What's up, Doc
- Infectious diseases can easily be passed from one person to another and are caused by micro-organisms (MO's)
- MO's are bacteria, viruses and fungi and can be cured with medicines
- When disease MO's get inside your body, they reproduce quickly, causing symptoms of that disease. Symptoms can be caused by the damage done to your cells through reproduction or poison made by the MO's.
- Micro-organisms are invisible to the naked eye, bacteria are biggest and viruses are smallest
- There are billions of MO's around you but you are not ill. Most MO's do not cause diseases and the body has natural barriers to keep them out (tears, sweat and skin)
- 100 years ago, infectious diseases were the main killer, but today better hygiene and health care mean that we are most at risk of getting lifestyle diseases
- Lifestyle disease are caused by things such as diet and are not infectious
- But MO's can still kill, as new MO's are discovered and become more common
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- If the conditions are right (warm,moist and plenty of nutrients), bacteria can rapidly reproduce by splitting in 2
- The body has the perfect conditions for bacteria to breed.
- If bacteria enter the body through a cut, the area may become red and swollen (inflammed). This is because white blood cells are being sent as extra blood. One type of white blood cell (phagocytes) surrounds bacteria and ingests them.
- Dead bacteria and broken cells collect as pus, and as the bacteria are killed, the pus and inflammation disappear
- Parts of your body that fight infection are called the immune system
- Antibiotics can be used to kill bacteria and fungi, but not viruses
- But, antibiotics cause all bacteria, good and bad, to be killed. This may give other MO's room to grow and infect.
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Everyone needs antibodies- not antibiotics
- Colds are caused by viruses, which cannot be killed with antibiotics, only by white blood cells (WBC's)
- When you have a cold, your neck glands may become swollen, as white blood cells are made there
- The WBC's make chemicals called antibodies, which stick to the unique, foreign antigen markers on MO's. The WBC's digest any cells that the antibodies stick to
- The antigens on MO's are all different, so a different antibody has to be made for each MO. This is why you feel ill before getting better
- Once your body has made an antibody it is not forgotten, so WBC's can make these antibodies quickly is the MO invades again. The body reacts very quickly and destroys the invader before symptoms occur. You are immune.
- There are 100's of different cold viruses and each time you catch a cold, it is caused by a different virus. The viruses have a very high mutation rate, their DNA changes very quickly. The markers on their surface also changes, so the WBC's need to fight the virus with a new antibody
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- Vaccinations stop us from getting diseases. They make use of the body defence system. They make your white blood cells (WBC) into making anti bodies so you become immune to that disease.
- Small amounts of dead disease MO are injected. The WBC's recognise the MO and make the right anti-bodies. The anti-bodies make the MO clump together, WBC digest the clump. If you meet the real disease MO the anti-bodies are made quickly and are destroyed before you get ill.
- Any medical treatment should improve you health and be safe to use. Vaccines can improve your health but may not be safe for some people.
- Doctors decide a treatment is safe if the risks are low and the benefits out weigh the risks.
- The flu virus reproduces very quickly and has a high mutation rate. New kinds of flu virus develop regularly so different vaccines are needed. This is because the antigen marker change.
- Aids is caused be the HIV virus and kills millions every year. It weakens the immune system and makes people suseptable to infections. Also HIV mutates quickly so there are no vaccines
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- To stop an outbreak of a disease almost everyone in the population needs to be vaccinated. If they are not large numbers of the disease causing MO will be left in effected people.
- Doctors encourage parents to have their children vaccinated. In the UK there are mass vaccination programmes for diseases such as measles. This means that few people suffer from the disease. For society as a whole, vaccination is the best choice.
- If everyone was vaccinated there would be a much lower risk of children catching the disease. Some would still get the disease. It would be possible for a vaccination to be compulsory but some dont agree.
- Due to a world wide vaccination the small pox virus has been wiped out. This is because the small pox virus has a low mutation rate.
- People in poorer countries are more likely to catch diseases and suffer because of poor diets and access to medicine. So they may think differently about vaccinations.
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The end for antibiotics
- Penicillin is a mould that can be used as an antibiotic. It was 1st used in the 1940's, when many people died from infectious diseases. It saved many lives and was even used to treat animals. But 10 years on,one type of bacteria was not killed by penicillin, it had become resistant.
- New antibiotics are discovered all the time, but each time a type of bacteria becomes resistant. There are now "Superbugs" which are resistant to all known antibiotics but 1
- The superbug's genes are what makes it resistant to antibiotics. A bacterial population is not resistant to the antibiotics. A mutation in 1 gene of 1 bacteria makes it resistant, and it survives unlike the others. It breeds rapidly, with no competition for space or food, and soon the whole population is resistant
- To reduce the risk of antibiotic resistance you should never take antibiotics unless needed and always finish the course of antibiotics
- There are plenty of ways to stop antibiotic resistance. New drugs can be made, hygiene can be improved in hospitals and educating people about antibiotic resistance can all help
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Where do new medicines some from
- Developing a new drug takes years of research and lots of money.
- Early tests are done on human cells grown in a lab. These tests work out the concentrations and how effective and safe it is.
- The second stage is on animals, to make sure it works as well in whole animals as it does in cells.
- If it passes animal tests, the drug can be tested on humans in clinical trails. Doctors ask people to take part in the trail if they could benefit from the new drug.
- The volunteers are split randomly into 2 groups. 1 Group will be given the new drug.
- The 2 Group (control group) will be given a placebo, it looks like a drug but has no chemical in it. Some people think it is unfair that the control group will miss out on the benefits of a new drug but the drug needs testing before it is prescribed.
- If the patients and the doctor do not know the drug the patient is getting it will be a double blind trail. This reduces bias.
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- Arteries take blood from the heart to the body and veins bring blood back to the heart.
- Blood brings oxygen and food to the cells, who use them to supply energy. The heart muscle is supplied with blood by the coronary arteries. Without energy the heart would stop.
- Fat can build up in coronary arteries and blood clots can form on the fatty lump. If the artery is blocked, part of the heart is starved of oxygen and cells start to die. This is a HEART ATTACK.
- Heart attacks are more common in the UK than in non-industrialised countries. This is because the typical UK diet is high in fat and people in the UK do little exercise.
- Your genes and your life style effect your risk of heart attacks. There are many risk factors associated with heart attacks - smoking, obesity, high fat diet and lack of exercise. The more risk factors you are exposed to the higher your chances of a heart attack.
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Causes of Diseases - How Do We Know
- Today we know that there is a correlation between smoking and lung cancer.
- Scientists publish their experiments in journals for other scientists to look at and find faults. If they carnt find any the claim is reliable. This is called peer-review.
- Good studies involve a large number of people as this improves the reliability of a claim. Also the people in the study are varied and random. Good studies have been repeated many times and the results are consistent.
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