits viruses.
●
Neutrophils, macrophages, and natural killer cells use different methods to attack and destroy invading pathogens.
GENERAL
Have students work in cooperative
groups. Ask each group to develop
a question to send to a newspaper
health advice columnist dealing
with any topic covered in this
chapter. Collect the questions
and redistribute them to other
groups. Each group should then
write an appropriate response to
the question. LS Interpersonal
pathogen (924)
mucous membrane (924)
inflammatory response (925)
histamine (925)
complement system (926)
interferon (926)
neutrophil (926)
macrophage (926)
natural killer cell (926)
Section 2
2 Immune Response
●
Receptors on white blood cells bind to specific antigens.
●
The T cell response is a defense in which cytotoxic T cells
destroy pathogens.
●
The B cell response is a defense in which antibodies
mark pathogens for destruction by white blood cells.
cytotoxic T cell (927)
B cell (927)
helper T cell (927)
antigen (927)
plasma cell (929)
antibody (929)
Chapter Resource File
• Science Skills Worksheet GENERAL
• Critical Thinking Worksheet
• Test Prep Pretest GENERAL
• Chapter Test GENERAL
Section 3
3 Disease Transmission and Prevention
Koch’s postulates (930)
immunity (931)
vaccination (931)
vaccine (931)
antigen shifting (932)
●
Diseases are transmitted to humans through person-toperson contact, air, food, water, and animal bites.
●
Biologists use Koch’s postulates to identify pathogens.
●
Memory cells can produce long-term immunity to pathogens.
●
Vaccination produces long-term immunity to pathogens.
●
Antigen shifting makes the immune response of memory
cells ineffective.
4 Disorders of the Immune System
●
Section 4
In an autoimmune disease, the immune system attacks
body cells as if they were pathogens.
●
HIV, the virus that causes AIDS, invades helper T cells, causing them to produce more HIV particles and eventually die.
●
HIV is transmitted by HIV-infected white blood cells in
body fluids, through sexual contact or by the sharing of a
hypodermic needle with an infected person.
●
An allergic reaction is an inappropriate response to normally
harmless antigens.
autoimmune disease (933)
AIDS (934)
HIV (934)
CD4 (934)
allergy (936)
937
Answer to Concept Map
Immune response
The following is one possible answer to the
Performance Zone item 15.
involves
macrophages
consume
dead cells
bacteria
are
pathogens
are a type of
viruses
activate
phagocyte
helper T cells
activate
cytotoxic T cells
B cells
become
plasma cells
make
antibodies
Chapter 40 • The Body’s Defenses
937
Performance
ZONE
CHAPTER 40
Using Key Terms
Using Key Terms
1. d TAKS 2 Bio 10A
2. b TAKS 2 Bio 10A
3. c TAKS 2 Bio 10A
4. c TAKS 2 Bio 10A
5. a. Macrophages ingest and
destroy pathogens and clear
debris. Neutrophils engulf and
poison pathogens.
b. Helper T cells activate cytotoxic T cells, which seek and
destroy pathogens.
c. Immunity is the body’s resistance to pathogens that have
been previously encountered.
A vaccine is a dose of dead or
deactivated pathogens given to
stimulate immunity.
d. An allergy is the body’s
overreaction to a normally
harmless antigen. Histamine
causes an allergic response
that includes swelling, redness,
increased mucus production,
runny nose, itchy eyes, and
nasal congestion.
1. Nonspecific defenses include
a. the T cell response.
b. the B cell response.
c. antibodies.
d. the inflammatory response.
10A
2. Mucous membranes
a. activate helper T cells.
b. secrete mucus, which traps pathogens.
c. prevent blood clots.
d. produce antibodies.
3. B cells and cytotoxic T cells are stimulated
10A
by interleukin-2, which is released by
a. macrophages.
c. helper T cells.
b. neutrophils.
d. natural killer cells.
pp. 938–939
11. Name three types of white blood cells, and
explain their roles in the immune system.
12. How do cytotoxic T cells recognize
antigens?
13. The graph below shows the decrease in
the number of helper T cells in a person
with AIDS. How many months after infec10A
tion did the onset of AIDS occur?
