Wednesday, May 03, 2006

Parts of the Ear and Its Functions

The Proposed Content Outline
A. Subject Name: Science and Health 3
B. Lesson Reference No: Science and Health 3 , pp. 13 -14 ,
Science Around Us : pp. 6 - 7
PELC 2.1.2
C. Lesson Title: Parts of the Ear and Its Functions
D. Lesson Concept: The ear has three main parts, the outer ear, the middle ear, and the
inner ear.
E. Lesson Description: The lesson makes the student to identify the parts of the ears
and the functions of its parts.
The lesson makes the student to observe keenly and caref
F. Learning Outcome:
At the end of the lesson the student identify the parts of the ears.
At the end of the lesson the student explain the function of its parts.
At the end of the lesson the student observe keenly and carefully.
At the end of the lesson the student label the parts of the ear.
At the end of the lesson the student appraise the value of its parts.
F. Learning Presentation:
Learning Object 1 - What to know, see the website link for information . Parts of the Ear
Learning Object 2 - What to know, see the website link for information . The Three Main Parts
of the Ears.
Learning Object 3 - What to know, link to e-learning presentation of the teacher in flash document.
Learning Activity:
Many people think our ears are the parts we see attached on the outside of our head. Would you be surprised to learn that the ear actually has three main parts? They are:
the outer ear
the middle ear
the inner ear
To learn how these three parts help us hear, see the webnsite link on- line at the drawings and read the following discussion. First we'll talk about each of the parts of the ear.
The outer ear is shaped like a funnel. The part you can see is called the pinna (pin'-uh). Inside the outer ear is the ear canal, a tunnel which ends at a round membrane called the eardrum. The eardrum separates the outer ear from the middle ear. The middle ear is a small air-filled space containing the Eustachian tube and a bridge of three bones. The Eustachian tube connects your ear and your throat and helps to keep a supply of fresh air in the middle ear. The three bones, called ossicles (ah'-sikuls), are the smallest in your body, and each has a name:
malleus (mal'-ee-us) or hammer;
incus (in-kus) or anvil;
stapes (stay-peez) or stirrup.
The bridge of ossicles hangs across the air space in the middle ear. This bridge starts with the malleus which is attached to the eardrum and ends with the stapes which is attached to the oval window, another kind of eardrum. The inner ear is the organ in our body responsible for hearing and balance. In the inner ear we find the cochlea (coke'- lee-a). The cochlea, which is spiral-shaped like a snail's shell, is made of three coils of bone. The coils are filled with special fluids (liquids). You already know that the stapes fits into the oval window on one side of the cochlea. Below the cochlea is the round window. It has no attachments. If we slice across the bony shell of the cochlea to look inside, we can see a thin flexible membrane, the basilar membrane, suspended in the center. This membrane is surrounded by fluid. Attached to the membrane are 15,000 to 20,000 tiny hair cells. These cells connect to nerve fibers that make up the nerve of hearing. The nerve of hearing is also called the eighth nerve in our body.
This illustration shows the important parts of the inner ear in cross section. You can see only a few hair cells here. Imagine this membrane and the hair cells as a continuous ribbon through the entire cochlea. The shaded areas represent the special cochlear fluids.
Each part of the ear has a special role to play in the hearing process. It's a process that begins only when sound reaches the ear.
Sound is created when an object vibrates (moves back and forth), pushing the air around it. The sound of thunder on a stormy night or the song on a music box sets the air in motion until the air molecules (ma'-le-kyools) closest to you begin the journey through your ear and up to your brain. Think of your favorite sound. Let's follow what happens when the sound moves through each of the parts of your ear until you "hear" it. The pinna of the outer ear functions like a baseball catcher's mitt to "catch" the sound waves and direct them down through the ear canal to the eardrum. The eardrum vibrates with the rhythm of the air molecules (sound waves) pushing against it.
