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Chapter 12 Communicable Disease > The specific immune system > Flashcards

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.


What is an example of an autoimmune disease?

-Type 1 diabetes; pancreas cells are affected, but there are insulin injections and immunosuppressant drugs to treat it.