A drug is any chemical you take that affects the way your body works. Alcohol, caffeine, aspirin and nicotine are all drugs. A drug must be able to pass from your body into your brain. Once inside your brain, drugs can change the messages your brain cells are sending to each other, and to the rest of your body. They do this by interfering with your brain's own chemical signals: neurotransmitters that transfer signals across synapses.
How does your brain work?
Your brain is the hub of your nervous system. It is made up of 100 billion nerve cells - about the same as the number of trees in the Amazon rainforest. Each cell is connected to around 10,000 others. So the total number of connections in your brain is the same as the number of leaves in the rainforest - about 1000 trillion.How can illness affect the brain?
Because the human brain is so complicated and has little capacity to regenerate, it is vulnerable to the effects of damage and disease. Losing part of the vast network of cells, or changing the level of a neurotransmitter, can have devastating results. Alzheimer's and Parkinson's diseases are examples of disorders of the nervous system in which brain cells gradually die. In disorders of the mind, such as schizophrenia and depression, the symptoms are caused by more subtle changes in the brain that are as yet poorly understood.
What happens when you’re asleep?
For about a third of your life, you are asleep. While you sleep, your heart rate drops, your muscles relax, your breathing slows and you respond less and less to the outside world. Sleep also restores the body's energy and may help you commit to memory things that have happened during the day.How do drugs affect your brain?
Why does a cup of coffee wake you up, and aspirin stop your headache? Many drugs work by copying or blocking the effects of naturally occurring chemicals in your brain.What is special about human language?
Human beings are the great communicators of the animal world. They are the only living creatures that use language – words or symbols that represent objects, actions, qualities, feelings and ideas. Other animals communicate in much less complex ways.
Why is your memory so important?
Your memory is your brain's filing system. It contains everything you have learnt. You can store an amazing amount of information – for example, as a child you learned around ten new words a day, and you may eventually know 100,000 or more.
