8.) Topic 8 Disease, Defence And Treatment Flashcards
What are micro-organisms?
Microscopic organisms
What is a non-pathogenic microorganism
Any microorganism that does not cause disease
Give an example of a non-pathogenic microorganism
- Gut bacteria to help digest food
- Skin flora help to prevent infection by competing with pathogens for resources
What is a pathogen?
A microorganism causing disease
Give 4 types of pathogens/microorganisms and give an example for each one
Bacteria - Salmonella
Viruses - HIV, potentially leading to AIDS
Protists - Malaria
Fungi - Athlete’s foot
Give 6 features of bacteria cells
- Cell membrane
- Cell wall (made of murein)
- Cytoplasm
- Plasmid loops of DNA
- No nucleus
- Reproduce by dividing in two to form clones - binary fission
- Exist as single cells
- Sometimes have a slime capsule around the cell wall to stop them drying out
- May have pili to attach to surfaces, or flagella to allow them to move
Give 4 features of viruses
- Smaller than bacteria
- Contain a protein coat surrounding a number of genes
- Only reproduce in a host cell
- Producing new viruses destroys the host cell as the new viruses are released. They are then free to attack other cells
What are diseases caused by pathogens called?
Communicable disease
Give 6 ways in which diseases can be spread
- Direct contact
- Aerosol
- Body fluids
- Water
- Insects
- Contaminated food
What is Tuberculosis caused by?
b) Type of organism
c) Symptoms
d) Prevention
Mycobacterium
b) Bacteria
c) Chest pain and a very bad cough. Occasionally may cough blood if infected
d) Vaccine
What is Malaria caused by?
b) Type of organism
c) Symptoms x4
d) Prevention x4
e) Mode of transmission
Plasmodium falciparum
b) Protist
c) Fever
Vomiting or diarrhoea
Headaches
Muscle and/or abdominal pain
d) Wear long clothing
Wear mosquito repellent
Sleep with mosquito nets
Use malaria prevention tablets
e) Insects/animals
What is Influenza caused by?
b) Type of organism
c) Symptoms x6
d) Prevention
Flu virus
b) Virus
c) Chills Sore throat Fever Muscle pains Coughing Severe headaches
d) Vaccine
What is food poisoning caused by?
b) Type of organism
c) Symptoms
d) Prevention
e) Mode of transmission
Salmonella or E. coli
b) Bacteria
c) Diarrhoea
Kidney failure
d) Meat is thoroughly cooked and vegetables are washed in clean water
e) Contaminated food
What is Chlamydia caused by?
b) Type of organism
c) Symptoms x3
d) Prevention
e) Mode of transmission
Chlamydia trachomatis
b) Bacteria
c) Pain when urinating
Painful discharge from the penis or vagina
Bleeding between periods for women
d) Wear condoms during sex
e) Direct contact
What is Athlete’s foot caused by?
b) Type of organism
c) Symptoms x2
d) Prevention x3
Dermatophytes or trichophyton
b) Fungi
c) Itching and flaking of the affected skin
Blisters
d) Avoid sharing towels and clean footwear and shower floors
What is Chicken pox caused by?
b) Type of organism
c) Symptoms x4
d) Prevention
e) Mode of transmission
Varicella
b) Virus
c) Itchy rash on head and neck
fever
Headache
Sore throat
d) Vaccine
e) Direct contact
Give 5 non-specific human defences to disease
The skin acts as a barrier
Stomach acid kills ingested pathogens
Mucus traps pathogens
Sweat contains antimicrobial chemicals
Blood clots prevent pathogen entry into wounds
What is the bodies 3 lines of defences against infection by pathogens?
- the skin stops microbes getting into the body
- Platelets stop microbes getting into the body through a cut
. White blood cells defend against microbes that are inside of the body by 3 ways:
1 - Phagocytes ingest bacteria
2 - Lymphocytes produce antibodies to inactivate bacteria or viruses
3 - Lymphocytes produce anti toxins that counteract toxins released by bacteria
What in inflammation and in which line of defence is it present?
Blood capillaries widen and more blood flows to the scene
2nd line of defence
What do white blood cells produce?
