Auditory physiology Flashcards
What id normal human hearing range?
20 - 20,000Hz
What does the outer ear do?
Collects and amplifies sound
What does the middle ear do?
Transmits sound
What does the inner ear do?
Coverts sound into neural impulses
What does the outer ear contain? (3)
- Pinna
- External auditory canal
- Tympanic membrane
The tympanic membrane vibrates slowly to what type of sound?
Low frequency sound
The tympanic membrane vibrates rapidly to what type of sound?
High frequency sound
What does the middle ear contain (5)
- Tympanic membrane
- Ossicles (malleus, incus, stapes) with synovial joints between them
- Eustachian tube
- Tensor tympani
- Stapedius
What does the inner ear contain?
- Cochlea
- Vestibular appratus (semicircular canals, utricle, saccule)
What does the cochlea contain?
- Cochlear duct (contains endolymph)
- Scala vestibuli (at oval window)
- Scala tympani (at round window)
What structures contain perilymph?
Scala vestibuli
Scala tympani
What is endolymph?
K+ rich
Na+ poor
Where does the organ of Corti sit?
On basilar membrane in the cochlear duct
The base of the basilar membrane is sensitive to what?
Is short & stiff
Sensitive to high frequencies
The apex of the basilar membrane is sensitive to what?
Is long & floppy
Sensitive to low frequencies
What do the stereocilia of the outer hair cells do?
Modulate sound (4-5 rows)
What do the stereocilia of the inner hair cells do?
Convert pressure waves into receptor potentials (single row)
How does the movement of endolymph cause a receptor potential to be generated? (7)
- 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
Describe the central auditory pathway
E.COLI MAn
- Eighth nerve
- Cochlear nucleus
- Olive (superior)
- Lateral lemniscus
- Inferior colliculi
- Medial geniculate nucleus (thalamus)
- Auditory cortex
What are the semicircular canals?
Endolymph-filled bony tubes at right angles to each other
What stimulates hair cells of the semicircular canals?
Angular acceleration/ deceleration during rotation of the head
How do the semicircular cells detect acceleration/deceleration? (4)
- Head movement causes semicircular canals to move with it
- Fluid remains stationary
- Ampulla pushed up against fluid causing stereocilia to bend
- Glutamate release altered
What do the utricle and saccule detect?
Linear acceleration of head in relation to gravity
What does the utricle respond to?
Tipping head away from horizontal plane e.g. tying shoelace
What does the saccule detect?
Lying to standing position
Vertical acceleration e.g. trampoline
What are otoliths?
Substance that covers stereocilia
Make gelatinous substance heavier than surrounding fluid so it moves in the direction of gravity
