Transcript MB_47_win

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Visual Concepts
Standardized Test Prep
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Chapter 47
The Body’s Defense Systems
Table of Contents
Section 1 Nonspecific Defenses
Section 2 Specific Defenses: The Immune System
Section 3 HIV and AIDS
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Chapter 47
Section 1 Nonspecific Defenses
Objectives
• Summarize Koch’s postulates for identifying a
disease-causing agent.
• Describe how the skin and mucous membranes
protect the body against pathogens.
• Describe the steps of the inflammatory response.
• Analyze the roles of white blood cells in fighting
pathogens.
• Explain the functions of fever and proteins in fighting
pathogens.
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Chapter 47
Section 1 Nonspecific Defenses
Identifying Pathogens
• A pathogen is any agent that causes disease and
can be spread to humans through the air, food,
water, or direct contact with an infected animal or
person.
• A disease that is caused by a pathogenic bacteria,
virus, fungi, or protist is called an infectious
disease.
• Koch’s postulates are “rules” for identifying the
particular pathogen that causes a specific
disease.
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Chapter 47
Section 1 Nonspecific Defenses
Pathogen
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Chapter 47
Section 1 Nonspecific Defenses
Koch’s Postulates
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Chapter 47
Section 1 Nonspecific Defenses
Koch’s Postulates
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Chapter 47
Section 1 Nonspecific Defenses
First Line of Defense: Barriers
• Nonspecific defenses, such as the skin and
mucous membranes, are barriers to potential
pathogens.
– In addition to being a physical barrier to
pathogens, skin also produces sweat, oils, and
waxes, which are toxic to many bacteria.
– A mucous membrane is a layer of epithelial
tissue that covers internal surfaces of the body
and secretes mucus, a sticky fluid that traps
pathogens.
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Chapter 47
Section 1 Nonspecific Defenses
Mucous Membranes
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Chapter 47
Section 1 Nonspecific Defenses
Second Line of Defense: Nonspecific
Immunity
• If a pathogen gets past the skin and the mucous
membranes, the body triggers the second line of
defense, which is nonspecific immunity.
– Nonspecific immunity works in the same way
against any pathogen.
– Nonspecific immunity includes the
inflammatory response, the temperature
response, and certain proteins.
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Chapter 47
Section 1 Nonspecific Defenses
Second Line of Defense: Nonspecific
Immunity, continued
• Inflammatory Response
– An inflammatory response is a series of events that
suppress infection and speed recovery.
– When cells are damaged they release chemical
messengers, such as histamine.
• Histamine is a substance that increases blood flow
to the injured area and increases the permeability
of surrounding capillaries.
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Chapter 47
Section 1 Nonspecific Defenses
Second Line of Defense: Nonspecific
Immunity, continued
• Inflammatory Response, continued
– Fluids and white blood cells called phagocytes
leak through capillary walls to fight any
pathogens that may have entered the body.
• Phagocytes are cells that ingest and
destroy foreign matter, such as
microorganisms.
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Chapter 47
Section 1 Nonspecific Defenses
Second Line of Defense: Nonspecific
Immunity, continued
• Inflammatory Response, continued
– The most common phagocyte in the body is
called a neutrophil.
• A neutrophil is a large leukocyte that
contains a lobed nucleus and many
cytoplasmic granules.
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Chapter 47
Section 1 Nonspecific Defenses
Second Line of Defense: Nonspecific
Immunity, continued
• Inflammatory Response, continued
– A macrophage is a white blood cell that
engulfs pathogens and other materials.
– Another type of white blood cell that attacks
pathogen-infected cells is called a natural
killer cell.
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Chapter 47
Section 1 Nonspecific Defenses
Inflammatory Response
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Chapter 47
Section 1 Nonspecific Defenses
Inflammatory Response
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Chapter 47
Section 1 Nonspecific Defenses
Second Line of Defense: Nonspecific
Immunity, continued
• Temperature Response
– When the body begins to fight pathogens, body
temperature may increase. This rise in temperature
is called a fever.
– The body triggers a fever in order to slow bacterial
growth or to promote white blood cell activity.
– Though a moderate fever can be helpful, high
fevers can be dangerous
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Chapter 47
Section 1 Nonspecific Defenses
Fever as Nonspecific Defense
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Chapter 47
Section 1 Nonspecific Defenses
Second Line of Defense: Nonspecific
Immunity, continued
• Proteins
– Proteins also provide nonspecific defenses.
• The complement system is a system of
proteins that circulate in the bloodstream
and become active when they encounter
certain pathogens.
• Interferon is a protein released by cells
infected with viruses that enables nearby
cells to resist viral infection.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Objectives
• Identify and describe the parts of the immune system.
• Explain how the immune system recognizes
pathogens.
• Compare the actions of T cells and B cells in the
immune response.
