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BIOLOGY GLOSSARY 7
glossary terms chapter 7
| Question | Answer |
|---|---|
| Adaptive immunity | an immune response that is specific to a particular antigen, only present in vertebrates |
| Aggluination | the process in which antibodies bind to antigens on the surface of cells and form antigen-antibody complexes that clump together and activate phagocytes and the complementary cascade, which leads to antigen/cell destruction |
| Allergen | an antigen that elicits an allergic response |
| Anitbody | also known as immunoglobulins, antibodies are proteins produced by plasma cells that are highly selective for, and bind to, specific antigen molecules |
| Antigen | a substance that reacts with antibodies and T lymphocyte receptors; antigens that induce an immune response are immunogens |
| Antigen-antibody complex | a specific chemical interaction between an antibody (immunoglobulin) molecule and an antigen molecule |
| Antigen presentation | the presentation of antigens by antigen-presenting cells |
| Antigen-presenting cell | a cell that uses MHC-II on its surface to present foreign antigens to helper T lymphocytes to elicit an adaptive immune response. Examples include dendritic cells and macrophages |
| Antigenic variation | the mechanism of changing surface antigens, usually to avoid detection or immune attacks. Employed by certain protozoans such as plasmodium sp. |
| Cell-mediated immunity | an immune response that is mediated by T lymphocytes |
| Cellular pathogens | cellular organisms that are a source of non-self antigens and cause disease. These include bacteria, protozoa, oomycytes, fungi, several types of worms, and arthropods |
| Chemokine | cytokines that attract white blood cells to the site of infection |
| Clonal selection | the theory that in a group of lymphocytes, a specific antigen will activate only the lymphocyte that has a receptor that specifically recognises it. This lymphocyte will proliferate into clones of itself |
| Complement proteins | proteins that are able to kill foreign cells by lysis. There are over 30 types, activated in response to anitgen-antibody complexes, antigens and carbohydrates on the surfaces of some bacteria and parasites |
| Constant region | the region of antibody molecules that remains the same and interacts with receptors on the body's cells |
| Cytotoxic T lymphocyte | T lymphocyte that is stimulated by cytokines to bind to antigen-MHC I complexes on infected host cells and release cytotoxic compounds that destroy the infected cells |
| Defensins | molecules active against bacteria, fungi and certain viruses |
| Fever | an increase in body temperature that results from the regulated body temperature set point in the hypothalamus of the brain being set to a higher level by inflammatory cytokines, to slow the replication of bacteria and improve the adaptive immune response |
| Heavy chains | the polypeptide chain that forms the 'stem' of a y-shaped antibody molecule |
| Helper T lymphocyte | helper T lymphocytes bind to antigen- MHC II complexes on antigen presenting cells and activate B lymphocytes to secrete antibodies, macrophages and phagocytose, and cytotoxic T cells to kill infected cells |
| Histamine | an organic compound involved in inflammatory responses ad allergic reactions, which causes surface blood vesicles to dilate and become more permeable to immune cells and fluids. Common hay-fever symptoms are the result of histamine action |
| Humoral immunity | an immune response involving B lymphocytes that produce specific antibodies against foreign antigens |
| Immunogens | antigens that elicit an immune response |
| Immunoglobulin | alternate name for an antibody |
| Immunological memory | the ability of lymphocytes of adaptive immune systems to 'remember' antigens after primary exposure, and mount to a larger and more rapid response when exposed to the same antigen again |
| Inflammation | a protective response triggered by damaged tissue or invading pathogens that leads to increased blood flow and migration of white blood cells to the site of damage/infection. It results in heat, pain, swelling, redness, and loss of function |
| Innate immunity | non-specifically protects against a wide variety of pathogens, It consists of physical, chemical and microbiological barriers that provides resistance to infection, and an innate immune response to infection that involves phagocytes & defensive molecules |
| Leukocyte | white blood cells; includes phagocytes and lymphocytes |
| Light chain | the short polypeptide chains that form the 'arms' of a Y shaped antibody molecule |
| Lymph | a colourless fluid that contains white blood cells, bathes tissues, and travels through the lymphatic system, draining into the bloodstream |
| Lymphatic system | the body system that transports immune cells including antigen-presenting cells throughout the body, and is where antigen recognition by lymphocytes occurs; important for adaptive immune responses in mammals |
| Lymphocyte | a type of leukocyte involved in the adaptive immune responses; includes B and T lymphocytes |
| Major histocompatibility complex (MHC) | a group of MHC proteins on the surface of cells, involved in antigen presentation to T cells. MHC proteins are known as human leukocyte antigens |
| Mast cell | an immune cell containing granules of histamine. This cell mediates allergic responses by binding IgE-allergen complexes and releasing histamines |
| Memory B lymphocyte | B lymphocytes activated against a specific antigen that remains in the lymphoid tissues for a long time, and permit a faster and more effective secondary immune response if the same antigen is encountered again |
| Memory T lymphocyte | T lymphocytes activated against a specific antigen that remains in the lymphoid tissues for a long time, and permit a faster and more effective secondary immune response if the same antigen is encountered again |
| Neutralisation | the binding of neutralising antibodies to toxins or antigens on the outer surface of pathogens that inhibits their action or ability to enter cells |
| Non-self antigen | antigens that do not belong to an organisms' own cells |
| Pathogen | an organism that can produce disease in another organism; includes many micro-organisms and parasites |
| Phagocyte | cells capable of engulfing pathogens or foreign particles to destroy them |
| Plasma cell | activated B-lymphocytes that produce large quantities of the same type of antibody |
| Primary immune response | the immune response to an antigen that has been encountered for the first time |
| Primary lymphoid organ | the major organs of the lymphatic system: the bone marrow and the thymus |
| Prion | a small protein particle that, when its shape is altered due to mutation, causes protein aggregation and is toxic to neurons. Prions are the cause of spongiform encephalopathy diseases, BSE in cattle, and CJD in humans |
| Secondary immune response | the immune response to an antigen that has previously been encountered and which elicited a primary immune response. The process activates memory cells and so is faster and more effective than the primary response |
| Secondary lymphoid organs and tissues | the organs and tissues of the lymphatic system in which adaptive immune responses initiate: the lymph nodes, spleen tonsils, adnoids, and appendix |
| Self-antigen | an organisms own antigens, which are normally tolerated (do not elicit an immune response) |
| Self-tolerance | the inability of the adaptive immune system to respond to self-antigen |
| T-cell receptor | a molecule found on the surface of T lymphocytes that is responsible for recognising fragments of antigen as peptide bounds to MHC proteins. It is made up of two polypeptide chains that have a variable and a constant region & only one antigen-binding site |
| Variable region | the region of an antibody molecule that varies between different antibodies and allows them to interact with different antigens |
| Virus | an infectious agent composed of genetic material (DNA or RNA) enclosed in a protein coat, and sometimes also a lipoprotein envelope; is only able to multiply in a host cell |
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