Paper 1: Topic 3 Infection & response - Fighting disease (IV form) Flashcards
Describe what a single-blind trial is
The patient doesn’t know if they are being given a drug or a placebo but the doctor knows what the patient takes
Explain why not all bacterial disease can be treated with penicillin
Different antibiotics kill different types of bacteria It is important medical professionals prescribe the correct antibiotic
Describe what is a placebo
Placebos are tablets/capsules that look identical to the new drug but contain no active ingredient i.e. they are a dummy tablet with no actual drug in them
Name a disease that has been eradicated completely due to vaccination
Smallpox
Explain why is it important that drugs test & trial results are peer reviewed before they are published?
To prevent false claims
Explain 2 ways that the hairs and mucus in the nasal passages act as a non-specific line of defence for the body
- The mucus traps the pathogens (any type hence non-specific response)
- The cilia then beat to waft the mucus to the top of the throat
- where it can be coughed out or swallowed
- and therefore prevent the entry of the pathogen to the lungs
Describe the importance of the discovery of antibiotics
The discovery of antibiotics has led to a significant reduction in communicable diseases
Explain why viral infections are harder to treat
The virus lives inside host cells Hence it is hidden from the immune system This prevents the lymphocytes and phagocytes from identifying and destroying the virus
Describe what the purpose is of a phase 2 of a clinical trial
To determine the effectiveness of the drug
Explain what antibodies are
Specialised proteins that bind to antigens on the surface of a pathogen
Describe what happens in phase 3 of a clinical trial
This will involve thousands of people It will include people with the disease The volunteers will be randomised The effects of the drug will be compared with established drugs
Describe the term ‘peer review’
When scientists who have not been involved in the drug trail in anyway check that the work has been carried out rigorously and the results are valid
State 2 disadvantages of vaccinations
Vaccines do not always work - some people do not produce the antibodies and develop immunity to the pathogen Some people experience side effects to the chemicals in the vaccine e.g. swelling, fever
State the 3 main stages of a drug test
1 Testing on human cells and tissues 2 Testing on live animals 3 Testing on human volunteers
Describe what happens in phase 2 of a clinical trial
The drug is tested on ~200 people This phase will involve the use of a placebo It can involve blind trials and double-blind trials This is used to determine the optimal dose of the drug
Describe phagocytosis
White blood cells engulf the pathogen The white blood cell then breaks down the pathogen
Explain what is meant by the ‘efficacy of the drug’?
How well the drug works to kill the pathogen or relieve the symptoms
What is the optimal dose for any drug?
The dose that has the best effect with minimal (preferably no) side effects
Who discovered penicillin?
Alexander Flemming
Describe how antitoxins help fight pathogens
Antitoxins counteract the toxins produced by the invading bacteria
Explain 2 ways that the skin acts as a non-specific line of defence for the body
The skin forms a barrier to prevent the entry of pathogens The skin secretes antimicrobial chemicals which kill pathogens
Describe what a double-blind trial is
Some patients are given a placebo and some get the new drug but neither the patient or the doctor knows what the patient takes until the trial is complete
Give 2 examples of medicinal drugs that have been obtained from plants. For each example state where it has been discovered
Aspirin - found in willow Digitalis - found in foxgloves
Explain what is meant by the ‘toxicity of the drug’?
Whether or not the drugs might cause harm to cells and tissues of the patient
Explain where antibiotics are obtained from
Many antibiotics are produced by moulds e.g. Penicillin
Why are dead or inactive pathogens used in vaccination?
If the actual pathogen was injected it would cause the disease By injecting dead or inactive pathogens the antigens are still present and therefore stimulate the B-lymphocytes to produce antibodies The dead or inactive pathogens are harmless
Describe what the purpose is of a phase 1 of a clinical trial
To determine the safety and effectiveness of the drug To make sure the drug does not have any harmful side-effects
Explain how society can help reduce the development of resistant strains of bacteria
Medical professionals must avoid over-prescribing antibiotics Patients must ensure they complete the antibiotic course (take all the tablets even if they feel better before they have finished them) Patients must not expect to be prescribed antibiotics for all sore throats, fevers etc - if they have a viral infection antibiotics will be of NO use
State the body system that destroys pathogen
Immune system
Describe what the purpose is of a phase 3 of a clinical trial
To determine the effectiveness of the drug
Describe how antibodies help fight pathogens Hint: 7 stages
- A pathogen invades the human body
- The antigens on the surface of the pathogen are detected by specific B-lymphocytes
- The selected B-lymphocyte produces many antibodies
- The antibodies are released into the plasma
- The antibodies bind to the antigens on the surface of the pathogen
- This stops the spread of the pathogen around the body
- The immobilised pathogen is then broken down by phaocytosis
Describe what is meant by ‘the placebo effect’
When the patient expects to feel better as they are taking medication,
Explain how vaccination can help prevent epidemics occurring
If sufficient people are vaccinated it reduces the number of people who can become infected with the pathogen This reduces the number of people who will then pass on the pathogen Hence preventing the spread of the disease
What are medicinal the uses ofthe chemcal extracted from foxgloves called digitalis?
