Lecture 42 4/25/24 Flashcards

1
Q

What is hearing?

A

the collection, neural processing, and analysis of vibrations generated by an object some distance away

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2
Q

What is sound?

A

the vibrations of air molecules

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3
Q

What are the characteristics of sound frequency?

A

-measured in Hertz/cycles per second
-tone of sound
-higher hertz means higher pitch

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4
Q

What are the characteristics of sound amplitude?

A

-measured in decibels
-loudness of sound
-higher decibels means louder sound

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5
Q

What are the characteristics of the pinnae?

A

-cartilage core with typical skin
-inner surface has less hair and more glands

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6
Q

What are the characteristics of the external acoustic meatus?

A

-vertical and horizontal portions
-cartilage lined by sparsely-haired skin
-sebaceous and ceruminous glands present

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7
Q

What are the characteristics of ear wax?

A

-composed of sebum and cerumen
-keeps tympanic membrane moist and flexible
-protects the ear canal
–antimicrobial
–water repellent
-removes debris

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8
Q

What is the function of the external ear?

A

collect and direct sound waves to the tympanic membrane

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9
Q

How does otitis externa differ from pinnal dermatitis?

A

-otitis externa is inflammation of external ear canal
-pinnal dermatitis is inflammation of the skin on the pinna

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10
Q

What are the characteristics of otitis externa in dogs?

A

-common, especially in long-eared breeds
-can be bacterial, fungal, or parasitic in origin
-can decrease ability to hear
-predisposes dogs to neoplasia

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11
Q

What is the main cause of otitis externa in cats?

A

ear mites

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12
Q

What is conduction deafness?

A

when the brain aspect of hearing works, but sound cannot be conducted

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13
Q

How can conduction deafness occur at the level of the external ear canal?

A

-ear wax that occludes external canal
-swelling and debris that occludes external canal
-tumor that occludes external canal

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14
Q

What are the characteristics of the tympanic membrane?

A

-separates external ear and middle ear
-in contact with bones of the middle ear

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15
Q

What are the bones of the middle ear?

A

-malleus
-incus
-stapes

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16
Q

What are the three layers of the tympanic membrane?

A

-outer cuticular layer (epithelial)
-middle fibrous connective tissue layer
-inner mucus layer (epithelial)

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17
Q

How does the tympanic membrane function in hearing?

A

transforms the energy of sound pressure wave into physical vibration of the auditory ossicles

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18
Q

How can conduction deafness occur at the level of the tympanic membrane?

A

failure of the tympanic membrane, due to inflammation, fibrosis, rupture, etc.

19
Q

What is the middle ear?

A

air-filled space surrounded by bone and the tympanic membrane

20
Q

Which structure partially divides the middle ear?

A

septum bulla

21
Q

Which animals have a honeycomb-like structure in their tympanic bullae?

A

-cow
-goat
-pig
-camelid
-horse

22
Q

What does the stapes bone connect to?

A

the oval window/entrance to the inner ear

23
Q

Which middle ear bone contacts the tympanic bulla?

A

malleus

24
Q

Which types of epithelium line the middle ear?

A

-simple squamous
-simple cuboidal
-pseudostratified ciliated columnar

25
Q

What are the characteristics of the Eustachian/auditory tube?

A

-continuous with nasopharynx
-lined by pseudostratified ciliated columnar epithelium with goblet cells

26
Q

Why is it important that sound waves are reflected when moving from the air-filled middle ear to the fluid-filled inner ear?

A

the sound must be amplified to account for any waves lost to reflection

27
Q

What is impedance matching?

A

mechanism that compensates for differences in resistance between air in the external ear and fluid in the inner ear

28
Q

How does impedance matching work?

A

-vibration of the middle ear bones magnifies the vibration of the tympanic membrane; creates fluid waves in inner ear
-sound pressure is transferred from large area of the tympanic membrane to the small area of the oval window; concentrates sound

29
Q

How does the middle ear protect the inner ear from excessive noise?

A

contraction of the small muscles associated with the middle ear bones can dampen noises

30
Q

What are the characteristics of otitis media?

A

-inflammation of the middle ear
-typically bacterial in origin

31
Q

How can conduction deafness occur at the level of the middle ear?

A

-inflammation
-bone fractures
-muscle/nerve issues
-fibrosis
-masses

32
Q

What is the petrous temporal bone?

A

bone that encases the inner ear

33
Q

What are the two portions of the inner ear?

A

-bony labyrinth
-membranous labyrinth

34
Q

Where is the perilymph located?

A

within the bony labyrinth, around the membranous labyrinth

35
Q

Where is the endolymph located?

A

within the membranous labyrinth

36
Q

What are the three parts of the inner ear?

A

-vestibule
-semicircular canals
-cochlea

37
Q

What are the characteristics of the vestibule?

A

-anteroom to the bony labyrinth
-entrance is the oval window
-exit is the round window
-filled with perilymph

38
Q

Which structures are found within the vestibule?

A

-utricle
-saccule

39
Q

What are the characteristics of the utricle and saccule?

A

-filled with endolymph
-contain maculae

40
Q

What are maculae?

A

patches of special hair cells in gel covered with otoliths

41
Q

What are the characteristics of the semicircular canals?

A

-filled with endolymph
-one end of each is dilated/has an ampulla
-contain cristae; similar to maculae but without otoliths

42
Q

What are the components of the vestibular system?

A

-vestibule
-semicircular canals
-associated nerves, ganglia, and nuclei

43
Q

What are the functions of the vestibular system?

A

-signal up to the cerebrum for awareness and processing
-signal down the spinal cord to control/correct/adjust body position