As the sound waves move the eardrum, the bridge of three ossicles vibrates back and forth. This vibration moves the oval window, carrying the rhythm of your favorite sound into the inner ear. When the sound waves move the inner ear fluid, the basilar membrane and the hair cells float in rhythm like a boat on the water. Next the hair or cilia (sil'-ee-uh) on top of the cells bend. This bending sends patterns of electrical signals through the nerve fibers of the nerve of hearing. A loud sound moves the hair cells much more than a soft sound. High pitch sounds, such as whistles or the speech consonants /t/ or /s/, cause a movement of the membrane and hair cells in a different place than low pitch sounds like drums or vowels. The inner ear fluid needs some room for its movement. The round window bumps in and out as the fluid moves. The electrical signals travel from the hair cells to the nerve of hearing up to the brain. The brain makes sense of the electrical patterns sent across the nerves and you "hear" your favorite sound.
The ear is not just for hearing. Some parts have other functions as well. Wax in your ear canal protects the other parts of the ear from dirt and bugs. But, too much wax in your ear canal can block sound from traveling further, cause you to hear less, and might require some attention from your doctor. Have you noticed that your ears sometimes tickle or hurt when you have a cold? The Eustachian tube makes it possible for a cold to cause this discomfort. It's through this passageway that cold germs travel from your nose and throat to your ears. The Eustachian tube has another helpful function: it can clear your ears when you yawn or swallow.
If you've ever had an ear infection, you may have noticed that you didn't hear as well. This change in hearing happens when the space in the middle ear fills with liquid. The liquid keeps the eardrum and ossicles from moving freely, and thus your hearing may change. After you take some medication, the liquid usually dries up, and your middle ear parts are again set in motion by sound. Have you ever visited an amusement park and gone on a ride that spins you around fast? If you have, you probably know what it feels like to be dizzy. Maybe you even closed your eyes so that-you would feel less dizzy. Let's find out why. Two other parts of your inner ear, the semicircular canals and the vestibule (ves'-ti-byool), have nothing to do with hearing. These two parts of the inner ear provide information to the brain about your balance and the position of your body in space. As you turn your body and head, different hair cells in the vestibule and semicircular canals change direction. When this happens, electrical signals are sent through the nerve fibers which connect to your eye muscles. Your eyes move in different directions depending on how your body is twisting and turning. These signals send information to the brain that lets you know if you are standing on your head, doing a somersault, or simply jumping rope.
ringing in the ears
saying "What?" often
watching a speaker's face intently
turning TV or radio on loud
confusing similar- sounding words ("messed" for "nest;" "dim" for
understanding others when they talk to you in the same room but not
if they are speaking from a different room
Do you know a friend, relative, or neighbor who has difficulty hearing? Have you wondered why that person has a hearing problem? Sometimes a person is hearing problem is only temporary—it lasts a short time. Other times the loss is permanent-it will remain the same or maybe become worse. Not all hearing problems are the same. Hearing loss is caused because of damage to one or more parts of the ear. How does this damage happen? Ear damage may happen before birth. When a baby is forming. in the mother's uterus, several things can happen which change the development of the baby's ear. A mother can become ill with a virus that damages the baby's ear. German measles is one type of virus known to cause damage to the hair cells of the inner ear. Some parts of a baby's ear may not form correctly; an outer or middle ear may not develop at all. We inherit hair color and eye color from parents. Your particular hair color may go back to a grandparent. In a similar way, some children or adults may inherit a hearing loss because their father, mother, or other close relative may have a hearing loss. It is harder to identify a hearing loss as an inherited loss when there is no record of previous hearing loss in a family and when no living relative, young or old, has hearing loss. Serious illness can cause damage to the delicate parts of the inner ear. Mumps and meningitis, for example, are illnesses that may cause permanent hearing loss. At times doctors need to make difficult decisions in order to save a sick person's life. Some life-saving drugs can cause permanent damage to ears. Doctors only choose to use this kind of medicine if someone is very ill. Accidents to the head can also damage the ear. A hard blow to the head can crack the bone of the inner ear or break the ossicles. Noises can damage hearing, too. The loss can be temporary or permanent. Exploding a firecracker close to the head, playing loud music, shooting guns or cap pistols, and working with power tools for long periods of time again and again can damage the inner ear. Noise can even cause a permanent, annoying ringing sound in the ear. Do you enjoy listening to music through head-sets on a portable radio/ cassette player? Worn at high volume for several hours, these devices can also cause hearing problems. Many older people, maybe even your grandmother or grandfather or a great aunt or uncle, have hearing problems. These problems may be caused by noise, medicine, accident, illness, or even by getting older. just like our eyes, some parts of the ear can wear out as we age.
