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78 terms

Chapter 21 - The Immune System: Innate and Adaptive Body Defenses

Part II
STUDY
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immunity
(medicine) the condition in which an organism can resist disease
innate defense system
responds immediately to protect the body from all foreign substances, whatever they are
adaptive defense system
Is aquired immunity due to infection or vaccination: Third line of defense mounts attack against particular foreign substances (Takes longer to react than innate system, Workds in conjunction with the innate system)
immune system
a system (including the thymus and bone marrow and lymphoid tissues) that protects the body from foreign substances and pathogenic organisms by producing the immune response
pathogens
Microbes that cause disease
phagocytes
Cells that use phagocytosis to engulf foreign organisms. The chief ___ are macrophages, created from monocytes.
lysozyme
an enzyme found in saliva and sweat and tears that destroys the cell walls of certain bacteria
neutrophils
A type of white blood cell that engulfs invading microbes and contributes to the nonspecific defenses of the body against disease.
phagocytosis
process in which phagocytes engulf and digest microorganisms and cellular debris
phagosome
Intracellular vesicle containing material taken up by phagocytosis.
phagolysosome
Intracellular vesicle formed by fusion of a phagosome with a lysosome, in which the phagocytosed material is broken down by degradative lysosomal enzymes.
adherence
process by which phagocytes attach to microorganisms through the binding of complementary chemicals on the cytoplasmic membranes
opsonization
process whereby opsonins make an invading microorganism more susceptible to phagocytosis
respiratory burst
metabolic change accompanied by a transient increase in oxygen consumption that occurs in neutrophils and macrophages when they have taken up opsonized particles. It leads to the generation of toxic oxygen metabolites and other anti-bacterial substances that attack the phagocytosed material.
inflammatory response
nonspecific defense reaction to tissue damage caused by injury or infection
mast cells
a vertebrate body cell that produces histamine and other molecules that trigger the inflammatory response.
histamine
amine formed from histidine that stimulates gastric secretions and dilates blood vessels
kinins
acute inflammation; increase vascular permeability, vasodilation, smooth muscle contraction, pain; made in liver
prostaglandins
A group of bioactive, hormone-like chemicals derived from fatty acids that have a wide variety of biological effects including roles in inflammation, platelet aggregation, vascular smooth muscle dilation and constriction, cell growth, protection of from acid in the stomach, and many more.
leukotrienes
potent biological substances produced from unsaturated fatty acids by mast cells that cause bronchospasm, attract inflammatory cells, and induce excessive mucus secretion
complement
one of a series of enzymes in the blood serum that are part of the immune response. (starts with C)
leukocytosis
an abnormal increase in the number of white blood cells in the blood as a result of infection (as in leukemia)
margination
the aggregating or lining up of substances along a surface or edge (eg, the lining up of white blood cells against the wall of a blood vessel during the inflammatory process)
diapedesis
passage of blood cells (especially white blood cells) through intact capillary walls and into the surrounding tissue
chemotaxis
movement by a cell or organism in reaction to a chemical stimulus
Phagocyte Mobilization
-leukocytosis
-inflammed areas release signaling proteins (selectins)
-margination
-diapedesis
-chemotaxis
-monocyte follows neurtrophils,become macrophage with 12hr
pus
a fluid product of inflammation
interferons
Antiviral proteins secreted by T cells
antimicrobial proteins
are short peptides that have a broad spectrum of antimicrobial activity. Besides killing a wide range of microbes, AMPs can attract dendritic cells and mast cells, which participate in immune responses. aka AMPs
complement system
Group of at least 20 proteins whose activites enhance or complement the body's other defense mechanisms. -destruction of pathogen-enhancement of phagocytosis-stimulation of inflammation
fever
elevated body temperature that occurs in response to infection
pyrogens
molecules that set the body's thermostat to a higher temperature. they are released by certain leukocytes
humoral immunity
specific immunity produced by B cells that produce antibodies that circulate in body fluids. (also called antibody-mediated immunity)
cellular immunity
Type of ACQUIRED IMMUNITY involving T-cell lymphocytes. Large numbers of activated lymphocytes are formed specifically to destroy the foreign agent. This is called what type of immunity?
antigens
foreign substances that trigger the attack of antibodies in the immune response.
nonself
Antigen recognized as foreign by an organism.
complete antigens
antigens that are able to stimulate the proliferation of specific lymphocytes and antibodies and to react with the activated lymphochytes and produced antibodies; can develop antibodies
reactivity
ability to react with the activated lymphocytes and antibodies released by immunogenic reactions.
hapten
small antigen incapable of stimulating antibody production unless attached to a "protein". E.g. ... Penicillin -- (aka. incomplete antigen)
antigenic determinants
otherwise known as epitopes; regions of the antigen that are recognized by immunoglobulin B cell receptors or T cell receptors
self-antigens
A term used to describe all the normal constituents of the body to which the immune system would respond were it not for the mechanisms of tolerance that destroy or inactivate self-reactive B and T cells.