• Relate vaccination to immunity.
• Distinguish between allergy, asthma, and
autoimmune disease.
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Chapter 47
Section 2 Specific Defense: The
Immune System
The Immune System
• The immune system
includes the cells and
tissues that
recognize and attack
foreign substances in
the body.
• The components of
the immune system
are found throughout
the body.
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Chapter 47
Section 2 Specific Defense: The
Immune System
The Immune System, continued
• Bone marrow, the thymus, lymph nodes, the
spleen, adenoids, and tonsils are all part of the
immune system.
• Each part of the immune system plays a special
role in defending the body against pathogens.
• The specialized cells of the immune system are
called lymphocytes. Lymphocytes are white
blood cells that exists in two primary forms: T
and B cells.
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Chapter 47
Section 2 Specific Defense: The
Immune System
The Immune System, continued
• B cells are white blood cells that are made in the
bone marrow and complete their development
there or in the spleen. B cells make antibodies.
• T cells are cells that are made in the bone marrow
but complete their development only after
traveling to the thymus. T cells also participate in
many immune reactions.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Recognizing Pathogens
• Lymphocytes can
provide specific
defenses because they
recognize pathogens by
the antigens on their
surface.
• An antigen is any
substance that the
immune system does
not recognize as part of
the body.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Recognizing Pathogens, continued
• Because the lymphocytes
do not recognize the
antigen, they start a
specific attack known as an
immune response.
• Lymphocytes recognize a
pathogen with molecules
on their surface called
receptor proteins.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Recognizing Pathogens, continued
• An antigen has a
complementary threedimensional shape that
allows the receptor protein to
bind to it. This is how the
lymphocyte recognizes the
antigen.
• Only the specific receptor
protein that is
complementary to the
antigen will be able to bind
there.
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Chapter 47
Section 2 Specific Defense: The
Immune System
How a Cytotoxic T Cell
Recognizes an
Infected Cell
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Chapter 47
Section 2 Specific Defense: The
Immune System
Recognition of Pathogens
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Chapter 47
Section 2 Specific Defense: The
Immune System
Immune Response
• An immune response is a two-part assault on a
pathogen. Both parts occur at the same time and
require a specialized lymphocyte called a helper T
cell.
• The two parts of the immune response are the cellmediated immune response and the humoral
immune response.
• T cells activate certain proteins that affect the
behavior of other immune cells. These proteins are
called cytokines.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Immune Response, continued
• Cell-Mediated Immune Response
– In the cell-mediated immune response,
cytokines activate more helper T cells and
another type of T cell called a cytotoxic T cell.
• Cytotoxic T cells recognize and destroy cells
that have been infected by a pathogen.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Immune Response, continued
• Cell-Mediated Immune Response, continued
– Also produced during the cell-mediated
immune response is a type of T cell called the
suppressor T cell.
– Suppressor T cells are thought to shut down
the immune response after the pathogen has
been cleared from the body.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Cell-Mediated Immune Response
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Chapter 47
Section 2 Specific Defense: The
Immune System
Immune Response, continued
• Humoral Immune Response
– The humoral immune response involves the action of B
cells and occurs when antibodies are activated within
body fluids.
– The humoral immune response occurs at the same time
as the cell-mediated immune response.
– During the humoral response, cytokines stimulate B cells
that have receptors that are complementary to the antigen
to divide and change.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Immune Response, continued
• Humoral Immune Response, continued
– Most B cells form plasma cells. A plasma cell is
a white blood cell that produces antibodies.
– Antibodies are defensive proteins that react to a
specific antigen or inactivate or indirectly
destroy toxins.
– Antibodies use various methods to disable a
pathogen or cause its destruction by
nonspecific responses.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Immune Response, continued
• Primary and Secondary Immune Responses
– The first time the body encounters an antigen,
the immune response is called a primary
immune response.
– During this first encounter, the immune system
fights off the disease. After the disease is
overcome, the immune system creates
memory cells.
• Memory cells are a B cell or T cell that will
recognize and attack the antigen or
invading cell during subsequent infections.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Immune Response, continued
• Primary and Secondary Immune Responses,
continued
– The second time the body encounters an
antigen, a secondary immune response occurs.
– During a secondary immune response, the
immune response is faster and more powerful.
– Most of the time, the secondary immune
response protects the body from reinfection by
a pathogen.
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Chapter 47
Section 2 Specific Defense: The
Immune System
The Immune Response
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Chapter 47
Section 2 Specific Defense: The
Immune System
The Immune Response, continued
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Chapter 47
Section 2 Specific Defense: The
Immune System
Primary and Secondary Immune Responses
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Chapter 47
Section 2 Specific Defense: The
Immune System
Primary and Secondary Immune Response
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Chapter 47
Section 2 Specific Defense: The
Immune System
Immunity and Vaccination
• Immunity is the ability to resist an infectious
disease.
