Disease Flashcards
What are the four types of pathogens?
A virus, bacterium, fungus, or protist
What is an example of a virus
HIV
What is an example of a bacterium
Salmonella
What is an example of a fungus
Athlete’s foot
What is an example of a protist?
Malaria
What is the life cycle of a pathogen?
They infect a host, reproduce themselves (or replicate, in the case of a virus), spread from their host, and infect other organisms.
What are diseases caused by pathogens called?
Communicable diseases, meaning they’re infectious
What features do bacterial cells have?
- No nucleus
- A cell wall made of murein
- A cell membrane and cytoplasm
- Sometimes loops of DNA called plasmids
This is a bacteria diagram
Are viruses considered alive?
No
What are viruses made up of?
A relatively short length of genetic material DNA which is surrounded by a protein coat.
Virus diagram upcoming
What are the five types of disease spreading?
- Direct contact
- Water
- Air
- Unhygienic food preparation
- A vector
What is clamydia caused by?
A bacterium (STI)
What are the results of chlamydia
Infertility and conjunctivitis in babies
What is malaria transmitted by?
The Plasmodium protist
What proportion of people die from malaria?
Half
What are the first defences against pathogens?
Non-specific barriers like the skin (a physical barrier), the nose (hairs form a barrier), trachea and bronchi (
What is the trachea and where is it?
Basically it’s the windpipe, and it runs from the larynx (voice box) to the bronchi
What do the cells of the trachea have?
Cilia, which are tiny hairs. They are called ciliated cells
What do ciliated cells do
Move mucus and pathogens upwards towards the throat where they are swallowed into your stomach.
Which cells create mucus
Goblet cells
How does the stomach protect you from pathogens
Its acid kills them
What does the immune system consist of?
Phagocyte and lymphocyte cells
What do phagocytes do?
Engulf a bacterial cell
Which pathogens do phagocytes attack?
Them all, so they are non specific
What do lymphocytes do?
They recognise proteins on the surface of pathogens called antigens and produce antibodies
What do lymphocyte antibodies do?
Cause pathogens to stick together so they can be engulfed
How do most pathogens make you feel ill?
By producing toxins
What do lymphocytes produce?
Antitoxins to neutralise toxins
Why are lymphocytes specific?
Because their antitoxins are highly specific to the pathogens they target
What happens after the body recognises a pathogen?
Memory cells are created which can produce a quick response - this is immunity
What do vaccines do?
They inject something containing an antigen into the blood stream causing the immune system to produce antibodies
Vaccine picture upcoming
What happens during each injection?
With the primary injection antibodies slowly increase over several days, but with the secondary one the same pathogen causes the white blood cells to respond quickly in order to produce lots of the relevant antibodies, which prevents infection
What do antibiotics do?
They slow down or stop the growth of bacteria without damaging their host cell
What are antibiotics not effective against?
Viruses
Why are commonly prescribed antibiotics becoming less effective?
- overuse of antibiotics
- failing to complete the fully prescribed course by a doctor
- use of antibiotics in farming
What’s an example of a superbug?
MRSA - resistant to methicillin
What measures do people take against superbugs?
- hand washing
- thorough cleaning of hospital wards
- use of alcohol gels
- MRSA screening
What is preclinical testing?
Testing drugs using computer models and human cells grown in a laboratory
What happens if drugs pass tests on computers and human cells?
They’re tested on animals, although testing cosmetics or tobacco is illegal on animals in the UK
What happens if new drugs pass animal tests?
They are used in clinical trials, on healthy people, and then on people with the illness
What are the strategies removed to avoid the placebo effect?
- The use of a placebo
- Blind trials
- Double blind trials (even the doctor doesn’t know if the placebo is being used or not)
How are monoclonal antibodies used in medicine?
They bind with the relevant substances, grouping them together and making them identifiable
How do we manufacture monoclonal antibodies?
- An antigen is injected into a mouse
- The mouse naturally produces lymphocytes, which produce antibodies specific to the antigen.
- Spleen cells which produce these lymphocytes are removed4.
- These spleen cells are fused with cancerous human white blood cells
- These hybridoma cells divide and produce millions of monoclonal antibodies specific to the original antigen.
What are human white blood cells known as?
Myeloma cells
What is the name of the cells which result from myeloma and mouse spleen cells?
Hybridoma
What are monoclonal antibodies often used for?
Cancer diagnosis and treatment
What are the antigens on the surface of a cancer cell called?
Tumour markers
How can monoclonal antibodies be used to treat cancer?
They are attached to anti-cancer drugs and deliver them straight to cancer cells
What does an immunoassay do?
It uses monoclonal antibodies to diagnose infections
How do monoclonal antibodies help with organ transplants?
They prevent rejection by combining and disabling T cells, which lymphocytes need to produce the antibodies that would result in rejection
What else can monoclonal antibodies help diagnose?
- Malaria
- HIV
- Chlamydia