Antibodies and anti toxins
What is an antigen
A protein found on the surface of the pathogen that triggers an immune response
What is an antibody
A protein produced by the immune system which attacks specific antigens
What is an antitoxin
A type of antibody produced by white blood cells to neutralise toxins
What is a phagocyte
A type of white blood cell which engulfs and digests pathogens
What is a lymphocyte
White blood cells which attack antigens by producing antibodies
Give 2 ways that the body can respond to detecting a pathogen
- They can produce antibodies that are specific to the antigens on the pathogen that activate phagocytes
- They can produce anti toxins to neutralise the toxins released by the pathogen
How do phagocytes respond to detecting a pathogen?
Phagocytes engulf and break down pathogens in a process known as phagocytosis
What do platelets release and cause?
Release chemicals that cause soluble proteins to form a mesh of insoluble fibres across the wound and stick together to form clumps when platelets get stuck in the mesh
Explain how the body responds to a foreign antigen the first time it is encountered and why the response if faster when the same antigen is encountered a second time. [4]
Foreign antigens stimulate an immune response to the body. Firstly, the lymphocytes recognise the ‘foreign’ antigen. Then the lymphocyte multiplies to form clones. The clones differentiate and most develop to form short lived plasma cells. These plasma cells produce antibodies and antibodies attach to the antigen and slowly destroys it or they ‘label’ the antigens for the phagocytes to ingest. Some other lymphocytes develop into long lasting memory cells. These memory cells will stimulate an immune response if they come across the same antigen. After more plasma cells are developed producing a large concentration of antibodies quickly and more memory cells are then produced which boosts immunity. Therefore, if the same antigen comes again, the memory cells will remember which antibodies to produce quickly which can destroy it with ease
Give 2 types of pathogen that vaccines can protect against
Bacteria and viruses
What do vaccines contain?
Dead pathogens Or Live but weakened pathogens Or Parts of the pathogen
Why do we need different vaccines for different diseases?
Because not all diseases have the same antigens, therefore the lymphocytes cannot produce the antibodies to destroy the certain antigen. With different antigens, the memory cells will not be able to remember what antibodies to produce
Why are flu vaccines made every year?
Because different strains of the flu virus mutate over time and give rise to new strains with different antigens. Because of this, different antibodies are needed to destroy the antigens as the memory cells produced cannot recognise the new antigens. the body is therefore not immune to the new stain of the flu
What are the 3 differences between active and passive immunity
Active immunity works slowly, lasts for a long period of time and occurs after a vaccination or illness
Where as
Passive immunity works quickly, last for a short period of time and the baby receives antibodies from its mother
Why might parents choose to have their child vaccinated? x2
Vaccines have saved lives and will prevent their child from certain diseases
Parents in countries without free healthcare may not be able to afford treatment if their child falls ill from a disease
Why might parents choose NOT to have their child vaccinated? x4
- They may be concerned about the potential side effects
- They may be unaware of the contents in the vaccine
- They may have religious or cultural objections to it
- They may believe that vaccines are linked to certain other diseases like autism, asthma and multiple sclerosis
What negative impacts could arise from the decision to not vaccinate children?
Can lead to breakouts of diseases which may cause pandemics or epidemics and put a strain on the healthcare system
How do vaccines work?
1 - Dead or inactive pathogens or antigens for a disease are injected into the body
2 - Lymphocytes produce antibodies against the pathogen
3 - These antibodies attach and clump pathogens together
4 - Phagocytes engulf the pathogens and so it is destroyed quickly (phagocytosis occurs)
5 - Memory cells are also created which provides long term immunity so if the microbe attacks the body again, the memory cells will remember to create the right antibodies to destroy the pathogen quickly
6 - The person is now immune and unlikely to get the same illness again
Why is the secondary response to a pathogen much faster than the initial response?
The activation of the immune system in response to a new pathogen is relatively slow. Memory cells that remain in the blood speed up the process and can produce antibodies much quicker
What are antibiotics?
What are they most commonly prescribed as?
Antibiotics are substances produced by a microorganism to kill other microorganisms. They help to slow down or stop the growth of bacteria.
They are most commonly prescribed as medicines
What was the first ever antibiotic discovered?
Penicillin by Alexander Fleming in 1928
Do antibiotics kill viruses and why?
No because viruses live inside the host cell and so an antibiotic cannot reach them
Outline how antibiotics work
Antibiotics damage the bacterial cells but do not damage the host cells. They have the ability to cure some bacterial diseases that would have previously killed many people.
