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Chapter 12
Textbook
The Lymphatic and Immune
Systems
3. Lymph nodes cleanse the lymph by trapping bacteria,
viruses, and other harmful substances that are
destroyed by white blood cells; they also store and
produce infection-fighting T cells and B cells.
4. the spleen
5. in the spleen
Chapter-Opening Question
Caption Questions
The lymphatic system works with the immune system to
keep the body healthy by quickly recognizing and mounting
a counterattack against infectious agents. As the lymphatic
system reabsorbs fluid from the capillaries, it removes
bacteria- and virus-infected cells from body tissues. It also
“sounds the alarm” that activates specific immune defenses, providing protection against disease.
Figure 12.1: Yes, lymph nodes are organs.
Lesson 12.1 The Lymphatic System
Before You Read
What are the two primary functions of the lymphatic system?
The lymphatic system (1) collects fluid from the
interstitial spaces in the body tissues and transports it back
to the cardiovascular system, and (2) protects the body
from disease by recognizing and fighting infectious agents
such as bacteria and viruses.
What would happen to the human body if it did not have a
lymphatic system?
If the body did not have a lymphatic system, excess
fluid leakage in the capillaries would cause a potentially
fatal drop in blood pressure, and the body would lack
an important mechanism in its constant battle against
infectious agents.
Check Your Understanding, page 415
1. The lymphatic system collects fluid from the
interstitial spaces in the body tissues and transports
it back to the cardiovascular system, and it protects
the body from disease by recognizing and fighting
infectious agents such as bacteria and viruses.
2. The lymphatic system resembles the cardiovascular
system in that both systems extend throughout
almost all parts of the body, and they both have a
network of vessels that vary in size from microscopic
capillaries to large vessels. Unlike the circulatory
system, however, the lymphatic system is not a
closed loop.
3. Lymph formation begins with fluid leakage from the
blood vessel capillaries.
4. Muscular contractions and movement of organs
compress the lymphatic vessels, propelling the lymph
through the vessels.
5. The lymphatic trunks were named based on their
location and the part of the body that they drain.
Check Your Understanding, page 419
1. T lymphocytes and B lymphocytes
2. Lymphatic tissues are found in mucous membranes
and certain organs throughout the body.
Figure 12.3: Lymphatic ducts were named based on their
location and the part of the body that they drain.
Figure 12.4: Lymph nodes cleanse the lymph by trapping
bacteria, viruses, and other harmful substances, which in
turn are destroyed by white blood cells. They also store and
produce infection-fighting T cells and B cells. When you
have a throat infection, the lymph nodes in your neck may
become swollen due to activation of an immune response.
This immune response activation causes lymphocytes to
multiply quickly, and as a result, the lymph nodes become
enlarged.
Figure 12.5: Although you can still lead a normal life without
a spleen, you would have increased susceptibility to infection.
Know and Understand
1. Lymphatic fluid is the fluid that leaks out of blood
vessel capillaries, blood plasma is the fluid that is
inside the blood vessels, and interstitial fluid is the
fluid that leaks out into the space between the cells.
2. The lymphatic system reabsorbs fluid that leaks from
the capillaries. If this excess fluid were not returned
to the cardiovascular system, a potentially fatal drop
in blood pressure would occur.
3. Endothelial cells form the lymphatic capillary walls.
These cells overlap and are tethered in a way that
makes it easy for fluid to enter the capillaries but hard
for it to leave.
4. Blood plasma becomes lymphatic fluid when it leaks
out of blood vessel capillaries.
5. The left and right jugular trunks are located in the
left and right sides of the neck, the left and right
subclavian trunks are located beneath the clavicle
(collarbone), the left and right bronchomediastinal
trunks are located in the middle of the chest, the
intestinal trunk is located near the intestines, and the
left and right lumbar trunks are located in the lower
back.
6. Both T cells and B cells play a vital role in immune
system function by fighting infection. T lymphocytes
migrate to the thymus to complete their maturation,
whereas B lymphocytes mature within the bone
marrow.
Analyze and Apply
7. Answers will vary. If students argue that the lymphatic
system’s role as a “plumber” is more important,
they should explain the lymphatic system reabsorbs
1
excess fluid from the capillaries and returns it to
the cardiovascular system, thereby preventing a
potentially fatal drop in blood pressure. If students
maintain that its role as a “soldier” is more important,
they should note that the lymphatic system protects
the body from disease by recognizing and battling
foreign invaders that could cause fatal infection or
disease.
