WARM UP 4/24 What does each do? 1. Medulla 2. Olfactory cell 3. Cones 4. Temporal lobe 5. Pituitary gland 6. Vestibulocochlear nerve 7. Taste bud 8. Hypoglossal nerve 9. Retina

NOTES CH 11 4/24 The ear

AUDIOLOGY The study of the ear

The ear consists of 3 parts: 1. Outer 2. Middle 3. Inner

OUTER EAR PINNA – part you see PINNA – part you see EXTERNAL AUDITORY CANAL EXTERNAL AUDITORY CANAL CERUMINOUS GLANDS – produce wax to protect the ear CERUMINOUS GLANDS – produce wax to protect the ear TYMPANIC MEMBRANE (eardrum) TYMPANIC MEMBRANE (eardrum)

MIDDLE EAR EUSTACHIAN TUBE – links the ear to the throat. Purpose is to equalize pressure in the ear. EUSTACHIAN TUBE – links the ear to the throat. Purpose is to equalize pressure in the ear. Normally flat – unequal pressure, EX: yawning or high altitudes – opens up and hear a “popping” sound Normally flat – unequal pressure, EX: yawning or high altitudes – opens up and hear a “popping” sound

Tube more horizontal when younger – reason to never give baby bottle on back. Tube more horizontal when younger – reason to never give baby bottle on back. Milk can go into the ears and cause infection/ earache OTITIS MEDIA – ear infection.

3 SMALLEST BONES 3 SMALLEST BONES HAMMER, ANVIL, STIRRUP HAMMER, ANVIL, STIRRUP (malleus, incus, stapes) (malleus, incus, stapes) These transmit vibration of the eardrum to the inner ear

INNER EAR COCHLEA – snail like area filled with fluid where auditory cells and hairs are located COCHLEA – snail like area filled with fluid where auditory cells and hairs are located

SEMICIRCULAR CANALS – 3 tubes where fluid located; helps with equilibrium SEMICIRCULAR CANALS – 3 tubes where fluid located; helps with equilibrium

EQUILIBRIUM 1. STATIC – detect up and down movement of head. (Tiny calcium stones in fluid hitting against hairs when move) 2. DYNAMIC – detects angles and whole body movement (Fluid moves in semicir canals) Both messages are sent to the cerebellum

Why still feel movement when stop? The fluid is still moving in the ears and sending message to brain that you are still moving. Why nausea? Eyes give message not moving, ears give message you are – conflict in the brain

Constant sound or constant movement (like in a car) – your body adapts and soon ignores it so you don’t notice it any more

DEAFNESS 1. CONDUCTION – vibration being stopped 2. SENSORINEURAL – damage to receptor cells (hairs), nerve or temporal lobe of brain

Facts About Hearing Loss More than 40 million Americans have hearing loss. Approximately 40% of the hearing-impaired are under age 65. About 2 million children under age 18 are hearing-impaired in the U.S. Minor decreases in hearing, especially of higher frequencies, are normal after age 20. Some form of hearing loss affects 1 out of 5 people by age 55.

Hearing loss is the third leading chronic disability, following arthritis and high blood pressure. Between 7 and 10 million people in American industry have noise-induced hearing loss, virtually all of which was preventable. About 15% of college graduates have a level of hearing loss equal to or greater than their parents; a significant cause is listening to loud music. In the U.S., 12 million people have hearing aids.

EAR LABELING 1. Pinna 2. External auditory canal 3. Tympanic membrane 4. Stirrup 5. Eustachian tube 6. SKIP 7. cochlea 8. Vestibulocochlear nerve 9. Semicircular canal 10. Anvil 11. Hammer

HEARING PHYSIOLOGY 1. Sound 2. Through auditory canal 3. Tympanic membrane vibrates 4. Hits hammer 5. Hits anvil 6. Hits stirrup 7. Presses on outside of cochlea

8. Fluid moves 9. Hairs bend (action potential starts) (# of cells stimulated determines loudness) (# of cells stimulated determines loudness) 8. Message through vestibulocochlear nerve 9. Brain interprets at the temporal lobe of cerebrum