1.2 The functions of the nervous system

The nervous system is a control and communication system. It controls and regulates body functions. Whilst the processes involved are complex, its basic function can be explained by thinking about it in terms of three basic components. These are:

• Sensation: Signals or messages from the receptors found in body tissues or from organs whose function it is to collect information from the external environment, are collected and transmitted to the CNS.
• Processing: The CNS integrates and processes the incoming information.
• Action: The CNS sends out motor signals to muscles and glands to modify body functions in response to the information it has received and processed.

Let’s take a simple example. When you get up from the couch to go out into the cold to buy a newspaper, the CNS receives immediate indications of changes such as blood pressure, temperature and oxygen requirements. This information is processed and the CNS then sends out a range of signals to organs such as the heart, lungs, skin and so on, to enable them to change their function appropriately in order to maintain homeostatic balance. Most of this happens without us even thinking about it, but of course, the response of our body to the desire to read the newspaper, the moving of muscles and so on that allow us to walk to the shop can also be considered in the light of the three components above. See if you can work out how. Think about what signals from which body tissues need to be sent to and from the CNS to achieve the actions.