Flashcards in The specific immune system Deck (18):
What are antibodies?
-Y-shaped glycoproteins called immunoglobulins which bind to a specific antigen on a pathogen.
-Specific for each antigen.
What are the characteristics of antibodies?
-Made of two identical long polypeptide chains called heavy chains, and two short polypeptide chains called light chains.
-Chains held by disulfide bonds.
-Antibodies bind to antigen with a lock and key mechanism.
-Has a binding site, and a variable region which is different on each antibody.
-Has a constant region which is the same shape for all antibodies.
What is an antigen-antibody complex?
-When antibody binds to antigen.
How do antibodies defend the body?
-Act as an opsonin so complex is easily engulfed and digested by phagocytes.
-Act as agglutinins causing pathogens to clump together which prevents them from spreading.
-Act as anti-toxins which bind to toxin and make them harmless.
What are lymphocytes?
-White blood cells.
-Two types; T lymphocytes which mature in thymus gland and B lymphocytes which mature in bone marrow.
What are T helper cells?
-Bind to surface antigens on APC's.
-Produce interleukins (cell-signalling molecule) which stimulate activity of B cells, this increases antibody and T cells production and attract macrophages to ingest pathogens.
What are T killer cells?
-Destroy pathogen carrying antigen.
-Produce perforin which kills the pathogen.
What are T memory cells?
-Part of immunological memory so, if they meet pathogen for second time then they divide rapidly and form T killer cells.
What are T regulator cells?
-Control and regulate immune system.
What are plasma cells?
-Produce antibodies to a particular antigen and release them.
What are B effector cells?
-Divide to form plasma cell clones.
What are B memory cells?
-Provide the immunological memory, so remember a specific antigen.
What is cell-mediated immunity?
-T lymphocytes respond to cells of organism that's been changed in some way by antigen processing or mutations.
-Particularly important against early cancers and viruses.
What are the steps of cell-mediated immunity?
-Macrophages engulf and digest pathogen in phagocytosis and process antigen to form APC.
-Receptors on some T helper cells fit antigen on APC, these T cells become activated and produce interleukins which stimulate more T cells to divide by mitosis. Form clones of activated T helper cells that carry right antigen to bind to pathogen.
-Cloned T cells can; develop into T memory cells, produce interleukins that stimulate phagocytosis and B cell division.
What is humoral immunity?
-Respond to antigens found outside the cells.
-Produces antibodies that are soluble in blood and tissue fluid.
-B lymphocytes have antibodies on cell-surface membrane, when pathogen enters body it will carry specific antigen, a B cell with complementary antibody will bind to it, engulf it and process it to become APC.
What are the steps of humoral immunity?
-Activated T helper cell binds to B cell APC (clonal selection).
-Interleukins produced by T helper cells activate B cells.
-Activated B cells divide by mitosis and give clones of plasma and B memory cells (clonal expansion).
-Cloned plasma cells produce antibodies to bind to antigen and destroy pathogen (primary immune response).
-Some cloned B cells develop into B memory cells, so if body is reinfected the B memory cells divide to form plasma cells and can produce antibodies (secondary immune response).
What is an autoimmune disease?
-When immune system stops recognising "self" cells and starts attacking healthy cells.