4.1.1 Diseases immunity bit Flashcards
active immunity
immune system makes its own antibodies after being stimulated by a pathogen
active immunity - natural
when you become immune after catching a disease
active immunity - artifical
when you become immune after you’ve been given a vaccination containing a harmless dose of the antigen
passive immunity
get given antibodies made by a different organism
immune system doesn’t produce any antibodies of its own
passive immunity - natural
when a baby becomes immune due to the antibodies it receives from its mother through placenta and breast milk
passive immunity - artifical
become immune after being injected with antibodies from someone else
active vs passive
active
- requires exposure to antigen
- takes a while for protection to develop
- protection is long term
- memory cells are produced
passive
- no exposure to antigen
- protection is immediate
- protection is short-term
- memory cells aren’t produced
what is an autoimmune disease
when an organism’s immune system isn’t able to recognise self-antigens
the immune system treats the self-antigens as foreign tissues and launches an immune response against the organism’s own tissues
a disease resulting from this abnormal immune response is known as an autoimmune disease
- usually chronic (longterm)
- often can be treated but not cured
autoimmune disease - lupus
caused by the immune system attacking cells in the connective tissues
this damages the tissues and causes painful inflammation
can also affect the skin and joints as well as organs - lungs and heart
autoimmune disease - rheumatoid arthritis
caused by immune system attacking cells in the joints
causes pain and inflammation
vaccines - why are they used
helps control disease and prevent epidemics
- avoid the slower primary immune response
vaccines - what
contain antigens - may be free or attached to a dead or attenuated (weakened) pathogen
this causes your body to produce memory cells against a particular pathogen without the pathogen causing disease
so become immune without getting any symptoms
vaccines - herd immunity
if most people in a community are vaccinated the disease becomes extremely rare
this means people who haven’t been vaccinated are unlikely to get the disease because there is no one to catch it from
this helps prevent epidemics - mass outbreak of disease
vaccination vs immunisation
vaccination - the administration of antigens (in a vaccine) into the body
immunisation - the process by which you develop immunity (doesn’t have to be vaccination but vaccination is immunisation)
routine vaccinations - MNR
protects against measles, mumps and rubella
usually given to children as an injection around a year old, and again before they start school
contains attenuated measles, mumps and rubella virus
routine vaccinations - meningitis C vaccine
protects against the bacteria that cause Meningitis C
first given as an injection at 3 months old
boosters are given to 1-year-olds and teenagers
vaccines/vaccination programs - why do they change?
eg. influenza
the influenza vaccine changes every year because the antigens on the surface of the influenza virus change regularly, forming new strains of the virus
- memory cells produced from vaccination with one strain will not recognise a different strain as the strains are immunologically distinct
every year, different strains circulating in population, so a different vaccination has to be made
- laboratories collect samples of these different strains, and organisations (world health organisation and centre for disease control) test the effectiveness of different influenza vaccines against them
- new vaccines developed and the most effective one against the recent virus is chosen
governments and health authorities then implement a program of vaccination using the most suitable vaccines - sometimes people are given a vaccine that protects then from a strain causing an epidemic in another country - helps stop strain spreading globally
what are medical drugs manufactured from
from natural compounds - in plants, animals or microorganisms
where does penicillin come from
fungus
where do cancer drugs come from
soil bacteria
what is used to treat alzheimer’s disease
daffodils
why do possible sources of drugs need to be protected
only a small proportion of organisms have been investigates - its possible that plants or microorganisms exist that contain compounds that could be used to treat currently incurable diseases
possible sources of drugs need to be protected by maintaining biodiversity
if we don’t protect then, some species could die out before we get a chance to study them
- even organisms that have already been studied could still prove useful sources if medicines as new techniques are developed for identifying, purifying and testing compounds
personalised medicines - why
your genes determine how your body responds to certain drugs
different people respond to the same drug in different ways
this makes certain drugs more effective for some people than others
personalised medicines - what
medicines that are tailored to an individual’s DNA
the theory is that if doctors have your genetic information, they can use it to predict how you will respond to different drugs and only prescribe the ones that will be the most effective for you
personalised medicines - future
scientists hope that by studying the relationship between someone’s genetic make-up and their responsiveness to drugs, more effective drugs can be produced in the future.
synthetic biology - what
involves using technology to design and make things like artificial proteins, cells and even microorganisms
synthetic biology - application
application in lots of different areas
medicine
- scientists are looking at engineering bacteria to destroy cancer cells, while healthy body cells intact
antibiotics - what?
chemicals that kill or inhibit the growth of bacteria
antibiotics - use? why?
used by humans as drugs to treat bacterial infections
because they can usually target bacterial cells without damaging human body cells
antibiotics - penicillin
the first antibiotic to be isolated (by Alexander Flemming, in 1928)
antibiotics - helpful?
widespread use from the mid-twentieth - partly thanks to the successful treatment of soldiers
been able to deal with bacterial infections pretty easily using antibiotics
- as a result of this the death rate from the infectious bacterial disease has fallen dramatically
antibiotics - risks
side effects
severe allergic reactions
antibiotic resistance
antibiotic resistance - what?
there is genetic variation in a population of bacteria
- genetic mutations make some bacteria naturally resistant
for the bacterium, this is an advantage - better able to survive even in a host whos being treated with antibiotics to get rid of the infection, and so it lives for longer and reproduces
- this leads to the allele for antibiotic resistance being passed on to lots of offspring (natural selection)
the how antibiotic resistance spreads and becomes more common in a population over time
antibiotic resistance - why is it bad?
this is a problem for people who become infected with these bacteria because you can easily get rid of them with antibiotics
increased use of antibiotics means that antibiotic resistance is increasing ‘superbugs’ that are resistant to known antibiotics are becoming more common
this means we are less able to treat some potentially life-threatening bacterial infections
antibiotic resistant bacteria - MRSA
meticillin-resistant Staphylococcus aureus
causes several serious wound infections
is resistant to several antibiotics - including meticillin
antibiotic resistant bacteria - clostridium difficile
infects the digestive system
- usually causing problems in people who have already been treated with antibiotic
it is thought that the harmless bacteria that are normally present in the digestive system are killed by the antibiotics which C.difficle is resistant to
this allows C.difficile to flourish - C.difficle produces a toxin, which causes severe diarrhoea, fever and cramps
antibiotic resistant - how to overcome
developing new antibiotics
modifying existing ones
- this isn’t easy
how to reduce likelihood of antibiotic resistance developing
doctors encouraged to reduce their use of antibiotics
- don’t prescribe them for minor infections
- don’t prescribe them to prevent infections (except in patients with weak immune systems, HIV)
patients are advised to take all of the antibiotics they’re prescribed to make sure the infection is fully cleared and all the bacteria have been killed
- which reduces the likelihood of a population of antibiotic-resistant bacteria developing
