1. 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

2. The Ear *

3. Parts of the Ear • Outer ear (external) • ______________________ • - This is the visible part of the ear. • 2) _______________________ • - 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 *

4. 3) The middle ear • The eardrum or tympanic membrane • Three small bones; called the hammer, anvil and stirrup. (________ -hammer, ________- anvil, ________- stirrup) • It is linked to the Eustacian tube; ot equalizes the air pressure on the two sides of the eardrum. (ear pops_ 4) The inner ear • a fluid filled cavity in the temporal bone. • Contains the ____________________ and ___________. FYI 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.

5. 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

6. Ear Receiver Conductor Auditory Nerve Cochlea Transformer Brain Analyzer • Ear • Cochlea • Auditory Nerve • Brain • Transformer • Analyzer • Conductor • Receiver

7. 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

8. Hearing Loss & Prevention • 3 Main causes of hearing loss: 1. ______________ 2. __________________________ • 3. ___________________ • ___________________ (eardrum, small bones of the middle ear)

9. Review Questions • 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? ____________________________________ 3) How does the ear protect itself from unwanted incoming particles? ______________________________________ 4) What two structures compose the inner ear? ______________________________________________ 5) What structure contains the hearing receptor cells? ______________________________________________ 6) Which part of the ear houses the nerve endings for hearing? ______________________________________ 7) When does a person experience the sensation of hearing? ______________________________________

10. Internet Resources • Slideshow: • http://www.nlm.nih.gov/medlineplus/tutorials/hearingloss/htm/_no_50_no_0.htm