Used to treat heart conditions
Explain how the stomach acts as a non-specific line of defence for the body
It produces hydrochloric acid The acid kills any pathogens that are ingested
Explain how bacteria can become resistant to antibiotics Hint: 5 stages
- A bacterium in the infected person mutates
- This mutation means the individual bacterium is not killed by the antibiotic
- The resistant bacterium can continue to grow and multiply in the infected person’s body
- The resistant bacterium survives and reproduces (by mitosis to produce identical resistant bacteria)
- The resistant bacterium will increase rapidly in number as the non-resistant bacteria will have been killed off therefore there is less competition for nutrients etc
- This is an example of natural selection
State which cells produce antitoxins
T-lymphoctyes
Explain what an antigen is
A protein or carbohydrate molecule on the outside surface of a pathogen that the body detects as foreign The presence of an antigen will stimulate an immune response
Describe what the purpose is of a preclinical stage of a drug test
To determine the safety and effectiveness of the drug
What are medicinal the uses of aspirin?
Used as a painkiller Can be used to lower fevers
Describe what the purpose is of a phase 4 of a clinical trial
To monitor long term effectiveness and side-effects
Explain 2 ways that the trachea and bronchi act as a non-specific line of defence for the body
The trachea and bronchi have specialised cells that secret mucus The mucus traps the pathogens The trachea and bronchi also have specialised cells that have cilia These ciliated cells waft the mucus containing the trapped pathogens to the mouth The body then swallows the mucus or coughs it out
What are the 3 main aspects that a drug trial investigates?
Toxicity Efficacy Dose
Explain what is meant by the term ‘multi-drug resistant bacteria’
These are bacteria that have evolved to be resistant to 2 or more antibiotics
Describe what happens in phase 1 of a clinical trial
The drug is tested on 20-30 healthy volunteers Initially very low doses of the drug are administered The dosage is slowly increased as phase 1 progresses
State a type of drug that kills bacteria and give an example of this type of drug
Type of drug = antibiotics Examples = penicillin, ampicillin, tetracycline, amoxycillin
State 3 advantages of vaccinations
They help control communicable diseases They help prevent epidemics of diseases When used for long enough and enough people are vaccinated they can lead to the eradication of a disease
Explain why do clinical trials begin with healthy volunteers?
To see if any side effects occur
Describe how antibiotics can be produced on a large scale
Using industrial fermenters in the pharmaceutical industry
State 2 types of medicinal drugs that can be used to relieve symptoms
Painkillers e.g. paracetamol Anti-inflammatories e.g. ibuprofen
Describe 3 ways white blood cells help to defence against pathogens
Phagocytosis Antibody production Antitoxin production
Explain why placebos are used in drug trials
Placebos are used to ensure valid & reliable data is collected with no bias
Explain why antibiotics are not prescribed for a person who has measles or the ‘flu
Antibiotics ONLY work on bacteria Antibiotics do not kill viruses
Name a drug resistant bacterium
MRSA methicillin-resistant Staphylcoccus aureus
Describe what a triple-blind trial is
Some patients are given a placebo and some get the new drug but neither the patient or the doctor or the statistician knows what the patient takes until the trial and data processing is complete
Explain what is meant by the ‘dosage of the drug’?
How much of the drug must be administered/taken to see a beneficial effect
Describe what vaccines are?
An injection of small amounts of the dead or inactive pathogen to stimulate an immune response
Explain the importance of using blind trials in a drugs trial
It eliminates the placebo effect Also prevents subconscious bias from doctors when reporting how effective the drug has been
State the 4 non-specific forms of defence that the body has to prevent the entry of pathogens
skin nose trachea and bronchi stomach
State which cells produce antibodies
B-lymphocytes
Describe what happens in the preclinical stage of a drug test
The drug is tested on human cells and tissues And then tested on 2 types of mammals
Describe what happens in phase 4 of a clinical trial
The effectiveness of the drug will be continually monitored The long term benefit(s) of the drug will be studied Any side effects will be monitored
State 4 ways the body prevents the entry of micro-organisms
- Skin - forms a barrier and secretes anti-microbial chemicals
- Stomach - secretes hydrochloric acid to kill any ingested pathogens
- Hairs in the nose trap pathogens and particles
- Mucus in the trachea and bronchi and nasal passages trap pathogen which is then wafted by cilia to the throat to be swallowed
Give 3 examples of cellular defence mecahnisms
- Production of antibodies by lymphocytes
- Production of antitoxins by lymphocytes
- Phaocytosis by phagocytes
Give 3 examples of chemical defence mechanisms
- Production of sweat by swaet glands
- Production of hydrochloric acid in the stomach
- Production of tears by tear glands
- Production of mucus to line alveoli
Give 2 examples of mechanical defence mechanisms
- Skin - acts as a barrier
- Nasal hairs
