Treating, curing and preventing disease Flashcards
what are the physical barriers of the body? (3)
-identify which ones are first and second line defences
skin (1st)
cilia (1st)
mucus (1st)
how does the ‘skin’ act as a physical barrier? (2)
prevents pathogens from entering
forms scabs if cut which prevent infection
how does mucus act as a physical barrier?
traps pathogens before they can enter the lungs
how do ciliated cells act as a physical barrier?
move mucus and pathogens upwards towards the throat where it is swallowed into your stomach.
what are the chemical barriers of the body? (4)
-identify which ones are first and second line defences
stomach acid (1st)
lysozymes (1st)
lymphocytes (2nd)
phagocytes (2nd)
how does stomach acid act as a chemical barrier?
strong hydrochloric acid which kills pathogens
how do lysozymes act as chemical barries?
contain enzymes that destroy bacterial cells by breaking down their cell walls
what are phagocytes?
how do phagocytes act as chemical barriers/?
non specific white blood cells which engulf pathogens
phagocytes’ membrane surrounds the pathogen and the enzymes found inside the cell, then break down the pathogen in order to destroy
what is the only specific form of defence?
lymphocytes
what are lymphocytes and what do they do?
specific white blood cells which have antibodies on their surface that attach to antigens and destroys its accompanying pathogen
what can a memory lymphocyte do?
and what will it result in if a second exposure to an antigen occurs?
-‘remember’ the antigens from an infection by a previous pathogen.
-Antibodies will be produced much quicker, resulting in a much faster immune response.
describe a graph of ‘antibody concentration’ and ‘days after infection’ (2)
During the primary infection the antibodies slowly increase, peak and then gradually decrease.
A second exposure to the same pathogen causes the white blood cells to respond quickly in order to produce lots of the relevant antibodies, which prevents infection.
what can lymphocytes do in response to the toxins that are produced by pathogens?
produce antitoxins to neutralise these toxins.
describe the process of immunisation: (4)
-what is the last step of this process called?
-inactive form of the disease causing pathogen is injected into the body
-white blood cells (lymphocytes) release antibodies which are complementary to the antigen
-antibodies attach and clump pathogens together
-pathogens are engulfed by phagocytes
-phagocytosis
what is meant by herd immunity? (2)
-majority of the population are immunised against serious diseases,
-people who have not been immunised will still be protected because they are less likely to come into contact with an infected person
describe herd immunity when no one is vaccinated, some of the population is vaccinated, and when all of the population is vaccinated: (3)
-no one is vaccinated = contagious disease spreads throughout the population
-some of the population is vaccination = contagious disease spreads to some of the population
-most of the population is vaccinated = spread of contagious disease is contained
what happens If the number of people immunised against a specific disease drops in a population?
-what does this lead to an increase of, and how could this affect people?
it leaves the rest of the population at risk of mass infection, as they are more likely to come across people who are infected and contagious
increases the number of infections, as well as the number of people who could die from a specific infectious disease.
what are the (rather obvious) advantages of immunisation? (3)
-when fewer people are immunised, the number of cases of the disease increases
-the chance of falling seriously ill or dying from the disease may be far greater than the chance of experiencing a serious side-effect
-using a vaccine may be much cheaper than treating a very ill person
how do antibiotics work?
damage the bacterial cells by inhibiting their cellular processes, but do not damage the host cells
what do we need to treat bacterial infections if different bacteria cause different diseases?
a range of different antibiotics is needed for the treatment of the whole range of bacterial diseases.
why can viral diseases NOT be treated by antibiotics?
as they reproduce inside the host cells
why is it difficult to develop anti-viral drugs?
as they might damage the host cell whist killing the virus
why can we not depend on anti-viral drugs for the treatment of viral diseases? (2)
-they only slow down viral development of the virus
-viruses change their antigens quickly which means new drugs have to be generated regularly.
describe the process of a virus infecting a cell: (6)
1- virus enters cells
2- substances in the cell begin to strip virus’ outer coat of protein
3- nucleic acid in the centre of the virus is released
4- nucleic acid gets into the cell’s chemical manufacturing system
5- cell ignore its own chemical needs and switches to making new viruses
6- cell is destroyed in process and viruses are released to infect other cells
what is the future of antibiotics like?
development of new antibiotics has slowed down as it becomes difficult to find new versions to tackle different bacterial infections
how quickly can bacteria replicate?
approximately every 20 minutes by binary fission
what does the level of replication will depend on for bacteria?
availability of nutrients and other suitable conditions such as temperature.
what are the two ways of culturing bacteria?
nutrient broth solution in a culture vial
colonies on an agar plate
what is a nutrient broth solution?
-what must it contain?
a liquid or gel that provides all the nutrients needed for bacteria to grow successfully.
-carbohydrates for energy, nitrogen for protein synthesis, plus other minerals.
how are agar plates created?
pouring hot molten agar into sterile Petri dishes, which are then allowed to set
what needs to happen to Nutrient broth solutions, culture vials, agar solution and Petri dishes before they can culture bacteria?
-what are these and what do they use?
sterilisation to stop any other microorganisms growing on or in them.
-autoclave. strong containers which use high temperatures and pressures to kill microorganisms.
why is it important to ensure that the bacteria culture is uncontaminated? (2)
-contaminating bacteria would compete for nutrients in the broth or agar.
-bacteria could be harmful (such as pathogens) and would complicate the results of experiments when testing the efficiency of antibiotics or other anti-microbial compounds.
what do aseptic techniques include? (3)
-killing all microorganisms on equipment such as inoculating loops by flaming equipment in a Bunsen burner or dipping them in alcohol
-keeping all lids on equipment when not in use
-wearing gloves, eye goggles, lab coats or other protective equipment
equation for ‘Bacteria at the end of the growth period’ :
Bacteria at the end of the growth period = bacteria at the beginning × 2^number of divisions of the growth period
