Transcript The Ear
The Ear The ear is the sensory organ that allows us to hear. It converts airborne sounds waves into nerve impulses that are decoded by the brain Parts of the ear 1) Outer ear (external) • Auricle or pinna • The auditory canal • This is the visible part of the ear • It gathers sound waves from the environment and directs them along the auditory canal – is 3.75 cm long – Has walls lined with hairs and glands that secrete wax these prevent foreign particles from entering the ear – Ends at the tympanic membrane or eardrum 2) The middle ear • The eardrum or tympanic membrane • Three small bones or ossicles (maleus -hammer, incusanvil, stapes- stirrup) • It is linked to the Eustacian tube which serves to equalize the air pressure on the two sides of the eardrum 3) The inner ear • a fluid filled cavity in the temporal bone • Contains the semicircular canals and the cochlea For your information http://video.about.com/pediatrics/Ear-Pressure.htm The takeoff or landing of an airplane, the acceleration of an elevator, deep-sea diving, or driving up a steep hill in a car all bring about changes in air pressure which may be experienced as discomfort in the ears. This feeling is the result of increased pressure being exerted on the eardrum, which causes it to bulge on one side or the other, depending where the pressure is higher. Usually the act of yawning, swallowing, or sneezing opens the Eustachian tube, equalizing the pressure on the two sides of the eardrum and relaxing this membrane. Cochlea • spiral-shaped • fluid-filled inner ear structure • lined with cilia (tiny hairs) that move when vibrated and cause a nerve impulse to form • The axons of cilia form the auditory nerve that sends auditory signals to the brain • http://www.youtube.com/watch?v=-WA7-k_UcWY Match the following words with the correct term • Ear • Cochlea • Auditory Nerve • Brain • • • • Transformer Analyzer Conductor Receiver Hearing & the ear This is the chain reaction which takes place in the hearing process: (put the following words in the appropriate order) sounds waves hearing Vibration of the eardrum auditory canal center for hearing in the brain the auricle three bones of the middle ear nerve impulse is triggered in the auditory nerve cilia move (inside cochlea) Chain Reaction of Hearing sound waves the auricle the auditory canal vibrations the eardrum the three bones of the middle ear cilia move (inside cochlea) nerve impulse is triggered in the auditory nerve the center for hearing in the brain hearing Hearing loss & prevention • Hearing loss: the total or partial inability to hear sound in one or both ears. • Preventing hearing loss is more effective than treating it after "the damage is done." • True or False Quiz: http://www.hearingcenteronline.com/factfic.shtml Hearing loss and prevention • 3 Main causes of hearing loss: 1. Partial or total blocking of the auditory canal by wax Hearing loss & prevention • 3 Main causes of hearing loss: 2. Rupture of the eardrum Ear Drum or Tympanic membrane Hearing loss & prevention • 3 Main causes of hearing loss: 1. Ear wax 2. Rupture of the eardrum 3. Loss of sensitivity of the mechanical structures (eardrum, small bones of the middle ear) Otitis • Inflammation and/or infection of the middle ear • Acute otitis media (acute ear infection) occurs when there is bacterial or viral infection of the fluid of the middle ear, which causes production of fluid or pus. • Chronic otitis media occurs when the eustachian tube becomes blocked repeatedly due to allergies, multiple infections, ear trauma, or swelling of the adenoids. Hearing loss & prevention • Guidelines to maintaining good hearing: A.Removing wax B.Be careful when diving C.Avoid high pitched sounds D.Avoid loud sounds • Wear protective ear wear (plugs, muffs, etc.) COCHLEAR IMPLANTS Surgery videos • TYMPANIC MEMBRANE SURGERGY • http://www.entusa.com/surgery_videos.htm Review Questions 1) 2) 3) 4) 5) 6) 7) What part of the ear gathers sound waves in the air? What name is given to the structure that connects the ear to the nose? How does the ear protect itself from unwanted incoming particles? What two structures compose the inner ear? What structure contains the hearing receptor cells? Which part of the ear houses the nerve endings for hearing? When does a person experience the sensation of hearing? 1) What part of the ear gathers sound waves in the air? - The auricle or the pinna 2) What name is given to the structure that connects the ear to the nose? - Eustacian tube 3) How does the ear protect itself from unwanted incoming particles? - The ear wax that lines the auditory canal 4) 5) 6) 7) What two structures compose the inner ear? - The semicircular canals and the cochlea What structure contains the hearing receptor cells? - The cochlea Which part of the hearing system houses the nerve endings for hearing? - The auditory nerve When does a person experience the sensation of hearing? - When the temporal lobe of the brain receives nerve impulses from the auditory nerve Internet resources • Meniere’s disease (loss of balance): • http://www.nlm.nih.gov/medlineplus/ency/ar ticle/000702.htm • Slideshow: • http://www.nlm.nih.gov/medlineplus/tutorial s/hearingloss/htm/_no_50_no_0.htm