1. Chapter 3 Lesson 4: Caring for Your Eyes and Ears

2. BELL ACTIVITY Why do people wear sunglasses? List as many reasons as you can.

3. How Your Eyes Work Your eyes tell you about the world – about light, darkness, shapes, colors, and movement. The data gathered by your eyes is interpreted by your brain, allowing you to recognize your friend coming toward you in the hallway.

4. The Eye – Figure 3.11, p. 76 Sclera – the white of the eye Cornea – the clear section that lets in light at the front of the eye Iris – colored part of the eye Pupil – dark opening in the center of the iris * Lens – focuses light on the retina Retina – the light-sensing part of the inner eye Optic Nerve – bundle of nerve fibers that send messages to the brain, which interprets them

5. Caring for Your Eyes Make sure you have enough light. Avoid having too much light. Sit at least 6 feet away from the TV. Don’t rub your eyes. Protect your eyes from injury.

6. Check ups Optometrist – trained to examine the eyes for vision problems and to prescribe corrective lenses. Ophthalmologist – a physician who specializes in the structure, functions, and diseases of the eye.

7. Problems with Vision Astigmatism – an eye condition in which images are distorted. Nearsighted Farsighted

8. How Your Ears Work Allow you to hear and keep your balance. Outer ear is shaped like a cup to pick up sound waves, which are vibrations in the air. The sound waves travel through the external auditory canal.

9. Continued… In the middle ear, these waves make the eardrum vibrate. The vibrations of the eardrum move three tiny bones called the hammer, the anvil, and the stirrup. These bones carry the vibrations to the oval window.

10. Continued…. In the inner ear, the oval window causes the fluid in the cochlea to move. Tiny hairs lining the cochlea vibrate in response, sending electrical messages to the auditory nerve. These messages travel to the brain, which identifies sound.

11. Caring for Your Ears Keep volume fairly low on your radio. Decibel – unit for measuring the loudness of sound waves. Normal conversation = 60 decibels Sounds over 125 decibels are loud enough to be painful.

12. Continued… Wear ear plugs, or other hearing protection if you are going to be exposed to loud, prolonged noise. Clean the outside of your ear with a wet wash cloth. On cold days, wear earrmuffs. Cold air can irritate your middle ear.

13. Activity On a separate sheet of paper, draw an eye. Label: SCLERA – white part of the eye PUPIL – Black part in the center IRIS – colored part of your eye Write the functions of each. *** USE PAGE 76 FOR HELP

14. Review/Closing Identify the cornea, iris, pupil, lens, and retina. Explain what an optometrist and an ophthalmologist are. What is a decibel?