ch8- defending ourselves against diseasae Flashcards
what causes infectious disease
pathogens thatre spread by vectors
whatre pathogens
microrganisms such as bacteria and viruses that cause disease
what does bacteria produce that makes us feel ill
toxins from reproducing rapidly inside your body
how do virusis damage cells
they live in cells to reproduce then burst the cell
how can we reduce the spread of infectious disease
-using antiseptics in hospitals to disinfect
-being hygenic
whatre the 4 ways pathogens can spread
-dropplets in air when you cough or sneeze
-direct contact
-contaminated food or drink
-cuts in skin
whatre the 4 mechanisms involved in the 1st line of defense
-mucus along the lining of lungs to stop pathogens from being moved down into the lungs
-skin
-scabs prevent pathogen from directly entering bloodstream
-stomach acid kills pathogens
whatre the 3 defense mechanisms taken by white blood cells
-phagocytosis where white blood cells injest pathogens
-production of antibodies that target specific virusis or bacteria then become familia memory cells to rapidly produce antibodies when youre reinfected by the same pathogen
-produce antitoxins that counteract toxins released by pathogens (bacteria)
describe immunity
when white blood cells called memory cells that become familiar with pathogens to rapidly produce matching antibodies if you get reinfected
how does your immune system recognise microrganisms
each cell contains unique antigens on surface so when a foreing body enters (pathogens) they detect its different antigens and make specific antibodies in response
why are memory white blood cells useful
they produce the matching antibodies for antigens thatre previously recognised to kill pathogens before they cause symptoms
how do vaccines work
introducing small quantities of dead or inactive forms of the pathogen into the body which stimulate the white blood cells to produce antibodies that destroy the pathogen. This makes the person immune to future infections by the microorganism, because the body can respond by rapidly making the correct antibody, in the same way as if the person had previously had the disease.
what is herd immunity
when a large population is immune to a pathogen which causes less infection risk
whats the MMR vaccine used for
protect children against measles, mumps and rubella.
why do antibodies kill only bacteria
difficult to develop drugs that kill viruses without also damaging the body’s tissues since viruses live inside the cells
who discovered antibodies
alexander flemming
why are painkillers not useful on the long run
cause they reduce symptoms without actually killing pathogens
whatre antibodies
protiens made by white blood cells that kill pathogens
how has antibiotic resistant bacteria strains increased
- Overuse and inappropriate use of antibiotics
- Antibiotics are not currently used to treat non-serious infections such as mild throat infections, in order to slow down the rate of development of resistant strains.
how do antibody resistant strains of pathogens develop
- Mutations of pathogens produce new strains. -
Antibiotics kill individual pathogens of the non-resistant strain but individual resistant pathogens survive and reproduce, so the population of the resistant strain rises. - Antibiotics and vaccinations may no longer be effective against a new resistant strain of the pathogen.
-The new strain will spread rapidly because people are not immune to it and there is no effective treatment.
give an example of antibody resistant bacterium strain
MRSA
how do you grow cultures of microrganisms
- provide them with a culture medium (containing nutrients)
-poor agar into a petri dish then let it vool
-keep bacteria free from other contaminators
whatre the 3 steps to grow useful microrganisms
step 1- steralise (usually bt heat)petri dishes and agar to kill unwanted microorganisms
step 2- inoculate steralised agar with the microganism (steralise loop then dip in bacteria,fix petridish to stop contamination,upside down to stop condensation from falling into it)
step 3-incubate (keep warm) the petridish (max temp of 25 do prevent harmful growth of pathogens
