Studied by 16 peoplewhat are pathogens?
microorganisms that cause infectious disease
name the four pathogens
virus, bacteria, fungi, protist
how does bacteria make us feel ill?
reproduce rapidly inside body
release toxins that damage tissues and make us feel ill
how do viruses make us feel ill?
live and replicate rapidly inside host cells
causing cell damage eg. cell bursts
what is a communicable disease?
a disease which can spread from person to person, they are spread by pathogens
name the pathogen which causes measles
virus
how is measles spread?
inhalation of droplets from coughs/sneezes from an infected person
what are the symptoms of measles?
fever
red skin rash
how can the spread of measles be prevented/reduced
vaccination-most young children are vaccinated
isolation
name the pathogen that causes HIV
virus
how is HIV spread?
sexual contact
exchange of bodily fluids eg. blood when drug users share needles
what are the symptoms of HIV?
initial flu like illness however there is usually no symptoms for years
how can the spread of HIV be prevented/reduced?
avoid sexual contact/use condoms
not sharing needles
what are the effects of HIV?
unless successfully controlled by antiretroviral drugs, virus attacks body's immune cells
AIDS (late stage HIV infection) can occur- immune system becomes so damaged that it can no longer deal with other infections/cancer
name the pathogen which causes tobacco mosaic virus (TMV)
virus
what are the symptoms of TMV?
“mosaic” pattern of discolouration on leaves
restricted growth due to lack of photosynthesis
how is TMV spread?
direct contact between diseased and healthy plants
how can the spread of TMV be reduced/prevented?
remove infected plants/leaves
wash tools in disinfectant after using on infected plants
name the pathogen that causes salmonella
bacteria
what are the symptoms of salmonella?
fever, abdominal cramps, vomiting, diarrhoea
how is salmonella spread?
bacteria ingested in food eg. chicken
bacteria on food prepared in unhygienic conditions
how can the spread of salmonella be reduced or prevented?
wash hands before preparing foods/disinfect surfaces
poultry eg. chickens vaccinated- so fewer bacteria in chickens/ eggs, so fewer bacteria ingested by humans
what medication is given to stop HIV from developing into AIDS?
antiretroviral drugs (not a cure, patient most take for rest of life)
what type of pathogen causes gonorrhoea?
bacteria
what are the symptoms of gonorrhoea?
thick yellow/green discharge from vagina or penis
pain when urinating
how is gonorrhoea spread?
sexual contact (it is an STD)
how can the spread of gonorrhoea be reduced/prevented?
use of barrier methods of contraception eg. condoms
antibiotics- was easily treated by penicillin until many resistant strains appeared
what type of pathogen causes rose black spot?
fungus
what are the symptoms of rose black spot?
purple/ black spots on leaves
leaves often turn yellow and drop early
affects growth of plant as photosynthesis is reduced
how is rose black spot spread?
in the environment by water or wind
how can the spread of rose black spot be reduced/prevented?
fungicides (kills fungi)
removing and destroying affected leaves
what type of pathogen causes malaria?
protist
what are the symptoms of malaria?
recurrent episodes of fever (can be fatal)
how is malaria spread?
mosquito (vector) feeds on infected blood then bites a human
how can the spread of malaria be reduced or prevented?
prevent mosquitos breeding eg. Drain water holes→ fewer to pass on pathogen
mosquito nets or insect repellent→ to avoid being bitten
how does the skin prevent entry of pathogens into the body?
scabs form over cuts- acts as a barrier
the outer layer of the skin consists of dead cells and is difficult for pathogens to penetrate
produces an oily substance- sebum, which can kill bacteria
how does the nose prevent entry of pathogens into the body?
hair and mucus trap pathogens that enter
how does the trachea and bronchi prevent entry of pathogens into the body?
covered with tiny hair like cells (cilia) which are covered in mucus- traps pathogens. The cilia then waft the mucus up to the throat where it is swallowed into the stomach
how does the stomach prevent entry of pathogens into the body?
contains hydrochloric acid- kills most pathogens in food/swallowed mucus
what do the non-specific defence systems do?
prevent pathogens from entering the human body
what are the two main functions of the immune system?
destroy pathogens and any toxins they produce
protects us in case the same type of pathogen infects us again in the future
what are the three ways white blood cells help to defend against pathogens?
phagocytosis
producing antibodies
producing antitoxins (a special type of antibody)
describe the process of phagocytosis
the WBC detects chemicals released from the pathogen and moves towards it
the WBC engulfs the pathogen and uses enzymes to destroy it
what are antibodies?
protein molecules produced by white blood cells
describe how producing antibodies help white blood cells defend against pathogens
WBCs release specific antibodies in response to antigens on the surface of a pathogen.
antibodies bind to antigens on the pathogens making pathogens clump together so more can be engulfed
what is an antitoxin?
a protein that neutralises the toxins made by bacteria
describe how producing antitoxins help white blood cells defend against pathogens
WBC's release specific antitoxins in response to toxins released by bacteria. These neutralise the toxins and prevent them from damaging cells- don't feel as ill
how does vaccination prevent illness in an individual?
small quantities of dead or inactive forms of a pathogen are introduced into the body
antigens (on surface of the pathogen) stimulates WBC's to produce antibodies against the dead/inactive pathogen
memory cells remain in body so if the same pathogen re enters the body, memory cells will respond quickly enough to produce the correct antibodies so pathogens are destroyed/killed before numbers are high enough to cause disease
what are antibiotics?
medicines that help to cure bacterial disease by killing infective bacteria inside the body without harming body cells
specific bacteria should be treated by specific antibiotics eg. penicillin
what are painkillers?
medicines used to treat symptoms of disease eg.pain
they do not kill pathogens
why is it difficult to develop drugs that kill viruses?
viruses exist/replicatw inside cells so its difficult to develop drugs that destroy viruses without also damaging body cells/tissues
where were drugs traditionally discovered and extracted from?
plants and microorganisms
where was digitalis extracted from?
foxgloves
where was aspirin extracted from?
willow trees
where was penicillin extracted from?
penicillium mold
how are most new drugs synthesised?
by chemists in the pharmaceutical industry
but the starting point is still often a chemical extracted from a plant
what 3 things are new drugs extensively tested for?
toxicity (side effects/ how poisonous/ safe)
efficacy (if it works)
dose (most suitable conc. to be used)
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