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Immune System - Innate & Adaptive Body Defenses

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What is the body's 1st line of defense against pathogens?
Skin, mucous and protective membranes.
What is the body's 2nd line of defense against pathogens?
The innate cellular and chemical defenses.
What are phagocytes and what do they do within the immune system?
A white blood cell that engulfs and destroys pathogens that breach epithelial barriers.
What is a lysin?
An antibody capable of causing destruction or dissolution of RBCs, bacteria, or other cellular elements.
Name the steps of the inflammatory process?
Exudate is formed; protective leukocytes enter the area; the area is walled off by fibrin; and tissue repair occurs.
What is the purpose of the inflammatory process?
To prevent spread of harmful agents, disposes of pathogens and dead tissue cells, and promotes healing.
What causes the "cardinal signs" of inflammation?
Vasodilation and increased permeability of blood vessels induced by inflammatory chemicals.
What are Interferons?
Group of related proteins synthesized by virus-infected cells and certain immune cells that prevent viruses from multiplying in other body cells.
Define complement.
Group of bloodborne plasma proteins activated after binding to antibody, that enhances phagocytosis and the inflammatory/adaptive immune responses.
Define lysis.
Dissolution or destruction of cells, such as blood cells or bacteria, as performed by specific lysin that disrupts the cell membrane.
Define Congenital thymic aplasia.
Immune deficiency disease where thymus fails to develop. Individuals have no T cells; hence, little or no immune protection.
Define Systemic lupus erythematosus (SLE).
Systemic autoimmune disorder occurring in young females. DNA/anti-DNA complexes localize in kidneys, blood vessels, brain, and joints, resulting in vascular problems, memory loss, and painful arthritis.
What does C-reactive proteins do?
Indicates level of infection or inflammation in body. Also activates complement, facilitates phagocytosis, and targets cells for disposal.
What important roles does fever play in the immune response?
Enhances body's fight against pathogens by increasing metabolism, and by prompting liver and spleen to sequester iron and zinc needed for bacterial multiplication.
What is the purpose of the adaptive immune system?
It recognizes something as foreign and acts to immobilize, neutralize, or remove it.
In order for a phagocyte to accomplish ingestion, what event must occur?
Adherence.
What is the difference between a complete antigen and an incomplete antigen?
Complete antigens have both immunogenicity and reactivity. Incomplete antigens or haptens must combine with a body protein before becoming immunogenic
What is an antigenic determinant?
Portions of antigen molecules that are recognized as foreign.
What are Major Histocompatibility Complex (MHC)proteins?
Membrane-bound glycoproteins that mark our cells as self.
What is the difference between a Class I and Class II MHC protein?
Class I MHC proteins are found on all body cells (except RBCs); the class II variety is found on surfaces of cells that function in the adaptive immune response.
Define immunocompetence.
Ability of the body's immune cells to recognize (by binding) specific antigens.
How is immunocompetence signaled?
By appearance of antigen-specific receptors on lymphocyte surfaces.
What is an Antigen-presenting cell?
Cells that phagocytize pathogens and present antigenic determinants on their surfaces for recognition by T cells. APCs include dendritic cells, macrophages, and activated B lymphocytes.
What is humoral immune response?
Immunity conferred by antibodies present in blood plasma and other body fluids.
Define clonal selection.
Process during which a B cell or T cell become sensitized through binding contact with an antigen.
What is a memory cell?
Members of B cell and T cell clones that provide for immunologic memory.
How is active humoral immunity acquired?
It is acquired during an infection or via vaccination and provides immunological memory.
How is passive immunity acquired?
Whenever a donor's antibodies are injected into bloodstream, or when a mother's antibodies cross the placenta. Protection is short-lived and immunological memory is not established.
What is the make-up of the antibody monomer?
4 polypeptide chains, 2 heavy, 2 light, connected by disulfide bonds. Each chain has both a constant and variable region.
What are the five classes of antibodies?
IgM, IgA, IgD, IgG, and IgE.
Define phagocyte.
WBC (macrophages, neutrophils, etc.) that engulf and destroy pathogens that breach epithelial barriers.
What is IgM?
Class of antibodies found in circulating body fluids and first antibodies to appear in response to initial exposure to antigens.
What is IgA?
Include antibodies found in external bodily secretions (as saliva, tears, and sweat)
What is IgD?
Antibodies found only on surface of B cells and possibly functioning as antigen receptors to initiate differentiation of B cells into plasma cells.
