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15 Cards in this Set
- Front
- Back
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What are infectious diseases caused by?
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A microorganism (pathogen) entering and attacking your body. People can pass these microorganisms from one person to another.
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What is the difference between bacteria and viruses?
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Many bacteria are harmless. Viruses are smaller than bacteria and cause diseases in every type of living organism, from people to bacteria.
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How do bacteria cause diseases?
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They divide rapidly by splitting in two (binary fission). They often produce toxins which affect your body but sometimes they directly damage the cells.
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How do viruses cause diseases?
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Viruses take over the cells of your body as they reproduce, damaging and destroying the cells. They very rarely produce toxins.
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What did Ignaz Semmelweis notice?
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Doctors didn't wash their hands before delivering babies, often having just finished another surgery or dissecting a cadaver. The women delivered by doctors and medical students were more likely to die than those delivered by midwives.
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What are the ways a pathogen can spread from one person to another?
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Droplet infection, direct contact, contaminated food and drink, and through a break in your skin.
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How does your body prevent microorganisms form getting inside it?
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Your skin acts as a barrier.
If you cut your skin, you bleed and your blood forms a clot which dries into a scab. This forms a seal over the cut. Your breathing system produces mucus which covers the lining of your lungs and tubes, trapping pathogens. They are then moved out of your body or swallowed down into your gut where the acid destroys them. Your stomach acid destroys most pathogens taken in through your mouth. |
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How do you become naturally immune to diseases?
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Your body must sort out the right antibody needed the first time it meets a pathogen. Next time the pathogens are destroyed quickly because some of your white blood cells remember which antibody to use.
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How does vaccination work?
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A vaccine is made from a dead or inactive form of the disease-causing microorganism. It stimulates your immune response to the invading pathogens. This gives your white blood cells a change to develop the right antigen without getting ill. Then your white blood cells can respond rapidly if they meet the live pathogens.
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What is herd immunity?
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If a large population is immune to a disease, the spread of the pathogen is very much reduced.
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What are antibiotics?
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Medicines that can work inside your body to kill the bacteria that causes diseases.
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How do bacteria become antibiotic-resistant?
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An antibiotic kills the bacteria of a non-resistant strain but individual resistant bacteria (which have a mutation) survive and reproduce. As a result this new strain will spread rapidly.
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How do we prevent new strains of resistant bacteria from appearing and spreading?
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Don't overuse antibiotics.
Use the right type of antibiotic for the right type of bacteria. Finish your course of medicine every time to make sure the bacteria in the early stages of developing resistance are killed. Medical staff should wash their hands with soap and water or alcohol gel between patients and wear disposable clothing that is regularly seterilised. Hospitals should have high standards of hygiene. Patients infected with antibiotic-resistant bacteria should be kept in isolation from other patients. Visitors to hospitals should was their hands as they enter and leave. |
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How do we grow microorganisms in a lab and what safety measures must we take?
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You must make sure they strains you are growing are free from other microorganisms (uncontaminated).
Sterilise your Petri dishes and the agar jelly to kill off unwanted microorganisms. Sterilise the inoculating loop by heating it until it is red hot in the flame of the Bunsen and letting it cool (so it doesn't kill the bacteria you're growing). Dip the loop into the bacteria and zigzag streaks across the agar jelly with the loop. Replace the Petri dish lid quickly to avoid contamination. Fix the lid with tape to prevent contamination, don't seal all the way so oxygen can get into the dish. Store the Petri dish upside down to stop condensation falling on the agar surface. |
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Why should bacteria grown in a lab be kept at 25°C?
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It reduces the chance that you will grow something harmful to people.
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