topic 2 - immunity and vaccines Flashcards
cgp (topic 2C) 48 - 49
what are vaccines
what do vaccines contain, what does this mean
antigens that cause your body to produce memory cells against a particular pathogen without the pathogen causing disease - this means you become immune without getting symptoms
what is herd immunity
a type of disease immunity that occurs when a large proportion of a population are vaccinated against a disease which prevents the spread of the disease to unvaccinated individuals
what are four states of pathogens do vaccines contain
(1) free
(2) attached
(3) dead
(4) attenuated (weakened)
what is the disadvantage to taking a vaccine orally
it could be broken down by enzymes in the gut or the molecules of the vaccines may be too large to be absorbed into the blood
what may be given later on to make sure that memory cells are produces
booster vaccines
what activates primary response
antigens on the surface of pathogens
how can the same pathogens evade the immune system after the primary response
by antigenic variation
what is antigenic variation
the mechanism by which pathogens alter the proteins or carbohydrates on its surface / different antigens are formed due to the changes in the genes of a pathogen to avoid a host immune response
what does antigenic variation result in
the immune system has to start from scratch and carry out a primary response against the new antigens - since the memory cells produced from the first infection will not recognise the different antigens
how does antigenic variation affect the production of vaccines (4 points)
(1) memory cells produced from vaccination with one strain of the virus will not recognise other strains with different antigens - the strains are immunologically distinct
(2) every year there’s different strains of the influenza virus circulating in the population so a different vaccine has to be made
(3) new vaccines are developed and chosen every year that is the most effective against the recently circulating virus
(4) governments and health authorities then implement a programme of vaccination using the most suitable vaccine
what is active immunity
a type of immunity you get when your immune system makes its own antibodies after being stimulated by an antigen
what are the two different type of active immunity
natural and artificial
what is natural active immunity
when you becomes immune after catching a disease
what is artificial active immunity
when you become immune after you’ve been given a vaccination containing a harmless dose of antigen
what is passive immunity
a type of immunity you get from being given antibodies made by a different organism - your immune system doesn’t produce antibodies of its own
what are the two types of passive immunity
natural and artificial
what is natural passive immunity
when a baby becomes immune due to the antibodies it receives from its mother through the placenta and in breast milk
what is artificial passive immunity
when you become immune after being injected with antibodies from someone else
name four differences between active and passive immunity
(1) active requires exposure to antigen - passive doesn’t
(2) active takes a while for protection to develop - passive protection is immediate
(3) active memory cells are produced - passive they aren’t
(40 active protection is long term as the antibody is produced (after activation in memory cells) in response to complementary antigen being present in the body - passive protection is short term as antibodies given are broken down
