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Chapter 22 Lymphoid System

The primary responsibilities of the lymphocytes in the lymphoid system are to respond to the presence of
invading pathogens, abnormal body cells, foreign particles
The anatomical barriers and defense mechanisms that cannot distinguish one potential threat from another are called
non-specific defenses
The major components of the lymphoid system include
lymphatic vessels, lymph, lymphatic organs
Lymphoid organs found in the lymphoid system include
spleen, thymus, lymph nodes
The primary function of the lymphoid system is
production, maintenance, and distribution of lymphocytes
Lymphocytes that assist in the regulation and coordination of the immune response are
helper T cells and suppressors cells
Normal lymphocyte populations are maintained through lymphopoiesis in the
bone marrow and lymphatic tissues
The largest collection of lymphoid tissue in the body is contained within the
adult spleen
The reticular epithelial cells in the cortex of the thymus maintain the blood-thymus barrier and secrete the hormones that
stimulate stem cell divisions and T-cell differentiation
Of the following selections, the one that includes only nonspecific defenses is
hair, skin, complement, inflammation, phagocytosis
The protective categories that prevent the approach of, deny entrance to, or limit the spread of microorganisms or other environmental hazards are called
nonspecific defenses
NK (natural killer) cells are sensitive to the presence of abnormal cell membranes are primarily involved with
immunological surveillance
A physical barrier such as the epithelial covering of the skin provides effective immunity due to its makeup which includes
multiple layers, a keratin coating, a network of desmosomes that lock adjacent cells together
The "first-line" of cellular defense against pathogenic invasion is
The constant monitoring of normal tissues by NK cells is called
immunological surveillance
The four general characteristics of specific defenses include
specificity, versatility, memory, and tolerance
The two major ways that the body "carries out" the immune response are
direct attack by T cells and attack by circulating antibodies
A specific defense mechanism is always activated by
an antigen
The type of immunity that develops as a result of natural exposure to an antigen in the environment is
naturally acquired active immunity
The fact that people are not subject to the same diseases as goldfish describes the presence of
innate immunity
When an antigen appears, the immune response begins with
the activation of specific T & B cells
When the immune "recognition" system malfunctions, activated B cells begin to
manufacture antibodies against other cells and tissues
T-cell activation leads to the formation of cytotoxic T cells and memory T cells that provide
cellular immunity
Before an antigen can stimulate a lymphocyte, it must first be processed by a
CD8 T cells are activated by exposure to antigens bound to
Class I MHC proteins
The T cells that limit the degree of immune system activation from a single stimulus are
suppressor T cells
Since each kind of B cell its own particular antibody molecule in its cell membrane, activation can only occur in the presence of a
corresponding antigen
Activated B cells produce plasma cells that are specialized because they
synthesize and secrete antibodies
An active antibody is shaped like a
The most important antibody action in the body is
activation of the complement systems
Antibodies may promote inflammation through the stimulation of
basophils and mast cells
The antigenic determinant site is that portion of the antigen's exposed surface where
the antibody binds
In order for an antigenic molecule to be a complete antigen, it must
have at least 2 antigenic determinant sites
The ability to demonstrate an immune response upon exposure to an antigen is called
immunological competence
Fetal antibody production is uncommon. Rather, the developing fetus has
natural passive immunity
When an immune response mistakenly targets normal body cells and tissues, the result is
an autoimmune disorder
Depression of the immune system due to chronic stress may cause
depression of the inflammatory response, a reduction in the activities and numbers of phagocytes in peripheral tissues, the inhibition of interleukin secretion
The effects of tumor necrosis factor (TNF) in the body are to
slow tumor growth and to kill sensitive tumor cells, stimulate granulocyte production, increase T-cell sensitivity to interleukins
The major functions of interleukins in the immune system are to
increase T-cell sensitivity to antigens exposed on macrophage membranes; stimulate B-cell activity, plasma-cell formation and antibody production; enhance nonspecific defenses
With advancing age, B cells are less responsive, causing a
decreased antibody level after antigen exposure
The lymphoid system influences nervous system activity by
releasing cytokines which affect hypothalamic production of CRH and TRH
The three different classes of lymphocytes in the blood are
T cells, B cells and NK cells
The primary effects of complement activation include
destruction of target cell membranes, stimulation of inflammation, attraction of phagocytes and enhancement of phagocytosis
Of the following selections, the one that best defines the lymphoid system is that is it
a one way route from the interstitial fluid to the blood
Tissue fluid enters the lymphoid system via the
lymph capillaries
The larger lymphatic vessels contain valves
A localized tissue response to injury is the
inflammatory response
Chemical mediators of inflammation include
histamine, kinins, prostaglandins, leukotrienes
T lymphocytes comprise approximately _______ percent of circulating lymphocytes
B lymphocytes differentiate into
memory and plasma cells
______ cells may activate B cells while _____ cell inhibit the activity of B cells
Helper T; suppressor T
The primary response of T cell differentiation in cell-mediated immunity is the production of _____ cells
cytotoxic T
The vaccination of antigenic materials into the body is called
induced activity immunity
In passive immunity ______ are induced into the body by injection
The lymphatic function of the white pulp of the spleen is
initiation of immune responses by B cells and T cells
A person with type AB blood has
neither anti-A nor anti-B antibodies
The antibodies produced and secreted by B lymphocytes are soluble proteins called
The genes found in a region called the major histocompatibility complex code for
human leukocyte antigens (HLAs)
Memory B cells do not differentiate into plasma cells unless they
are exposed to the same antigen a second time
The 3-dimensional "fit" between the variable segments of the antibody molecule and the corresponding antigenic determinant site is referred to as the
antibody-antigen complex
One of the primary nonspecific effects that glucocorticoids have on the immune response is
depression of the inflammatory response