Topic 5 - Health, Disease And The Development Of Medicines (Unfinished) Flashcards
Diseases can be..
Communicable or non-communicable
How does the WHO define health?
“A state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity”
This means that if someone if very physically fit, they can still be unhealthy due to mental health disorders or social isolation
What are communicable diseases?
Diseases that can be caught and passed on from one organism to another
What are non-communicable diseases?
Diseases that can’t be transmitted
What bacterium causes cholera?
Vibrio cholerae
What pathogen causes malaria?
A protist
What pathogen causes ebola?
A virus
What is a pathogen?
A microorganism that causes disease
What pathogen causes chalara ash dieback?
A fungus
How is cholera spread?
Via contaminated water
How is ebola spread?
Via bodily fluids
How can you prevent tuberculosis?
Infected people should avoid public areas, practise good hygiene and sleep alone
Homes should be well ventilated
How can you prevent ebola?
By isolating infected individuals and sterilising areas where the virus may be present
How can you prevent malaria?
By using mosquito nets and insect repellents
Viruses can only reproduce in living cell
True or false?
True
Are viruses cells?
No - they are just a protein coat around a strand of genetic material
What are the two different ways that viruses can reproduce?
Lytic pathway
Lysogenic pathway
What happens in the lytic pathway?
The virus attaches itself to a specific host cell and injects genetic material
Virus uses proteins and enzymes in the host cell to replicate genetic material and produce components of new viruses
The components assemble and the host cell splits open, damaging the cell and releasing new viruses, which infect more cells
What happens in the lysogenic pathway?
The injected genetic material is incorporated into the genome of the host cell (DNA)
The viral genetic material gets replicated along with the host DNA every time the cell divides - but the virus is dormant and so no new viruses are made
Eventually a trigger causes the viral genetic material to leave the genome and enter the lytic pathway
What are STI’s?
Sexually transmitted infections
What is chlamydia?
Is a bacterium, but behaves like a virus as it needs host cells in order to reproduce
I doesn’t always show symptoms, but it can cause infertility in men and women
How can the transmission of chlamydia be prevented?
Can be reduced by wearing a condom, screening individuals so they can be treated for the infection or avoiding sexual contact
What is HIV?
Human Immunodeficiency Virus
Will eventually lead to AIDS (Acquired Immune Deficiency Syndrome)
What does HIV do?
It kills white blood cells, which are very important in the immune response
What causes HIV to develop into AIDS?
When the infected person’s immune system deteriorates and eventually fails due to the lack of white blood cells that have been killed by HIV
Because of this, the person becomes very susceptible to infections by other pathogens
How is HIV spread, and how can transmission of the virus be prevented?
Spread by bodily fluids e.g. blood, shared needles
Can be prevented by using a condom. Drug users should avoid sharing needles. Medication can reduce the risk of an infected individual passing on the virus to others
Screening and proper treatment are very important
What are some physical defences against pathogens that plants use?
Waxy cuticles to stop them or pests from damaging them
Cell walls made from cellulose, which acts as an additional barrier if pathogens get past the waxy cuticle
What are some chemical defences against pathogens that plants use?
They produce chemicals called antiseptics which kill bacteria and fungal pathogens. They also produce chemicals to deter pests from feeding on their leaves
Some chemicals include aspirin and quinine which can also be used to treat human diseases
What two things might laboratory based diagnostic testing involve?
- Detecting antigens
- Detecting DNA
How can detecting antigens be used to produce accurate identifications of pathogens?
Pathogens have unique molecules on their surface which are called antigens
Antigens for a particular pathogen will be present in a plant infected, and it will be detectable in a sample of plant tissue using monoclonal antibodies
The detection of the antigen is unique to a particular pathogen and can be diagnosed
What do physical and chemical barriers prevent?
Pathogens from entering the body
What physical barriers do we have to prevent infection?
The skin acts as a barrier to pathogens, and if it gets damaged then the blood will clot quickly and seal cuts to keep microorganisms out
Hairs and mucus in your nose trap particles which could contain pathogens
Cells in the trachea and bronchi also produce mucus which traps pathogens. Other cells that line these passages are cilia cells, which are hair like cells which move the mucus away from important organs and towards the back of the throat where it can be swallowed
What chemical barriers do we have to prevent infection?
The stomach produced hydrochloric acid - this kills most pathogens that are swallowed
The eyes produce a chemical called lysozyme which kills bacteria on the surface of the eye
How does the immune system prevent infection if a pathogen enters the body?
White blood cells immediately search for pathogens, and travel all around the body
B-lymphocytes are a type of white blood cell that are involved in the specific immune response - this is the immune response to a specific pathogen
How does the specific immune response work?
Every pathogen has specific antigens (proteins) on their surface
When B-lymphocytes come across an antigen on a pathogen, they produce proteins called antibodies. These bind onto the pathogen so it can be found and destroyed by other white blood cells
The antibodies then rapidly flow all around the body to ensure all the pathogens have been killed
What do memory lymphocytes do?
Give immunity to later infection
How does immunity to a pathogen occur?
When the pathogen first enters, there anent many B-lymphocytes so the response is very slow - the person may show symptoms of the disease until more B-lymphocytes are produced
Over time, more of these lymphocytes will be in the blood stream after the pathogen has been destroyed, and these will remain in the blood stream for a long time
Memory lymphocytes stay in the body for a long time, so therefore this person becomes immune from the pathogen because they have the ability to respond quickly to the pathogen and prevent infection
What is the secondary immune response?
If the same pathogen enters the body after immunity has been reached, then there are more cells that will recognise it and produce antibodies against it
This means that the secondary immune response is much faster and stronger
The secondary immune response often destroys pathogens before you show any symptoms of the disease
What is immunisation?
Usually involved injecting dead or inactive pathogens into the body. These are antigenic (carry antigens) so even though they are harmless to the body, the body still makes an immune response against them
This therefore triggers the production of memory lymphocytes, so if the pathogen appears again, then the secondary immune response will be quicker
This causes immunity without actually catching the disease and showing symptoms - it is a much quicker way to immunity
What are advantages of immunisation?
Big epidemics of a disease can be prevented if a large percentage of people are immunised
Even the people who aren’t immunised are unlikely to catch the disease because there are fewer people to catch it and pass it on
This is called herd immunity
Some diseases, such as smallpox, have been virtually wiped out due to immunisation programmes across the world
What are disadvantages of immunisation?
Immunisation doesn’t always make you immune
You can sometimes have a bad reaction to a vaccine - e.g. swelling or potentially something more serious such as a fever and seizures. However, bad reactions are very rare
What are monoclonal antibodies?
Identical antibodies
How are monoclonal antibodies produced?
From lots of clones of a single B-lymphocyte
This means that all the antibodies are identical and will only target one specific protein antigen
