How hair cells work?
These hair cells are important processes.
These hair cells allow for him to be
there move from direction or the other.
They’re structures is very specific and have
very specific amounts of fluid that they’re filled in.
So the endolymph is associated with
the top portions of the hair cells.
Perilymph is associate with
the bottom portion of the cell.
What is in special about endolymph?
Is its high potassium concentration.
Its high potassium concentration is
different than other areas in the body
where usually have the high potassium concentration
inside the cell versus outside the cell.
Perilymph is more normal in nature, in which
it has a low potassium concentration.
So one of these two different potassium concentrations
allow for then the signal process to work.
Well a sound wave is going to be travelling
down membrane, pushing on this tectorial membrane
that will push down against the hair cells.
As it pushes down against the hair cells,
the hair cells will deflect.
As the hair cells deflect, potassium
is allow to rush into those hair cells.
Why does potassium wants to rush in?
Because the endolymph has such
high potassium concentration.
There’s a gradient between
the endolymph and the cell itself.
Membrane potential depolarizes.
These opens up calcium channels.
These calcium influx causes synaptic vesicles
which have glutamate in them to be released.
Therefore, these whole processes is set up by potassium
entering into the cell to cause depolarization.
It is then the release of glutamate
that is stimulatory to the next nerve
that will transmit the information back to the brain.
You might ask, what happens to the potassium?
The potassium exits the cell into the perilymph
and then is recycled and brought back to the endolymph.
Sound Frequency Mapping.
So now that you understand how a hair cell works.
We can then bring in more information
about how you hear different sounds.
And different sounds of course have different
frequencies, from a high sound to a low sound.
These different sounds give you the insight
into how a particular wave is coming through.
So you have hair cells allocated
from the base all the way to the apex.
These will now be responsive to different frequencies.
If you have a high frequency sound, this is
going to stimulate the membrane closer to the base.
This high frequency sound is because
of the greater amount of frequency
not talking about amplitude here.
Frequency is so its occurring through
a large number of frequency waves
will hit the hair cells closer to the base.
Sounds that are lower frequency have a slower wave.
Those who travel in further into the
membrane before they will hit a hair cell.
That is how you will distinguish
between a high pitch and a low pitch
is where the wave comes in
to stimulate those particular hair cells
associated with the depression in the membrane.