8. Lymphatic fluid assumes a milky appearance upon
draining from the small intestine because of the lipids
that it collects while traveling through this part of the
digestive tract.
9. Muscular contractions and movement of organs
compress the lymphatic vessels, advancing the
lymph along its route. This process is aided by
lymphatic valves, tissue flaps that act as one-way
valves inside the lymphatic vessels, ensuring that the
lymph moves in only one direction.
In the Lab
10. Models will vary, but students should demonstrate
one or both of the following major differences
between the lymphatic and cardiovascular systems:
In the lymphatic system, lymph flows in an open
circuit from body tissues into lymphatic vessels;
once inside the vessels, lymph flows only in one
direction. Also, lymph is either clear or milky. In
the cardiovascular system, blood flows in a closed,
continuous loop throughout the arteries, capillaries,
and veins of the body. Also, blood contains liquid
plasma through which red and white blood cells and
platelets are transported.
11. Figures will vary, but lymphatic trunks and associated
organs should be accurately labeled. Students may
refer to Figure 12.3.
Lesson 12.2 Nonspecific Defenses
Before You Read
What are phagocytes, and what role do they play in the
defense systems of the body?
Phagocytes are cells that engulf and consume
bacteria, other foreign material, and debris. Phagocytes
serve the extremely important of protecting the body
against foreign invaders.
Why does inflammation occur in the body? What important
purpose does it serve?
Inflammation occurs when tissues have been injured
by bacteria, toxins, trauma, or another cause. Inflammation
promotes the repair of damaged tissue.
Check Your Understanding, page 425
1. Defenses against infectious agents begin with
physical barriers to their entry—for example, the skin.
2. keratin
3. phagocytosis
4. 11
5. NK (natural killer) cells bind to abnormal cells and
release perforins—proteins that destroy foreign
cells—by exocytosis into the narrow space between
the cells. The perforins embed themselves in
the target cell membrane and self-assemble into
Introduction to Anatomy and Physiology
doughnut-shaped pores. This process causes
perforations, or small holes, in the target cell, causing
the cell to die soon thereafter. MACs (membrane
attack complexes) are produced by the activation
of complement proteins that insert themselves into
bacterial cell membranes, creating large, lethal holes
in the membranes.
Check Your Understanding, page 428
1. alpha interferons, beta interferons, and gamma
interferons
2. heat, redness, swelling, and pain
3. the hypothalamus
Caption Questions
Figure 12.6: The skin is not an effective barrier to infectious
agents when it is not intact.
Figure 12.7: Phagocytosis is the process by which cells
engulf and destroy foreign matter and cellular debris. In
phagocytosis, a cell such as a neutrophil or a monocyte
(called a phagocyte) adheres to a foreign cell and forms
a pseudopod, which engulfs the foreign cell particles and
forms a phagosome, a membrane-bound compartment
containing the ingested particles. This compartment protects the cell from damaging itself with the chemicals that
it uses to destroy the engulfed material. A lysosome, which
contains acid and lysosomal enzymes, fuses with the material engulfed by the phagocyte. The acid and lysosomal
enzymes destroy the target, and the debris is released from
the cell by exocytosis. Exocytosis is a process in which the
cell membranes fuse and then push the debris from the cell
vesicles to the outside of the cell.
Figure 12.8: 11; they complement, or balance out, the effects of antibodies
Figure 12.9: Inflammation promotes the repair of damaged
tissue.
Figure 12.10: the hypothalamus
Know and Understand
1. The skin acts as a barrier against infectious agents
in several ways. Its outer layer, the epidermis, is
a stratified squamous epithelium, meaning that
its cells are flattened and arranged in layers. This
configuration makes skin an effective barrier as long
as it is intact. The epidermis also contains keratin, a
protein that is strong, flexible, and hard to penetrate.
2. The sweat glands and sebaceous glands secrete
acidic substances that contain toxic chemicals, which
help thwart bacterial growth and reduce the risk of
infection.
