Immunity AS Flashcards
define pathogen
microorganisms that cause disease
how do pathogens cause disease
damage cells/tissues and produce toxins
non specific defenses
barriers/phagocytes
specific defence
lymphocytes
how do lymphocytes learn to recognise your own body cells
proteins on surface allow cells to be distinguished from one another in foetus adult lymphocytes collide with own material. if lymphocytes fit with body cells they are deleted (apoptosis)
what cells can lymphocytes distinguish between
pathogens, non-self material, toxins, cancer cells
where do T cell develop
Thymus
what are T cells associated with
cell mediated immunity
where do B cells mature
bone marrow
what are B cells associated with
antibodies/humoral immunity. memory and plasma cells
function of memory cells
carry immunological memory of the specific antigen
steps of cell mediated immunity
pathogen contains antigens. pathogen taken up by phagocyte and presented on surface. binds
phagocytosis
phagocyte recognises antigens or chemicals on pathogen as foreign. phagocyte attaches to chemicals on pathogen. engulfs pathogen. bacteria in phagosome (vacuole) lysosome empties vacuole bacteria digested
stages of humoural response
B cell presents antigen. T cell attaches and actives B cell. B cell divides by mitosis to form clones. cloned plasma cells secrete antibodies. on second exposure memory cells produce antibodies rapidly
what are monoclonal antibodies
single clone of B cells, used in pregnancy tests
what are monoclonal antibodies used in?
pregnancy testing, medication (cancer cells) medical diagnosis (PSA/mumps) (all variations of ELSA)
what percentage vaccinated do you need for herd immunity
95%
define antigen
foreign protein on the cell surface that stimulates an immune response
role of antibodies in an ELISA test
antibody binds to complementary antigen.
second antibody with enzyme attached is added.
second antibody attaches to antigen
solution added and colour changes
ethical issues with mabs
mice are used to produce both antibodies and cancer cells. some trials have been unsuccessful and some have been successful for cancer and diabetes.
steps in vaccination
antigen injected. these bind to receptor on T helper cells. they release cytokines. B cells divide by mitosis. plasma cells make antibodies. memory cells produce antibodies rapidly at the next exposure
natural active immunity
own antibodies produced from being exposed to a disease under normal circumstances
artificial active immunity
own antibodies produced from vaccination
passive immunity
temporary introduction of antibodies e.g. antivenom. faster.
difference between primary and secondary immune response
primary after first exposure, secondary after second. after secondary memory cells produce antibodies more quickly after primary plasma cells produce antibodies
structure of HIV
attachment proteins, lipid envelope, matric, capsid, RNA and reverse transcriptase
replication of HIV
HIV binds to CD4 on T helper cells. protein capsid fuses with the cell membrane of T cell. RNA to DNA (reverse transcriptase). DNA inserted into T cells genetic material. mRNA created. mRNA can leave nucleus and use host cells material to make HIV particles
why is it hard to develop a HIV vaccine
antigenic variability
