Human defences (infections pt2) Flashcards
What the non-specific defence systems of the human body against pathogens? (5/6)
- skin
- nose
- trachea and bronchi
- stomach
- eyes
what does non-specific defences against disease mean?
the first line of defence against pathogens in general
How does the skin protect the body from diseases?
it acts as a barrier to pathogens and secretes antimicrobial substances which kill pathogens.
the sebaceous gland produces sebum which kills bacteria and fungi
How does the nose protect the body from diseases?
the mucas and the hairs traps particles and bacteria
How does the trachea and bronchi protect the body from diseases?
sheet of mucas traps particles and bacteria. Cilla waft the mucas up to the back of the throat where it can be swallowed
How does the stomach protect the body from diseases?
glands and hydrochloric acid, kills bacteria in food
How does the eyes protect the body from diseases?
enzymes in tears destroy micro-organisms
How does white blood cels help defend against pathogens?
phagocytosis
antibody production
antitoxin production.
What is phagocytosis
engulfying foreign cells and digesting them
How does the white blood cells use antibodies to defend against pathogens?
- When white blood cells come across a foreign antigen they will start to produce antibodies to lock onto the invading cells so that they can be found and destroyed by other white blood cells
- Antibodies are produced rapidly and carried around the body to find all similar bacteria or viruses
Why wont antibodies lock onto every antigen
because antibodies produced are specific to that of the antigen - they won’t lock onto any other
What would happen if the person is infected with the same pathogen again?
the white blood cells will rapidly produce the antibodies to kill it - the person is naturally immune to that pathogen
What are vaccintions?
introducing small quantities of dead or inactive forms of a pathogen into the body
why do vaccinations have pathogens?
to stimulate the white blood cells to produce antibodies. .
this means if the same pathogen re-enters the body, the white blood cells respond quickly to produce the correct antibodies, preventing infection.
What is herd immunity?
when a large proportion of the population are vaccinated so the pathogen won’t be spread easily
What are the advantages of vaccinations?
- help control lots of communicable diseases that were once common in the UK
- Epidemics can be prevented if a large percentage of the population is vaccinated. this means people who aren’t vaccinated against the disease would be protected through herd immunity
What would happen if a signifcant amount of people aren’t vaccinated against a communicable disease?
the diease can spread quickly through them and lots of people will be ill at the same time
What are the disadvantages of vaccinations?
- Vaccines dont always work: sometimes they don’t give immunity
- You can have bad reaction to a vaccine . But these are rare
What are examples of bad reactions to vaccinations
swelling or fever
What do Antibiotics do?
Antibiotics, (e.g.penicillin) are medicines that help to cure bacterial disease by killing infective bacteria inside the body.
specific bacteria should be treated by specific antibiotics.
Why is it difficult to destroy viruses?
because viruses reproduce using your body cells which makes it very difficult to develop drugs that destroy viruses without killing the body cells
How has the use of antibiotics impacted society?
The use of antibiotics has greatly reduced deaths from infectious bacterial diseases.
However, the emergence of strains resistant to antibiotics is of great concern.
How are resistant bacteria strains created?
bacteria mutations which can cause bacteria to be resistant to antibiotics
the resistant bacteria will survive and reproduce and the population of the resistant strain will increase (natural selection)
What is an example of a bacteria strain that is resistant to antibiotics?
MRSA
causes serious wound infections and is resistant to the most powerful meticillin
How can the rate at which resistant strains of bacteria develop be decreased?
by doctors avioding over-prescribing antibiotics
why is it important for paitents to finish the whole course of antibiotics?
so that they are killed and none survive to form resistant strains
What are the 2 main roles drugs can have?
- cure the problem
- relieve the symptoms
What is the job of an anti-viral drug?
To kill the virus without also damaging the body’s tissues
What is digitalis and where did it originate from?
- heart drug
- foxgloves
What is aspirin and where did it originate from?
- painkiller
- willow
who discovered Penicillin and where did it originate from?
- Alexander fleming
- penicillium
Most new drugs are synthesised by ……
chemists in the pharmaceutical industry but the starting point may still be a chemical extracted from a plant
New drugs are extensively tested for what three factors?
toxicity, efficacy and dose.
What are the two main stages in testing drugs?
1) preclinical testing
2) clinical trials
Where is preclinical testing done
in the laboratory using cells, tissues and live animals
what are the substages in preclinical testing?
1) drugs are tested on human cells and tissues in the lab
* This allows efficacy and possible side effects to be tested
2) Drug is tested on live animals to see how the drug effects whole or multiple body systems
* allows testing for efficacy, toxicity and optimum dosage
What happens in clinical trials?
- drug is tested on healthy volunteers to make sure it doesn’t have harmful side effects when the body is working normally
- dosage increases during the trial
- next the drug is tested on patients, the optimum dose is found (most effective with the least side effects)
Double-blind trials are normally used to test patients.
What happens in a double-blind trial?
some patients are given a placebo, some are not.
- They are put randomly into 2 groups
- neither the doctor nor the patient knows who has what
why are some patients in double-blind trials given placebos?
so the doctor can see the actual difference the drug makes - allows for the placebo effect
why are doctors also “blind” during the double-blind trials?
so the doctors monitoring the patients and analysing the results aren’t subconsciously influenced by their knowledge
Results of drug testing and drug trials aren’t published until they’ve neem through peer review. Why is this?
to prevent false claims
