Physiology Of Hearing AnimationđUnderstanding the Sound Journey đ¶
Summary
TLDRThis video provides a detailed overview of the physiology of hearing, explaining the anatomy of the ear, which is divided into three regions: the outer, middle, and inner ear. It highlights the functions of each part, especially the cochlea, which converts sound waves into neural signals. The video discusses the roles of hair cells in sound amplification and frequency detection, and introduces the traveling wave theory of Von Békésy, which explains how different frequencies are processed within the cochlea. It concludes by emphasizing the importance of outer and inner hair cells in hearing.
Takeaways
- đŠ» The ear is divided into three regions: the outer ear, middle ear, and inner ear, each with distinct functions for hearing and balance.
- đ The outer ear, which includes the pinna and external auditory canal, collects and amplifies sound waves.
- đ§ The middle ear contains three small bones (malleus, incus, and stapes) that amplify sound waves and transmit them to the inner ear.
- đ The inner ear houses the cochlea, vestibule, and semicircular canals, which are involved in hearing and balance.
- đ¶ The cochlea, a 35 mm long spiral organ, converts sound waves into neural signals through vibrations of the basilar membrane.
- đ” Different frequencies of sound cause specific parts of the basilar membrane to vibrate, allowing the cochlea to analyze sound frequencies.
- đĄ Hair cells in the organ of Corti are responsible for converting sound vibrations into electrical impulses that are sent to the brain.
- đ€ Outer hair cells in the cochlea amplify sound waves, enhancing sensitivity to various frequencies.
- ⥠Inner hair cells are the primary transmitters of sensory information, while outer hair cells amplify the signal.
- đ§ The auditory nerve fibers transmit electrical signals from the cochlea to the brain, where sound is processed and interpreted.
Q & A
What are the three functionally distinct regions of the ear?
-The three functionally distinct regions of the ear are the external (outer) ear, the middle ear, and the internal (inner) ear.
What is the main function of the outer ear?
-The main function of the outer ear is to collect sound waves through the pinna and direct them into the external auditory canal, which helps amplify the sound.
How do the ossicles in the middle ear contribute to hearing?
-The ossicles (malleus, incus, and stapes) in the middle ear amplify sound waves and transmit them from the eardrum to the inner ear.
What is the function of the cochlea in the inner ear?
-The cochlea is responsible for converting sound waves into neural signals that are transmitted to the brain and interpreted as sound.
How does the basilar membrane contribute to hearing?
-The basilar membrane vibrates in response to sound waves in the cochlea, causing hair cells to bend and release neurotransmitters, which generate electrical impulses sent to the brain.
What is the role of the outer hair cells in the cochlea?
-The outer hair cells in the cochlea amplify vibrations of the basilar membrane, enhancing the sensitivity and selectivity of the cochlea to different sound frequencies.
How do the inner hair cells differ from the outer hair cells in terms of function?
-The inner hair cells are primarily responsible for transmitting sensory input to the auditory nerve fibers, whereas the outer hair cells amplify sound signals before they are transmitted.
What is the role of tip links in hair cells?
-Tip links are elastic structures that connect stereocilia on hair cells, allowing mechanically sensitive cation channels to open when stretched, leading to ion flow into the cell and signal transmission.
How does the basilar membrane analyze different sound frequencies?
-The basilar membrane is stiffer at the base and more flexible at the apex, allowing it to respond to different sound frequenciesâhigh frequencies peak near the base, while low frequencies peak near the apex.
What is the traveling wave theory of Von Békésy?
-According to the traveling wave theory of Von Békésy, sound waves entering the cochlea create a traveling wave along the basilar membrane, peaking at a specific location that corresponds to the frequency of the sound.
Outlines
đ Introduction to the Physiology of Hearing
This paragraph introduces the anatomy of the ear, which is divided into three functionally distinct regions: the external, middle, and inner ear. The external and middle ear structures are involved in hearing, while the internal ear is responsible for both hearing and balance. The outer ear, consisting of the pinna and external auditory canal, collects and amplifies sound. The middle ear, which contains three small bones (malleus, incus, and stapes), transmits sound waves to the inner ear. The inner ear is crucial for converting sound into neural signals and maintaining equilibrium.
đ Structure and Function of the Cochlea
This section explains the anatomy and physiology of the cochlea, the primary organ of hearing. It details how sound waves travel through the cochlea, vibrating the basilar membrane and stimulating hair cells, which convert these vibrations into electrical impulses. The hair cells interact with the tectorial membrane, releasing neurotransmitters that activate auditory nerve fibers. Different frequencies of sound are processed by different parts of the basilar membrane, allowing the brain to interpret the sound.
⥠Cochlear Amplification and Frequency Analysis
This paragraph describes the cochlear amplifier, a specialized system where outer hair cells contract and expand to enhance sound sensitivity. It highlights the role of the organ of Corti and its hair cells, which are sensory receptors for hearing. Inner hair cells are fewer but more critical for transmitting sensory input. The spiral ganglion neurons relay electrical signals from the hair cells to the brain, while the basilar membrane acts as a frequency analyzer, responding to different sound frequencies at various locations along its length.