3. cilia—tiny, hair-like structures
4. The process by which cells engulf and destroy foreign
matter and cellular debris is called phagocytosis. The
process begins when a cell such as a neutrophil or
a monocyte (called a phagocyte) recognizes its target
and binds to it. The phagocyte adheres to the foreign
cell and forms a pseudopod, which engulfs the foreign
cell particles and forms a phagosome, a membranebound compartment containing the ingested
particles. This compartment protects the phagocyte
from damaging itself with the chemicals that it uses
Chapter 12 Answer Key
2
to destroy the engulfed material. A lysosome, which
contains acid and lysosomal enzymes, fuses with the
material engulfed by the phagocyte. The acid and
lysosomal enzymes destroy the target, and the debris
is released from the cell by exocytosis. Exocytosis is
a process in which the cell membranes fuse and then
push the debris from the cell vesicles to the outside
of the cell.
5. Histamine is a compound that activates an
inflammatory response. It attracts phagocytes and
lymphocytes to the injured or diseased area.
Analyze and Apply
6. The classical is a mode of complement system
activation in which a circulating complement protein
recognizes an antibody bound to a foreign target. The
activated protein kicks off a cascade of complement
protein activation. The alternative pathway is
activated when a circulating complement protein
recognizes foreign materials such as bacterial cell
walls.
7. A virus is tiny, is not a cell, and cannot reproduce
itself. To spread, a virus enters a cell and takes
over the intracellular machinery, enabling the virus
to make many copies of itself. Those copies, when
released, can invade nearby cells, causing the
infection to spread.
8. The inflammatory response is responsible for the
sensation that the part of the body affected by injury
or illness feels as though it is on fire. This response,
characterized by redness, swelling, heat, and pain, is
triggered when tissue has been injured by bacteria,
toxins, trauma, or other affliction.
In the Lab
9. Models will vary, but structures should be accurately
labeled and adequately described.
Lesson 12.3 Specific Defenses
Before You Read
Why is the specific immune system also called the adaptive
immune system?
It is able to recognize new challenges, adapt to those
challenges, and “remember” what it has learned.
What is an antibody, and what function does it serve?
An antibody is a protein that recognizes particular
antigens with great specificity; it interferes with antigen
function and marks the antigens for destruction.
Check Your Understanding, page 432
1. The immune system is also called the specific
immune system because it is highly specific in its
responses to foreign substances.
2. An antigen is a large, complex molecule (such as a
protein, polysaccharide, glycolipid, or nucleic acid),
or parts of a molecule on the surface of a cell. An
antigen identifies a cell as either a “self” or “nonself”
cell, making it possible for the body to distinguish
between its own cells and foreign cells.
3. Examples: macrophages, dendritic cells, and B cells
4. MHC (major histocompatibility) proteins are a type of
protein that displays antigens on the surfaces of cells.
Introduction to Anatomy and Physiology
There are two classes of MHC proteins: class I MHC
proteins and class II MHC proteins.
5. For a lymphocyte not to be characterized as inactive,
it has to “meet” its corresponding antigen.
Caption Questions
Figure 12.11: Answers will vary, but students might mention how they would be unable to leave their houses to
attend school, go to work, or hang out with their friends, for
example.
Figure 12.12: Humoral immunity is effective against specific
pathogens located outside of cells, such as extracellular
viruses, bacteria, and bacterial toxins. Cellular immunity
is not only assisted by T cells but also is directed at cells
infected by a specific virus, bacterium, toxin, or cancer.
Interferons, by contrast, are proteins released by cells
that have been infected with a virus; they interfere with
viral replication and spreading and, as such, do not help
the already-infected cells. Instead, they help neighboring
cells resist viral infection. In short, interferons work without
regard for the specific identity of an infectious agent. The
mechanisms of inflammation operate in a similar fashion.
During the inflammatory response, cells release chemicals
that cause the blood vessels to leak fluid into the tissues,
resulting in swelling. This swelling helps isolate the foreign
invader, preventing further contact with body tissues.
Figure 12.14: If antibodies did not display specificity in
targeting pathogens, they would not be able to interfere
with antigen function and mark antigens for destruction. As
a result, antibodies would not be able to neutralize viruses
or otherwise protect the body from infection.
Figure 12.15: Answers will vary and will depend on the
antibody functions that students individually determine to
be the most important. The following summaries, in conjunction with the material in this chapter, may help students
answer this question.
IgA antibodies bind to antigens while they are still on the
“outside” of the body, preventing them from crossing the
epithelium and entering the body tissue. IgD antibodies
signal the activation of B cells; by being activated, the B
cells are ready to participate in the body’s humoral defense.
