Normal body temperature is 37?C. This is set by part of your nervous system and the hypothalamus, which is found in the brain stem. The hypothalamus monitors your body temperature and changes it if it becomes too hot or too cold. Your body temperature doesn't have to be exactly 37?C: exercise can make you hotter, while going outside on an icy day can make you cooler. The place in which you measure your temperature is very important. Putting a thermometer under your armpit will show you your peripheral temperature, and this can be quite a bit lower than your 'real' body temperature called your core temperature, or the temperature at the centre of your body. This varies very little at all in day to day life. It can best be measured by putting a thermometer in your bottom! You have to get very cold to change your core temperature, such as being stuck in freezing weather for a long time. People who have a drop in core body temperature have what is known as hypothermia. This makes them drowsy, and if left untreated, they will eventually become unconscious. When the body is cold, the chemical reactions that provide your cells with energy don't work as well. This makes cells function abnormally and, if prolonged, can be fatal.

Plants make food for themselves via photosynthesis. This process involves a number of chemicals, enzymes and pigments, including green chlorophyll. Copper stops the photosynthetic process from working, which is why copper is toxic to plants and algae. The lines on the roof are likely to have been caused by copper: some builders purposely build copper strips into roofs to stop them going green. As for killing a tree with a copper nail, I'm not sure that that is true. Trees are very large and contain lots of water to dilute any copper particles put into it. Therefore, lots of copper would be needed to kill a tree. Metallic copper (which a nail would be made from) does not go into solution easily and would find it hard to get into the tree's food and water transport systems. In terms of humans, I think copper poisoning is unlikely in this area. The east of England has very hard water, which makes the water pipes fur up. This makes it hard for our drinking water to come into contact with the pipes. Copper in small amounts is actually important for humans as it helps some of our enzymes work. Only in the genetic 'Wilson's disease' can copper be a problem where sufferers accumulate too much of the metal in their brains.

Thyroxin is given to people with an under-active thyroid that can't make enough thyroxin by themselves. People with low levels of thyroxin in their blood often have a slower heart rate, have a tendency to put on weight, and feel lethargic. Interestingly, only one in five of all cases of thyroid under-activity will be in men. Doctors tailor the amount of thyroxin given to patients to ensure that the patient's body is working at the right level. Without knowing exactly what is wrong with your thyroid, it is hard to say what caused it to become under-active. Sometimes its caused by insufficient iodine in the diet. Historically underactive thyroids were common in Derbyshire causing people to develop a neck 'goitre' (swollen thyroid) - termed 'Derbyshire neck' - because their diets were deficient in iodine. However, most cases are caused by an autoimmune response, whereby the body starts attacking its own tissues. The reasons for thyroid problems can therefore be partly genetic, and partly environmental.

Tablets taken by mouth contain a lot of the actual antibiotic. They also contain lots of other substances which enable the manufacturer to produce a tablet that can be kept in packets and are easy to swallow. For example, the smooth outer coatings of some tablets are often made out of vegetable products. Once the tablet is in your stomach, the active bits distribute around the body through the bloodstream, reach the site(s) of infection, and kill the offending bacteria. There are three different ways antibiotics kill bacteria. Some stop bacteria from growing by stopping their protein production; others stop them from making chromosomes; and the third type stop bacteria from making cell walls. Without a proper cell wall, the bacteria explode and die.

The ears have the same linings and are connected to the nose and throat through the eustacian tube. This means that any of the viruses that cause colds and sore throats can get through into your ears. Viruses are the main invaders, but bacteria can cause secondary infection. They seize the opportunity to invade after a virus has caused the initial problem - such as damaging the protective lining of the airway, or blocking up the eustacian tubes in your ears with mucus