• Immunity can come about in two ways: surviving
an initial infection or through vaccination.
– Vaccination is the introduction of antigens
into the body to cause immunity.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Immunity and Vaccination, continued
• Vaccines
– Vaccination usually involves an injection of a vaccine.
– A vaccine is a solution that contains a dead or
weakened pathogen or material from a pathogen that
still contains antigens.
– The immune system will produce a primary immune
response to the antigens. Memory cells can then
provide a quick secondary immune response if the
antigen ever enters the body again.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Vaccine
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Chapter 47
Section 2 Specific Defense: The
Immune System
Problems of the Immune System
• Sometimes the immune system can react to
harmless antigens. Three examples of this are
allergies, asthma, and autoimmune diseases.
• Allergies
– An allergy is a physical response to an
antigen, which can be a common substance
that produces little or no response in the
general population.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Allergy
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Chapter 47
Section 2 Specific Defense: The
Immune System
Problems of the Immune System
• Asthma
– Allergies can trigger asthma. Asthma is a
respiratory disorder that causes the
bronchioles to narrow due to an overreaction
to substances in the air.
– During an asthma attack, the lining of the
bronchioles and other respiratory tissues may
also swell and become inflamed.
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Chapter 47
Section 2 Specific Defense: The
Immune System
Problems of the Immune System
• Autoimmune Diseases
– An autoimmune disease occurs when the
immune system attacks an organism’s own
cells.
– Autoimmune diseases can affect organs and
tissues in various areas of the body.
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Chapter 47
Section 3 HIV and AIDS
Objectives
• Describe the relationship between HIV and AIDS.
• Distinguish between the three phases of HIV
infection.
• Identify the two main ways that HIV is transmitted.
• Determine how the evolution of HIV affects the
development of vaccines and treatment.
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Chapter 47
Section 3 HIV and AIDS
The Course of HIV Infection
• AIDS (acquired immunodeficiency syndrome) is a
disease caused by HIV (human immunodeficiency
virus).
– Infection by HIV causes the immune system to
lose its ability to fight off pathogens and
cancers.
– HIV infection usually progresses to AIDS in
three phases.
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Chapter 47
Section 3 HIV and AIDS
AIDS (Acquired Immunodeficiency Syndrome)
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Section 3 HIV and AIDS
The Course of HIV Infection, continued
• Phase I
– Phase I of HIV infection is called the
asymptomatic stage, because there are few or
no symptoms of the disease.
– During this period of the disease the viruses
increase rapidly due to replication.
– Phase I can last up to 10 years or more.
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Section 3 HIV and AIDS
The Course of HIV Infection, continued
• Phase II
– The beginning or worsening of symptoms
marks the start of the second phase of HIV
infection.
– B cells continue making antibodies, but T cells
begin to decline steadily as the virus continues
to replicate.
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Chapter 47
Section 3 HIV and AIDS
The Course of HIV Infection, continued
• Phase III
– Phase III of HIV infection is the point where the
number of helper T cells drops so low that they
can no longer stimulate B cells and cytotoxic T
cells to fight invaders.
– AIDS is diagnosed when the helper T-cell
count drops below a certain level.
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Chapter 47
Section 3 HIV and AIDS
The Course of HIV Infection, continued
• Phase III, continued
– AIDS is also diagnosed if an opportunistic infection has
developed.
• Opportunistic infections are illnesses caused by
pathogens that produce disease in people with
weakened immune systems. These organisms
usually do not create problems in people with a
healthy immune system.
– Drug therapy can slow the progress of HIV infection to
AIDS, but there is no cure for AIDS.
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Chapter 47
Section 3 HIV and AIDS
Course of HIV Infection
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Chapter 47
Section 3 HIV and AIDS
Transmission of HIV
• HIV is transmitted by the transfer of body fluids
containing HIV or HIV-infected cells.
• This most commonly occurs by sexual contact
with an infected person or by use of syringes and
hypodermic needles that have been contaminated
with blood containing HIV.
• HIV cannot be transmitted through casual
contact.
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Chapter 47
Section 3 HIV and AIDS
Known Routes of HIV Transmission
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Chapter 47
Section 3 HIV and AIDS
Course of an HIV Infection
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Chapter 47
Section 3 HIV and AIDS
Vaccines and Treatments
• Effective treatments and vaccines for HIV are
difficult to create, because HIV has a rapid
mutation rate.
• Treatment is also difficult because HIV quickly
becomes resistant to antiviral drugs.
• Most HIV treatments are expensive and require a
complicated multidrug therapy.
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Chapter 47
Section 3 HIV and AIDS
Spread of AIDS
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Chapter 47
Standardized Test Prep
Multiple Choice
1. Which of the following is part of the nonspecific
defenses?