IgE antibodies bind to mast cells and basophils, causing
them to release histamine and other chemicals that mediate inflammation and allergic responses. IgG antibodies
are the most common type of circulating antibodies; they
provide resistance against many different infectious microorganisms. IgM antibodies are the first class of antibodies
secreted by activated B cells; they activate the complement
system. Because IgM antibodies have ten binding sites,
they are effective at causing agglutination, or clumping up,
of antigens.
Figure 12.16: A secondary immune response to infection
is larger and faster than the primary response because the
secondary response mainly involves activation of memory
cells. The body “remembers” the harmful invader from the
initial exposure; therefore, its immune response is stronger
during the second, or subsequent, exposure.
Figure 12.17: The helper T cells will activate cytotoxic T
cells (killer T cells).
Chapter 12 Answer Key
3
Know and Understand
1. “Bubble boy” disease, or severe combined immune
deficiency (SCID), is a genetic immune system
deficiency. Patients with SCID have such a severely
compromised immune system that they are
susceptible to infections and diseases that never
trouble those with a normal immune system.
2. macrophages, dendritic cells, and B cells
3. The thymus is the organ in which some lymphocytes
travel to complete their maturation as T lymphocytes
(T cells), upon which they move out to the blood and
the rest of the body.
4. B cells and T cells
5. The T lymphocytes mature in the thymus, and the B
lymphocytes mature in the bone marrow.
Analyze and Apply
6. Some lymphocytes continually circulate throughout
the body, and others settle in the lymph nodes, spleen,
or lymphatic tissues. Only a fraction of lymphocytes
will ever “meet” the antigen that binds to its particular
antigen receptor; the other lymphocytes—those that
settle in the lymph nodes, spleen, and lymphatic
tissues—may never “meet” their specific antigen.
7. When a lymphocyte meets an antigen, the antigen
binds to the antigen receptor on the lymphocyte.
This binding process stimulates the lymphocyte
to differentiate, or divide repeatedly, making many
copies of itself. Each copy of the lymphocyte is
an exact genetic duplicate (clone). These clones
become short-lived effector cells that fight infectious
invaders.
8. When a B cell encounters the antigen that binds to
its particular antigen receptor, it undergoes clonal
selection. The B cell divides repeatedly, making
many copies of itself. Each copy is an exact genetic
duplicate of the original B cell that was stimulated.
Some of these clones, or daughter cells, become
memory helper B cells; however, most become
plasma cells.
In the Lab
9. Project results will vary.
10. Essay content will vary.
Lesson 12.4 Disorders and Diseases
of the Immune System
Before You Read
What causes an allergy?
an inappropriately strong response of the immune
system to an environmental antigen, such as dust mites,
pet dander, pollen, or certain foods
What is the difference between the human immunodeficiency virus (HIV) and acquired immune deficiency syndrome
(AIDS)?
HIV is the virus that causes AIDS.
Check Your Understanding, page 439
1. As a solid tumor grows, cancerous cells sometimes
break free from the tumor and migrate to other areas
of the body.
Introduction to Anatomy and Physiology
2. Lymphedema is caused by a disruption in the
lymphatic drainage system, leading to a buildup of
lymphatic fluid in the interstitial space. This fluid
buildup causes tissue swelling and damage.
Check Your Understanding, page 440
1. an allergy—an overreaction of the body’s immune
system to an antigen
2. Excessive amounts of histamine in the body can lead
to life-threatening symptoms, including pulmonary
obstruction and extremely low blood pressure.
3. an injection of epinephrine or antihistamine drugs
4. rheumatoid arthritis, multiple sclerosis, and type I
diabetes
Caption Questions
Figure 12.18: Some people have a more sensitive or
overactive immune system. There may also be a hereditary
factor.
Taking It Further, page 441
1. Report content will vary.
Know and Understand
1. An oncologist surgically removes one or more lymph
nodes or performs a needle biopsy using a syringe to
determine whether cancer has spread.
2. Lymph node removal disrupts lymphatic drainage in
the affected area of the body, causing a buildup of
extracellular fluid, or lymphedema.
3. a compression sleeve, physical therapy, and carefully
designed, light exercise
4. IgE antibodies are a class of antibodies that interact
with mast cells and basophils, which become
sensitive to allergens. IgE antibodies are produced
when allergen presentation activates a helper T cell,
which in turn activates B cells.
