unit 3.6: specific cellular defences against pathogens Flashcards
what 2 lymphocytes are involved in specific responses
B
T
where do T-lymphocytes mature
they leave the bone marrow and mature in the thymus gland
where do B-lymphocytes mature
they remain in the bone marrow and mature there
how do lymphocytes respond to invasion
by detection of specific antigens found on the pathogen
where can the antigens be found
virus infected cells
bacteria
cancer cells
molecules on surface of transplant cells
how do lymphocytes distinguish between harmful and non harmful antigens
body cells have cell surface proteins unique to that person, an ‘antigen signature’
what do lymphocytes contain
a single type of membrane receptor which is specific for one antigen
how is clonal population achieved
the binding of a specific antigen to the specific site on the lymphocyte leads to division in lymphocytes creating a clonal population of identical activated lymphocytes
what do B-lymphocytes do
produce antibodies leading to the destruction of the pathogen
what are antibodies
Y shaped proteins that have receptor binding sites to a particular antigen of a pathogen, these bind creating a antigen-antibody complex which can be destroyed by phagocytosis
what is an allergic reaction
B-lymphocytes having a hypersensitive reaction to harmless antigens in the body e.g. pollen
what do T-lymphocytes do
they destroy the infected body cells by recognising the antigens on the pathogens cell membrane and inducing apoptosis, they release proteins which diffuse into the infected cell causing production of self destructive enzymes
what is apoptosis
programmed cell death
which cells are responsible for autoimmune
T-lymphocytes
give 2 example of autoimmune diseases
rheumatoid arthritis
type 1 diabetes
why does autoimmunity happen
T-lymphocytes treat self antigens as foreign and attack healthy cells
what happens in the primary response to a pathogen
it’s slower as it takes time to raise the immune response, select the correct T or B cells and produce antibodies
what are the cells that stay in the body after the primary response
memory cells
what happens in the secondary response
memory cells remain in the body so when a secondary response occurs, they can rapidly give rise to more clones of specific lymphocytes, destroying the pathogen before the individual shows symptoms and preventing disease
what is HIV
human immunodeficiency virus
what does HIV do
attacks and destroys T cells, causing depletion over a long time which leads to development of AIDS
what is AIDS
acquired immunodeficiency syndrome
