| A | B |
|---|
| pathogen | a disease-causing organism |
| infectious disease | disease caused by a pathogen |
| nonspecific defense | physical or chemical barrier that prevents pathogens from entering the body |
| inflammatory disease | nonspecific defense against infection, characterized by redness, heat, swelling, and pain |
| histamine | chemical alarm signal released by mast cells that causes blood vessels to dilate during an inflammatory response |
| interferon | protein produced by cells in response to being infected by a virus; helps other cells resist the virus |
| immunity | resistance to a specific pathogen |
| antigen | foreign molecule that provokes an immune response |
| antibody | protein in blood plasma that attaches to a particular antigen |
| B cell | lymphocyte that matures in the bone marrow and later produces antibodies; responsible for humoral immunity |
| T cell | lymphocyte that matures in the thymus; is responsible for cell-mediated immunity and also plays a role in humoral immunity |
| plasma cell | antibody-secreting B cell |
| humoral immunity | specific immunity produced by B cells that produce antibodies that circulate in body fluids |
| cell-mediated immunity | type of immunity produced by T cells that attack infected or abnormal body cells |
| cytotoxic T cell | lymphocyte that attacks body cells infected with pathogens |
| helper T cell | lymphocyte that activates cytotoxic T cells and stimulates B cells to produce antibodies |
| memory cell | long-lasting lymphocyte formed during the primary immune response that is reactivated on exposure to the same pathogen, quickly producing many clones |
| vaccine | dose of a disabled or destroyed pathogen (or part of a pathogen) used to stimulate a long-term immune defense against the pathogen |
| active immunity | immunity provided by the body producing its own antibodies against a particular antigen; results from exposure to the antigen via infection or vaccine |
| passive immunity | resistance to a particular pathogen that results when the body acquires antibodies for it, as when a baby receives antibodies from it mother |
| allergy | abnormal immune system sensitivity to an otherwise harmless antigen |
| autoimmune disease | disorder in which the immune system attacks the body's own molecules |
| AIDS | acquired immune deficiency syndrome; the late stages of HIV infection |
| HIV | human immunodeficiency virus; virus that destroys helper T cells and causes AIDS |
