give 4 ways in which the spread of pathogens can be reduced:
hygiene - handwashing, disinfectants, tissues
reducing contact with infected individuals - quarantine
removing vectors - use of pesticides and insecticides, removal of habitats
vaccination
why is it important to prevent the spread of viral diseases?
scientists have not yet developed cures for many viral diseases
how can HIV/AIDS be prevented?
use of condoms
screening of blood for transfusions
not sharing needles
use of antiretroviral drugs to prevent the development of AIDS
how can the spread of salmonella be limited?
vaccinating animals intended for consumption
keep raw meat away from cooked meat
thoroughly cook meat
how can rose black spot be treated?
using fungicides
destroying infected leaves
how can the spread of malaria be reduced?
using insecticides
using insect nets to avoid bites
prevent mosquito breeding by removing stagnant water
antimalarial drugs
how can the skin prevent pathogens from entering the body?
the skin acts as a physical barrier
scab formation after skin is cut/wounded
antimicrobial secretions which can kill pathogens
how does the respiratory system prevent pathogens from entering the body?
nose - has hairs and mucus which trap pathogens
trachea and bronchi - have mucus that traps pathogens. ciliated cells move mucus to the mouth so it can be swallowed
how does the stomach prevent pathogens from entering the body?
-secretes hydrochloric acid which kills any pathogens present
how does phagocytosis protect us against disease?
white blood cells ingest and destroy pathogens so they cannot infect more cells
how does antibody production protect us against disease?
white blood cells produce antigens which are complementary to a specific antigen on a pathogen
the binding of antibodies to antigens causes pathogens to clump together, making them easier to destroy
in the case of a 2nd infection, the correct antibodies can be produced rapidly, preventing the person getting the same disease again
how does antitoxin production protect us against disease?
antitoxins bind to toxins released by pathogens and neutralise them
vaccination
contains a dead or inactive pathogen which stimulates white blood cells to produce complementary antibodies to the pathogen in the case of a second infection, memory cells can rapidly produce the correct antibodies and prevent illness
herd immunity
a sufficiently high proportion of a population which are immune to a disease, the spread of a disease will be limited
advantages of vaccination
have eradicated many deadly diseases
epidemics can be prevented
herd immunity protects those who cannot have vaccinations
disadvantages of vaccinations
not guaranteed to work - might not protect against multiple strains of a pathogen
may be side effects or adverse reactions
how are bacterial diseases cured?
with antibiotics that kill pathogens inside the body
how do antibiotics work?
kill bacterial pathogens inside the body, but will not kill human cells
why do antibiotics not work to treat viral diseases?
they have no effect on viral pathogens as they live inside the host's cells; therefore it is difficult to design drugs that would kill the virus and not destroy human cells at the same time
antibiotic resistance
occurs when mutations lead to individua bacteria being resistant to an antibiotic. these bacteria are able to survive, reproduce and pass on their alleles, leading to a greater proportion of antibiotic-resistant bacteria
how can we prevent antibiotic resistance
avoid overuse and unnecessary use of antibiotics - e.g. only prescribe them for viral infections
finish the full course to ensure all bacteria is killed
painkillers -> infectious diseases
only treat the symptoms but do not kill pathogens
what plant is digitalis extracted from?
foxgloves
what painkiller originates from a willow bark tree?
aspirin
what antibiotic was discovered by fleming?
penicillin
what are the 4 qualities of a good medicine?
safe
effective
stable
able to be taken in and removed easily
what 3 factors are tested when developing new drugs?
toxicity
efficacy
dosage
preclinical testing
-carried out in a lab
-uses cells, tissues and live animals
clinical testing
-uses healthy volunteers and patients
drugs are tested at a low dose on healthy people
then on patients and at a larger scale to find the optimum dose
often, one group receives a placebo and another group receive the actual drug in order to assess the efficacy
single-blind trial
only a doctor knows whether the patient is receiving the drug or the placebo
double-blind trial
neither the patients nor doctors know who gets what
-helps removes bias
peer review
where the results of drug trials are checked over by the scientists knowledgeable in this field