Topic 5 - Health, disease and the development of medicines Flashcards
Describe health
Health is described as a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity
Describe the main difference between communicable and non-communicable diseases
COMMUNICABLE - can be passed from one person to another
NON COMMUNICABLE - not passed between people
Explain why the presence of one disease can lead to a higher susceptibility to other diseases
Defects in the immune system mean that an individual is more likely to suffer from infectious diseases
Describe what a pathogen is and how it affects you
PATHOGENS make you feel ill when they damage cells or change how they work, they reproduce rapidly. These include:
- bacterium : bacteria may release toxins that make us feel ill, some types invade and destroy body cells
- virus : viruses take over a body cells dna, making toxins or causing damage when new viruses are released from cells (these are much smaller than bacteria)
- fungi : fungi are eukaryotic organisms
- protist : protists are eukaryotic organisms. Many are free living but some are pathogens
Describe some common infections including:
- cholera
- malaria
- HIV/AIDS
- tuberculosis
- Ebola
- stomach ulcers
- chalara ash die back
CHOLERA (caused by bacteria) - causes diarrhoea
MALARIA (caused by protist) - causes damage to blood and liver
HIV/AIDS (caused by virus) - destroys white blood cells, leading to the onset of AIDS
TUBERCULOSIS (caused by bacteria) - causes lung damage
EBOLA (caused by virus) - causes haemorrhagic fever
STOMACH ULCERS (caused by bacteria) - causes inflammation, pain and bleeding in stomach
CHALARA ASH DIE BACK (caused by fungus) - causes leaf loss, bark damage ad die back of top of tree
Explain how pathogens are spread and how this spread can be reduced or prevented, including:
- cholera
- tuberculosis
- Chalara ash dieback
- malaria
- stomach ulcers
- Ebola
CHOLERA - water
TUBERCULOSIS - airborne
CHALARA ASH DIEBACK - airborne
MALARIA - animal vector
STOMACH ULCERS - oral transmission
EBOLA - body fluids
Describe how a virus affects the host cells
- Virus attaches to host cell
- Virus enters cell and injects its dna or rna into the cell
- Virus RNA or DNA copies itself and causes new virus proteins to be made, using the organelles in the host cell
- The DNA or RNA and virus proteins are packaged together to make new viruses. These are released from the cell, which usually destroys the host cell
Describe the life cycle of a virus including the lytic and lysogenic cycle
Viruses infect host cells. They multiply by the lytic cycle or the lysogenic cycle.
LYSOGENIC CYCLE - virus inserts its dna into the chromosomes of the host cell, it is called a provirus, this then replicates with the rest of the host dna every time the host cell divides.
At some stage the provirus can become active and make new viruses in the lytic cycle
Explain how sexually transmitted infections (STIs) are spread and how this spread can be reduced or prevented, including:
- Chlamydia (bacteria)
- HIV (virus)
- using condoms during sexual intercourse
- screening people, including pregnant women
- supplying intravenous drug abusers with sterile needles (hiv)
- treating infected people using antibiotics
Describe how some plants defend themselves against attack from pests and pathogens by physical barriers, including the leaf cuticle and cell wall
- leaves are covered with a waxy cuticle to prevent their cells from becoming infected
- each plant cell has a cellulose cell wall which acts as another barrier against infection
Describe how some plants defend themselves against attack from pests and pathogens by physical barriers
- leaves are covered with a waxy cuticle to prevent their cells from becoming infected and stop pest getting through
- each plant cell has a cellulose cell wall which acts as another barrier against infection
- some have adaptations like thorns or spikes
Describe how plants defend themselves against attack from pests and pathogens by producing chemicals
Some plants plants produce toxins and poisons to deter pests trying to eat them
Some plants produce antibacterial chemicals in response to being attacked To kill pathogens
Describe different ways plant diseases can be detected and identified in the field
VISIBLE SYMPTOMS:
- change in appearance of plant
- overgrowth of plant
- under-development of part of plant
- death of parts of the plant
Different diseases may result in different symptoms so other tests are done to determine the cause
DISTRIBUTION ANALYSIS:
- how many plants are affected?
- where are the diseases plants found?
- is just one species of plant affected or several?
