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AP Immunology
Thib Chapter 21 Immune System
102
Medical
Graduate
02/13/2010

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Term
The immune system
Definition
protects against assaults on the body
Term
external assaults
Definition
include microorganisms: protozoans, bacteria, and viruses
Term
internal assaults
Definition
include abnormal cells tha reproduce and form tumors that may become cancerous and spread
Term
the immune system
Definition
is continually at work patrolling and protecting the body
Term
markers or antigens
Definition
are unique molecules recognized by the immune system
Term
self-markers
Definition
molecules on the surface of cells that are unique to an individual, thus identifying the cell as “self” to the immune system
Term
non-self markers
Definition
molecules on the surface of foreign or abnormal cells or particles that identify the particle as “non-self” to the immune system
Term
self-tolerance
Definition
the ability of the immune system to attack abnormal or foreign cells but spare normal cells
Term
innate and adaptive immunity
Definition
Two major categories of immune mechanisms
Term
innate immunity
Definition
provides a general, nonspecific defense against anything that is not “self”
Term
adaptive immunity
Definition
acts as a specific defense against specific threatening agents
Term
-epithelial barrier cells
-phagocytes (neutrophils, macrophages, dendritic cells)
-natural killer cells
Definition
Primary cells for innate immunity:
Term
complement and interferon
Definition
chemicals used in innate immunity:
Term
lymphocytes called T cells and B cells
Definition
Primary types of cells for adaptive immunity:
Term
cytokines
Definition
any of several kinds of chemicals released by cells to promote innate and adaptive immune responses (e.g., interleukin, interferon, leukotriene)
Term
species resistance
Definition
genetic characteristics of an organism or species that defend against pathogens
Term
mechanical and chemical barriers
Definition
first line of defense
Term
skin and mucous membranes
Definition
Internal environment of the body is protected by a barrier composed of the
Term
sebum, mucus, enzymes, and hydrochloric acid in the stomach
Definition
Skin and mucous membranes provide additional immune mechanisms
Term
inflammation and fever
Definition
second line of defense
Term
inflammatory response
Definition
tissue damage elicits responses to counteract injury and promote normalcy
Term
histamine, kinins, prostaglandins, and related compounds
Definition
Inflammation mediators include
Term
chemotactic factors
Definition
substances that attract white blood cells to the area in a process called chemotaxis
Term
heat, redness, pain, and swelling
Definition
Characteristic signs of inflammation
Term
systemic inflammation
Definition
occurs from a bodywide inflammatory response
Term
fever
Definition
abnormally high temperature triggered by inflammation mediators
Term
fever
Definition
Triggered in systemic inflammatory response syndrome and events such as viral infections, tumors, allergies
Term
pyrogens
Definition
released from damaged tissues (endogenous) or introduced into the body (exogenous) promote prostaglandin (PG) production
Term
prostaglandins
Definition
reset the hypothalamic “thermostat” to a higher temperature; aspirin and other cyclooxygenase inhibitors interfere with their production
Term
fever
Definition
believed to increase immune function and inhibit pathogens
Term
phagocytosis
Definition
ingestion and destruction of microorganisms or other small particles by phagocytes
Term
antigen presenting cells
Definition
phagocytes that ingest foreign particles, isolate protein segments (peptides), and display them as antigens on their surface to trigger an immune response when recognized by a specific (adaptive) immune cell
Term
chemotaxis
Definition
chemical attraction of cells to the source of the chemical attractant
Term
diapedesis
Definition
process by which immune cells squeeze through the wall of a blood vessel to get to the site of injury or infection
Term
neutrophil
Definition
most numerous phagocyte; usually first to arrive at site of injury; migrates out of bloodstream during diapedesis; forms pus
Term
macrophage
Definition
large phagocytic cells
Term
dendritic cell
Definition
type of phagocytic antigen-presenting cell with long branches or extensions
Term
phagocytes
Definition
Examples are histiocytes in connective tissue, microglia in nervous system, and Kupffer cells in liver
Term
natural killer cells
Definition
lymphocytes that kill tumor cells and cells infected by viruses
Term
target cell is killed if killer-inhibiting receptor on NK cell does not bind to a proper major histocompatibility complex surface protein
Definition
Method of recognizing abnormal or non-self cells--
Term
lysing cells by damaging plasma membranes
Definition
NK method of killing cells--
Term
interferon
Definition
protein synthesized and released into circulation by certain cells if invaded by viruses to signal other nearby cells to enter a protective antiviral state
Term
complement
Definition
group of enzymes that produce a cascade of reactions resulting in a variety of immune responses
Term
Complement
Definition
Lyse cells when activated by either adaptive or innate mechanisms
Term
opsonization
Definition
mark cells for destruction by phagocytes
Term
toll-like receptors
Definition
pattern recognition receptors in the membranes of host cells; when triggered, stimulate many different kinds of innate immune responses
Term
adaptive immunity
Definition
part of the third line of defense consisting of lymphocytes—two different classes of a type of white blood cell
Term
B lymphocytes (B cells) and T lymphocytes (T cells)
Definition
Two classes of lymphocytes
Term
CD surface markers
Definition
Subsets of lymphocytes are defined by the ____ that the cells carry
Term
lymphocytes
Definition
flow through the bloodstream, become distributed in tissues, and return to the bloodstream in a continuous recirculation
Term
antibody-mediated immunity (humoral immunity); produce antibodies that attack pathogens
Definition
B-cell mechanisms
Term
T-cells
Definition
attack pathogens more directly; classified as cell-mediated immunity (cellular immunity)
Term
lymphocytes
Definition
have protein markers on their surfaces that are named by the CD system
