Chapter 3Lesson 4: Caring for Your Eyes and Ears

BELL ACTIVITYWhy do people wear sunglasses? List as many reasons as you can.

How Your Eyes WorkYour 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.

The Eye Figure 3.11, p. 76Sclera the white of the eyeCornea the clear section that lets in light at the front of the eyeIris colored part of the eyePupil dark opening in the center of the iris *Lens focuses light on the retinaRetina the light-sensing part of the inner eyeOptic Nerve bundle of nerve fibers that send messages to the brain, which interprets them

Caring for Your EyesMake sure you have enough light.Avoid having too much light. Sit at least 6 feet away from the TV.Dont rub your eyes.Protect your eyes from injury.

Check upsOptometrist 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.

Problems with VisionAstigmatism an eye condition in which images are distorted.NearsightedFarsighted

How Your Ears WorkAllow 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.

ContinuedIn 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.

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.

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

ContinuedWear 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.

ActivityOn a separate sheet of paper, draw an eye.Label:SCLERA white part of the eyePUPIL Black part in the centerIRIS colored part of your eyeWrite the functions of each.*** USE PAGE 76 FOR HELP

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