5. basophils and mast cells
6. Allergen immunotherapy involves administration
of allergy shots, a long-term treatment whose goal
is to prevent allergic reactions before they occur.
In allergen immunotherapy, a specific allergen is
injected beneath the skin, starting with tiny amounts
and gradually building up to larger amounts. This
incremental approach often leads to the development
of immune system tolerance of the antigen, thereby
reducing or eliminating the allergic response.
7. HIV is a virus; AIDS is the disease caused by HIV.
8. A B lymphocyte and a cultured cell derived from
a cancerous lymph cell are fused. This fused cell
can divide without limit. It is allowed to divide, grow,
and secrete its antibody product. The product is
harvested from the fluid bathing the cells and is
packaged as a drug.
Analyze and Apply
9. Breast cancer often metastasizes to the axillary
(underarm) lymph nodes. Students should label this
area on a diagram of the human body.
10. Histamine could cause inflammation and swelling of
the airways, or it could cause capillaries to become
excessively leaky, leading to leakage of blood plasma
into the interstitial space.
Chapter 12 Answer Key
4
In the Lab
11. patient A: cancer; patient B: rheumatoid arthritis;
patient C: allergies; patient D: AIDS
12. Poster content will vary.
Chapter Assessments
Lesson 12.1 The Lymphatic System
1. The lymphatic system (1) collects fluid from the
interstitial spaces in the body tissues and transports
it back to the cardiovascular system, and (2) protects
the body from disease by recognizing and fighting
infectious agents such as bacteria and viruses.
2. True
3. True
4. False
5. subclavian
6. False
7. The spleen has a thin covering and is soft inside, so
it can be easily torn during contact sports. If a torn
spleen cannot be repaired, the organ would need
to be surgically removed. Although their son can
still lead a normal life without a spleen, he would be
much more susceptible to infections.
8. Lymph nodes cleanse the lymph by trapping bacteria,
viruses, and other harmful substances, which in turn
are destroyed by white blood cells. They also store
and produce infection-fighting T cells and B cells.
When you have a throat infection, for example, the
lymph nodes in your neck may become swollen due
to activation of an immune response. This immune
response activation causes lymphocytes to multiply
quickly, and as a result, the lymph nodes become
enlarged.
Lesson 12.2 Nonspecific Defenses
9.
10.
11.
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14.
15.
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True
B
Monocytes
exocytosis
complement system
A
True
The classical pathway is activated when a circulating
complement protein recognizes an antibody bound
to a foreign target; the activated protein kicks off
a cascade of complement protein activation. The
alternative pathway is activated when a circulating
complement protein recognizes foreign materials
such as bacterial cell walls.
Lesson 12.3
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18.
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the lymphatic organs and tissues
antigen
B
the thymus
C
True
five
antigens
The first time the body is exposed to a virus or
bacterium through a vaccine, a primary immune
response occurs. If the body is exposed to the
Introduction to Anatomy and Physiology
same virus or bacterium a second or subsequent
time, a secondary response occurs. The secondary
response is larger and faster than the primary
response because the secondary response mainly
involves activation of memory cells. The body
“remembers” the harmful invader from the initial
exposure; therefore, its immune response is stronger
during the second, or subsequent, exposure.
26. Clonal selection occurs when a lymphocyte meets
the antigen that binds to its particular antigen
receptor. This binding of antigen to antigen receptor
causes the lymphocyte to differentiate, or divide
repeatedly, making many copies of itself. These
clones become short-lived effector cells that fight
infectious invaders.
Lesson 12.4 Disorders and Diseases of the
Immune System
27.
28.
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metastatic
55%
D
allergy
human immunodeficiency virus (HIV)
tolerance
anaphylaxis
The patient is said be “HIV positive” after initial
infection with HIV; the immune system is still able to
replace CD4-positive cells almost as quickly as they
are lost. When the concentration of T helper cells in
the blood drops below 200/mm3, the patient is said to
have AIDS.
Building Skills and Connecting
Concepts
Analyzing and Evaluating Data
35 60%
36. Mozambique, Nigeria, United States, Argentina,
Colombia, and Chile
37. Europe
38. C
Communicating about Anatomy and
Physiology
39. Argument content will vary.
40. Responses will vary.
Lab Investigations
41. Recommended vaccine schedules and tracking tools
will vary.
