vaccinations Flashcards
2.63B
what are vaccines used for?
to induce immunity to infectious diseases
what does a vaccine contain?
harmless versions of a pathogens
what methods do scientists use to ensure that vaccines contain harmless pathogens?
killing the pathogen
making the pathogen unable to grow or divide (attenuated vaccine)
using fragments of pathogens, rather than whole cells
how may a vaccine be administrated?
orally, nasally or via an infection
how do vaccines work?
once in the bloodstream, the antigens contained within the vaccine can trigger an immune response in the following way
lymphocytes recognise the antigens in the bloodstream
the activated lymphocytes produce antibodies specific to the antigen encountered
memory cells and antibodies remain circulating in the blood stream
what do memory cells mean?
long term immunity
why are vaccines important? (spread)
they don’t only protect the vaccinated individual but they also reduce the likelihood that an infected individual will spread the pathogens to others
if a large proportion of the population is vaccinated, it is unlikely that an unvaccinated individual will spread the pathogens to others
what is herd immunity?
if a large proportion of the population is vaccinated, it is unlikely that an unvaccinated individual will become infected with the pathogen- this can prevent the spread of the disease
what have vaccines done around the world?
reduced the cases of certain diseases drastically or even eradicated diseases worldwide- includes smallpox, measles and mumps
what are some disadvantages to vaccinations that reduce how effective vaccination programs are?
mutations in the pathogens DNA/RNA can result in significant changes to the antigen of the pathogen meaning that lymphocytes no longer recognise the pathogen
side effects of vaccinations can reduce the uptake in the population
what are advantages of vaccinations?
diseases that were once common are now fairly rare due to widespread vaccinations e.g. measles and polio
epidemics can be prevented if large numbers of the population are vaccinated
disadvantages of vaccinations?
the vaccine doesn’t always give immunity
there can be side effects to the vaccine e.g. swelling/rash to more severe reactions like seizures
why do lymphocytes produce memory cells?
to prevent the body being infected by the same pathogen time and time again
what does it mean if we have “gained immunity”?
when the body next encounters the same pathogen, the memory cells react to the pathogen very quickly, producing lots of antibodies much earlier than the first time. this kills the pathogen before we feel ill and so prevents us being infected twice by the same pathogen
where do lymphocytes hang out in?
the lymph gland- the base of the immune system
