much, not to worry about that, but to make sure you drink plenty of fluid. And ideally, this should have a little bit of salt and sugar in. You can get special rehydrating fluids, which are specially mixed. But if you want to make your own by adding just a teaspoonful of sugar and a pinch of salt, then it's obviously perfectly reasonable to do that. Part III Immunity
The environment contains many potentially destructive microorganisms. It is impossible for us to avoid contact with microbes. That's why our body is constantly under attack from invading germs and infections. Then why don't we suffer from constant illness? Do we have our own defense system? B.
potentially：潜在地 destructive：破坏性的 microorganisms：微生物 impossible：不可能
microbes： 微生物，细菌 invading germs：侵入的细菌 suffer from：生病；忍受 defense system：防护系统
lash：鞭挞，鞭子;责骂;讽刺;眼睫毛 immunity：免疫 constant (ly)：持续 come into play：起作用 germ：细菌
literally：字面上 assist：帮助
reserve：保存，储备，储存
backup：支持，后援;阻塞;（计）备份文件 bone marrow：骨髓 antibody：抗体 measles：麻疹
polio：脊髓灰质炎；小儿麻痹症 tuberculosis：肺结核
The human body is constantly under attack from invading germs and infections. And the only reason we don't suffer from constant illness is our bodies have their own defense mechanism to fight off disease. This resistance to infection is called immunity. A: How does immunity work?
B: Well, the immune system is the body's own secret army, which fights infection. And it consists of a whole range of troops, soldiers, their cells and their molecules. Now the headquarters of this army is really the blood. That's where it does most of its fighting. And sometimes it needs some reserve, and that comes from the bone marrow. That's where the immune cells are made.
A: So there are many different kinds of cells, different kinds of molecules in the immune system. I guessed the ones that we're probably more familiar with are white blood cells.
B: That's right. White blood cells form a major part of the body's defense. But there are also antibodies in their life, more proteins. They just lash onto the invaders. The white cells can
sometimes actually gobble up invaders. The clever thing is that once the infection has attacked our body, the immune system seems to have a memory of the invader, so that the next time it sees the invader it can attack very quickly.
A: There are some things which we're not naturally immune to and that's where vaccination comes in, isn't it?
B: Exactly. Vaccination plays on the body's ability to remember infection. So what happens is that someone is given a version of an illness, for instance, measles or polio, or tuberculosis, and the body thinks that it is actually being infected with that infection. And the next time it sees it, the body can respond very quickly. All the troops of its immune system can come into play. A: Now sometimes the immune system doesn't work very well, does it?
B: No. It’s a remarkably complex system. And sometimes it can go wrong. Either it can be overactive, so it actually starts to attack our own body self, or it can be underactive sometimes, and we are more likely to be infected in that situation.
A: Are there any important illnesses which result from the immune system so that it's turning on our bodies themselves?
B: There are. One example would be a disease like multiple-sclerosis, where the body's own immune system attacks the lining of nerves, which means that people's nerves don't work properly. A: We're able to assist the body in its fight against the illness in many cases, but there are some diseases which we don't seem to be able to produce a vaccine for. AIDS is one of them. Why not? B: The problem is AIDS, which is caused by the HIV virus, attacks the human immune system, which means that our normal defenses aren't there to fight off that infection. The other problem with trying to produce a vaccine against HIV or AIDS is that the virus, HIV, can change itself so easily. That's very difficult to find a vaccine which can recognize all the different types of HIV. So one vaccine may be effective against one type of the virus but it may absolutely be no good for another type. C.
Presenter: The human body is constantly under attack from invading germs and infections. And the only reason we don't suffer from constant illness is our bodies have their own defense mechanism to fight off disease. This resistance to infection is called immunity. And here with me to discuss how it works is Grime Easton. He is a family doctor, and a member of the Science In It here in the BBC World Service. Grime, how does immunity work?
Grime: Well, the immune system is the body's own secret army, if you like, which fights infection. And it consists of a whole range of troops, soldiers, their cells and their molecules. Um, now the headquarters of this army is really the blood. That's where it does most of the fighting. And sometimes it needs some reserve, some backup, and that comes from the bone marrow. That's where the immune cells' factories are.
Presenter: So there are many different kinds of cells, and different kinds of molecules tied up in the immune system. I guessed the ones that we're probably more familiar with are white blood cells.
Grime: That's right. White blood cells form a major part of the body's defense. But there are also antibodies in their life, more proteins, which just lash onto the invaders. Um, but, as you say, the white cells can sometimes actually gobble up invaders. So the clever thing is that once the infection has attacked our body, the immune system seems to have a memory of the invader, so that the next time it sees the invader it can attack very quickly. The immune system in the human
body fights invading disease. Immunity occurs because the immune system can remember the chemical makeup of invading germs and attack them very quickly.
