Topic 5 - Health, Disease And Medicines Flashcards
Health definition
- A state of complete physical, mental and social well being, and not merely the absence of disease or infirmity.
Communicable disease definition
Diseases that can be spread between individuals
Non communicable disease definition
Diseases that cannot be transmitted between individuals.
Define a pathogen:
Organisms such as viruses, bacteria, fungi and protists that cause communicable diseases.
Example of a viral disease, symptoms, spread and treatment
- Ebola
- Causes haemorrhaging fever (fever with bleeding)
- Spread via bodily fluids
- Isolate infected individuals and sterilise any areas where the virus may be present.
Example of a fungal disease, symptoms, spread and treatment
- Chalara ash dieback
- Leaf loss, bark lesions (wounds)
- Carried through air by wind. Can spread when diseased ash trees are moved between areas.
- Remove young, infected trees and replant with different species or restrict the import/movement of ash trees.
Example of a protist disease, symptoms, spread and treatment
- Malaria
- Damage to red blood cells, liver
- Mosquitoes act as animal vectors (pass on the protist to humans but don’t get the disease themselves).
- Mosquito nets and insect repellent can be used to prevent mosquitoes biting people.
Cholera - symptoms, spread and treatment
- Caused by a bacterium
- Causes diarrhoea
- Spreads via contaminated water sources
- Make sure people have access to clean water supplies.
Tuberculosis - symptoms, spread and treatment
- Caused by a bacterium
- Causes coughing and lung damage
- Spread through air when infected people cough
- Infected people should avoid crowded public spaces, practise good hygiene and sleep alone. Have a well-ventilated home.
Stomach Ulcers - symptoms, spread and treatment
- Caused by a bacterium
- Stomach pain, nausea, vomiting
- Spread through oral transmission e.g swallowing contaminated water/food
- Have clean water supplies and hygienic living conditions.
STI definition -
Sexually Transmitted Infections are infections that spread through sexual contact, including sexual intercourse.
Chlamydia - symptoms, spread and treatment
- Bacterium
- Doesn’t always cause symptoms, can result in infertility
- Wear a condom, screen individuals so they can be treated or avoid sexual contact.
HIV - symptoms, spread and treatment
- Caused by a virus
- Kills white blood cells, which are important in the immune response
- Leads to AIDS
- This is when the immune system deteriorates and fails so because of this, the person becomes vulnerable to infections by other pathogens.
- Spread via infected bodily fluids.
- Use a condom, don’t share needles, take medication to reduce the risk of passing the virus on during sex. Screening and proper treatment are important.
Lytic Pathway of a virus:
1) - Virus attaches itself to a specific host cell and injects its genetic material into the cell.
2) - The virus uses proteins and enzymes in the host cell to replicate its genetic material and produce the components of new viruses.
3) - The viral components assemble.
4) - The host cell splits open, releasing the new viruses, which infect more cells.
Lysogenic Pathway:
1) - Injected genetic material is incorporated into the genome of the host cell.
2) - The viral genetic material gets replicated along with the host DNA every time the host cell divides - but the virus is dormant and no new viruses are made.
3) - Eventually a trigger (e.g the presence of a chemical) causes the genetic material to leave the genome and enter the lytic pathway.
Waxy Cuticle as a Physical Defence:
- Plant leaves and stems have a waxy cuticle, which provides a barrier to stop pathogens entering them or pests from damaging them.
- It may also stop water collecting on the leaf, which could reduce the risk of infection by pathogens that are transferred between plants in water.
Cell Wall as a Physical Defence:
- Cell walls made from cellulose
- These form a physical barrier against pathogens that make it past the waxy cuticle.
Plant Chemical Defences:
- Produce chemicals that help prevent damage to the plant.
- Antiseptics for example kill bacterial and fungal pathogens.
- Chemicals can deter pests e.g insects from feeding on their leaves.
How can plant chemical defences be used as drugs to treat human disease or relieve symptoms?
- Quinine comes from the bark of the cinchona tree. It was a main treatment for malaria.
- Aspirin is used to relieve pain and fever. It was developed from a chemical found in the bark and leaves of willow trees.
How can plant diseases be detected in the field?
1) - Detected by observations. Plant pathologists recognise the symptoms e.g galls (abnormal growths) might indicate crown gall disease in apples and fruit trees.
