Auditory physiology

Question 1

What id normal human hearing range?

Answer 1

20 - 20,000Hz

Question 2

What does the outer ear do?

Answer 2

Collects and amplifies sound

Question 3

What does the middle ear do?

Answer 3

Transmits sound

Question 4

What does the inner ear do?

Answer 4

Coverts sound into neural impulses

Question 5

What does the outer ear contain? (3)

Answer 5

• Pinna
• External auditory canal
• Tympanic membrane

Question 6

The tympanic membrane vibrates slowly to what type of sound?

Answer 6

Low frequency sound

Question 7

The tympanic membrane vibrates rapidly to what type of sound?

Answer 7

High frequency sound

Question 8

What does the middle ear contain (5)

Answer 8

• Tympanic membrane
• Ossicles (malleus, incus, stapes) with synovial joints between them
• Eustachian tube
• Tensor tympani
• Stapedius

Question 9

What does the inner ear contain?

Answer 9

• Cochlea

- Vestibular appratus (semicircular canals, utricle, saccule)

Question 10

What does the cochlea contain?

Answer 10

• Cochlear duct (contains endolymph)
• Scala vestibuli (at oval window)
• Scala tympani (at round window)

Question 11

What structures contain perilymph?

Answer 11

Scala vestibuli

Scala tympani

Question 12

What is endolymph?

Answer 12

K+ rich

Na+ poor

Question 13

Where does the organ of Corti sit?

Answer 13

On basilar membrane in the cochlear duct

Question 14

The base of the basilar membrane is sensitive to what?

Answer 14

Is short & stiff

Sensitive to high frequencies

Question 15

The apex of the basilar membrane is sensitive to what?

Answer 15

Is long & floppy

Sensitive to low frequencies

Question 16

What do the stereocilia of the outer hair cells do?

Answer 16

Modulate sound (4-5 rows)

Question 17

What do the stereocilia of the inner hair cells do?

Answer 17

Convert pressure waves into receptor potentials (single row)

Question 18

How does the movement of endolymph cause a receptor potential to be generated? (7)

Answer 18

• Pressure waves displace basilar membrane
• Stereocilia graze tectorial membrane
• Stereocilia bend TOWARDS kinocilium
• Tip-links pull open K+ channels
• Depolarisation
• Ca2+ enters
• Neurotransmitter glutamate released

Question 19

Describe the central auditory pathway

Answer 19

E.COLI MAn

• Eighth nerve
• Cochlear nucleus
• Olive (superior)
• Lateral lemniscus
• Inferior colliculi
• Medial geniculate nucleus (thalamus)
• Auditory cortex

Question 20

What are the semicircular canals?

Answer 20

Endolymph-filled bony tubes at right angles to each other

Question 21

What stimulates hair cells of the semicircular canals?

Answer 21

Angular acceleration/ deceleration during rotation of the head

Question 22

How do the semicircular cells detect acceleration/deceleration? (4)

Answer 22

• Head movement causes semicircular canals to move with it
• Fluid remains stationary
• Ampulla pushed up against fluid causing stereocilia to bend
• Glutamate release altered

Question 23

What do the utricle and saccule detect?

Answer 23

Linear acceleration of head in relation to gravity

Question 24

What does the utricle respond to?

Answer 24

Tipping head away from horizontal plane e.g. tying shoelace

Question 25

What does the saccule detect?

Answer 25

Lying to standing position

Vertical acceleration e.g. trampoline

Question 26

What are otoliths?

Answer 26

Substance that covers stereocilia

Make gelatinous substance heavier than surrounding fluid so it moves in the direction of gravity