retina Layer of light-sensing cells that covers the back of the eye.
visible light Electromagnetic radiation that humans can detect with their eyes.
vision Ability to see light.
Points to Consider
- The sense of sight is important to humans and other animals, but other senses may be
equally important. What are some of our other senses? - Why are these other senses important to us? For example, what are some ways we
depend on our sense of hearing?
20.3 Lesson 20.3: Other Senses
Lesson Objectives
- Explain how the ears hear and help maintain balance.
- Outline how we sense pressure, temperature, and pain.
- Describe how we identify different tastes and smells.
- Explain why hearing, balance, touch, taste, and smell are important.
Check Your Understanding
- What is the role of the nervous system?
- How do signals (”messages”) get from one area of the body to the brain?
Introduction
Imagine walking through the fruit market shown inFigure20.23. Your sense of sight would
be stimulated by all the brightly colored fruits. But your other senses would be stimulated,
too. You would hear the noisy bustle of the market. As you checked to see if a piece of fruit
was firm, you would feel its smooth skin. If you tried a sample of the fruit, you would taste
its juicy sweetness and smell its appetizing aroma. Clearly, a market like this is a feast for
all of the senses. In this lesson, you will read how your nervous system senses the sound,
feel, taste, and smell of a market like this—and of everything else around you.