HIV Infection
5. For each pair of terms, explain the differ-
ences in their meanings.
a. macrophage, neutrophil
b. helper T cell, cytotoxic T cell
c. immunity, vaccine
d. allergy, histamine
Understanding Key Ideas
3F
6. Robert Koch
a. treated smallpox patients.
b. established a four-step procedure for
4C
because
a. influenza viruses mutate often.
b. influenza is caused by bacteria.
c. very few memory cells are produced.
d. macrophages cannot engulf flu viruses.
4C
8. HIV can be transmitted by
a. sexual contact. c. shaking hands.
b. mosquito bites. d. vaccination only.
800
600
400
200
0
0
9
18 27 36 45 54 63 72 81
Infection
identifying pathogens.
c. perfected vaccination.
d. identified complement proteins.
7. Flu vaccinations are given each year
Time (months)
14.
What symptoms are usually
11C
associated with an asthma attack?
15.
Concept Mapping Make a concept
map that describes the immune response.
Include the following terms in your map:
pathogen, macrophage, helper T cell,
cytotoxic T cell, B cell, plasma cell, and
3E
antibody.
938
13. between 49 and 54 months TAKS 2 Bio 10A
14. The respiratory passages become inflamed
and swollen, mucus collects in the lungs, and
muscles around the bronchial tubes tighten,
all leading to reduced airflow. Bio 11C
15. One possible answer to the concept map is
found at the bottom of the Study Zone page.
Bio 3E
Review and Assess
TAKS Obj 1 Bio/IPC 2C, 2D
TAKS Obj 2 Bio 10A, 10B
TAKS Obj 3 Bio 4C, 4D
TEKS Bio 3D, 3E, 3F, 4C, 10A, 11C
TEKS Bio/IPC 2C, 2D
Chapter 40 • The Body’s Defenses
10A
4C
10. HIV disables the immune system by
a. blocking the action of macrophages.
b. destroying helper T cells.
c. activating production of B cells.
d. All of the above
10A
4. Plasma cells
a. are directly stimulated by interleukin-1.
b. result from cytotoxic T cells.
c. produce antibodies.
d. engulf pathogens.
Understanding Key Ideas
6. b Bio 3F
7. a TAKS 3 Bio 4C
8. a TAKS 3 Bio 4C
9. b TAKS 2 Bio 10A
10. b TAKS 3 Bio 4C
11. Macrophages consume pathogens
and infected cells; cytotoxic
T cells attack and kill infected
cells; B cells label invaders for
destruction; helper T cells activate both cytotoxic T cells and
B cells.
12. Receptors on the T cells recognize and bind to antigens that
match their particular shape.
10A
9. Rheumatoid arthritis is an example of
a. an allergic reaction.
b. an autoimmune disease.
c. an AIDS-related infection.
d. a bacterial infection.
Number of helper T cells
(per mL of blood)
ANSWERS
938
CHAPTER REVIEW
Assignment Guide
Section
1
2
3
4
Questions
1, 2, 5a
3, 4, 5b, 11, 12, 15, 17
5c, 6, 7, 21
5d, 8, 9, 10, 13, 14, 16, 19, 20, 22
Critical Thinking
Alternative Assessment
Critical Thinking
16. Recognizing Relationships Under what
20. Finding Information Scientific research
16. When its mother is infected
with HIV. TAKS 3 Bio 4C
17. The Golgi apparatus and endoplasmic reticulum are responsible
for protein mobilization. Because
plasma cells produce antibodies,
high protein synthesis activity
would be expected.
circumstances can a child be born with
4C
HIV?
17. Analyzing Information Plasma cells contain
a large Golgi apparatus and large amounts
of rough endoplasmic reticulum. How is
the presence of these organelles related to
10A 10B
the function of plasma cells?
18. Inferring Relationships People who are
into treatments and a possible cure for
AIDS is an ongoing process. Find out
about the latest research into HIV and
prospective cures for AIDS. Research the
most recent pharmaceutical developments
and other treatments. Evaluate public
awareness and education programs and
campaigns. Present your findings in a
4C
written report.
severely burned often die from infection.
