Chapter 17 Flashcards
humoral immunity
Immunity produced by anitbodies dissolved in body fluids, mediated by B cells; also called antibody
thymus
a mammalian organ responsible for the maturation of the immune system.
B cell
a type of lymphocyte; differentiates into antibody-secreting plasma cells and memory cells. They mature in the bone marrow and recognize an antigen and build antibodies against them.
T cells
A lymphocyte which develops from a stem cell processed in the thymus gland, that is responsible for cell-mediated immunity.
TCR- T cell receptor
Molecules on a T cell that recognize antigens
antigen
any substance that causes antibody formation. they are usually large polysaccharides or proteins.
epitope/ antigenic determinant
a specific region on the surface of an antigen against which antibodies are formed.
hapten
a substance of low molecular weight that does not cause the formation of antibodies by its self but does so when combined with a carrier molecule.
antibodies
a protein produced by the body in response to an antigen and capable of combining specifically with an antigen.
Immunoglobulin (Ig)
a protein antibody formed in response to an antigen and can react with that antigen.
Can a bacterium or virus have more than one epitopes?
yes. a bacterium or virus may have several epitopes that cause the production of different antibodies
antigen binding sites
a site on an antibody that binds to an antigenic determinant. each antibody has at least two binding sites
monomer
the simplest molecular structure of an antibody; bivalent;four protein chains; 2 identical heavy chains and 2 identical light chains
variable regions
the two ends of the “Y” that bind to the epitopes s
constant region/Fc region
the stem of the “Y” antibody. they are the same for a particular class of immunoglobin/antibody
IgG
monomer; located in the lymph, blood, intestines; they enhance phagocytosis;neutralize toxins and viruses, and protect fetus and newborns since they can cross the placenta; they make up 80%; they readily cross the blood vessels and enter tissues; does activate the complement fixation
IgM
five monomers held together by a J chain; located in the blood, and B cell surface; they are so large they usually dont leave the blood ; especially effective against microorganisms and agglutinating antigens; first antibodies produced in response to an initial infection; can cause complement fixation
IgA
a dimer with a secretory complement; located in the secretions (tears, saliva, mucus intestines, and milk) blood and lymph; localized protection on mucosal surfaces; prevents attachment of microbes to mucosal surfaces; does not activate the complement fixation
IgD
monomer; located in the B cell surface, blood and lymph, serum function not know but the presence on B cells functions in initiation response; does not activate the compliment fixation
IgE
monomer; located bound to mast and basophil cells through out the body, and in the blood, functions in allergic reactions; possibly lysis of parasitic worms; does not activate the complement system
T dependent antigen
an antigen that will stimulate the formation of antibodies only with the assistance of T helper cells
MHC ( major histocompatibility complex
the genes that code for histocompatibility antigens
plasma cells
a cell that an activated B cell differentiates into; plasma cells manufacture specific antibodies
memory cell
a long-lived B or T cell responsible for the memory or secondary response
