2.8 DISEASE, DEFENCE AND TREATMEANT Flashcards
WHAT IS A PATHOGEN?
a micro-organism which causes disease
WHAT ARE SOME EXAMPLES OF PATHOGENS?
- bacteria
- virus
- fungi
HOW CAN PATHOGENS PASS FROM ONE PERSON TO THE NEXT?
by contact, aerosol, body fluids, water, insects and contaminated food
WHAT IS THE CAUSATIVE AGENT OF AIDS?
HIV (passed by blood to blood contact + sexual contact)
WHAT IS THE CAUSATIVE AGENT OF CHLAMYDIA?
Chlamydia trachomatis bacterium (passed by sexual contact)
WHAT IS THE CAUSATIVE AGENT OF MALERIA?
Plasmodium single celled organism (passed by female mosquitoes)
WHAT IS THE EFFECT OF AIDS?
infects lymphocytes which are part of the body’s immune system. Without immunity, the body can become infected with a variety of micro-organisms, e.g. tuberculosis or pneumonia
WHAT IS THE EFFECT OF CHLAMYDIA?
could cause infertility in adults. It could also cause conjunctivitis in babies during the process of birth if the mother is infected
WHAT IS THE EFFECT OF MALERIA?
causes a fever when it destroys red blood cells in humans
WHAT IS THE TREATMENT/PREVENTION OF AIDS?
the use of condoms, and disposable gloves should be used where there is any danger of contact with contaminated blood. Antiviral agents can be used, but they only prevent the multiplication of the virus inside cells and must be taken throughout life
WHAT IS THE TREATMENT/PREVENTION OF CHLAMYDIA?
prevented by the use of condoms. It can be treated with antibiotics such as tetracycline or erythromycin
WHAT IS THE TREATMENT/PREVENTION OF MALERIA?
Treatment - killing Plasmodium with anti-malarial drugs, such as paludrine or daraprim.
prevention - a vaccine against Plasmodium, killing mosquitoes with insecticide, releasing large numbers of infertile male mosquitoes, biological control of mosquitoes, and use of mosquito nets and repellents
WHAT ARE THE TWO WAYS OUR BODY STOPS THE ENTRY OF MICROBES?
Skin - provides physical barrier
Blood clotting - seals wounds and prevents entry through the cut skin
WHAT ARE THE TWO WHITE BLOOD CELLS OF DISEASE DEFENCE?
Phagocyte and Lymphocyte
WHAT DOES THE LYMPHOCYTE DO?
1) detects the foreign antigen
2) splits itself by mitosis, makes many plasma cells and produces antibodies
3) antibodies are specific to the antigen
4) antibodies attach to the antigens making it a noticeable microbe for phagocytes
5) memory cells are made for immunity to the specific antigen
WHAT DOES THE PHAGOCYTE DO?
Detects microbe and engulfs it to break it down.
WHAT IS THE PRIMARY IMMUNE RESPONSE?
the response that takes place the first time an individual encounters an antigen. the primary immune response takes time
WHAT IS THE SECONDARY IMMUNE RESPONSE?
the response that takes place the second time an individual encounters an antigen. The lymphocytes recognise the antigen so produce antibodies much faster.
WHY CAN PEOPLE SUFFER FROM THE FLU MULTIPLE TIME?
the antigens on the surface of the flu virus mutate and change rapidly, giving rise to new strains which have not been previously encountered and so immunity has not developed
WHAT IS USED TO MAKE A VACCINE?
non-active, disease-causing micro-organisms, antigens or parts of antigens from disease-causing micro-organisms to stimulate an immune response
WHAT IS THE AIM OF A VACCINE?
use antigens from the disease-causing micro-organism to stimulate the production of antibodies specific to the antigen that would protect the body against the pathogen
WHY DOES ANTIBIOTIC RESISTANCE HAPPEN?
because of a mutation in the bacteria, which can now pass the resistance between itself. If an infection is then treated by antibiotics, the resistant bacteria survive and reproduce (an example of natural selection), therefore becoming very widespread
WHAT IS MRSA?
A superbug (resistant to antibiotics)
HOW IS MRSA CONTROLLED?
- more rigorous hygiene in hospital wards
- MRSA screening – testing people to see if they are carrying the bacteria
WHAT ARE THE STAGES OF TESTING A NEW DRUG?
1) The drug is tested on human cells grown outside the body in a laboratory.
2) The drug is then tested on animals.
3) The drug is tested on healthy volunteers.
4) Further trials are carried out to establish the optimum dose for the drug.
5) The drug is then trialled with a sample of people who have the disease or condition to see if it is more effective than current treatments.
6) If all these tests are passed, the drug is then licensed for general use.
HOW ARE MONOCLONAL ANTIBODIES PRODUCED?
1) lymphocytes are taken from a mouse
2) these are fused with tumour cells forming a hybridoma
3) Divides rapidly in lab conditions to form a clone
4) These clones are monoclonal antibodies
WHAT ARE THE USES OF MONOCLONAL ANTIBODIES?
Diagnosis - used to detect Chlamydia, HIV and Plasmodium
Tissue typing - for transplants
Monitoring the spread of malaria - detect Plasmodium
Destroying cancer cells - act against tumour markers
