Immune systems and defences Flashcards
Skin defense system
- physical barrier to pathogens
- secretes antimicrobial substances -
kills pathogens
respiration defense system
- hairs and mucus in nose
- mucus in trachea and bronchi
- lined with cilia
Cilia
Hair-like structures that waft the mucus up to the throat where it can be swallowed to the stomach
- the stomach releases hydrochloric
acid which kills pathogens
Phagocytosis
enlgufs foreign cells and digest them
Antibodies
produce by white blood cell so it can bind to it and destroy
antitoxins
Bind and neutralise the toxins produced by bacteria
Pros of vaccines
- Protection from diseases
- control of common diseases
- prevent outbreaks (epidemic)
Cons of vaccines
- dont always work (no full immunity)
- bad reactions
How do vaccines work?
injecting inactive pathogens carrying the antigens so the body can produce antibodies that attack them so if the live pathogen appear the white blood cells can rapidly produce those antibodiees
What are examples of drugs that relieve the symptoms
- aspirin
- paracetamol
- cough medicine
Antibiotics
- kill pathogens
-stops them from growing - only if bacteria is the cause
Why can you use antibiotics on viruses?
- made specifically to interfere with bacteria and viruses are so different
- wouldn’t be able to find them as they hide within our body cells which makes it hard to develop a drug without killing the body’s cell
What is aspirin?
- painkiller
- lower fever
Where is aspirin originally from?
willow trees
What does digitalis treat?
- heart problems
Where are digitalis originally from?
foxgloves
What are the 3 things when testing drugs
- efficacy
- toxicity
- dosage
efficacy (drug testing)
How well the drug works
toxicity (drug testing)
how harmful the drug is
- side effects?
dosage (drug testing)
how much of the drug ( concentration)
- more drug = more effect = more side
effects
Stage 1 (drug testing)
- drug tested on human cells and tissues
- benefit = easily and cheaply test lots of substances
- con= doesn’t tell us how if effects an entire organism
stage 2 (drug testing)
- testing on live animals (mice and mammals)
- we are mammals too so it gives us a good idea of the efficacy and toxicity of drug
preclinical
Do not involve humans
stage 3 (clinical testing)
- give drugs to healthy humans starting
off with a low dose - slowly increase dose while doctor
keeps an eye of the patients health- checking for side effects
- aim is to find max dosage before side
effects
part 2 (clinical testing)
- give drug to a person with the
particular illness the drug is trying to
target - slowly increase dose
- aim for the optimum dosage
Optimum dosage
efficacy = maximized
toxicity = minimized
How do we make sure that the results are fair and valid?
- clinical trails should be blind and use of placebo
- double - blind
- one half of volunteer with placebo and
others with the real drugs - purpose = avoid bias
placebo
like the real drug but doesn’t do anything
What happens after the completion of the drug testing?
results written up and peer- reviewed
- analysed by other scientists to check is
the tests were fair
Why is it important for drugs to undergo testing?
- make sure its effective
- safe to use
- determine optimum dose
Why is double-blind trails important?
- to avoid unconscious bias
- patients may report side effects
- researchers may pay closer attention
to those patients
