Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Section 14.3 Your Eyes and Ears Your Eyes and Ears Objectives Explain how your eyes allow you to see. Identify two ways to keep your eyes healthy. Explain how your ears allow you to hear and maintain your balance. Identify ways to keep your ears healthy. Slide 1 of 29 Section 14.3 Your Eyes and Ears Dear Advice Line, One of my friends likes to play loud music when I am at his house. Sometimes when I leave, my ears are ringing and I have trouble hearing for several hours. I’ve asked him to lower the music, but he just laughs at me. I don’t want to stop hanging out with him. What should I do? Write a response to this teen to help solve the problem. Slide 2 of 29 Section 14.3 Your Eyes and Ears Your Eyes • The eyes are complex organs that respond to light by sending impulses. • Your brain then interprets the impulses as images. Slide 3 of 29 Section 14.3 Your Eyes and Ears How Light Enters Your Eye • The cornea (KAWR nee uh) is the clear tissue that covers the front of the eye. • The pupil is the opening through which light enters the eye. • The iris is a circular structure that surrounds the pupil and regulates its size. Slide 4 of 29 Section 14.3 Your Eyes and Ears How Light Is Focused • The lens is a flexible structure that focuses light. • The lens of your eye functions something like the lens of a camera, which focuses light on photographic film. Slide 5 of 29 Section 14.3 Your Eyes and Ears How You See an Image • The retina is a layer of cells that lines the back of the eye. • When light strikes the rods and cones, nerve impulses travel through the optic nerves to the brain. • In the cerebrum, the brain turns the flipped image right-side up. Slide 6 of 29 Section 14.3 Your Eyes and Ears The Eye Cornea Retina Lens Iris Optic nerve Pupil Blood vessels Slide 7 of 29 Section 14.3 Your Eyes and Ears Caring for Your Eyes • It is important to protect your eyes from damage and to have regular eye exams. • To protect your eyes from damage wear protective goggles when you work with harmful substances or around machinery. • Wear sunglasses that provide UV protection. Slide 8 of 29 Section 14.3 Your Eyes and Ears Detecting Vision Problems • An optometrist is a professional who provides eye and vision care, and checks you for vision problems. • Three common vision problems are • Nearsightedness People who are nearsighted can see nearby objects clearly, but not faraway objects. • Farsightedness People who are farsighted can see faraway objects clearly, but nearby objects appear blurry. • Astigmatism People with astigmatism have distorted vision. Slide 9 of 29 Section 14.3 Your Eyes and Ears Vision Problems Slide 10 of 29 Section 14.3 Your Eyes and Ears Treating Eye Diseases • Glaucoma is a buildup of pressure in the eye. • Cataracts The clouding of the eye’s lens is known as a cataract. • Detached Retina Aging or an injury to the eye can cause the retina to separate from the lining of the eye. • Macular Degeneration This condition occurs when cells in the center of the retina break down. Slide 11 of 29 Section 14.3 Your Eyes and Ears For: Updates on eye diseases Click above to go online. Slide 12 of 29 Section 14.3 Your Eyes and Ears Treating Eye Infections • A sty is a painful swelling that occurs when an oil gland at the base of an eyelash becomes infected. • Conjunctivitis is an inflammation of the outside layer of the eye. • Sties and conjunctivitis can be treated with prescription medications. Slide 13 of 29 Section 14.3 Your Eyes and Ears Slide 14 of 29 Section 14.3 Your Eyes and Ears Your Ears • The ears convert sounds into nerve impulses that your brain interprets. • In addition, structures in the ear detect the position and movement of your head. • Your ears help you to stand upright, walk smoothly, and adjust your body’s position. Slide 15 of 29 Section 14.3 Your Eyes and Ears The Outer Ear • In the outer ear, the vibrations are channeled into the ear canal, a narrow cavity that leads to the middle ear. • At the end of the ear canal is a thin membrane called the eardrum. • The eardrum vibrates when sound vibrations strike it. Slide 16 of 29 Section 14.3 Your Eyes and Ears The Middle Ear • Vibrations from the