Term
a specific antigen and activating chemicals
Definition
Activation of lymphocytes requires two stimuli:
Term
in bone marrow, thymus gland, lymph nodes, and spleen
Definition
Lymphocytes are densest where they develop—
Term
-Pre–B cells develop by a few months of age
-The second stage occurs in lymph nodes and spleen—activation of a naive B cell after it binds to a specific antigen
Definition
B cells develop in two stages:
Term
B cells
Definition
serve as ancestors to antibody-secreting plasma cells
Term
antibodies
Definition
proteins (immunoglobulins) secreted by activated B cell
Term
an antibody molecule consists of two heavy and two light polypeptide chains; each molecule has two antigen-binding sites and two complement-binding sites
Definition
Structure of antibody molecules:
Term
bone marrow, lymph nodes, and spleen;
variable
Definition
infants are born with different clones of B cells in ___, ___, and ___; cells of the clone synthesize a specific antibody with a sequence of amino acids in its ___ region that differs from the sequence synthesized by other clones
Term
immunoglobulins M, G, A, E, and D
Definition
Five classes of antibodies--
Term
IgM
Definition
antibody that naive B cells synthesize and insert into their own plasma membranes; the predominant class produced after initial contact with an antigen
Term
IgG
Definition
makes up 75% of antibodies in the blood; predominant antibody of the secondary antibody response
Term
IgA
Definition
major class of antibody in mucous membranes, in saliva and tears
Term
IgE
Definition
small amount; produces harmful effects such as allergies
Term
IgD
Definition
small amount in blood; precise function unknown
Term
plasma
Definition
Antibody molecules produce antibody-mediated immunity (humoral immunity) within
Term
Antibodies
Definition
resist disease first by recognizing foreign or abnormal substances
Term
epitopes
Definition
bind to an antibody molecule’s antigen-binding sites, which forms an antigen-antibody complex that may have several effects
Term
complement
Definition
a component of blood plasma consisting of several protein compounds
Term
complement
Definition
kills foreign cells by cytolysis or apoptosis
Term
complement
Definition
causes vasodilation, enhances phagocytosis, and has other functions
Term
innate immune mechanisms
Definition
Complement activity can also be initiated by
Term
alternate pathway
Definition
Formation by innate immunity is called the
Term
complement protein 3
Definition
activated without antigen stimulation, produces full complement effect by binding to bacteria or viruses in presence of properdin
Term
Primary response (antibody mediated immunity)
Definition
initial encounter with a specific antigen triggers the formation and release of specific antibodies that reaches its peak in a few days
Term
Secondary response
Definition
a later encounter with the same antigen triggers a much quicker response; B memory cells rapidly divide, producing more plasma cells and thus more antibodies
Term
-The body contains many diverse clones of cells, each committed by its genes to synthesize a different antibody
-When an antigen enters the body, it selects the clone whose cells synthesize its antibody and stimulates them to proliferate and create more antibody
-The clones selected by antigens consist of lymphocytes and are selected by the shape of antigen receptors on the lymphocyte’s plasma membrane
Definition
What is the Clonal selection theory?
Term
T cells
Definition
lymphocytes that go through the thymus gland before migrating to the lymph nodes and spleen
Term
thymocytes
Definition
Pre–T cells develop into ___ while in the thymus
Term
spleen
lymph nodes
Definition
Thymocytes stream into the blood and are carried to the T cell–dependent zones in the __ and the __
Term
antigen receptors
Definition
T cells display ___ on their surface membranes that are similar to antibodies
Term
antigen (presented by an antigen-presenting complex) binds to its receptors (at an immunological synapse), causing the T cell to divide repeatedly to form a clone of identical T cells
Definition
A T cell is activated when an
Term
effector T cells and memory T cells
Definition
Cells of the clone differentiate into
Term
Effector T cells
Definition
go to the site where the antigen entered, bind to antigens, and begin their attack
Term
lymphotoxin
Definition
Cytotoxic T cells: T cells release ___ to kill cells
Term
Helper T cells
Definition
regulate the function of B cells, T cells, phagocytes, and other leukocytes
Term
Suppressor T cells
Definition
regulatory T cells that suppress lymphocyte function, thus regulating immunity and promoting self-tolerance
Term
T cells
Definition
function to produce cell-mediated immunity and help regulate adaptive immunity in general
Term
Adaptive/acquired immunity
Definition
resistance developed after birth; two types: natural and artificial
Term
natural immunity
Definition
results from nondeliberate exposure to antigens
Term
artificial immunity
Definition
results from deliberate exposure to antigens, called immunization
Term
Natural and artificial immunity may be active or passive
Definition
Natural and artificial immunity may be x
Term
active immunity
Definition
when immune system responds to a harmful agent regardless of whether it is natural or artificial; lasts longer
Term
passive immunity
Definition
immunity developed in another individual is transferred to an individual who was not previously immune; temporary but provides immediate protection
Term
adaptive immunity
Definition
specific immunity targeting specific antigens
Term
B cells
Definition
antibody-mediated (humoral) immunity
Term
T cells
Definition
cell-mediated (cellular) immunity
Term
-Recognition of antigen
-Activation of lymphocytes
-Effector phase (immune attack)
-Decline of antigen causes lymphocyte death (homeostatic balance)
-Memory cells remain for later response if needed
Definition
Adaptive immunity occurs in a series of stages:
Term
B cells and T cells
Definition
work together in a coordinated system of adaptive immunity
Term
nervous and endocrine systems
Definition
Immune system regulated to some degree by
Term
blood cells, skin cells, mucosal cells, brain cells, liver cells, and other types of cells and their secretions
Definition
Agents of the immune system include
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