A. The inflammatory response
B. The primary immune response
C. The humoral immune response
D. The secondary immune response
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
1. Which of the following is part of the nonspecific
defenses?
A. The inflammatory response
B. The primary immune response
C. The humoral immune response
D. The secondary immune response
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
2. Which of the following statements is false?
F. Autoimmune diseases can be fatal.
G. Autoimmune diseases are a type of cancer.
H. Multiple sclerosis is an autoimmune disease.
J. Autoimmune diseases target the body’s cells.
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
2. Which of the following statements is false?
F. Autoimmune diseases can be fatal.
G. Autoimmune diseases are a type of cancer.
H. Multiple sclerosis is an autoimmune disease.
J. Autoimmune diseases target the body’s cells.
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
3. Which of the following is the most common means of
HIV transmission?
A. receiving a blood transfusion
B. performing experiments with HIV
C. shaking hands with a person who has AIDS
D. having sexual contact with an HIV-infected person
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
3. Which of the following is the most common means of
HIV transmission?
A. receiving a blood transfusion
B. performing experiments with HIV
C. shaking hands with a person who has AIDS
D. having sexual contact with an HIV-infected person
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Use the image below to
answer questions 4 - 6. The
image shows two kinds of
structures involved in an
immune response.
4. What are the
structures labeled A?
F. antigens
G. interferons
H. interleukins
J. receptor proteins
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Use the image below to
answer questions 4 - 6. The
image shows two kinds of
structures involved in an
immune response.
4. What are the
structures labeled A?
F. antigens
G. interferons
H. interleukins
J. receptor proteins
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Use the image below to
answer questions 4 - 6. The
image shows two kinds of
structures involved in an
immune response.
5. What are the
structures labeled B?
A. antigens
B. interferons
C. interleukins
D. receptor proteins
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Use the image below to
answer questions 4 - 6. The
image shows two kinds of
structures involved in an
immune response.
5. What are the
structures labeled B?
A. antigens
B. interferons
C. interleukins
D. receptor proteins
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Use the image below to
answer questions 4 - 6. The
image shows two kinds of
structures involved in an
immune response.
6. Why do structures A and
B interact with each
other?
F. Both are viral
proteins.
G. Both are “nonself”
proteins.
H. They are
complementary shapes.
J. They are produced by
the same cells.
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Use the image below to
answer questions 4 - 6. The
image shows two kinds of
structures involved in an
immune response.
6. Why do structures A and
B interact with each
other?
F. Both are viral
proteins.
G. Both are “nonself”
proteins.
H. They are
complementary shapes.
J. They are produced by
the same cells.
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Complete the following analogy:
7. T cell : cell-mediated :: B cell :
A. humoral
B. infectious
C. secondary
D. inflammatory
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Complete the following analogy:
7. T cell : cell-mediated :: B cell :
A. humoral
B. infectious
C. secondary
D. inflammatory
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Use the graph below to answer
question 8. The graph
shows the number of helper
T cells over time from the
onset of HIV infection.
8. About how many
months after infection
did the number of T
cells first drop below
200 mL?
F. 18
G. 39
H. 51
J. 58
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Chapter 47
Standardized Test Prep
Multiple Choice, continued
Use the graph below to answer
question 8. The graph
shows the number of helper
T cells over time from the
onset of HIV infection.
8. About how many
months after infection
did the number of T
cells first drop below
200 mL?
F. 18
G. 39
H. 51
J. 58
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Chapter 47
Standardized Test Prep
Short Response
A person infected with HIV today might not test
positive for HIV antibodies for up to 6 months.
Explain why an HIV antibody test may not be
positive until several weeks after a person’s
exposure to HIV.
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Standardized Test Prep
Short Response, continued
A person infected with HIV today might not test
positive for HIV antibodies for up to 6 months.
Explain why an HIV antibody test may not be
positive until several weeks after a person’s
exposure to HIV.
Answer: The immune system can destroy many of
the original HIV viruses, leaving few in the blood
for detection by a blood test. Eventually, some of
the HIV viruses enter helper T cells and use the
cells to reproduce many more viruses.
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Chapter 47
Standardized Test Prep
Extended Response
Base your answers to parts A & B on the information
below.
The inflammatory response results from cell injury.
Part A Explain the role of histamine in the
inflammatory response.
Part B Explain the usefulness of having more than
one type of white blood cell respond in the
inflammatory response.
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Chapter 47
Standardized Test Prep
Extended Response, continued
Answer:
Part A Histamine increases the permeability of
the capillaries surrounding injury.
Part B Sample answer: When a pathogen enters
the body, it could be a bacterium, virus,
fungus, protist, or some other kind of infective
agent. Therefore, it is useful for the body to
have several different kinds of defensive cells
that can deal with several different kinds of
pathogens.
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