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Transcript
START REVISING HERE Microorganisms are Very Small Biggest FUNGI Smallest BACTERIA VIRUSES (On a needle) When millions of them grow in one place then you can see them Colonies of Bacteria and Fungi growing in an agar plate. Agar jelly is their food. Some microorganisms are Pathogenic Pathogenic means they cause diseases • Athletes foot, Thrush • Smallpox , Flu • Tuberculosis, Cholera Fungal Viral Bacterial If you are infected with one of these you will show symptoms: E.g. runny nose, high temp, spots, sneezing etc. Some diseases are caused by the things we do: Over eating, cigarettes, alcohol, drugs These are called LIFESTYLE diseases: Obesity, Heart disease, lung cancer. Remember: YOU can change your lifestyle How do bacteria Grow? Real Fast !!! Just give them: WARMTH – FOOD – WATER (Not O2) 1 cell – 2 – 4 – 8 – 16 – 32 – 64 – 128 – 256 – 512 - In just 3 Hrs ------------ And it looks like this ------------Growth rate = death rate (running out of food or too much excretory products) Getting used to their Petri dish food supply Rapid growth Lots of food, water, warmth and space Time More dying than growing So why don’t we get ill all the time? • Skin stops them getting into our bodies and makes antibacterial chemicals • Tears also kill them BURP! • Stomach acid kills them And if that doesn’t stop them – WBCs will: That’s me, the white one The Immune System ‘’ It’s me your friendly neighbourhood white blood cell again. This is how we kill microbes’’ 1. We find them, surround them and digest them, BURP! (phagocytosis) AND 2. Some of us make chemicals called antibodies that stick on to the outside of microbes. Each microbe has a different covering or antigens. Different antibodies recognises the shape of each different antigen. Death follows Arghhh Foreign blood cell being attacked ‘’OK, but what if I’m too sick and my immune system isn’t stopping them’’? • • • • If it’s a bacteria take a course of antibiotics – And don’t stop just because you feel better And you might experience side effects, even death!! And, they might kill all your good Microbes. ‘’SO WHAT’’ If it’s a fungus it will have as much food, space and water as it wants. ‘’And what next’’? -- Itch Itch Scratch Scratch -And this arrow is NOT pointing at your feet Better get the bio yoghurt out ‘’Ahh, that’s better’’ Antibiotic Resistant Bacteria – Superbugs – MRSA These are all the exactly the same thing, NASTY bacteria that cannot be killed by Antibiotics Why are they so common? People take AB’s for colds & flu People don’t finish the course click for video Final resistant population It’s just normal variation and natural selection ALMOST FORGOT: Antibiotics don’t kill VIRUSES ‘’I’ve had chickenpox, why can’t I catch it again’’? ‘’Because your now immune to it silly’’ 1. First Infection How does that happen? Antibodies attach to nasty microbes & kill them WBC make antibodies 2. If there is a second Infection Me again Yeh and I remember you ‘cos I’m a memory cell The differences between 1 & 2 are: 1. Antibodies are made slowly and you may feel ill before all the MO’s are all killed 2. Antibodies are made really fast and you don’t get ill at all. You are IMMUNE I think I’m dying! Once killed, the WBC’s become memory cells which remember the microbes antigens Zap Bang Wallop! I’m dead! This is what an Immune Response looks like Memory cells become active Antibody numbers Memory cells created here First encounter with pathogen Second encounter with pathogen Pathogen rapidly destroyed Vaccines & Vaccinations • A vaccination make you immune from a disease • A vaccine contains either: • A dead MO, parts of a MO, or a weakened MO WHY? • They ALL contain the MO’s antigens/markers • They all lead to memory cells being made Some Problem Microbes • Flu Virus – mutates rapidly (changes it’s antigens) • HIV virus – Attacks the immune system and also mutates rapidly…NASTY MO MO Original antigens New antigens Can you describe what's happening in the picture? When you have written your 5 descriptions, check your answers on the next slide. No peeking! 5. what about memory cells? 1. 4 2 3 No Peeking until you have completed the first slide 1. Vaccine containing weakened, dead pathogen or parts of it. Each of these has the pathogens antigens (markers). All induce an immune response 4. Antibodies attach to the pathogen’s antigens (markers). They neutralise the pathogen or attract phagocytotic WB Cells 2. Sometimes there are side effects 3.White Blood cells produce antigens which match the pathogens antigens (markers) 5. Special types of White Blood Cells called memory cells are produced so when you come in contact with the real pathogen they REMEMBER IT and produce antibodies SO FAST you don’t get sick; this is immunity. Drug Safety • Taking any drug involves some risk. • Side effects can be minor, severe or even cause death • Vaccinations have the same risks but the risk to the individual is outweighed by the benefits to the rest of the population. • If 95% of the public are vaccinated it stops a disease from spreading and can lead to its eradication (disappearance) •Smallpox has been completely eradicated over the whole world Testing Drugs • Drugs are tested for safety (side effects) and effectiveness (if it works) • Testing involves 3 stages: • On human cells (relatively cheap & quick and may indicate how safe it is) • On animals (gives more information on safety and effectiveness) • On people in a clinical trial (gives even more data & information) Issues with Drug Tests • Can take 10 years to get a new drug to market • VERY expensive: staff & clinical trials, salaries, looking after animals, hospital & lab costs, security • Ethical issues with using live animals • Ethical issues with testing it on humans, especially if a placebo is involved. • Must be approved & licensed by the government Clinical (Human) Trials • Trials have to be designed scientifically to be fair & reliable tests • Participants put in to two groups • Participants chosen randomly (increases reliability) • One group gets the drug the other no drug, (the control group) • A control group allows the groups/drugs effect to be compared • If it’s a totally new drug the control group has a placebo • A placebo looks exactly like the real drug but contains no drug • Placebos raise ethical issues; if the new drug may cure a serious disease and does work, people in the control group may die The Circulatory System • The heart is made of muscle cells. • Every cell needs oxygen and glucose to make energy (respiration) • The blood transports oxygen and glucose to every cell • Blood leaves the heart under high pressure and returns under low pressure • Veins transport blood into the heart • Arteries transport blood away from the heart • Coronary arteries supply heart cells with blood Why Do Arteries and Veins Look Different? thick layer of muscle and elastic fibres Arteries carry blood at high pressure, thick walls prevent them bursting, elastic fibres allow them to stretch and go back to their normal shape Veins carry blood at low pressure so only need thin walls. They also have valves which prevent blood moving backwards ARTERY thick outer layer thin outer wall VEIN AND FINALLY, THE LAST SLIDE thin layer of muscle and elastic fibres Bad Lifestyle = Increased Risk of a Heart Attack • Risk factors: Smoking, lack of exercise, high salt/fat diet & family history 1. Bad lifestyle 2. Build up of fat in artery 3. Blood flow is now reduced to the heart muscle cells A heart attack animation 4. Cells now starved of oxygen heart attack simple version 6. Heart attack takes place 5. Heart muscle cells begin to die The End AND Don’t forget to do as many past papers as you can. Check your answers using the mark schemes Good Luck