What is IgG ?
Most abundant antibodies found in blood serum, lymph. Trigger action of complement system.
What is IgE?
Antibodies produced in lungs, skin, and mucous membranes and responsible for allergic reactions.
Define the two types of antibody regions.
Constant regions determine antibody function and class; variable regions enable antibodies to recognize its appropriate antigen.
What are monoclonal antibodies?
Pure preparations of a single antibody type useful in diagnostic tests and in treatment for some types of cancer.
How are immunocompetent helper cells (TH) and cytotoxic (TC) T cells activated?
By binding simultaneously to an antigen and a MHC protein displayed on the surface of an APC.
What's the difference between humoral immunity and cellular immunity?
Humoral (humors = fluids) immunity is provided by antibodies produced by B lymphocytes present in body's humors; cellular immunity is associated with T lymphocytes and has living cells as its protective factor.
Define immunodeficiency.
Any congenital or acquired condition that causes immune cells, phagocytes, or complement to behave abnormally.
How does the primary immune response come about?
It occurs on 1st exposure to a particular antigen, with a lag time of about 3-6 days.
How does the secondary immune response come about?
It occurs when someone is re-exposed to the same antigen, only acts fasters, more prolonged and more effective.
Define Helper T cell. (aka CD4, T4 cells)
Any T cell that when stimulated by a specific antigen, releases lymphokines that promote activation and function of B cells and killer T cells.
Define Natural Killer (NK) cells.
Defensive cells that can lyse and kill cancer cells and virus-infected cells before the immune system is activated. Does not need to recognize specific antigen to kill.
Define suppressor T cell.
T cell that reduces or suppresses the immune response of B cells or other T cells to antigens.
Define Gamma delta T cell.
T cell located in the intestine that is more similar to NK cells than other T cells.
Define autoimmune disease.
Immune system loses its ability to differentiate between self and non-self and ultimately destroys itself.
Define allergy.
Result of immune system causing tissue damage as it fights off a perceived threat, otherwise harmless.
What is AIDS?
Acquired immune deficiency syndrome cripples the immune system by interfering with helper T cells.
Define autograft.
Tissue grafts transplanted from one body site to another in the same person.
Define isograft.
Grafts donated to a patient by a genetically identical individual such as an identical twin.
Define allograft.
Grafts transplanted from individuals that are not genetically identical, but belong to the same species.
Define xenograft.
Grafts taken from another animal species.
What is a HIV?
An immunodeficiency virus that destroys TH cells, thus depressing cell-mediated immunity.
Define autoimmunity.
Occurrence where immune system loses ability to distinguish itself from foreign antigens.
Define anaphylactic shock.
Bodywide, systemic response that occurs when allergen directly enters blood and circulates rapidly through body (bee stings, spider bites, injections).
How are subacute hypersensitivites activated?
By antibodies (IgG and IgM rather than IgE) and can be transferred via blood plasma or serum.
How does allergic contact dermatitis react within the body.
Following skin contact with poison ivy, heavy metals, cosmetics, deodorants), these agents act as haptens, and after diffusing through skin and attaching to self-proteins, they become foreign to immune system.
What is the function of free macrophages?
To wander through tissue spaces in search of cellelur debris.
What is the role of fixed macrophages?
Same as free macrophages but they remain "fixed" to a particular organ.
Which WBCs become phagocytic when encountering infections?
Neutrophils, Eosinophils (worms).
What process makes adherence more probable?
Opsonization, where complement proteins and antibodies coat foreign particles. Coating provides handles.
What is a respiratory burst?
An event that liberates a deluge of free radicals that have potent killing abilities.
What are 3 qualities of the adaptive immune response?
Antigen-specific, systemic, and memory. Is 3rd line of defense.
What are cytokines?
Powerful chemical substances secreted by cells. Includes lymphokines and monokines.
Define Severe Combined Immunodeficiency Disease (SCID).
A life threatening condition where babies are born without any major immune defenses.
What is an antigen challenge and where does it take place?
1st encounter between an immunocompentent, naive lymphocyte and an invading antigen. Usually takes place in spleen or lymph node.
What are buboes?
Infected lymph nodes that become inflamed, swollen, and tender to touch. Often called swollen glads.
What are the functions of antibodies?
Complement fixation, antigen neutralization, precipitation, agglutination.
Define cytoxic T cells (aka CD8, T8 cells, Killer T cells).
The only cells that can directly attack and kill other cells. Rejects organ grafts.

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