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

phagocytes

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

macrophage

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

Y

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

true

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

70-80

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

antibodies

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

immunoglobins

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