42. Information sheet content will vary.
Workbook
Lesson 12.1: Learning the Key Terms
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Chapter 12 Answer Key
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Lesson 12.1: Study Questions
1. The lymphatic system reabsorbs fluid leaking from
the capillaries, removes bacteria and virus-infected
cells from body tissues, and activates specific
immune defenses.
2. Lymph is a fluid collected from tissues through the
body and flows in the lymphatic vessels. It is normally
clear, transparent, or sometimes faintly yellow.
3. Both systems extend throughout almost all parts of
the body, and also have a network of vessels that
vary in size from microscopic capillaries to large
vessels. Unlike the circulatory system, however, the
lymphatic system is not a closed loop.
4. The normal leakage rate is 2 to 3 mL per minute.
This tiny amount could cause all of a person’s
blood plasma to be lost in a single day if it were not
returned to the cardiovascular system.
5. Answers may vary. As the fluid leaks out of the
capillaries, it gathers in the space between cells
called the interstitial space. The fluid, now called
interstitial fluid, builds in the interstitial space,
eventually moving into the lymphatic capillaries via
the endothelial cells that form the walls of these
lymphatic capillaries. Once the fluid, or lymph as it is
now know, enters the lymphatic capillaries, it begins
flowing into the lymphatic trunks. Muscular contracts,
organ movements, and lymphatic valves help move
the lymph through the lymphatic vessels and trunks.
6. When inside the blood vessels, it is called blood
plasma. When it leaks out and enters the spaces
between cells, it is called interstitial fluid. Once
the fluid is in the lymphatic capillaries or the larger
lymphatic vessels, it is called lymph.
7. an enlarged chamber through which lymph flows;
located just in front of the vertebral column, at the
diaphrahm level
8. Lymphocytes are white blood cells. Lymphocytes
make up about 20% to 30% of the white blood cells in
whole blood and are abundant in lymphatic tissues,
such as lymph nodes and the spleen.
9. B lymphocytes and T lymphocytes
10. When a white blood cell called a monocytes migrates
out of lymphatic circulation and into the surrounding
tissue, it becomes a macrophage. Macrophages are
cells that phagocytize (surround and destroy) foreign
cells and substances.
Introduction to Anatomy and Physiology
11. Lymphatic tissue is loose connective tissue that
contains many lymphocytes. Lymphatic tissue
is present in mucous membranes that line the
respiratory, digestive, urinary, and reproductive
tracts. Lymphatic tissue is also found in certain
organs in the body, including the lymph nodes,
spleen, and thymus.
12. Lymph nodes cleanse the lymph by trapping bacteria,
viruses, and other harmful substances, which in turn
are destroyed by white blood cells. Lymph nodes also
store and produce T cells and B cells that help fight
infection.
13. They often become enlarged.
14. the blood
15. a disease-causing agent
16. the endocrine system
17. The thymus is not a site where lymphocytes wait
to fight off infectious agents. Rather, the thymus
functions as a nursery for T cells.
Lesson 12.1: Labeling the Lymphatic
System
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Lesson 12.1: Lymphatic Ducts and
Vessels
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Lesson 12.2: Learning the Key Terms
1. Phagocytosis
2. classical pathway
Chapter 12 Answer Key
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exocytosis
interferons
Mast cells
opsonins
Prostaglandins
Fever
Complement proteins
alternative pathway
Monocytes
Pyrogens
neutrophils
inflammatory response
Phagocytes
complement system
Lesson 12.2: Study Questions
1. physical barriers; cellular and chemical barriers;
inflammation; and fever
2. Answers may vary. skin, hair, mucous membranes,
cilia in the respiratory tract
3. keratin; a protein
4. a cellular defense
5. phagocytosis
6. Virus-infected and cancer cells often have unusual
proteins on their surface, or fail to show typical
proteins on the surface.
7. Perforins are proteins released by NK cells
that destroy foreign cells. The perforins embed
themselves in the target cell membrane and create
perforations in the target cell. The target cell soon
becomes full of holes and dies.
8. 11
9. The process of making cells attractive to phagocytes
is called opsonization, and opsonins are proteins that
make cells more attractive to phagocytes.
10. Both NK cells and complement proteins penetrate
and create holes in their targets. NK cells do this
directly, while complement proteins form a membrane
attack complex (MAC), which creates a large, lethal
hole in the cell membrane.
11. Interferons received their name because they
interfere with viral replication and spreading.
