B1.1.2 The body's defence system Flashcards
What do bacteria and viruses do that make us feel ill?
Reproduce rapidly inside the body and produce toxins
Viruses are unique how?
They damage the cells in which they reproduce
How do white blood cells protect the body from pathogens?
- ingesting pathogens
- producing antibodies, which destroy particular bacteria/viruses
- producing antitoxins, which counteract the toxins released by the pathogens
What is an antibody?
An antibody is produced by a white blood cell to destroy particular pathogens
What is an antitoxin?
An antitoxin counteracts the toxins released by the pathogens
What sort of antibodies does the immune system produce?
Specific antibodies to kill a particular pathogen, which leads to immunity
What did Semmelweis do?
Recognised the importance of hand washing in the prevention of spreading infectious diseases.
What did he insist?
That doctors washed their hands before examining patients. (this lead to a reduction in deaths from infectious diseases)
What do painkillers and some medicines do to the body when ill?
Relieve the symptoms of disease, but don’t kill the pathogens
What is a pathogen?
A microorganism that causes disease
What is an antibiotic?
A medicine that helps to cure bacterial disease by killing infectious bacteria inside the body
What can antibiotics not be used for?
Killing viral pathogens
Should specific bacteria be treated by specific antibiotics?
Yes
What has overuse of antibiotics increased?
Rate of development of antibiotic resistant strains of bacteria
What’s MRSA?
A strain of bacteria that has developed resistance to antibiotics
Why do bacteria develop resistance to antibiotics?
As a result of natural selection
How does the resistance process occur?
- mutations of pathogens produce new strains
- antibiotics may no longer be effective against this new resistant strain
- the new strain will then spread fast as people aren’t immune to it and there is no effective treatment available!
What are antibiotics used to treat?
Only serious infections to slow down rate of development in resistant strains
How can people be immunised against a disease?
By introducing small dead or inactive quantities of the pathogen into the body (vaccination)
How do vaccines work?
They stimulate the white blood cells to produce antibodies that destroy the pathogens. These can be reproduced if the person gets the disease.
What is MMR vaccine used to protect children against?
Measles, mumps and rubella
What are required for investigating the action of disinfectants and antibiotics?
Uncontaminated cultures of microorganisms
How would you conduct the Petri dish testing?
- sterilise Petri dish and culture media to kill unwanted microorganisms
- use sterilised inoculating loops (done by passing through flame) to transfer microorganisms to the media
- close lid of Petri dish with adhesive tape to prevent microorganisms from the air contaminating the culture
- incubate cultures at a max of 25c