21. Summarizing Information Use the media
Given what you know about disease transcenter or the Internet to research three dif4D 10A
mission, explain why this is common.
ferent vaccines. Make a large chart or table
19. Forming Reasoned Opinions A government
on poster board listing the pathogens they
agency is reviewing two proposals for HIV
protect against, their effectiveness, side
research but can fund only one. Which proeffects, and boosters required, if any. Preposal would you recommend that the
2C 2D 3F
sent your chart to your class.
agency fund? You should consider not only
22. Career Focus Immunologist Research the
the likely effectiveness of the treatment but
field of immunology, and write a report on
also possible side effects. Explain how you
your findings. Your report should include a
made your choice. Proposal 1: Develop a
job description, education and training
drug that interferes with protein production.
required, kinds of employers, growth
Proposal 2: Develop a substance that binds
3D
prospects, and starting salary.
4C 10A
to CD4 receptors on helper T cells.
TAKS Test Prep
Use the diagram below and your knowledge of
science to answer questions 1–3.
Virus
10A
1. What are the structures labeled A?
A antigens
C interleukins
B antibodies
D receptor proteins
10A
2. What are the structures labeled B?
F interferons
H receptor proteins
G interleukins
J antigens
A
Cytotoxic T cell
3. Why do structures A and B interact with
10A
each other?
A They have matching shapes.
B They are produced by the same cells.
C Both of them are “nonself.”
D Both of them are viral proteins.
B
Test
Whenever possible, highlight or underline important
numbers or words critical to correctly answering
a question.
939
TAKS 2 Bio 10A, Bio 10B
(grade 11 only)
18. The barrier of the skin prevents
many infections. Severe burns
result in skin loss and subsequent
infection.
TAKS 2 Bio 10A; TAKS 3 Bio 4C
19. The solution described in proposal 1 might interfere with all
protein production in the body,
and it would work only after
infection by HIV. Proposal 2 is a
better choice because if CD4
binding sites on helper T cells
were occupied, the sites would
not be available for HIV to attach
to. TAKS 2 Bio 10A; TAKS 3 Bio 4C
Alternative Assessment
20. Answers will vary. Some important developments and treatments
include a clinical trial of a potential HIV vaccine conducted in 15
U.S. medical centers and a new
medication, which combines two
proven medications, 3Tc and
AZT, into one tablet and may
help people with HIV live longer,
healthier lives. Another medication, alitretinoin, treats lesions of
Kaposi’s sarcoma. AIDS awareness campaigns include the red
ribbon campaign, the AIDS quilt,
and World AIDS Day. TAKS 3 Bio 4C
21. Answers will vary.
TAKS 1 Bio/IPC 2C, 2D; Bio 3F
1. A. Correct. Antigens form on the surface of
viruses. B. Incorrect. Antibodies are produced
to fight viruses. C. Incorrect. Interleukins are
proteins released by the immune system to fight
pathogens. D. Incorrect. Receptor proteins are
sites on the white blood cells that attach to
complementary sites on viral particles.
TAKS 2 Bio 10A
2. F. Incorrect. Interferons are proteins released
by cells that are infected by viruses.
G. Incorrect. Interleukins are proteins released
by the immune system to fight pathogens.
H. Correct. White blood cells have receptor
proteins on their surface that bind to specific
antigens. J. Incorrect. Antigens are proteins
found on the surface of viruses that match to
receptor proteins on white blood cells.
TAKS 2 Bio 10A
3. A. Correct. The matching shapes fit together
and allow interaction between the white blood
cell and virus. B. Incorrect. Structure A is produced by the virus and structure B is produced
by the white blood cell. C. Incorrect. Only the
invading virus would have antigens indicating
“non-self.” D. Incorrect. Structure B is not produced by a virus, but by the white blood cell.
22. Immunologists are scientists who
diagnose, treat, and research
immunological diseases and disorders. Immunologists attend
medical school after college.
Immunologists work in private
practice, in hospitals, and for
pharmaceutical companies. The
growth potential of the field is
excellent. Starting salary will
vary by region. Bio 3D
TAKS 2 Bio 10A
Chapter 40 • The Body’s Defenses
939