12. Alpha interferons are produced by virus-infected
leukocytes. Beta interferons are produced by virusinfected fibroblasts (connective tissue cells). Both
alpha and beta interferons can bind to receptors on
neighboring cells, causing those cells to express
proteins that slow down protein synthesis and hinder
the reproduction of viral particles. Gamma interferons
are produced by NK cells and T cells that have been
activated by detection of foreign materials. Gamma
interferons help macrophages to resist viral infection
and attack virus-infected cells more quickly.
13. Interferons are useful for treating certain diseases,
including hepatitis C, some forms of leukemia, and
certain types of lymphoma because they tend to
hinder cell growth and division, including the rapid
growth and division of cancer cells.
14. Inflammation occurs when tissues have been injured
by bacteria, toxins, trauma, or another cause.
15. heat, redness, swelling, and pain
Introduction to Anatomy and Physiology
16. the maintenance of body temperature at a higherthan-normal level
17. the hypothalamus
18. Pyrogens are chemicals that raise the set-point
temperature of the neurons in the hypothalamus,
which increase the temperature of the body.
Lesson 12.3: Learning the Key Terms
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Lesson 12.3: Study Questions
1. the specific immune system, or the adaptive immune
system
2. a successful bone marrow transplant
3. Antigens identify cells as either “self” or “nonself”
cells, thereby making it possible for the body to
distinguish between its own cells and any nonself,
or foreign, cells. This in turn makes it possible for
the immune system to recognize foreign cells and
produce antibodies that bind to and mark the foreign
antigens.
4. macrophages, dendritic cells, and B cells
5. B lymphocytes complete their maturation in bone
marrow (thus the “B”), while T lymphocytes complete
their maturation in the thymus (thus the “T”).
6. Each lymphocyte has many antigen receptors in its
membrane. But all the receptors in a lymphocyte
membrane recognize one—and only one—antigen;
thus the idea of “specific” defenses.
7. During differentiation, the lymphocyte divides
repeatedly, making many copies of itself. Each copy
is an exact genetic duplicate, or clone, of the original
cell. Their purpose is to become short-lived effector
cells that fight the infectious invader.
8. MHC proteins display antigens on the surfaces of
cells in order for an immune response to be activated.
There are two classes of MHC proteins—Class I
MHC and Class II MHC.
9. Humoral immunity, or antibody-mediated immunity, is
effective against pathogens located outside of cells
such as extracellular viruses, bacteria, and bacterial
toxins.
10. RER is a membranous network in the cytoplasm of
plasma cells that are involved in protein synthesis in
humoral immunity.
11. Antibodies are y-shaped proteins that recognize
particular antigens with great specificity. Antibodies
are also called immunoglobulins. Although they
Chapter 12 Answer Key
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12.
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do not directly destroy antigens, they interfere
with antigen function and mark the antigens for
destruction.
Answers may vary.
A. An antibody can neutralize a virus or toxin by
occupying the binding site that the virus/toxin
would use to attach to a target cell.
B. Precipitation causes small antigen molecules
to clump together, forming antigen complexes
that are too big to remain dissolved in the
bloodstream.
C. Agglutination causes cells, viruses, and bacteria
to clump together.
D. The antibody can bind to its target, exposing
the binding sites of the antigen and activating
the complement system. The antibodies and
complement proteins make the pathogen more
appealing to phagocytes.
E. Antibody-antigen complexes stimulate
inflammation by causing mast cells and basophils
to release histamine and other chemicals.
The primary immune response occurs when the body
is first exposed to a foreign invader. When the same
virus or bacterium enters the body for a second time,
the secondary immune response occurs. This is a
strong response to a lesser amount of antigen and
mainly involves memory cells.
Answers may vary. The secondary immune response
explains why vaccination works—the secondary
immune response, through its memory cells, learns
how to fight specific antigens. When a vaccine is
administered, an individual receives the first dose of
a virus or bacterium, initiating the primary response.
Then, when the individual naturally encounters the
virus or bacterium, the strong, secondary immune
response is initiated.
In active immunity, antibodies are actively produced
by the body’s blood plasma cells; in passive
immunity, antibodies are received from an outside
source.
Cellular immunity is immunity that arises from the
activation of T cells by antigen-presenting cells.
The division of cytotoxic T cells produces active
cytotoxic T cells, which seek out and destroy antigendisplaying cells that initiated the immune response. It
also creates memory cytotoxic T cells and suppressor
T cells, which prevent the cellular response from
being too strong or too long lasting.
