specific cellular defences against pathogens 3.6 Flashcards
what are lymphocytes
white blood cells involved in the specific immune response
what do lymphocytes respond to
specific antigens on invading pathogens
what are antigens
molecules often proteins located on the surface of cells that trigger a specific immune response
how do lymphocytes and antigens bind
lymphocytes have a single type of membrane receptor which is specific for one antigen
how do clonal populations form
antigen binding leads to repeated lymphocyte division resulting in the clonal population of identical lymphocytes
B lymphocytes function
produce antibodies against antigens and this leads to the destruction of the pathogen
what are antibodies
y shaped proteins that have receptor binding site’s specific to a particular antigen on a pathogen
how is the antigen antibody complex formed
antibodies become bound to antigens, inactivating the pathogen the resulting antigen antibody complex can then be destroyed by phagocytosis
how do allergic reactions form
when B lymphocytes respond to antigens on substances that are harmless to the body
T lymphocytes
destroy infected cells by recognising antigens of the pathogen on the cell membrane and including apoptosis
what is apoptosis
programmed cell death
how do T lymphocytes cause apoptosis
T lymphocytes attach on to the infected cells and release proteins that diffuse into the infected cell and cause production of self destructive enzymes and the remains are then removed by phagocytosis
how do autoimmune diseases develop
T lymphocytes can’t distinguish between self antigens on the body’s own cells and non self antigens on infected cells so respond to self antigens and attack the body’s own cells
how are memory cells formed
when some of the T and B lymphocytes produced in response to antigens by clonal selection survive long term
what happens to on the second exposure of a disease
antibody production is greater and more rapid than the primary response
