Infection and response - Fighting disease Flashcards
how does the skin defend against pathogens
- has antimicrobial substances which kill bacteria
- outer layer of skin consists of dead cells which makes it difficult for pathogens to penetrate
how does mucus in the nose defend against pathogens
the hair in your nose traps particles that could contain pathogens
how do the trachea and bronchi defend against pathogens
- they secrete mucus to trap pathogens
- they are lined with cilia which are hair - like structures which waft the mucus up the back of the throat where it can be swallowed
how does the stomach defend against pathogens
- contains hydrochloric acid which kills pathogens that make it that far from the mouth
how does your immune system attack pathogens
by using white blood cells to consume them and produce antibodies
what is phagocytosis
when white blood cells engulf foreign cells and digest them
how does the immune system react to bacteria producing toxins to damage tissues (antitoxins)
The immune system responds to this by producing antitoxins, which neutralise the toxins released by the bacteria and prevent them from causing harm.
what are antibodies and how do they prevent disease
protein molecules that are produced when a foreign antigen comes in contact with a white blood cell
Antibodies are specific to particular pathogens
- produced rapidly around the body to find similar virus or bacteria to kill it
how do vaccines work step by step
- dead or inactive pathogen injected into the body
- these carry antigens which cause your body to produce antibodies to attack them even though the pathogen is harmless
- At the same time, the white blood cell divides by mitosis to produce lots of copies of itself
- these copies of the white blood cell can stay in the blood for decades and theyre called memory cells - If your body comes into contact with the live version of the pathogen , the white blood cells can rapidly produce the correct antibodies to kill off the pathogen and prevent infection
pros of vaccines
stops big outbreaks of disease
controls the spread of disease, herd immunity
cons of vaccines
- sometimes they don’t work, sometimes you don’t get immunity
- someone could have a bad reaction to the vaccine, these are rare
what are antigens
proteins found on the surface of cells
what is herd immunity
immunising a large proportion of the population will make it very hard for a pathogen to be spread. This is called herd immunity.
what kind of shape do antibodies have and why
Antibodies have a complementary shape to the antigen on the surface of the pathogen and lock onto them, effectively ‘tagging’ them
what are painkillers
drugs that reduce symptoms but don’t kill pathogens- e.g - aspirin
what are antibiotics
drugs that kill or prevent the growth of the bacteria causing the problem without killing your body cells
- they have greatly reduced the amount of deaths from communicable diseases
cons of antibiotics
- don’t destroy viral pathogens
- some bacteria can mutate and become resistant to the antibiotics ( MRSA ) meaning the antibiotic will only kill the non - resistant strain and the resistant one will reproduce
- this can happen if someone takes the wrong antibiotic or doesn’t take it for the full length that they are told to
how do some antibiotics work
by destroying the cell wall of bacteria so they can’t replicate
what are the 3 main stages of drug testing
- preclinical testing on human cells and tissues in a lab
- preclinical testing on live animals
- clinical testing on human volunteers in a clinical trial
what plant did aspirin originate from
willow
what plant did digitalis originate from
foxgloves
what drugs are used to treat viral infections
antiviral
what questions need to be asked when testing a drug
- is the drug safe? Toxicity
- does the drug work? Efficacy
- how much of the drug is needed? Dose
summarise preclinical testing
done in a laboratory using cells, tissues and live animals.
Testing on animals is useful for working out how toxic (harmful) a drug is to cells.
In the UK, new medicines have to undergo tests on two different live mammals.
summarise clinical testing
if the drug passes preclinical testing, the drug is tested on healthy volunteers to make sure it is safe
- the patients are randomly put into two groups, one is given the new drug, one is given the placebo, this is so that the doctor can see the actual difference the drug makes
- clinical trials are double blind, the patients do not know if they got the real or placebo, the doctor doesnt know either
why must the results of drug testing be assessed by peer reviews
to prevent false claims
What term is used to describe whether a drug works or not
efficacy
how do antiretroviral drugs help someone with HIV
They stop the virus replicating in the persons body
how can we slow down the rate of antibiotic resistant strains developing
- doctors should avoid over prescribing antibiotics, so you should only get them for something serious
- dont prescribe for viruses
- make sure to finish the whole course of antibiotics, don’t just stop when you feel better
what is the function of the immune system
to destroy pathogens and any toxins they produce
- to protect us in case the same type of pathogen invades us again in the future
how do wbcs prevent disease
- phagocytosis
- releasing antibodies
- releasing anttoxins to neutralise toxins released by bacteria
what was the first painkiller
penicillin
what is antibiotics resistance
when bacteria has evolved to a point where they can no longer be killed by a certain antibiotic
why would it be difficult to develop drugs that kill viruses
because viruses live and reproduce INSIDE human cells, so it would be difficult to develop drugs that kill viruses without damaging the bodys tissue
Why are placebos used in a double blind trial?
To prevent bias
what does mmr stand for
measles mumps rubella
what is thalidomide used to treat
leprosy
why do legal non prescribed drugs have a greater impact on the health of the population than illegal drugs
- because they are more readily available
- more people use them
why is it difficult for a person to stop taking certain drugs
because of addiction or dependency
