topic 3 - infection and response (flashcards)

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?

1. inject a mouse with antigens

2. the mouse produces lymphocytes to produce antibodies

3. remove lymphocytes from the mouse’s spleen

4. lymphocyte (makes antibodies, cannot divide) fuses with cancer/tumour cell (cannot produce antibodies, can divide)

5. 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