SENSE ORGANS

The role of our sense organs is to ‘capture’ the various forms of energy that convey information about the external world, and to change it into a form that the brain can handle. This process is called transduction. [transduction the process of transforming one type of energy (e.g. sound waves, which are mechanical in nature) into another kind of energy – usually the electrical energy of neurons] As a transducer, a sense organ captures energy of a particular kind (e.g. light) and transforms it into energy of another kind – action potentials, the neural system’s code for information. Action potentials are electrical energy derived from the exchange of electrically charged ions, which inhabit both sides of the barrier between the neuron and its surroundings (see chapter 3). So our eyes transduce electromagnetic radiation (light) into action potentials, our ears transduce the mechanical energy of sound, and so on. Transduction is a general term, which does not apply only to sense organs. A microphone is a tra sducer, which (rather like the ear) transduces mechanical sound energy to electrical potentials – but in a wire, not in a neuron. There are many other examples of transduction in everyday equipment. As we gradually move away from physics and into psychology, we pass through an area of physiology – how biological transducers work.