B6 Preventing and treating disease Flashcards
Vaccination
involves introducing small
quantities of dead or inactive forms of
a pathogen into the body. specific antigens on the surface of
the pathogen stimulate the wbc to produce specific and
complementary antibodies to destroy
the pathogen
Herd Immunity
achieved when a large
enough proportion of the population is
immune to the pathogen so it cannot spread.
Memory white blood cells
stay in the blood after vaccination and make the specific antibody very quickly if you are infected with the live pathogen in the future. You are said to be immune to the disease
How were drugs originally made?
How are most new drugs made?
Traditionally drugs were extracted from plants or microorganisms.
Most new drugs are synthesized by chemists in the pharmaceutical
industry but the starting point may still be a chemical extracted
from a plant.
Digitalis, Aspirin and Penicillin originates from?
The heart drug digitalis originates from foxgloves.
* The painkiller aspirin originates from willow trees.
* Penicillin was discovered by Alexander Fleming from the
penicillium mould.
Painkillers vs antibiotics
Painkillers treat the symptoms of an illness; they do not kill pathogens.
Antibiotics (e.g., penicillin) kill bacteria inside the body. They damage bacterial cells without harming your own cells. Specific bacteria should be treated with specific antibiotics.
Antibiotic resistant straints:
Antibiotic resistant strains of bacteria are evolving. Antibiotics that used to work against aparticular type of bacteria no longer have an effect, they do not cure the disease. This is of
great concern.
test
Antibiotics do not…
Antibiotics do not kill viral pathogens. Viruses reproduce inside body cells so it is very difficult to develop antiviral drugs that will kill the virus without damaging body cells.
Clinical trials
In clinical trials doctors use a double-blind trial.
The patients taking part are
randomly divided into groups, some are given a placebo (fake drug) and others are given the new medicine.
Neither the doctor nor the patients know who is receiving what treatment to prevent bias.
New medical drugs must be tested and trialled before being used to
check…
New medical drugs must be tested and trialled before being used to
check…
* If they are safe - toxicity
* If they work - efficacy
* How much should be given - dosage
Name the stages of developing drugs
Preclinical testing is carried out in laboratories using cells, tissues then live animals to check for toxicity.
Drugs that are successful in move onto clinical trials using healthy volunteers then patients.
1. Very low doses of the drug are given at the start of the clinical trial to healthy volunteers to check for side effects.
2. A small number of patients are trialed to see if the drug treats the disease.
3. A larger group of patients are trialed to find the optimum dose for the drug and check it works.
Scientist check each others work in a process called peer review to
prevent false claims.
If successful, the drug can be licensed.
Binary fission
Bacteria multiply by binary fission as often as
once every 20 minutes if they have enough
nutrients and a suitable temperature.
Example question: The mean division time for bacteria population A is 20 minutes. If you begin with one
bacteria, calculate how many bacteria will be present after 6 hours.
^Step 1: Calculate how many times the bacteria divide. In this example bacteria divides every 20 minutes, so will divide three times every hour (60/20=3).
If the bacteria grow for 6 hours, each bacterium will divide 3 times per hour × 6 hours = 18 times.
Step 2: Calculate the number of bacteria in the population. Every time the bacteria reproduce, the
number doubles. You can use an equation to do this.
Bacteria at the end of the growth period
= bacteria at the beginning × 2^number of divisions. Number of bacteria at the beginning = 1
Number of divisions = 18
Using the above equation: 1 × 218 = = 262,144 bacteria
Where can bacteria be grown?
Uncontaminated cultures of microorganisms are required for?
Bacteria can be grown in a
nutrient broth solution or as
colonies on an agar gel plate.
Uncontaminated cultures of microorganisms are required for investigating the action of disinfectants and antibiotics.
Name the aseptic techniques for:
Innoculation
An inoculating loop can be used to
transfer bacteria. It is sterilised by
heating it to red hot in a flame before
and after use, in order to prevent
contamination.
To inoculate the agar, the lid of the
petri dish is lifted and tilted. The lid
is not fully removed or placed on the
desk to prevent microorganisms in
the air contaminating the culture.
