INFECTION + RESP.

• what are pathogens?


  pathogens are microorganisms that enter the body and cause communicable diseases
• what are the different types of pathogens


  Bacteria

  Viruses

  Protists

  Fungi
• what is bacteria


  bacteria is a small living cell that reproduces inside your body

  they release toxins that damage your cells and tissues
• what are viruses


  viruses live inside cells and replicate making the cell burst damaging them and releasing more viruses

  the cell damage makes you ill
• what are protists


  single cell eukaryotes

  some are parasites
• what are parasites


  parasites live on or inside microorganisms causing damage

  transferred by vectors
• what is fungi


  fungi is made up of hyphae

  hyphae penetrates the human skin or the surface of plants

  produces spores that spread to other plants and animals
• how do pathogens spread


  air (inhaling airborne droplets)

  water (drinking or bathing in dirty water)

  direct contact (touching contaminated surfaces)
• what is measles

  measles is a viral disease

  measles is spread from an infected persons sneeze or cough

  causes red skin rash or a fever

  can lead to pneumonia and brain inflammation
• what is HIV


  HIV is a virus spread by sexual contact or sharing of bodily fluids (blood)

  it causes flu like symptoms for a few weeks and during this period it is controlled by antiretroviral drugs

  HIV attacks the immune cells

  once the immune system is badly damaged it won't be able to cope with other infections and cancers this is known as AIDS
• what is AIDS


  AIDS is when your immune system is badly damaged it won't be able to cope with other infections or cancers
• what is TMV


  a virus that affects plants

  causes discolouration in leaves meaning the plant can't photosynthesise well affecting its growth
• what is rose black spot


  a fungal infection that causes purple or black spots to develop on leaves

  the leaves turn yellow and then drop off

  meaning photosynthesis can't happen and leaves drop off

  its spread through water or wind

  can be treated with fungicides or stripping plant of infected leaves and destroying them so they don't spread to other plants
• what is malaria


  malaria is a disease caused by a protist

  mosquitos pick up the protist when they feed on an infected animal

  they spread the protist by feeding on an animal and injecting the protist into their blood vessels

  causes repeating episodes of fever

  can reduce spread by stopping mosquito breeding

  can be protected by insecticides or mosquito nets
• what is salmonella


  a bacteria that causes food poisoning

  suffer fevers cramps vomiting and diarrhoea

  eating food that has been contaminated by the bacteria or food made in unhygienic conditions

  most poultry have been given vaccinations
• what is gonorrhoea


  its an STD

  transmitted through sexual contact

  caused by bacteria

  symptoms are pain when urinating, or green and yellow discharge

  treated by penicillin but strains of bacteria have become resistant

  prevented by barrier methods of contraception
• how can you reduce the spread of infection


  being hygienic - prevent the spread of disease

  destroying vectors - preventing the disease from being passed on by getting rid of the microorganism that carries the disease.

  isolating infected individuals - prevents than from passing it on

  vaccinations - reduces the risk of contracting the disease
• how does the body have a defence system


  skin acts as a barrier for pathogens and secretes antimicrobial substances to fight against pathogens

  hair and mucus in nose trap particles that may contain pathogens

  trachea and bronchi secrete mucus to trap pathogens

  trachea and bronchi have cilia that waft mucus up to the back of the throat where it can be swallowed

  stomach has hydrochloric acid that kills the pathogens in the stomach
• what is phagocytosis


  when white blood cells engulf foreign cells and digest them
• how do white blood cells fight against pathogens


  pathogens carry antigens on its surface

  white blood cells detect the antigen they will produce antibodies that lock onto invading cells so they can be found or destroyed

  antibodies are specific to the antigen

  they are then rapidly carried around the body to find all similar bacterias

  if someone is infected with the same pathogen again the white blood cells will rapidly produce the antibodies to kill it so they are therefore naturally immune
• how do vaccinations protect against future infections


  inside the vaccine there are dead or inactive pathogens which carry antigens triggering your body to create antibodies to attack them although they are harmless

  if live versions of the pathogen appear afterwards the white blood cells can rapidly produce antibodies to kill them off
• pros of vaccination


  helped control lots of communicable diseases

  prevented large outbreaks of diseases if the population is mostly vaccinated meaning that people who aren't vaccinated have a lower chance of contracting the disease because there are fewer people to pass it on
• cons of vaccination


  don't always work and don't always give you immunity

  can have a bad reaction to vaccinations
• what are painkillers


  painkillers reduce the symptoms of a disease but don't actually tackle the cause of the disease or kill pathogens
• what are antibiotics


  antibiotics kill or prevent the growth of bacteria without killing your body cells

  different antibiotics kill different types of bacteria
• why don't antibiotics destroy viruses


  viruses are reproduced inside the body cells which makes it difficult to kill viruses without killing the body cells
• how does bacteria become resistant to drugs


  mutation
• why are only non resistant strains of bacteria killed when you treat an infection


  because there are some resistant strains of bacteria
• the resistant strain of bacteria will reproduce and form more resistant strains of bacteria which causes a serious infection that can't be treated by antibiotics
• why is it important that doctors don't over prescribe antibiotics

  so the rate of resistant strains of bacteria being produced
• why is it important to finish the full course of antibiotics


  to reduce the production of resistant strains of bacteria
• what is aspirin


  painkiller used to lower fevers, found in willow
• what is digitalis


  used to treat heart conditions, developed from a chemical found in fox gloves
• how did Alexander Fleming discover penicillin


  cleaning out a Petri dish with bacteria

  found mould in one of the Petri dishes and the area around the mould was free of bacteria

  mould contained a substance that kills bacteria (penicillin)
• stages of drug testing


  testing on human cells and tissues

  testing on live animals

  testing on healthy volunteers

  testing on unhealthy volunteers

  clinical trials

  peer review
• why do we test on live animals

  to see the efficacy toxicity and dosage
• what is efficacy


  efficacy is if the drug works and is producing the desired effect
• what is toxicity


  how harmful the drug is
• what is dosage


  how much of a drug should be taken and how many times it should be taken
• what are the issues with animal testing


  some people think its cruel but its the safest way to make sure a drug isn't dangerous

  some people think that animals are so different to humans so there is no point