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58 Cards in this Set
- Front
- Back
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Innate immunity
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inborn, rapid and non-specific
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Acquired immunity
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in response to a specific antigen - it is slower and longer lasting (slow and specific)
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Passive acquired immunity
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requires a donor who has antibodies against a pathogen and is temporary (as the donated antibodies will break down) - gamma globulin, administration of antibody against Hep A, the transfer of maternal antibodies across the placenta to the fetus, or maternal antibodies in breast milk.
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Examples of passive acquired immunity
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breast milk, placenta, and gamma globulin
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Active acquired immunity
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it's a hosts own response to an antigen. It is specific to an antigen, and is long lasting, as the body produces memory cells that can produce a more rapid and larger response when exposed to the same antigen again.
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Active immunity is produced in the body
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after either natural exposure to a antigen, or by immunization.
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An antigen
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is a molecule that can react with antigen receptors on B or T cells, or with an antibody.
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Antigens can be
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bacteria, viruses, fungi, pollens, food proteins, drugs, or chemicals
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Immunogens
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antigens that are large enough to cause an immune response
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Immunogenicity
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- the most important criterion is foreignness - other factors are size, chemical complexity, and quantity.
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Antibody
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Immunoglobulin (Ig)
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What are the 5 classes of immunoglobulins (Ig)
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IgM, IgG, IgA, IgE, IgD
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IgM
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The largest pentamer structure - produced during the initial (primary) response, that is after the first exposure to an antigen - transiently produced during the secondary response (a subsequent exposure to an antigen) but the amount in the secondary exposure is far less than IgG
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IgG
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Most abundant class of immunoglobulins in the body. Small monomer structure - able to cross the placenta to the fetus - produced after IgM - concentrations (titer) higher in second response
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IgA
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Dimer (2 together) structure - IgA1 mostly in the blood - IgA2 - in secretions
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IgE
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Monomer structure - involved in mediating allergic responses and protection against parasites
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IgD
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Monomer structure - function not understood
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IgM
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Mama is big - 1st exposure - largest structure - comes out first
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IgG
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Grandma is old - later exposure
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IgE
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Eosinophil - allergies and parasites
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IgA
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secretions
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Antibodies are made
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to combat antigens
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Antigen
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is something that stimulates the immune system
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Lymphocytes are formed
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from lymphoid stem cells in the yolk sac of the embryo, then the liver of the fetus, and later in the bone marrow of a child or adult
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The lymphoid stem cells migrate
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to the central lymphoid organs (the thymus or the bone marrow) - where they divide and differentiate and undergo the generation of clonal diversity
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What are the central lymph organs
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thymus and bone marrow
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T lymphocytes (T cells) develop from the
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thymus
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B lymphocytes (B cells) develop from the
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bone marrow
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The T cells and B cells undergo clonal diversity by the following process
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There are genes (V,J, and D genes) on chromosome 14. During cell maturation, enzymes select a random V gene and a random J gene out of a possible 50 each and combine them. This random selection allows for millions of different DNA segments that in turn code for millions of different protein chains (similar to how we can create millions of different license plate numbers using only 7 characters) - The BCR's and TCR's (B cell and T cell receptor complexes) are protein structures that each have 2 of these protein chains with variable areas. These protein chains make receptors that are therefore unique to millions of antigens - so the human has T cells and B cells that can react to virtually any antigen found in nature
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Immunocompetent
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After clonal diversity the T and B cells can respond to an immunogen (antigen that causes an immune response) - each individual T and B lymphocyte specifically recognized only one particular antigen
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After clonal diversity
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the cells migrate to the secondary lymphoid organs (spleen, adenoids tonsils, appendix, and lymph nodes - including the Peyer's Patches which are the lymph nodes of the gastrointestinal system)
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When an antigen (pathogen) invades a host
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the first response is the inflammatory response - some of the cells involved in the innate immune response communicate with the B and T lymphocytes in the secondary lymphoid organs
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What happens when an antigen enters the lymph nodes?
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macrophages (which develop from monocytes) ingest (phagocytose) the infectious agent or fragments of a microorganism - they then function as antigen-processing (presenting) cells (APC's) to present the antigen to the B cells and T cells - Helper T cells are also involved - when the antigen is presented to the immunocompetent B cell whose receptor site matches the antigen, the B-cell receptor (BCR) complex communicates information about the antigen to the cell nucleus - the B cell begins to produce antibodies and is then called a plasma cell. B cells proliferate in the lymph nodes.
