Lecture 34. Hearing: Sound Transduction and Auditory Processing Flashcards
How do we experience sound?
As a roughly equal increment per 10-fold increase in intensity
What is the magnitude of sound expressed on?
A logarithmic scale
What is the mechanical analyser of sound?
Basilar membrane
What are the three compartments of the cochlea filled with?
Fluid
Features of the Basilar membrane
33 mm long
At apex it is ~10 times wider than at the base
Membrane is thin and floppy at apex, thicker and taught
at base
How many hair cells are there in the two cochlea?
~30,000
What can damage the outer hair cells?
Loud sounds
What is the name for the sounds produced by the ear?
Otoacoustical emissions
What is prestin?
The motor protein in the plasma membrane
What does 499 mutation do?
Removes electromotility from single hair cells
Increases threshold for hearing across the frequency range
What are sterocilia?
The sites of mechanotransduction
How does the influx of K⁺ occur in the ear?
The endocochlear potential provides the driving force on K⁺ to give the inward currents into hair cells during mechano-sensory transduction
What are the advantages of K⁺?
Influx of K⁺ ions into the sensory cells causes the least change in the cytosolic concentration compared to any other ion. This is because K⁺ is by far the most abundant ion in the cytosol
Influx and extrusion of K⁺ are energetically inexpensive for the sensory cell since both occur down an electrochemical gradient
How many children are born with serious hearing impairment?
1 in 800
What percentage of people older than 70 require a hearing aid?
> 60%
