define communicable
diseases that can be spread between people
examples: cold, chickenpox, malaria, HIV, tuberculosis, measles
define non-communicable
diseases that develop within a person from genetic or environmental factors and cannot be spread between people
examples: diabetes, cancer, heart disease
what are the risk factors for communicable diseases?
poor sanitary conditions
not washing hands
undercooked food
dirty water
not covering mouth when coughing/sneezing
lack of medical treatment to stop spread of infection e.g. antibodies
what is a pathogen?
microorganism which causes disease - common examples: bacteria, viruses
not all bacteria are pathogenic/harmful, but all viruses are
how do pathogens spread?
contact
bodily fluids
droplets
uncooked food
poor hygiene
vectors
what are the types of transmission?
by air (droplet) - when ill, you expel droplets full of pathogens from your breathing system, others will breathe these droplets in
direct contact - pathogens can pass from one organism to another through direct sexual contact, cuts, scratches and sharing needles
food or water - drinking untreated water or eating raw/undercooked food can cause a pathogen to enter via digestive system
vectors - organisms can spread pathogens between hosts (e.g. malaria is spread by moquitoes)
what is bacteria?
single-celled organisms
they reproduce quickly
many give off toxins, which can damage tissues
what is a virus?
infectious microbe that replicates only inside the living cells of an organism
kills cells or disrupts function of cells
produce toxins and damage cells in which they reproduce
replicate by invading cells, reproducing inside and bursting them → damage to tissues
what are protists?
single-celled organisms
usually caused by protozoa
they multiply and damage tissues and take nutrients from hosts → causing sickness and disease
what are fungi?
some fungi reproduce through tiny spores in the air that can be inhaled
fungus replicates
fungal cells can invade tissues and disrupt their function, immune response and competitive metabolism
examples of non-specific defenses
earwax
breathing organs produce mucus to cover the lining of organs and trap microbes
platelets seal wounds by clotting
tears
saliva
skin - sebum produced with pH of 5, which isn’t ideal for pathogens
stomach acid
what are phagocytes?
non-specific
phagocytosis:
phagocytes contain enzymes
when a pathogen meets a phagocyte, the phagocyte will engulf the pathogen
the enzymes will attach to the pathogen and destroy it
pathogen will be broken down and recycles
what are lymphocytes?
specific
there will be a specific lymphocyte for each pathogen
the correct lymphocyte for the pathogen will activate and multiply and produce antibodies
antibodies will attach to the antigens, causing them to immobilise, and then the phagocyte will engulf it
remaining lymphoctes will stay in blood as memory cells, for immunity
what are antibiotics?
medicine that helps to cure diseases cause by bacteria
antibodies cannot kill viruses because viruses live and reproduce inside body cells
the effect of different antibodies can be measured in laboratories through gel tests
what is immunisation (vaccination) and how does it work?
involves injecting or swallowing a vaccine containing small amounts of dead or weak form of the pathogen
as the pathogen is weak/inactive, the vaccine doesn’t cause illness, but the white blood cells still produce antibodies to destroy the pathogen → makes us immune to future infection of the pathogen
aseptic techniques for preparing an uncontaminated culture
petri dishes and culture media sterilised before use
inonculating loops used to transfer microorganisms to media
lid of petri dish secured with adhesive tape + stored upside down
cultures generally incubated at 25°C
define drug
a substance that changes or alters the way we work
describe stage 1 of drug discovery
testing using:
predictions based on published research
computer models
pure proteins
cultured cells
where:
large scale - high throughput
research laboratories
describe stage 2 of drug discovery
testing on animals
mostly:
mice, rats, guinea pigs
eventually:
dogs, pigs, monkeys
describe stage 3 of drug discovery
testing on healthy volunteers
low dose saftey test on a few patients, then more patients to check for efficacy with higher doses
how do blind trials work?
patients do not know if they have been given drugs
how do double blind trials work?
both patient and doctor do not know who has been given drugs
what is a placebo?
a substance that does not contain any drugs
what is an antibody?
y-shaped protein produced by lymphocytes which are specific to a pathogen’s antigen
what is an antigen?
the surface of components of a cel or structure
what is the process of making monoclonal antibodies?
inject a mouse with antigens
the mouse produces lymphocytes to produce antibodies
remove lymphocytes from the mouse’s spleen
lymphocyte (makes antibodies, cannot divide) fuses with cancer/tumour cell (cannot produce antibodies, can divide)
creates a hybridoma cell which can make anitbodies and divide
how are transgenic mice made?
human gene is placed inside the mice so that they can produce human antibodies rather than mouse ones