Microorganisms Flashcards
What are pathogens?
Microorganisms that enter a plant or animal and cause communicable disease
There are several types
What are bacteria?
Small cells which reproduce rapidly
Make you feel ill by producing toxins that damage cells and tissues eg salmonella causes food poisoning
What are viruses?
Name examples of viral disease?
They are not cells.
Tiny and reproduce rapidly and live inside your cells
Use the cells’ machinery to reproduce until the cell bursts spreading the virus and making you feel ill
Eg HIV - spread by sexual contact or bodily fluids like blood destroys cells that defend body against disease so make it easier for other pathogens to attack the body. When the body cannot cope it is called AIDS and is often deadly.
Measles - droplets from sneezes and coughs causes skin rash and fever , most people are vaccinated but it can be deadly
Tobacco Mosaic virus affecting plants eg tomatoes
What are protists?
Eukaryotes and usually single cells
Some are parasites living on other organisms and causing them damage
Often transferred by a vector - which doesn’t get the disease itself eg the insect like a mosquito carrying malaria
Malaria is a protist - prevented by mosquito nets and repellant spray and tablets
What are fungi?
Some are single cells
Other are hyphae which grow and penetrate plants and animals
Produce spores which then spread to other plants and animals eg black spot on roses - destroyed by fungicide and removing damaged leaves
How do pathogens spread?
Drinking or bathing in dirty water eg cholera
Air when breathed in eg influenza virus
Direct contact - from contaminated surfaces like skin eg athletes foot is a fungus making skin itch and flake spreads by towels and showers
How do we prevent disease?
Simple hygiene measures
Destroying vectors
Isolating infected individuals
Vaccination
Salmonella poisons you when you eat food that had the disease or was prepared in unhygienic conditions eg stomach, cramps, diarrhoea and vomiting
Food control stops it
STD like gonorrhoea is bacterial prevented treated by antibiotics called penicillin
How does the body defend against disease?
Skin acts as a barrier against pathogens
Hairs and mucus trap pathogen particles
Trachea and bronchi secrete mucus to trap pathogens
They are lined with cilia, waft the mucus up to back of throat
Stomach produces hydrochloric acid which kills pathogens
How does the immune system work?
White blood cells attack invading microbes by:
Consuming them
Producing anti toxins
Producing antibodies
How do vaccinations work?
A new pathogen will make your blood cells learn to fight it but it takes a while and may be too late
Vaccinations inject small amount of dead or inactive pathogen so white blood cells attack them and learn to fight them eg MMR against mumps, measles and rubella
White blood cells ready if these pathogens reappear
Vaccinations have removed big diseases like small pox and epidemics don’t occur
Sometimes they don’t work or you get a bad reaction but it is better than getting the disease
How do drugs fight diseases?
Painkilllers relieve pain don’t attack cause of disease - eg aspirin
Antibiotics eg penicillin attack the bacteria without killing own body cells. Need right antibiotics for each disease eg cure for pneumonia
But don’t destroy viruses
And body can learn to resist antibiotics - eg MRSA
So don’t overuse antibiotics because body will resist them more quickly if overused
