b3 Flashcards
what is a pathogen?
- a micro-organism that causes an infectious disease
name 4 pathogens
- bacteria
- fungi
- virus
- protist
how does bacteria make you feel ill?
- reproduce very rapidly
- then release harmful chemicals called toxins
- Toxins damage tissues and make us feel ill
how do viruses make you ill?
- the virus invades the host cell
- then it reproduces inside the host cell
- this is very damaging to the cell
- when the virus leaves the cell, it can cause the cell to burst
open and die
antibiotics are prescribed for which pathogen?
bacteria
state 3 ways pathogens spread
- air
- water
- direct contact
how do you reduce the spread of pathogens?
- hygiene
- clean, drinking water
- vaccination
- protection
- isolation
what is health?
- the state of physical and mental wellbeing
what is a communicable disease?
- it can be spread from person to person or by pathogens
what is a non-communicable disease?
- it cannot spread from person to person
give examples of a non-communicable disease
- coronary heart disease (CHD)
- cancer
- diabetes
give examples of acommunicable disease
- tuberculosis (TB)
- measles
- malaria
which pathogen causes salmonella?
bacteria
how is salmonella spread and what are the symptoms?
- spread in poultry such as chickens.
- symptoms include a fever, vomiting, abdominal cramps and diarrhoea.
how can you reduce the spread of salmonella?
all chickens are vaccinated in the UK
which pathogen causes gonorrhoea?
bacteria
which pathogen causes measles?
virus
which pathogen causes HIV?
virus
how is measles spread and what are the symptoms?
- spread by droplets of a sneeze or cough.
- symptoms include a fever and red-skin rash
how is gonorrhoea spread and what are the symptoms?
- spread from sexually transmitted disease (STD)
- symptoms include thick yellow/green discharge and pain when urinating.
how is HIV spread and what are the symptoms?
- spread by unprotected sex or sharing needles.
- symptoms are a flu-like illness.
how can you reduce the spread of measles?
vaccination
how can you reduce the spread of gonorrhoea?
use protection during sexual intercourse
how can you reduce the spread of HIV?
antiretroviral drugs
what kind of disease is malaria?
- a communicable disease
which pathogen causes malaria?
protist
how is malaria spread?
- A mosquito bites the infected person and the malaria pathogen passes into the mosquito.
- The mosquito now bites a different person and passes the malaria pathogen onto them.
how do you prevent the spread of malaria?
- stop the vector (the mosquito) from breeding:
- find an area of still water and drain them.
- additionally, spray areas of still water with insecticide, which kills the mosquitoes. - prevent mosquitos from biting humans:
- sleep under a mosquito net.
- spray the net with insecticide to kill the mosquitoes that land on it.
what is a vaccination?
- a small quantity of dead/inactive pathogen being introduced to the body
how does a vaccination work?
- A small quantity of dead or inactive pathogens is introduced into the body.
- The WBC divides by mitosis to produce many copies of itself.
- The WBCs produce the right antibody.
- The body can produce the right antibodies to fight the disease.
what is meant by herd immunity?
- when a large number of people are vaccinated against a pathogen
what are painkillers used for?
- to treat a patient’s symptoms, not the pathogen
how do antibiotics work?
- they kill infective bacteria in the body, without harming other body cells
why can’t antibiotics be used to kill viruses?
- as viruses live and reproduce inside human cells, therefore it is difficult to develop drugs that kill viruses without also damaging the body’s tissues.
what is meant by antibiotic resistant?
- when antibiotics have been overused, so they are ineffective against bacteria.
- the bacteria has evolved, therefore no longer killed by antibiotics.
describe the process of drug trialling/testing
stage 1 = pre-clinical testing
- not carried out on humans - as it could be toxic
- carried on cells, tissues or live animals
stage 2 = clinical testing
- very low doses are given to healthy volunteers - to check if the drug is safe for humans
stage 3 = clinical testing continued
- clinical testing is continued to find the optimal dose
what is a placebo?
- a tablet or injection with NO active drug in it.
why do we use a placebo?
- so that some patients get better when you give them a placebo because they think they’re being treated, so they believe they’ll get better.
what is a double-blind trial?
- when neither the patients nor doctors know which people are receiving the active drug and which are receiving the placebo.
why is a double-blind trial important?
- to prevent bias
state three medicinal drugs
- digitalis
- aspirin
- penicillin
why do drugs need to be trialled and tested?
- to check the toxicity of the drug
- to check if the drug is effective
- to work out the best dose for the drug
what is digitalis used as?
- heart drug
what is aspirin used as?
- painkiller
where does digitalis come from?
- foxglove plant
where does penicillin come from?
- mould penicillium
where does aspirin come from?
- willow trees
what is penicillin used to treat?
- bacterial infections
how is tobacco mosaic virus (TMV) caused, and what are the symptoms?
- it is caused by a widespread plant infection and affects a number of different plants.
- symptoms include discolouration of the leaves in a mosaic pattern, as a result, the rate of photosynthesis is reduced and so the growth of the plant is also reduced.
how is rose black spot caused and what are the symptoms?
- it is caused by a widespread plant infection
- symptoms include purple or black spots and then the leaves often turn yellow and
state two ways rose black spot is spread?
- water
- wind
what is the treatment of a rose black spot?
- spray with fungicides to kill the fungi
- remove the affected leaves and destroy them
how does the immune system protect us?
- destroys pathogens and any toxins they produce.
- it also protects us in case the same type of pathogen invades us again in
the future.
which three ways do white blood cells (WBC) destroy pathogens?
- phagocytosis
- antibodies
- anti-toxins
how does phagocytosis work?
- The WBC detects chemicals released from the pathogen and moves towards it.
- The WBC then ingests the pathogens
- The WBC uses enzymes to destroy the pathogens
how do antibodies work?
- the WBC produce antibodies.
- the antibodies stick to the pathogens and trigger them to be destroyed.
how do anti-toxins work?
- anti-toxins stick to toxin molecules and neutralise them.
- this prevents them from damaging cells.
what is the job of the non-specific defence system?
- it prevents pathogens from entering the human body.
which 4 parts of the defence system protect us?
- skin
- eyes
- breathing system (nose, trachea, bronchi etc)
- stomach
how does the skin defend us?
- tough, dry outer layer, which acts as a barrier.
- oil on surface of the skin which repels pathogens.
- scabs form over cuts and platelets are involved in forming the scab.
how does the eyes defend us?
- produce tears, which are antiseptic
- they also contain enzymes to kill off bacteria.
how does the breathing system defend us?
- the nose/trachea/bronchi produce mucus
- mucus is sticky and traps bacteria
- therefore, it is carried away by cilia.
how does the stomach defend us?
- contains hydrochloric acid, which kills bacteria.
- this occurs when swallowing food or mucus.