Lesson 12.3: Antigen Presentation
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Introduction to Anatomy and Physiology
12. 5
13. 1
Lesson 12.4: Learning the Key Terms
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acquired immune deficiency syndrome (AIDS)
Lymphedema
allergen
human immunodeficiency virus (HIV)
autoimmune disorder
opportunistic infection
tolerance
Anaphylaxis
metastasis
immunotherapy
Lesson 12.4: Study Questions
1. Normal control of cell division (mitosis) fails, and a
cell starts to divide quickly and without limit.
2. Cancerous cells from the original tumor break free
and migrate to other areas of the body.
3. to see if the cancer has spread; metastasizing
cancers are carried through lymphatic vessels to the
lymph nodes
4. Lymphatic drainage in the affected area of the body
could be disrupted, and as a result, fluid that leaks
out of blood capillaries builds up in the interstitial
space, causing tissue swelling and damage. This
extracellular fluid buildup is caused lymphedema.
5. Answers may vary. sneezing, coughing, itchy and
watery eyes
6. An allergy is an inappropriately strong response of
the immune system to an environmental antigen; the
problem is not really the antigen, but an overactive
immune system.
7. T cells
8. histamine
9. anaphylaxis
10. with an injection of epinephrine, or doses of
antihistamine
11. In autoimmune disorders, the antigen is part of the
body’s own tissue, but in the case of an allergy, the
antigen comes from outside the body.
12. more than 80 different types
13. Answers may vary. rheumatoid arthritis, multiple
sclerosis, type I diabetes
14. It causes immune deficiency, compromising the
body’s ability to fight disease-causing organisms.
15. Antibody-based drugs bind very specifically, limiting
the side effects that affect their usefulness because
the drug is only treating the specific disease
mechanism for which it is intended.
16. T cells are essential for strong activation of both the
humoral and cellular immune responses.
Lesson 12.4: Diagramming an
Allergic Reaction
1.
2.
3.
4.
5.
initial contact with allergen
allergen
B cell
plasma cell
released IgE antibodies
Chapter 12 Answer Key
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6.
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8.
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11.
mast cell
IgE receptor
subsequent contact with allergen
granule
histamine and other chemicals
allergic reaction
Drainage Regions
1. right lymphatic duct
2. thoracic duct
Lymphatic Organs
1-2.
Lesson 12.4: Researching
Autoimmune Disorders
Answers will vary.
Chapter 12: Spelling Challenge
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allergen
metastasis
lymphedema
humoral immunity
apoptosis
complement proteins
exocytosis
interferons
neutrophils
opsonins
phagocytes
pyrogens
interstitial fluid
lymphatic nodules
macrophages
pharyngeal tonsil spleen
spleen
antigen
perforin
capillaries
Chapter 12 Lab Investigation:
Lymphatic System
Lymphatic Vessels
1-3.
Lymphatic vessel
3. 3
Conclusions
1. lymph
2. the circulatory system
3. Lymph nodes serve a dual purpose. They cleanse
the lymph by trapping bacteria, viruses, and other
harmful substances, which in turn are destroyed
by white blood cells. Lymph nodes also store and
produce T cells and B cells that help fight infection.
4. mucosa associated lymphatic tissue
5. blood plasma, interstitial fluid, lymph.
6. left and right jugular trunks
7. left and right subclavian trunks
8. left and right bronchomediastinal trunks
9. intestinal trunk
10. left and right lumbar trunks
Chapter 12 Practice Test
4. to prevent back flow
Introduction to Anatomy and Physiology
1. spleen
2. Keratin
Chapter 12 Answer Key
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Vaccination
immune system
human immunodeficiency virus (HIV)
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Introduction to Anatomy and Physiology
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The lymphatic system reabsorbs fluid leaking from
the capillaries, removes bacteria and virus-infected
cells from body tissues, and activates specific
immune defenses.
37. The primary immune response occurs when the
body is first exposed to a foreign invader, such
as a virus or bacterium. The secondary immune
response occurs when the virus or bacterium enters
the body for a second or subsequent time, with a
stronger response to a lesser amount of antigen.
The secondary immune response mainly involves
memory cells, which developed during the body’s
initial exposure to the potentially harmful invader.
Chapter 12 Answer Key
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