Physiology of Hearing Flashcards
What is infrasound?
Sounds below the frequency of perception
What is ultrasound?
Sounds above the frequency of perception
What is the middle ear cavity?
Air filled space that can adjust with changes in air pressure
What is the function of the auditory tube?
A narrow canal that is normally closed but opens with yawning or swallowing to balance pressure
What are the three auditory ossicles?
Malleus, Incus and Stapes
What is the function of the auditory ossicles?
Transmits vibrations from the tympanic membrane to the inner ear with minimal energy loss
What is the cochlea?
Fluid filled coils that contain sensory cells
What are semi-circular canals?
fluid filled tubes that assist with balance
What is the function of the two small muscles tensor tympani and stapedius?
they contract to reduce movement of ossicles in response to high intensity sound
Which canal is the uppermost canal (scala vestibuli) directly connected to?
The lowest canal (scala tympani)
What are scali tympani and vestibuli filled with?
a fluid called perilymph
What is the scala media?
The middle canal, it is separated from the lowest canal via a fibrous membrane called the basilar membrane
What is the name of the fluid that fills the scala media?
Endolymph
What is the organ of Corti?
A sensory structure found in the scala media that processes sound information
What occurs when the tympanic membrane oscillates?
Waves are transmitted via the ossicles onto the oval window, they can then travel along the basilar membrane
What does movement of the basilar membrane cause?
It causes the tectorial membrane of the sensory structure to be displaced
What are stereocilia?
Actin based protrusions on auditory and vestibular sensory cells that are required for hearing and balance
What occurs when the sensory cells bend in the direction of increasing sensory hair length?
Filaments that hold them together taughtened, the channels open which causes an influx of K+ and the they become depolarised
What does depolarisation of the sensory cells cause?
Opening of voltage-gated Ca2+ channels, the neurotransmitter
What is the function of the otolith organs?
They sense linear acceleration
What is the function of the semi-circular canals?
They sense angular acceleration in the head
What do the signals from the semi-circular canals and otolith organs form?
They form the vestibular system and allow the vestibular system to trigger head and eye movements therefore allowing the retina to make a stable image
What acceleration does the ultricle control?
horizontal acceleration
What acceleration does the Saccule control?
Vertical acceleration
