6: Physiology of hearing and balance Flashcards
Audiogram used to determine hearing loss:
20dB - 40dB mild
41 - 70 moderate
71 - 95 severe
95+ profound
The outer ear is a ___ for sound.
The middle ear is an ___ for sound.
The inner ear is a ___ for sound.
receiver
amplifier
converter
Which tube connects the middle ear and the nasopharynx and equalises the pressure of the ears?
Eustachian tube
What are the two openings found in the cochlea?
Oval window
Round window
A pressure wave transmitted through the ___ window by the stapes causes ___ cells to depolarise.
oval window
hair cells
If vibrations were to be passed straight from the air to the cochlea, 99% of it would be reflected due to the impedance of the liquid.
What structures overcome this?
What is this process called?
Auditory ossicles (malleus, incus, stapes)
Impedance matching
Which fluid does pressure waves travel through?
Perilymph
What frequency of sound is hear at the cupula of the cochlea?
What frequency is heard in the modiolus (spirals)?
Low
High
Which spaces are found above and below the scala media?
What fluid do they both contain?
Scala vestibuli above
Scala tympani below
Both contain perilymph
___ of the cilia by pressure waves causes ___ channels to open and the hair cells to depolarise.
Bending
Na+
What space sits between the scala vestibuli and the scala tympani?
What organ does it contain?
What fluid does it contain?
Scala media
Organ of Corti
Endolymph
Which organ contains hair cells and is found in the scala media?
Organ of Corti
Is the endolymph high or low in sodium?
Why?
Low
to allow action potentials to travel through it
The inner hair cells are involved in (hearing / balance).
hearing
(Repolarisation / depolarisation) occurs when stereocilia are deflected towards the longest fibres.
Depolarisation
(Repolarisation / depolarisation) occurs when the stereocilia are deflected away from the longest fibres.
Repolarisation
Which part of the brain processes sound?
Temporal lobe
(primary auditory cortex)
What are the vestibular end organs of the inner ear?
Anterior, lateral and posterior semicircular canals
Urticle
Saccule
What hair cells do the urticle and saccule contain?
When are they depolarised?
Stereocilia
On movement
What is otoconia?
Calcium carbonate crystals found in the urticle and saccule
Help stimulate stereocilia supposedly
The otolith organs allow the brain to detect linear motion.
What directions do the
a) urticle
b) saccule
help with?
a) Horizontal motion
b) Vertical motion
At what angle are the semicircular canals oriented away from one another?
90 degrees
Cilia ___ or ___ depending on which way they are deflected.
depolarise
hyperpolarise
The organs of balance on one side of the head are (stimulated / inhibited) when you turn towards that side.
stimulated
