ch8- defending ourselves against diseasae

Question 1

what causes infectious disease

Answer 1

pathogens thatre spread by vectors

Question 2

whatre pathogens

Answer 2

microrganisms such as bacteria and viruses that cause disease

Question 3

what does bacteria produce that makes us feel ill

Answer 3

toxins from reproducing rapidly inside your body

Question 4

how do virusis damage cells

Answer 4

they live in cells to reproduce then burst the cell

Question 5

how can we reduce the spread of infectious disease

Answer 5

-using antiseptics in hospitals to disinfect
-being hygenic

Question 6

whatre the 4 ways pathogens can spread

Answer 6

-dropplets in air when you cough or sneeze
-direct contact
-contaminated food or drink
-cuts in skin

Question 7

whatre the 4 mechanisms involved in the 1st line of defense

Answer 7

-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

Question 8

whatre the 3 defense mechanisms taken by white blood cells

Answer 8

-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)

Question 9

describe immunity

Answer 9

when white blood cells called memory cells that become familiar with pathogens to rapidly produce matching antibodies if you get reinfected

Question 10

how does your immune system recognise microrganisms

Answer 10

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

Question 11

why are memory white blood cells useful

Answer 11

they produce the matching antibodies for antigens thatre previously recognised to kill pathogens before they cause symptoms

Question 12

how do vaccines work

Answer 12

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.

Question 13

what is herd immunity

Answer 13

when a large population is immune to a pathogen which causes less infection risk

Question 14

whats the MMR vaccine used for

Answer 14

protect children against measles, mumps and rubella.

Question 15

why do antibodies kill only bacteria

Answer 15

difficult to develop drugs that kill viruses without also damaging the body’s tissues since viruses live inside the cells

Question 16

who discovered antibodies

Answer 16

alexander flemming

Question 17

why are painkillers not useful on the long run

Answer 17

cause they reduce symptoms without actually killing pathogens

Question 18

whatre antibodies

Answer 18

protiens made by white blood cells that kill pathogens

Question 19

how has antibiotic resistant bacteria strains increased

Answer 19

• 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.

Question 20

how do antibody resistant strains of pathogens develop

Answer 20

• 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.

Question 21

give an example of antibody resistant bacterium strain

Answer 21

MRSA

Question 22

how do you grow cultures of microrganisms

Answer 22

• provide them with a culture medium (containing nutrients)
  -poor agar into a petri dish then let it vool
  -keep bacteria free from other contaminators

Question 23

whatre the 3 steps to grow useful microrganisms

Answer 23

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