MHC proteins
Major histocompatibility complex; A family of genes that encode a large set of cell surface proteins. Class I and class II molecules function in antigen presentation to T cells. Foreign molecules on transplanted tissue can trigger T cell responses that may lead to rejection of the transplant.
b lymphocytes
form in the bone marrow and release antibodies that fight bacterial infections (aka. b cells)
t lymphocytes
provide cell-mediated immunity and are processed by the thymus gland. (aka. t cells)
antigen-presenting cells
macrophages that break down pathogens and present the antigens so t cells can recognize them.
clone
a group of genetically identical cells or organisms derived from a single cell or individual by some kind of asexual reproduction
plasma cells
cells that develop from B cells and produce antibodies.
memory cells
B lymphocytes that do not become plasma cells but remain dormant until reactivated by the same antigen.
primary immune response
the initial immune response to an antigen, which appears after a lag of several days
secondary immune response
The adaptive immune response provoked by a second exposure to an antigen. It differs from the primary response by starting sooner and building more quickly.
immunological memory
The capacity of the immune system to make quicker and stronger adaptive immune responses to successive encounters with an antigen. Immunological memory is specific for a particular antigen and is long-lived.
active humoral immunity
involves B cells being exposed to antigen; develops immunological memory, long term protection. Naturally- through infection or contact with pathogen; Artificially- vaccine, dead or attenuated
vaccines
dose of a disabled or destroyed pathogen used to stimulate a long-term immune defense against the pathogen. A weakened form of the virus is given to the person so their immune system can build up immunity to the virus.
passive humoral immunity
received from donor, placental transfer and breast milk, administration of immune serum (antivenom)
antibodies
Specialized proteins that aid in destroying infectious agents. (aka. immunoglobulins "igs")
gamma globulin
a plasma protein containing the immunoglobulins that are responsible for immune responses
antibody monomer
basic structural unit of an antibody, composed of four polypeptides linked by disulfide bonds
H chains
heavy polypeptide chains of antibodies that pair with L chains to form a functional immunoglobulin molecule. The constant end binds to an isotype-specific receptor site of T cells at one end and the variable end on the opposite pole of the immunoglobulin molecule pairs with L chains and binds specifically to antigen on target cells
L chains
Identical to H chains but half as long.
antigen-binding site
The site on an immunoglobulin or T-cell receptor molecule that binds specific antigen.
neutralization
The mechanism by which antibodies binding to sites on pathogens prevent growth of the pathogen and/or its entry into cells. The toxicity of bacterial toxins can similarly be neutralized by bound antibody.
agglutination
An antibody-mediated immune response in which bacteria or viruses are clumped together, effectively neutralized, and opsonized.
precipitation
soluble molecules are cross-linked into large complexes that settle out the solution. (an immune complex)
complement fixation and activation
chief antibody defensed used against cellular antigens. (an immune complex)
helper T cells
T cells that help the immune system by increasing the activity of killer cells and stimulating the suppressor T cells
cytotoxic T cells
T cells that can kill other cells. Almost all cytotoxic T cells are CD8 T cells. Cytotoxic T cells are important in host defense against viruses and other cytosolic pathogens, because they recognize and kill the infected cells.
Class I MHC proteins
Found on virtually all body cells
Class II MHC proteins
protein found only on the surface of B lymphocytes, macrophages, and dendritic cells that serves as a reference point for self (looked for by T helper cells)
T Cell Activation
The stimulation of mature T cells by antigen presented to them by professional antigen-presenting cells. It leads to their proliferation and differentiation into effector T cells.
Antigen Binding
First step of T Cell Activation, caused by T cell antigen receptors binding to an antigen-MHC complex on the surface of an APC.
cytokines
chemicals released by T helper cells that stimulate B cells
interleukin 1 & 2
A cytokine secreted by a macrophage that is in the process of phagocytizing and presenting antigen. It in combination with the antigen, activates the helper T cell to produce IL2 and other cytokines.
T cell-independent antigens
-no T cell activation, no memory T cells
macrophage can't engulf CHO capsule unless opsonized by Ab (protective- hard to make Ab to CHO)
-infants under 2-> no T cell independent (susceptible to capsular pathogens)
T cell-dependent antigens
Most antigens require Helpter T Cells co-stimulation to activate B cells. These are called:
cytotoxic T cells
T cells that can kill other cells. Almost all cytotoxic T cells are CD8 T cells. Cytotoxic T cells are important in host defense against viruses and other cytosolic pathogens, because they recognize and kill the infected cells.
perforins
Chemicals secreted by certain lymphocytes that create holes in the membrane of a host cell which causes the host cell to swell and rupture
allergies
overreaction of the immune system to antigens
allergen
any substance that can cause an allergy