How Does Our Body Defend Themselves Against Infectious Diseases Flashcards
What may bacteria and viruses do?
They may reproduce rapidly inside the body and may produce poisons (toxins) that make us feel ill. Viruses damage the cells in which they reproduce
Who do white blood cells help defend against pathogens?
Ingesting pathogens
Producing antibodies, which destroy particular bacteria or viruses
Producing antitoxins, which counteract the toxins released by the pathogens
How do antibodies work?
The immune system in our body produces specific antibodies to kill a particular pathogen. This leads to immunity from that pathogen. In some cases, dead of inactivated pathogens stimulate antibody production. If a large proportion of of the the population is immune to a pathogen the spread of the pathogen is very much reduced
What did Semmelweis recognise?
The importance of hand-washing in the prevention of spreading some infectious diseases. By insisting that doctors washed their hands before examining patients, he greatly reduced the number of deaths from infectious diseases in his hospital
What do some medicines, including painkillers, do?
They help to relieve the symptoms of infectious diseases, but do not kill the pathogen
What do antibiotics, including penicillin, do?
They are medicines that help cure bacterial diseases by killing infectious bacteria inside the body. Antibiotics cannot be used to kill viruses, which live and reproduce inside cells. It is important that specific bacteria should be treated by specific antibiotics. The use of antibiotics has increased the rate of development of antibiotic resistant strains of bacteria
What have many strains of bacteria, including MRSA, developed?
They have developed resistance to antibiotics as a result of natural selection.
How can you prevent further resistance of bacteria against antibiotics?
Avoid over-use of antibiotics
What may mutations of pathogens produce?
New strains
Antibiotics and vaccinations may no longer be effective gassing a new resistant strain of the pathogen. The new strain will then spread rapidly because people are not immune to it and there is no effective treatment
What is the problem with resistant strains?
The problem is that the antibiotics kill individual pathogens of the non-resistance and individual resistant pathogens survive and reproduce, so the population of the resistant strains increase
Why are antibiotics not used to treat non-serious infections, such as mild throat infections?
So that the rate of development of the resistant strains is slowed down
Who do vaccines work?
You introduce a small quantity of dead or inactive forms of the pathogen into the body. The vaccine stimulates the white blood cells to produce antibodies that destroy the pathogens. This makes the person immune to future infections by the microorganism. The body an respond by rapidly making the correct antibody, in the same way as if the person had previously had the diseases
What is the MMR vaccine used for?
To protect children against measles, mumps and rubella
Uncontaminated cultures of microorganisms are required for investigating the action of disinfectants and antibiotics. What are the steps in this investigation?
Petri dishes and culture media must be sterilised before use to kill unwanted microorganism
Inoculating loops used to transfer microorganisms to the media must be sterilised by passing them through a flam
The lid of the Petri dish should be secured with adhesive tape to prevent microorganisms from the air contaminating the culture
At what temperature should cultures in school and collage laboratories be incubated at, and why?
At a maximum of 25oC, which greatly reduces the likelihood of growth of pathogens that might be harmful to humans
In industries conditions higher temperature can produce more rapid growth
