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.