798
UNIT 4
Maintenance of the Body
21
members differentiate into either the appropriate effector T
cells that mount the primary immune response (e.g., helper or
cytotoxic T cells) or memory T cells.
3.
±e immune response is enhanced by cytokines such as
interleukin 1 released by macrophages, and interleukin 2, gamma
interferon, and others released by activated T cells.
Roles of Specific Effector T Cells
(pp. 787–790)
4.
Helper T cells are required for full activation of most B and
T cells, activate macrophages, and release essential cytokines.
Cytotoxic T cells directly attack and kill infected cells and cancer
cells. Regulatory T (T
Reg
) cells help to maintain tolerance.
Organ Transplants and Prevention of Rejection
(pp. 790–792)
5.
Cell-mediated responses reject graFs and foreign organ
transplants unless the recipient is immunosuppressed. Infections
are major complications in such patients.
Immune System; Topic: Cellular Immunity, pp. 3–4, 11–14.
Homeostatic Imbalances of Immunity
(pp. 792–796)
Immunodeficiencies
(pp. 793–794)
1.
Immunodeficiency diseases include acquired immune deficiency
syndrome (AIDS), caused by HIV, and severe combined
immunodeficiency (SCID) syndromes. Overwhelming infections
are fatal because the immune system is unable to combat them.
Autoimmune Diseases
(p. 794)
2.
Autoimmune disease occurs when the body regards its own
tissues as foreign and mounts an immune attack against them.
Examples include rheumatoid arthritis and multiple sclerosis.
Hypersensitivities
(pp. 794–796)
3.
Hypersensitivity is an abnormally intense reaction to an
otherwise harmless antigen. Immediate hypersensitivities
(allergies) are mounted by IgE antibodies. Subacute
hypersensitivities, involving both antibodies and complement,
include antibody-mediated cytotoxic and immune-complex
hypersensitivities. Cell-mediated hypersensitivity is called delayed
hypersensitivity.
Developmental Aspects of the Immune System
(p. 796)
1.
Development of the immune response occurs around the time
of birth. ±e ability of the immune system to recognize foreign
substances is genetically determined.
2.
±e nervous system plays an important role in regulating
immune responses. Emotional stress impairs immune function.
3.
With aging, the immune system becomes less responsive. ±e
elderly more oFen suffer from immune deficiency, autoimmune
diseases, and cancer.
Immune System; Topic: Common Characteristics of B and
T Lymphocytes, pp. 8–13.
Humoral Immune Response
(pp. 778–784)
Activation and Differentiation of B Cells
(p. 779)
1.
When B cells are activated, most of the clone members become
effector cells called plasma cells, which secrete antibodies. ±is is
the primary adaptive immune response.
Immunological Memory
(pp. 779–780)
2.
Other clone members become memory B cells, capable of
mounting a rapid attack against the same antigen in subsequent
encounters (secondary immune responses). ±e memory B cells
provide humoral immunological memory.
Active and Passive Humoral Immunity
(p. 780)
3.
Active humoral immunity is acquired during an infection or
via vaccination and provides immunological memory. Passive
immunity is conferred when a donor’s antibodies are injected
into the bloodstream, or when the mother’s antibodies cross the
placenta. Its protection is short-lived; immunological memory is
not established.
Antibodies
(pp. 780–784)
4.
±e antibody monomer consists of four polypeptide chains,
two heavy and two light. Each chain has both a constant and a
variable region. Constant regions determine antibody function
and class. Variable regions enable the antibody to recognize its
specific antigen.
5.
²ive classes of antibodies exist: IgM, IgA, IgD, IgG, and IgE. ±ey
differ structurally and functionally.
6.
Antibody functions include complement fixation and antigen
neutralization, precipitation, and agglutination.
7.
Monoclonal antibodies are pure preparations of a single antibody
type useful in diagnostic tests and treating some types of cancer.
Immune System; Topic: Common Characteristics of B and
T Lymphocytes, pp. 14–15; Topic: Humoral Immunity, pp. 3–14.
Cellular Immune Response
(pp. 784–792)
MHC Proteins and Antigen Presentation
(pp. 784–786)
1.
MHC proteins present antigens to T cells. Class I MHC proteins
are found on all nucleated cells, but class II MHC proteins are
found only on APCs.
Activation and Differentiation of T Cells
(pp. 786–787)
2.
Immunocompetent CD4 and CD8 T cells are activated by
binding to an antigen-MHC complex on the surface of an APC.
A co-stimulatory signal is also essential. ±e resulting clone
Multiple Choice/Matching
(Some questions have more than one correct answer. Select the best
answer or answers from the choices given.)
1.
All of the following are considered innate body defenses
except
(a)
complement,
(b)
phagocytosis,
(c)
antibodies,
(d)
lysozyme,
(e)
inflammation.
2.
±e process by which neutrophils squeeze through capillary walls
in response to inflammatory signals is called
(a)
diapedesis,
(b)
chemotaxis,
(c)
margination,
(d)
opsonization.
3.
Antibodies released by plasma cells are involved in
(a)
humoral
immunity,
(b)
immediate hypersensitivity reactions,
(c)
autoimmune disorders,
(d)
all of the above.
Review Questions
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