Give 3 reasons why prescribed antibiotics are becoming less effective
- Overuse of antibiotics
- Failing to complete the fully prescribed course by the doctor
- Use of antibiotics in farming
What is antibiotic resistance
The ability of certain bacteria to survive and reproduce in the presence of an antibiotic
What type of microorganism produces penicillin?
A fungus called penicillium
What is semisynthetic penicillin?
Penicillin that has been modified chemically
What is synthetic penicillin?
Penicillin that has been produced from scratch chemically rather than being produced naturally by microorganisms
Give one example of an antibiotic resistant bacterium
MRSA
State 5 ways of controlling the spread of MRSA
- Cover wound with sterile dressings
- Wash hands
- Use of alcohol gels or antibacterial gels
- MRSA screening before surgery
- Thorough cleaning of hospital wards
Give 3 ways diseases can be prevented
Wash hands
Have a balanced and healthy diet
Drink clean water
What is health
The complete physical, mental and social well-being
What is a drug?
A drug is a substance that affects chemicals processes within the body. It alters how the body works in a certain way.
What are the 2 main stages of drug testing
Preclinical and clinical testing
What are the 4 stages in the development of new medicine
1- The drug is tested on human cells grown outside the body in a laboratory
2- Drug is tested on animals
3- Drug then is tested on healthy volunteers
4- Drug is then tested on people who have the disease
If all of these tests are passed, the drug is then licensed for use
Stages 1-3 are preclinical and stage 4 is clinical
What are preclinical trials?
Testing the drug on lab grown cells and tissues and using computer modelling to understand the effects of the drug
What is a placebo?
A substance which looks the same and is ideally indistinguishable from the actual rug but has no effect when taken
What are placebos used for?
Placebos are used to test the effectiveness of the new drug by providing a comparison point
What is a blind trial?
The patients are not told if they are in the trial group of the placebo group
What is a double blind trial?
Neither the patient nor the doctor administering the drug knows if the patient is receiving the drug or a placebo in an attempt to eliminate bias altogether
What are monoclonal antibodies?
Antibodies that are all identical and specific to a single type of pathogen
What are monoclonal antibodies produced from?
Lymphocytes
How do lymphocytes produce monoclonal antibodies
- Lymphocytes are activated and produce antibodies that are specific to a pathogen
- The lymphocytes divide so that lots of antibodies can be made at once
What is the formation of monoclonal antibodies
1 - An antigen is injected into a mouse.
2 - The mouse naturally produces lymphocytes, which produce antibodies specific to the antigen.
3 - Spleen cells which produce the lymphocytes are removed during a small operation.
4 - The spleen cells are fused with human cancerous white blood cells called myeloma cells to form hybridoma cells which divide indefinitely.
5 - These hybridoma cells divide and produce millions of monoclonal antibodies specific to the original antigen.
6 - The antibodies are extracted from the culture medium by centrifugation, filtration and chromatography
How can monoclonal antibodies be used to detect diseases like chlamydia, HIV and malaria?
Specific monoclonal antibodies that are attached to fluorescent dyes are mixed with bodily fluids so that they will fluoresce if the pathogen is present
How are monoclonal antibodies used in tissue and organ transplants (Higher)
They are used to deactivate T cells so that there is no immune response
How are monoclonal antibodies used to help chemotherapy?
They are used to deactivate T cells so that there is no immune response
How are monoclonal antibodies used for monitoring the spread of malaria
Blood is taken from samples of people and tested with labelled monoclonal antibodies. These will detect the plasmodium present in the blood stream as they have specific antigens and will attach to the labelled monoclonal antibodies. This enables the success of antimalarial drugs and the potential spread of malaria to be monitored.
How are monoclonal antibodies used to help cancer diagnosis and treatment
Some types of cancerous cells have specific antigens on their surface called tumour markers. Monoclonal antibodies can be produced to bind specifically with these antigens. When injected into a person’s body, the monoclonal antibodies will bind with these cancer cells and clump them together. This makes it easier to identify a cancerous tumour, which can then be treated or removed. If these are attached to anti-cancer drugs, they will deliver the drug directly to the cancer cells.
2 ways how monoclonal antibodies can treat cancer by:
Monoclonal antibodies can treat cancer by:
Carrying drugs that have been attached to them to the tumour
Encouraging your immune system to attack the cancer cells directly
