1. Keeping Healthy Revision

2. Natural Barriers Skin Skin Sweat Sweat Tears Tears Stomach acid Stomach acid

3. Infection Micro-organisms increase in numbers rapidly. Micro-organisms increase in numbers rapidly. The symptoms of a disease are caused by the micro organisms or their toxins. The symptoms of a disease are caused by the micro organisms or their toxins. The body has an immune system to fight infection. The body has an immune system to fight infection.

4. White Blood Cells Some white blood cells ‘eat’ invading micro organisms (phagocytosis). Some white blood cells ‘eat’ invading micro organisms (phagocytosis). Some white blood cells produce antibodies that stick to invading micro organisms. Some white blood cells produce antibodies that stick to invading micro organisms. Each antibody will be specific to a particular micro organism eg chicken pox. Each antibody will be specific to a particular micro organism eg chicken pox. Once produced, the white blood cells remember the micro organism and kill it very quickly next time it invades. Once produced, the white blood cells remember the micro organism and kill it very quickly next time it invades.

5. Vaccines Vaccines inject a small amount of ‘safe’ micro organisms causing the body to produce antibodies. Vaccines inject a small amount of ‘safe’ micro organisms causing the body to produce antibodies. The White blood cells remember the ‘safe’ version and attack the disease causing micro organism when it invades giving immunity. The White blood cells remember the ‘safe’ version and attack the disease causing micro organism when it invades giving immunity. Vaccines can produce side effects in some and so are never totally safe. Vaccines can produce side effects in some and so are never totally safe. Some micro organisms (eg influenza, HIV) mutate (change) so quickly that the antibodies don’t recognise them. This makes it difficult to get immunity Some micro organisms (eg influenza, HIV) mutate (change) so quickly that the antibodies don’t recognise them. This makes it difficult to get immunity Some organisms eg AIDS damage the immune system making it difficult to get immunity. Some organisms eg AIDS damage the immune system making it difficult to get immunity.

6. Vaccination (cont) Need a lot of people to be vaccinated to prevent epidemics (herd immunity). Need a lot of people to be vaccinated to prevent epidemics (herd immunity). Some people may not wish to risk the side effects (MMR). This may prevent herd immunity being achieved. Some people may not wish to risk the side effects (MMR). This may prevent herd immunity being achieved.

7. Antibiotics Antibiotics kill bacteria but not fungi or viruses. Antibiotics kill bacteria but not fungi or viruses. Bacteria can mutate and become resistant to the antibiotic. Bacteria can mutate and become resistant to the antibiotic. We should therefore only use antibiotics when necessary and complete the course. We should therefore only use antibiotics when necessary and complete the course. The resistant bacteria will survive better if we take too many antibiotics and kill all the competition The resistant bacteria will survive better if we take too many antibiotics and kill all the competition

8. Drug Testing New drugs must be tested to make sure they are safe and effective. New drugs must be tested to make sure they are safe and effective. This may involve animal trials. This may involve animal trials. Human trials involve ‘blind’ and ‘double blind’ trials, and placebos. Human trials involve ‘blind’ and ‘double blind’ trials, and placebos. Ethical issues are involved with respect to animal testing and selecting people for trials. Ethical issues are involved with respect to animal testing and selecting people for trials.

9. Heart Disease Very common in the UK and industrialised countries. Very common in the UK and industrialised countries. Is caused by a build up of fatty deposits in the coronary arteries. Is caused by a build up of fatty deposits in the coronary arteries. Lifestyle factors such as poor diet, smoking, stress and alcohol increase the chances of heat disease. Lifestyle factors such as poor diet, smoking, stress and alcohol increase the chances of heat disease. Regular, but not excessive, exercise reduces the chance of heart disease. Regular, but not excessive, exercise reduces the chance of heart disease.

10. Analysing Data Distinguish between correlation and cause. Distinguish between correlation and cause. Assess critically whether studies are reliable. Assess critically whether studies are reliable. Describe the relationship between 2 factors on a graph, such as increase, decrease, steady, uniform and proportional. Describe the relationship between 2 factors on a graph, such as increase, decrease, steady, uniform and proportional.