Mindmap
Keywords
đĄOuter Ear
đĄMiddle Ear
đĄInner Ear
đĄCochlea
đĄBasilar Membrane
đĄHair Cells
đĄOssicles
đĄTectorial Membrane
đĄTraveling Wave Theory
đĄSpiral Ganglion
Highlights
The ear is divided into three regions: external ear, middle ear, and inner ear, each with distinct roles in hearing and equilibrium.
The outer ear consists of the pinna and external auditory canal, which collect and amplify sound waves.
The middle ear contains three small bonesâthe malleus, incus, and stapesâwhich amplify sound and transmit vibrations from the eardrum to the inner ear.
The inner ear contains the cochlea, vestibule, and semicircular canals; the cochlea is crucial for hearing, while the vestibule and canals are responsible for balance.
The cochlea converts sound waves into electrical impulses that are sent to the brain for interpretation.
The cochlea contains three chambers: the scala vestibuli, scala tympani, and scala media, with endolymph in the scala media being rich in potassium ions.
Different sound frequencies cause different regions of the basilar membrane in the cochlea to vibrate, enabling frequency detection.
Hair cells on the basilar membrane, embedded in the tectorial membrane, convert mechanical vibrations into electrical signals via glutamate release.
Outer hair cells in the cochlea amplify sound vibrations, improving hearing sensitivity and frequency selectivity.
The organ of Corti, located in the cochlea, houses hair cells that serve as sensory receptors for sound.
Inner hair cells are primarily responsible for transmitting auditory signals to the brain, while outer hair cells amplify the sound.
95% of sensory neurons innervate the inner hair cells, playing a major role in hearing, while only 5-10% innervate outer hair cells.
The spiral ganglion contains the cell bodies of sensory neurons that transmit electrical signals from the cochlea to the brain.
The basilar membrane's varying stiffness allows it to perform frequency analysis of sound waves, responding differently to high and low frequencies.
Von Békésy's traveling wave theory explains how sound waves create a traveling wave along the basilar membrane, peaking at points corresponding to sound frequency.
Transcripts
[Music]
physiology of
hearing
introduction the ear is divided into
three functionally distinct regions the
external outer ear middle ear and
internal inner ear the external and
middle ear structures are involved in
hearing and the structures of the
internal ear are involved in both
hearing and
equilibrium outer ear the outer ear
consists of the Penna in the external
auditory canal sound waves are collected
by the p and directed into the external
auditory canal the PA helps in
localization of sound while the external
auditory canal amplifies the sound
waves middle ear the middle ear is an
air-filled space located behind the
eardrum the middle ear consists of three
small bones called OES the malus enus
and stapes these bones amplify the sound
waves and transmit them from the e drum
to the inner
ear inner ear the inner ear is located
deep within the temporal bone and the
skull the inner ear consists of the ccka
vestibule and semicircular canals
the ccka is the main organ of hearing
and is responsible for converting sound
waves into neural
signals the vestibule and semicircular
canals are responsible for
balance ccka
physiology ccka is 35 mm long and makes
2 and 3/4 turns the upper Scala
vestibuli and the lower Scala Tony
contain paraly which is rich in sodium
ion the Scala media is the the Middle
cckar Chamber which has stria vascularis
that secretes endolymph which is rich in
potassium ion Scala media is
electrically positive by 85 molt in no
cular potential relative to the Scala
vestibuli and Scala
tempany the ccka is responsible for
converting sound waves into electrical
impulses that are transmitted to the
brain where they are interpreted as
sound sound waves enter the ccka through
the oval window
a membrane that separates the middle ear
from the inner ear as the sound waves
travel through the fluid and the ccka
they cause the Bassel membrane to
vibrate the Bassel membrane is a thin
flexible structure that runs the length
of the ccka and contains thousands of
tiny hair cells that are responsible for
converting sound waves into electrical
impulses the hair cells are embedded in
the tectorial membrane a gel-like
structure that overlies the hair cells
as the Basel membrane V vibrates the
hair cells move back and forth causing
their hair-like projections to bend this
bending of the hair cells triggers the
release of neurotransmitter
glutamate which in turn stimulate the
auditory nerve fibers that are connected
to the hair cells the auditory nerve
fibers then transmit electrical signals
from the ccka to the brain stem where
they are processed in relay to various
parts of the brain for further
processing and
interpretation different frequencies of
sound waves cause different parts of the
Bassel membrane to vibrate which leads
to the stimulation of different
populations of hair cells the location
of the hair cells on the Basel membrane
that are stimulated corresponds to the
frequency of the sound waves the ccka
also has a specialized system for
amplifying sounds called the cockier
amplifier this system involves outer
hair cells in the ccka that are able to
actively contract and expand in response
to electrical signals from from the
brain stem this contraction and
expansion of the outer hair cells
amplifies the vibrations of the Basel
membrane and enhances the sensitivity
and selectivity of the ccka to different
frequencies of
