Defence against disease TOPIC 3 Flashcards
What is the first line of defence
natural human defence systems
What are specific defence systems
a defence against a certain type of pathogen due to its unique antigens
Define non-specific defence system
a generalised defence against any pathogen
is the first line of defence specific or non-specific
non-specific
what are the natural human defence systems
- skin
- stomach
- nose
- trachea & bronchi
- tears
how does the skin defend against pathogens
- acts as a physical barrier
- sebaceous glands produce oils to kill microbes
what glands in the skin produce oil
sebaceous
how does the stomach defend against pathogens
- contains hydrochloric acid whih kills swallowed micorbes
how does the nose defend against pathogens
- nasal hairs act as a physical barrier
- sticky mucus trabs dust and microbes
how does the trachea and bronchi defend against pathogens
- goblet cells produce mucus
- ciliated cells propel mucus back up the air way
what happens to the mucus once it has been propelled by the ciliated cells
you either cough the mucus up or swallow it and it gets digested naturally
how do tears defend against pathogens
- they contain ensymes called lysozymes which destroy microbs, preventing them entering the eye
what are the enzymes in tears
lysozymes
what is the second line of defence
the bodys immune system ~ phagocytosis
what are the 3 types of white blood cells
- phagocytes
- B-Lymphocyte
- T-Lymphocyte
where do you find white blood cells
- circulating around the body in plasma
- static in some organs
is phagocytosis specific or non-specific
non-specific
what causes pathogens to clump together in pathocytosis
antibodies
why is it good that pathogens clump together in pathocytosis
becuase it makes the process quicker
what happens in phagocytosis
- antibodies cause pathogens to clump
- pathocyte engulfs pathogens into a vacuole
- digestive enzymes are added to break down pathogens
what is the bodies 3rd line of defence
lymphocytes
what do B-lymphocytes produce
antibodies
what do T-lymphocytes produce
antitoxins
are lymphocytes specific or non-specific
specific
why are lymphocytes specific
because each antibody/toxin has to be complementry to the antigens on the surface of the pathogen
how many different types of anitbody/toxin do lymphocytes produce
only one
what do antitoxins do to toxins
they counteract them ~ neutralising them
how do you make a monoclonal antibody
- mouse injected with specific antigen
- B-lymphocytes produce anitbodies, then extracted
- antibodies fused with tumour cell
- forms hybridoma cell which is cloned
- anibodies colleced and purified
what is the name of a tumour cell fused with a anigbody
hybridoma
why is a control window good in a pregnancy test
will show that the test has worked
how does a pregnancy test work
- monoclonal anitbodies in the strip have a blue latex bead on them
- if she is pregnant the hormone will bond to the monoclonal antibodies
- then the monoclonal antibodies will stop at the test window showing a positive
how does vacination work, what does it intorduce
- dead or inactive forms of a pathogen into the body
- stimulates the white blood calls to rpoduce antibodies
what are the pros and cons of vacines
+ helped reduce numbers of communicable diseases
+ prevents large outbreaks because many are vaccinated
-dont always work
-some suffer side effects, although rare
how do antibiotics work
they kill infected bacteria inside the body
why is it important for anitbiotics to be specific
because different antibiotics kill different types of bacteria
do antibiotics work against viruses, why
no because viruses live inside host cells and are therefore out of reach of the anitbiotics
why is it difficult to kill viruses medically
because it is hard to do it without damaging the body’s tissues
what do painkillers do
they treat the symptoms of a disease byt do not kill the pathogens causing it
why are new drugs tested and trialed
to check they are safe and effective
what are new drugs tested for
- toxicity ~ if they cause harm
- efficacy ~ how well they work
- dose ~ how much needs to be taken for best results
what happens in the clinical trial
- given to healthy individuals in very low doses
why are placebos used in drug trialing
to ensure valid and reliable data is collected with no bias
what are the three stages of drug testing
- on human tissues and cells ~ cheap, doesnt tell much
- on live animals ~ find efficacy & toxicty
- clinical testing ~ healthy volunteers, dose increased
what are monoclonal antibodies
identical copies of antibodies that have been made in labs
what are the pros and cons of moloclonal antibodies
+ target any molecule
+ dont kill adjacent cells
+ produced in huge quantities
+ many uses
-can create more side effects
-not as widely used as hoped
how does a preganancy test work
- dipstick is dipped into urine
- it contains monoclonal antibodies, specific for a hormone in pregnant women, with blye dye paticle attached
- the hormone binds to the complementary monoclonal anitbodies
- the first widndow shows the result, where blue dye molecules will accumalate if positive
- the control window shows the strip is working
what is the hormone present in womens urine which indicates they are pregnant
hCG
what time and why this time are women advised to use a pregnancy test
- after they first wake up
- the concentration of hCG is higher and the test will be more reliable
how are monolconal antibodies used to diagnse prostate cancer
- blood test for PSA uses monoclonal anitbodies
- antibodies bind to PSA
- washed to remove unbound antigens
- anitbody with enzyme added & only binds if PSA present
- well washed again
- colourless substrate for enzyme added
- enzyme converts to coloured product so PSA present