Each person's hearing loss differs depending on how much damage has happened to the ear and where the damage has happened. Some individuals with a hearing loss can understand part of what is spoken. Others can hear better when sound is made louder. For other people, making sound louder only makes it more annoying or garbled. If you have a temporary hearing loss, see your doctor and have your hearing tested by an audiologist. An audiologist is a professional who knows how to test hearing. An audiologist works with people of all ages who have hearing problems. Some audiologists work in schools to test children's hearing and help them with their hearing problems in their classrooms. Your doctor or an ENT (Ear, Nose, and Throat) specialist can examine your ears and recommend whether medicine or surgery will heal them. Can a hearing aid help? For many people a hearing aid can be helpful. The hearing aid doesn't give these people normal hearing, but many people can use them to hear better at home or work. Some individuals cannot benefit from a hearing aid because their ears are too damaged. Hearing aids, like cars, come in different models. Different hearing aids amplify or make sounds louder in different ways. An audiologist after a careful evaluation can help a person decide which type of hearing aid—if any—will help.
Other devices are available to help people with hearing loss. Special telephones or telephone attachments amplify or make sound louder. A law passed by Congress in 1982 makes these special phones available in public places such as the airport, train station, or library. Some new devices make it possible for persons with hearing problems to make the sound of the television louder—without bothering family and friends in the same room. Similar listening devices in churches, synagogues, theaters, and public meeting rooms allow hearing impaired people to hear the speaker—even from the back of the room. These devices have special microphones that send the sound to a receiver or headset worn by the person. This is similar to the way a radio disc jockey can transmit music to your radio receiver over the air waves. New surgery permits some doctors to implant a hearing aid type of device inside the inner ear. This device, known as a cochlear implant, is similar to a hearing aid. The implant sends signals through the nerve of hearing to the brain. This surgery has helped some individuals who could not hear anything—even with a hearing aid. But more research needs to be done before the cochlear implant will help people to understand speech clearly. Some people cannot hear and understand spoken words even with special listening devices. They use other devices to talk on the telephone or to watch television. They may use a TDD (Telecommunication Device for the Deaf) to type conversations over the telephone; they may use a telecaption adapter or decoder which makes it possible to read on the television screen the words spoken by actors, actresses, and announcers.
How can we protect our hearing so that we will always enjoy our favorite sounds? If we have healthy ears now, we can do things to prevent hearing loss later.
Avoid very loud and dangerous noise. Even loud music may permanently harm your hearing.
Wear hearing protectors, special ear inserts, or ear muffs around noisy equipment.
Work in your community to keep it quiet. City and county governments often have committees to make suggestions about reducing loud noise. Let elected officials know that you are concerned about protecting ears and hearing.
Eat nourishing foods. Ears are nourished by the body's blood supply. Fatty foods can change the blood supply to the ears. In some countries where people eat a vegetarian diet, the people were found to have normal hearing even when they were quite old. This is not true in our country. Researchers believe this may be due to our "junk food" eating habits and noisy surroundings.
Activity 2 - What to know, see the website link for the on-line games.
Activity 3 - Take note the important information.
H. Learning Evaluation:
A. FILL IN THE BLANKS: Choose the correct answers from the answer box below.
Answers: ossicles balance 3 movement wax 2 sound waves fluid 8th pinna eardrum body position
1. The ear consists of __________ main parts.
2. Vibrating air molecules moving in rhythm are called ____________.
3. The ____________ gathers the sound waves and directs them through the ear canal.
4.______ in the ear canal protects our middle and inner ears from injury.
5. The outer ear ends at the _____________.
6. The smallest bones in our body, the ___________ , form a bridge between the eardrum and the oval window in the middle ear.
7. There are ____________ windows into the cochlea.
8. The inner ear is filled with ____________ . ______________ of the hair cells causes the nerves to send a signal about sound to the brain.
9. The nerve of hearing is known as the _________ nerve.
10.The vestibule and semicircular canals send information to our brain about our ___________ and ___________ .

I. Assignment
Get a cut out of ears and paste it in your notebook, then label the parts.


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