- do the symptoms of the plant change over time?
Describe different ways plant diseases can be detected and identified in the lab
- microscopic examination of plant material for signs of pathogens
- antibodies to test for the presence of a pathogen
- genetic testing to identify any pathogens found
- soil sample testing to rule out any soil factors, eg nutrient deficiency
- trying to grow pathogens on nutrient medium to produce a larger sample for identification
Describe how the physical barriers and chemical defences of the human body provide protection from pathogens
CHEMICAL DEFENCES:
- lysozyme enzyme in tears kills bacteria by digesting their cell walls
- lysozyme enzyme is also preset in saliva and mucus
- hydrochloric acid in stomach kills pathogens in food and drink
PHYSICAL DEFENCES:
- unbroken skin provides a thick barrier stopping pathogens entering
- sticky mucus in breathing passages and lungs trap pathogens
- cilia on the cells lining the lungs move mucus and trapped pathogens out of lungs towards throat where it’s swallowed
Describe the advantages and disadvantages of immunisation
ADVANTAGES:
- immunity is produced without being ill
- immunity lasts a long time, often for life
- if most people are immune, then the few people who are unvaccinated are also less likely to catch the disease, this is herd immunity
DISADVANTAGES:
- some people get a mild reaction of swelling or soreness, or a mild form of the disease
- very rarely, a person has a major harmful reaction
Explain why antibiotics can only be used to treat bacterial infections
This is because antibiotics inhibit cell processes in the bacterium but not the host organism.
For example some antibiotics stop bacterial cell walls forming properly. This doesn’t harm the host animal because animal cells do not have cell walls
Explain the aseptic techniques used in culturing microorganisms in the laboratory
1. STERILISING DISHES AND CULTURE MEDIA - sterilisation kills microorganisms, Petri dishes can be sterilised by autoclave great or heating to a high temperature. Culture media (substances the microorganisms grow on) are sterilised by heating to a high temperature
- STERILISING INOCULATING LOOPS - the loop is sterilised in a hot flame and then cooled, before using it to transfer microorganisms to the growth medium
- SEALING PETRI DISHES - lid is secured to stop microorganisms from the air getting in. Vials containing bacteria must be kept covered for the same reason
Describe the role of the specific immune system of the human body in defence against disease
The immune system helps to protect the body by attacking pathogens if they manage to enter the body. Lymphocytes are part of this immune system
Explain how the lymphocytes work in the immune system with antibodies
- Each pathogen has unique antigens on its surface
- A lymphocyte with an antibody that fits the antigen is activated
- The lymphocyte divides many times to produce clones of identical lymphocytes
- Some of the lymphocytes produce lot of antibodies which stick to the pathogen and destroy it. Other lymphocytes stay in the blood as memory lymphocytes, ready to respond quickly if the same antigen return
Explain the body’s response to immunisation using an inactive form of a pathogen (how vaccines work)
- A vaccine contains antigens from the pathogen, often in the form of dead or weakened pathogens (cannot cause disease)
- The person’s lymphocytes produce antibodies against the pathogen and also memory lymphocytes
- If the person gets infected by the real pathogen, the memory lymphocytes will give a very rapid secondary response to the pathogen. This means the person is very unlikely to become ill
Explain the method of the investigation of the microbial cultures
- Turn the bacterial plate upside down and mark the base into sections - one section for each test disc. Label each section with the substance or concentration used
- Turn the plate the right way up. Lift the lid of the dish just enough to be able to place a disc on the lawn
- Use the sterile forceps to place one paper disc on to the bacterial lawn in the correct section. Then briefly flame the forceps in a blue Bunsen flame to sterilise them again.
- Repeat stage 3 for each disc
- Tape the lid to the base of the dish without completely sealing it, to avoid the risk of harmful anaerobic bacteria growing
- Incubate the plate for a few day at 25 degrees Celsius
Explain the investigation of microbial cultures conclusion
The larger the diameter of a clear area around a disc, the better the test substance was at killing bacteria
Calculate cross-sectional areas of bacterial cultures and clear agar jelly
Calculate it with the cross sectional area of each clear area using πr2
Remember to change the diameter to radius by diving by 2