Presenter: There are some things which we're not naturally immune to and that's where vaccination comes in, isn't it?
Grime: Exactly. Vaccination plays on the body's ability to remember infection. So what happens is that someone is given a version of an illness, for instance, measles or polio, or tuberculosis, and the body thinks that it is actually being infected with that infection. And the next time it sees it, um, the body can respond very quickly. And all the troops of its immune system can come into play. Vaccination can be used to protect the body against specific infections.
Presenter: Now sometimes the immune system doesn't work very well, does it?
Grime: No. It's a remarkably complex system. It's a very complicated system. And sometimes it can go wrong. Either it can be overactive, so it actually starts to attack our own body self, or it can be underactive sometimes, and we are more likely to be infected in that situation.
Presenter: Are there any important illnesses which result from the immune system so that it's turning on our bodies themselves?
Grime: There are. And one example would be a disease like multiple-sclerosis, where the body's own immune system, we think, attacks the lining of nerves, which means that people's nerves don't work properly.
Presenter: We're able to assist the body in its fight against the illness in many cases, but there are some diseases which we don't seem to be able to produce a vaccine for. Um, AIDS is one of them. Why not?
Grime: Well, the problem is AIDS, which is caused by the HIV virus, is that HIV itself attacks the human immune system, which means that our normal defenses aren't there to fight off that infection, or indeed many other sorts of infection. The other problem with trying to produce a vaccine against HIV or AIDS is that the virus, HIV, can change itself so easily. Um, that's very difficult to find a vaccine which can recognize all the different types of HIV, which there are. So one vaccine may be effective against one type of the virus but it may absolutely be no good for another type.
HIV is the virus that causes AIDS. HIV destroys the body's immune system, and puts the body at greater risk from other common infections.
Presenter: I was talking to Dr. Grime Easton of the Science In It about immunity. The reason why he, I, and I hope you, are able to remain as healthy as we are. Part Ⅳ Why do I catch colds
Virus are most definitely going to get you. And when they do, they will give you anything, from a cold to Ebola. And yet, technically, virus have no life of their own. So why do they cause so much trouble? More to the point, why do I catch colds?
See that guy with the blocked nose. When he sneezes, 40,000 droplets will fly twelve feet in their air, infecting up to 150 people. You should have ducked. A cold virus just can’t live without you. With no cells of its own, it needs to take over your cells and replicate. Here’s something to think about. The virus can only travel around inside a blob of macus. And that mean whenever you catch a sniffle, someone else’s snot has been up your nose. Anyway, your immune system is constantly on the prowl for attackers like these. If it wasn’t, you could end up with fatal pneumonia. So, when it spots a viral invasion, it grabs a sample. Here, a T cell first identifies the invader and then deploys an army of tailor-made immune cells to your nose. These provide special
backup for the standard immune cells already fighting your cold. Your nose has become a battleground. Meanwhile, to stop infection spreading to your lungs, you’re manufacturing a daily pint of macus. This snot gives you a headache. While the virus irritates your nose, so you have to blow it around 45 times a day. Beating a cold takes you about seven days and you’ll catch about four a year.
This is the golden age for the cold virus. It hops on planes with its human hosts, visits new cities and finds hundreds of new homes with every sneeze. As it replicates, it mutates. So by the next year it may be back in a different form. Part V Dental Health
People have been troubled by tooth and gum problems for thousands of years. The earliest record of dental treatment comes from ancient Egypt. Books say the Egyptians treated gum swelling by using a substance made of spices and onions. The earliest known person to treat tooth problems was also from Egypt. He lived about five-thousand years ago. He was known as a \
Experts say Chinese people living almost five-thousand years ago treated tooth pain by acupuncture -- placing small sharp needles in different parts of the body. About one-thousand-three-hundred years ago, the Chinese filled holes in the teeth with a mixture of the metals mercury, silver and tin. That was almost one-thousand years before a similar substance was first used in western countries. Some ancient people like the Maya did not treat dental disease. But they made their teeth pretty by placing pieces of stone and metal on them.
The ancient Romans were careful about keeping their teeth clean. More than two-thousand years ago, the Romans treated toothaches, filled holes in teeth, and made false teeth to replace those that had been lost.
From the fifth to the fifteenth centuries, Europeans with tooth problems went to people called barber-surgeons. These people performed many services, including cutting hair, pulling teeth and treating medical conditions. Dental treatment improved during the fourteenth and fifteenth centuries as doctors increased their knowledge about teeth.
Modern dentistry began in the Seventeen-Hundreds in France. That was when Pierre Fauchard published his book called \Surgeon Dentist.\It was the first book about dental science. The book provided information about dental problems for other dentists to use. And it described ways to keep teeth healthy. Pierre Fauchard is considered the father of modern dentistry. His work was important in helping establish dentistry as a separate profession.