2) - Plants may show symptoms of a disease due to environmental causes, like a nutrient deficiency. By changing the environmental conditions (e.g adding nutrients to the soil) and observing any change in the plant’s symptoms, you can determine whether a plant is diseased or if the symptoms were due to something else.
3) - Different pathogens are spread in different ways - so plant pathologists can analyse the distribution of diseased plants to identify the kind of pathogen involved.
How does detecting antigens in the lab help to identify plant diseases?
1) - Pathogens have unique molecules on their surface called antigens.
2) - Antigens from a particular pathogen will be present in a plant infected with that pathogen and can be detected in a sample of plant tissue (using monoclonal antibodies).
3) - The detection of an antigen unique to a particular pathogen allows that pathogen to be identifies and the disease diagnosed.
How does detecting DNA in the lab help to identify plant diseases?
1) - If a plant is infected with a pathogen, the pathogen’s DNA will be present in the plant’s tissues.
2) - Scientists have techniques that allow them to detect even small amounts of pathogen DNA in a sample of plant tissue, allowing them to identify the particular pathogen that is present.
Human Physical Barriers:
1) - The skin acts as a barrier to pathogens and if it gets damaged, blood clots quickly seal cuts and keep microorganisms out.
2) - Hairs and mucus in your nose trap particles that could contain pathogens.
3) - Cells in your trachea and bronchi produce mucus, which trap pathogens. Other cells that line the trachea and bronchi have cilia. These are hair-like structures which waft the mucus up to the back of the throat where it can be swallowed.
Chemical Barriers in Humans:
1) - The stomach produces hydrochloride acid which kills most pathogens that are swallowed.
2) - The eyes produce a chemical called lysozyme (in tears) which kills bacteria on the surface of the eye.
How does the specific immune response work?
1) - Every pathogen has unique molecules on its surface called antigens.
2) - When your B-lymphocytes (type of white blood cell) come across an antigen on a pathogen, they start to produce proteins called antibodies.
3) - Antibodies bind to the new invading pathogen, so it can be found and destroyed by other white blood cells. The antibodies produced are specific to that pathogen (they won’t lock on to any other pathogens).
4) - The antibodies are then produced rapidly and flow all around the body to find all similar pathogens.
Secondary Immune Response (6 marks):
1) - When a pathogen enters the body for the first time, the response is slow because there aren’t many B-lymphocytes that can make the antibody to lock on to the antigen.
2) - Eventually, the body will produce enough of the right antibody to overcome the infection. Meanwhile, the infected person will show symptoms of the disease.
3) - As well as antibodies, memory lymphocytes are also produced in response to a foreign antigen. Memory lymphocytes remain in the body for a long time, and remember a specific antigen.
4) - The person is now immune - their immune system has the ability to respond quickly to a second infection.
5) - If the same pathogen enters the body again, there are more cells that will recognise it and produce antibodies against it. This secondary immune response is faster and stronger.
6) - The secondary response often gets rid of the pathogen before you begin to show nay symptoms.
How can immunisation stop you getting infections?
1) - To make it less likely that you’ll get ill, you can immunised against some diseases like measles.
2) - Immunisation usually involves injecting dead or inactive pathogens into the body. These are antigenic so even though they’re harmless, your body makes antibodies to help destroy them.
3) - The antigens also trigger the production of memory lymphocytes.
4) - So, if live pathogens of the same type get into the body, there will already be memory lymphocytes that can cause a fast secondary immune response. This means that you’re less likely to get the disease.
Pros of Immunisation:
1) - Epidemics can be prevented if a large percentage of the population are immunised. Even the people who aren’t immunised are unlikely to catch the disease because there are fewer people able to pass it on - this is known as herd immunity.
2) - Some diseases e.g smallpox have been virtually wiped out by immunisation programmes.
Cons of immunisation:
1) - Immunisation doesn’t always work - sometimes it doesn’t give you immunity.
2) - You can sometimes have bad reaction to a vaccine (e.g swelling, fever, seizures). Bad reactions are very rare.
What are antibodies produced by?
B-lymphocytes which are a type of white blood cell.
What are monoclonal antibodies produced from?
- Lots of clones of a single B-lymphocyte.
- This means all the antibodies are identical and will only target one specific protein antigen.
How easily do lymphocytes divide?
Not very easily.