eardrum pass to the middle ear, which contains three small bones • the hammer • the anvil • the stirrup • The vibrating eardrum causes the hammer to vibrate, which pushes against the anvil, which then moves the stirrup. Slide 17 of 29 Section 14.3 Your Eyes and Ears The Inner Ear • Vibrations are passed through the oval window to a hollow, coiled tube filled with fluid called the cochlea (KAWK lee uh). • When the cochlear fluid moves, the cells stimulate impulses in nerves. • The impulses travel through the auditory nerve to the brain, where they are interpreted as sound. Slide 18 of 29 Section 14.3 Your Eyes and Ears Outer Ear Sound enters through the outer ear and reaches the eardrum. Middle Ear Vibrations pass from the hammer to the anvil and stirrup. Hammer Anvil Ear canal Stirrup Eardrum Auditory tube Inner Ear Vibrations in the cochlea cause nerve cells to transmit signals to the brain. Semicircular canals Auditory nerve Cochlea Oval window (behind stirrup) Slide 19 of 29 Section 14.3 Your Eyes and Ears The Inner Ear and Balance • The semicircular canals are structures that send information to your brain about the movements of your head. • Two sacs located behind the canals capture information about your head’s position. • When your head moves, the fluid inside the semicircular canals and sacs causes the “hairs” to move. • The movement stimulates nerve cells, which send impulses to your brain. Slide 20 of 29 Section 14.3 Your Eyes and Ears Caring for Your Ears • Besides keeping your ears clean, you also need to monitor noise levels. • You should see a doctor if you experience ear pain or hearing difficulties. Slide 21 of 29 Section 14.3 Your Eyes and Ears Ear Care • Use a wet washcloth to clean your outer ear and the front part of your ear canal. • Dry your ears thoroughly after you wash them. • Never insert a cotton-tipped swab or any other object into your ear canal. Slide 22 of 29 Section 14.3 Your Eyes and Ears Monitoring Noise Levels • Partial hearing loss or deafness can result from damage to nerves or to the vibration-sensing cells in the cochlea. • The intensity, or loudness, of sound is measured in units called decibels (DES uh bulz). • To avoid hearing damage • Keep your television and stereo low enough that you can comfortably hear a person speaking at a normal level. • Never turn the music player up to more than 60 percent of its potential volume. Slide 23 of 29 Section 14.3 Your Eyes and Ears Decibel Levels of Daily Life Slide 24 of 29 Section 14.3 Your Eyes and Ears Treating Ear Infections • Bacterial infections of the middle ear can sometimes result in some hearing loss. • A middle-ear infection may cause the eardrum to break, or rupture. • Scar tissue makes the eardrum less flexible and less able to transmit sound. Slide 25 of 29 Section 14.3 Your Eyes and Ears Treating Hearing Problems • Some types of hearing loss can be inherited. • Diseases, high fevers, and large doses of medication can also cause hearing loss. • People with hearing problems see an audiologist (aw dee AHL uh jist) . • Audiologists are professionals who are trained to evaluate hearing and treat hearing loss. Slide 26 of 29 Section 14.3 Your Eyes and Ears Vocabulary cornea pupil iris Clear tissue that covers the front of the eye. The opening through which light enters the eye. The structure that surrounds the pupil and regulates the amount of light that enters the eye. lens A flexible structure in the eye that focuses light on the retina. retina A layer of light-sensing cells that lines the back of the eye. optometrist A professional trained to provide eye and vision care. Slide 27 of 29 Section 14.3 Your Eyes and Ears Vocabulary eardrum The membrane at the end of the ear canal that passes vibrations to the middle ear. cochlea A coiled, fluid-filled tube in the inner ear that contains cells that sense sound vibrations. semicircular canals audiologist Structures in the inner ear that help control balance. A professional who evaluates hearing and treats hearing loss. Slide 28 of 29 Section 14.3 Your Eyes and Ears QuickTake Quiz Click to start quiz. Slide 29 of 29 Section 14.3 Your Eyes and Ears End of Section 14.3 Click on this slide to end this presentation. Slide 30 of 29