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Secondary immune response
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macrophages also present the antigen to memory T helper cells - if the antigen has been seen before it initiates a rapid and large response
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Besides macrophages, what 2 other cells act as primary present cells (APCs)
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B cells present antigens to T helper cells and dendrite cells (other specialized white blood cells) which migrate to the site of inflammation in the peripheral tissues of the skin or intestinal tract, phagocytose the antigen, and then return to the lymph nodes to present it to the T cells.
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Humoral Immunity
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antibodies produced by the plasma B cells circulate in the blood and bind to antigens - the binding can directly inactivate the microorganism, or can activate inflammatory mediators that destroy the pathogen - antibodies protect against bacteria and viruses
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Humoral
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comes from ancient Roman and Greek medicine - they thought there were 4 Humors that flowed through the body - each was associated with a mood, an element, and a season - disease was an imbalance of these humors
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4 Humors
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Black bile ( melancholy, earth, autumn)
Yellow bile (choleric, fire, summer) Phlegm (phlegmatic, water, winter) Blood (sanguine, all 4 elements, spring) |
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Cell-Mediated Immunity
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when an antigen is presented to immunocompetent T cells, they differentiate into specialized functional T cells, such a cytotoxic T cells (Tc cells) that attack targets, such as cells infected by viruses and cancer cells
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T1 helper cells
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are induced by antigens from viral or bacterial pathogens, or by cancer cells - they provide more help in the cell-mediated immunity
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T2 helper cells
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are induced by multicellular parasites and allergens and provide more help in the humoral immunity
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T helper cells (Th cells)
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a subpopulation of T cells - they magnify the interaction between the APC's and the B cells and T cells and facilitate their maturation into cells capable of producing antibodies - T helper cells are critical to most immune responses and T helper cell defects can lead to severely diminished immune repsonse
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Major histocompatibility complex (MHC) molecules
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are located on the surface of all body cells except erythrocytes - these molecules are encoded in a large complex of genes on chromosome 6 - each of these genes has a huge number of possible choices, or alleles (between 56 for one gene to 559 for another) - this huge number of choices (many times more than the choices for hair or eye color, nose shape, etc) is what really makes our cells unique - this is what makes it hard to find a perfect match for bone marrow or organ transplant
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How many copies of the MHC ( major histocompatibility complex) molecules do we have?
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every human has two copies of the MHC, one inherited from each parent as a group of genes - the genes are co-dominant so that the MHC genes of both parents are expressed as molecules on the cell surfaces of the child
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What are the MHC molecules present on the leukocytes called?
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Human leukocyte antigens (HLA's) - in transplants the donor and recipient are typed as to their HLA's - the more closely the HLA's match the more likely the tissue will not be rejected
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Tolerance
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the B cells and T cells undergo generation of clonal diversity - if the B cell or T cell creates a receptor for an antigen which is part of the host, the immune system eliminates or suppresses those cells.
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Regulatory T cell (Treg)
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the T cell that limits the immune response to protect the host's own tissues against an autoimmune response - this process limits the autoimmune response
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Viruses that cause measles and herpes
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are inaccessible to antibodies after the initial infection because they do not circulate in the blood, but invade and remain inside infected cells
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What does the systemic immune system do
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protects the entire body
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Secretory immune system =
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mucosal immune system
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The secretory immune system or mucosal immune system
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is a partially independent immune system that is located at the possible entry points for pathogens, especially mucous membranes
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Lymphocytes of the secretory immune system are found in
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lacrimal glands, salivary glands, bronchial tissue, mammary tissue, Peyer's patches, and genital lymph tissue - thus antibodies are present in many bodily fluids, including tears, sweat, saliva, mucus and breast milk - these protect the body against antigens before they penetrate the skin or mucous membranes from inhalation, swallowing, etc
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The predominant antibody found in the secretory immune system is
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IgA
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Cytokines
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are low-molecular weight proteins or glycoproteins that function as chemical signals between cells
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Cytokines are produced by
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a wide variety of cells and play important roles in both inflammation and the acquired immune response - their effect depends on which cellular receptors they bind to.
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Some cytokines are
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growth factors that induce proliferation and differentiation of cells
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Cytokines include
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Interleukins (IL), Interferons (INF), tumor neucrosis factors (TNF), and transforming growth factor (TGF)
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Infants and the elderly have deficiencies in their immune system
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making them more susceptible to infection
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