How organisms use nerves and hormones is one of the topics covered in GCSE Science. This is the first of five quizzes on the subject and it looks at the senses we, and other animals, use for detecting our environment. This refers not only to the five senses of sight, hearing, taste, touch and smell, but also to other senses such as balance.
All animals, humans included, need to have a system that can be used for detecting their surroundings or environment. Without such a system it would not be possible to move around, find food, escape danger and so on. Evolution has equipped animals with several senses, including the obvious five of sight, hearing, touch, taste and smell. These detect the environment and send messages to the brain. The brain then interprets these signals so that animals can make sense of the world around them.
Messages are carried by the nervous system. This enables animals to react to or interact with their surroundings and to coordinate their behaviour according to the exact situation. The nervous system is made up of long thin nerve cells (neurons) that join together in long strings to make nerves, but with a little gap between them. Inside the nerve cell messages are carried along as electrical signals, but between nerve cells the messages are usually transmitted across the gap by chemcals.
When we humans are deprived of one or more of our senses, it is still possible for us to function almost normally. We can find other ways of detecting our surroundings. For example, people who have lost their sight can learn to get around using a stick or with the help of a guide dog and people who have lost their sense of hearing learn to communicate in different ways.