TOPIC 3 INFECTION AND RESPONSE Flashcards
what is a pathogen
microorganisms that enter the body and cause communicable diseases
-BOTH plants and animals can be infected
Examples of diseases caused by viruses
-common cold
-flu
-measles
how does bacteria make us feel ill
-small cells that produce toxins that damage your cells and tissues
what makes us feel ill in viruses
-they live inside cells and replicate using cell machinery to produce many copies of themselves
-the cells burst which releases new viruses
state 3 ways pathogens are spread
- contaminated water, (drinking dirty water)
- air (pathogens can be carried in air and breathed in)
- direct contact (by touching contaminated surfaces e.g skin)
explain the viral disease measles
-spread by droplets from an infected persons sneeze or cough
symptoms a red skin rash and fever
-leads to pneumonia
-prevent, vaccinated when young
state another virus
HIV
-spread by sexual contact or exchanging bodily fluids
-SYMPTOMS flu-like symptoms
-attacks immune cells
-controlled by antiretrovial drugs
what is the disease TMV
-tobacco mosaic virus, a widespread plant pathogen
-affects many species of plants
-cause a mosaic pattern on leaves (discoloured)
-**effect **plant cannot carry out photosynthesis
state a fungal disease
rose black spot
-causes purple or black spots to develop on leaves and the leaves turn yellow and drop off
-the loss of leaves means that there are less chloroplasts for photosynthesis
-spreads through environment in water or by wind
-**treat **by stripping the plant of its affected leaves
state a disease caused by a protist
malaria
-mosquitos are vectors that pick up malarial protst when they feed on infected animal
-every time the mosquito feeds on another animal it infects it
symptoms repeated fevers and shaking
-reduce spread by mosquito nets or stopping them from breeding
state 2 bacterial diseases
-salmonella
-gonorrhoea
what is salmonella
-a type of bacteria that causes food poisoning, found in the gut of many animals
-causes fever, stomach cramps, vomitting
-get it by eating contaminated food
-most poultry in UK is given a vaccination against this
what is gonorrhoea
-sexually transmitted disease (STD)
-**transmitted by sexual contact
-symptom pain when urinating, yellow discharge from the vagina
-treated by **antibiotics
-use condoms to stop spread
4ways to reduce disease
- be hygenic, wash hands with soap thoroughly
- destroy vectors
- isolate infected individuals
- vaccinations
how does the skin act as a defence system
-acts as a barrier to pathogens
non-specific defence systems of the human body against pathogens
skin
nose
trachea and bronchi
stomach.
how does your nose act as a defence system
-hair and mucus trap particles that contain pathogens
how does the trachea and bronochi act as a defence system
they secrete mucus to trap pathogens
-lined with cilia
how does the stomach act as a defence system
-produces hydrochloric acid
How do white blood cells help to defend against pathogens by
-phagocytosis
-production of antibodies
-production of antitoxins
Phagocytosis
-Engulf and digest pathogens
-the phagocyte surrounds the pathogen and releases enzymes to digest and break it down to destroy it
Antibody production
-lymphocytes produce antibodies
-antibodies are Y shaped proteins and each individual has the potential to make millions of different types of antibodies
-aim of antibody production is to produce the antibody
-is a protein made by lymphocytes that is complementary to an antigen and, when attached, clumps them together and signals the cells they are on for destruction
Antitoxin production
-pathogens produce substances which act as toxins which make you feel unwell
-lymphocytes produce antibodies against substances
antitoxin is a protein that neutralises the toxins produced by bacteria
what is an antigen
a molecule found on the surface of a cell
what does the immune system do if pathogens enter the body
-kicks in to destory them
-the white blood cells travel around and when coming across an invading microbe they
* consume them
* produce antibodies
* produce antitoxins
describe the 1st process of white blood cells
-engulf cells and digest them
-called phagocytosis
describe the 2nd process of white blood cells
-invading pathogens have antigens on its surface
-start to produce proteins called antibodies
-antiboides are produced rapidly
-if the person ifnected with the same pathogen again, the persons naturally immune to that pathogen
3rd process of white blood cells
-produces antitoxins
-counteract toxins produced by invading bacteria
how does the spread of pathogens be reduced by immunising a large proportion of population
If a large number of the population are vaccinated, it is unlikely that an unvaccinated individual will become infected with the pathogen
State the 3 scenarios for this
-There are no vaccinations and the disease spreads quickly
Some of the population are vaccinated and the disease spreads to less people
Most of the population are vaccinated and this prevents the spread
Vaccination processes
-involves introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies.
-If the same pathogen **re-enters the body **the white blood cells respond quickly to produce the correct antibodies, preventing infection.
PROS of infections
-they control many communicable diseases that were common
-outbreaks of diseases can be prevented if a large percentage of the population is vaccinated
CONS of infection
-dont always work
-can causes bad reactions, e.g swelling or fever
state what relieves symptoms
-painkillers
the use of antibiotics and other medicines in treating disease
they kill the growth bacteria but dont destory viruses
-greatly reduced the deaths from infections in the last century
the use of the antibiotic penicillin
is used to kill or stop the growth of bacteria
-It is important that specific bacteria should be treated by specific antibiotics.
Advantages of antibiotic uses
-it has greatly reduced deaths from infectious bacterial diseases.
-but the emergence of strains resistant to antibiotics is of great concern.
why can we not develop drugs that kill viruses
as this damages the body’s tissues.
3main stages of drug testing
- preclincal testing, drugs are tested on human cells and tissues in the lab
- test drug on live animals
- tests for efficacy
- tests toxicity
- LAW must be tested on 2different live mammals - if passes them tests its treated on human volunteers in a clincial trial
-then tested on people suffering from the illness
State traditional drugs which were extracted from plants and microorganisms
-The heart drug digitalis originates from foxgloves.
-The painkiller aspirin originates from willow.
-Penicillin was discovered by Alexander Fleming from the Penicillium mould.
How are new drugs synthesised
by chemists in the pharmaceutical industry. However, the starting point may still be a chemical extracted from a plant.
What has to happen to new medical drugs
-have to be tested and trialled before being used to check that they are safe and effective.
-New drugs are extensively tested for toxicity, efficacy and dose.
-Preclinical testing is done in a laboratory using cells, tissues and live animals.
State what happens at clinical trials
they use healthy volunteers and patients
-Very low doses of the drug are given at the start of the clinical trial.
-If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug.
-In double blind trials, some patients are given a placebo.