sound the organ of CTI organ of Cy
contains the receptors for hearing hair
cells hair cells are the sensory
receptors of hearing the resting
membrane potential of the hair cells is
about 60 molt hair cells have a motor
protein namely Preston stereocilia and
kinocilia they're named for their
hairlike protrusions which are called
stereocilia kyos cyia on the other hand
are specialized single long cilium found
on one end of the bundle of stereocilia
and some non- mamalian species in
mammals kinocilia are only present
during the early stages of development
and are later lost as the hair cell
matures
stereocilia are arranged in a row of
progressively decreasing height with the
tallest stereocilium located at one end
of the bundle and the shortest at the
other end they're connected to each
other by fine elastic structures called
tip links these tip links contain
mechanically sensitive cat ion channels
which are channels that allow positively
charged ions such as potassium and
calcium to flow into the cell when
they're activated by mechanical
forces when sound waves enter the inner
ear and cause the stereo cyia to bend
the tip links stretch and pull on the
mechanically sensitive cat ion channels
opening them up and allowing ions to
flow into the hair cell def flection of
the stereocilia toward the kyum opens
the potassium channels depolarizing the
inner hair cell and causing the influx
of calcium that stimulates the release
of the neurot transmitter glutamate
which then stimulates the aper neurons
to transmit neural impulses to the
auditory cortex at rest the potassium
channels are partially
[Music]
open therefore deflection of stereocilia
toward the shortest stereocilia closes
the potassium channels and inhibits
signal transmission by the afrite
neurons outer and inner hair cells the
hair cells in the organ of CTE are
arranged in four rows with the three
rows of outer hair cells and one row of
inner hair
cells the outer hair cells are more
numerous with about 20,000 cells while
the inner hair cells are fewer in number
with only around 3500 cells however
despite being fewer in Number the inner
hair cells are more important for
hearing as they're responsible for
transmitting the majority of the sensory
input from the hair cells to the
auditory nerve fibers the the outer hair
cells play a critical role in amplifying
The Sound signals before they're
transmitted to the auditory nerve fibers
note 95% of these Sensory neurons
innervate the inner hair cells only 5 to
10% innervate the outer hair cells the
spiral gangion the spiral gangion
contains the cell bodies of the sensory
neurons that inate the hair cells of the
organ of Cy these Sensory neurons are
known as spiral gangan neurons and they
form sinaps es with the hair cells that
transmit the electrical signals
generated by the hair cells to the brain
the spiral ganglia neurons are bolar
neurons with one dendrite that synapses
with the hair cells and one axon that
extends to the brain stem where it
synapses with other neurons in the
auditory pathway the spiral gangan
neurons are essential for transmitting
the sensory information from the organ
of qute to the brain where it's
processed and interpreted as
sound roll a Bassler membrane in hearing
process the frequency
analyzer the Bassler membrane is a
critical component of the hearing
process playing a vital role in the
frequency analysis of sound waves the
Bassler membrane is a thin flexible
membrane that runs the length of the
ccka and separates the fluid-filled
chambers of the ccka into two
compartments when sound waves enter the
ccka they create waves in the
fluid-filled chambers that cause the
Bassel membrane to vibrate the Bassel
membrane is stiffer at the base of the
ccka near the oval window and becomes
more thin and flexible towards the apex
of the cocka as a result different
frequencies of sound waves cause maximum
displacement at different points along
the length of the Bassel membrane with
higher frequencies causing maximum
displacement near the base of the ccka
and lower frequencies causing maximum
displacement near the Apex this
frequency analysis is important because
it allows the auditory system to
distinguish between different
frequencies of sound waves and identify
the pitch of the
sound the hair cells of the organ of CTI
are located on the Bassel membrane and
they respond to the mechanical
vibrations of the Basel membrane by
generating electrical signals that are
transmitted to the brain the spatial
arrangement of the hair cells on the
Bassel membrane corresponds to the
frequency analysis with the Heros cells
at the base of the ccka responding to
high frequency C sounds and the hair
cells at the Apex responding to low
frequency sounds this gives the
appearance of a traveling wave in
Bassler membrane this series called
traveling wave theory of Von
Becki traveling wave theory of Von Becki
according to the traveling wave theory
when sound waves enter the ccka they
create a traveling wave that moves along
the Bassler membrane from the base of
the ccka near the oval window to the
apex of the
ccka the wave Peaks at a specific
location along the Bassel membrane that
corresponds to the frequency of the
sound wave with higher frequencies
causing maximum displacement near the
base of the ccka in lower frequencies
causing maximum displacement near the
Apex as a traveling wave moves along the
Basel membrane it causes the hair cells
to bend and generate electrical signals
that are transmitted to the brain the
outer hair cells of the organ of quarty
play a critical role in amplifying The
Traveling wave and enhancing the
sensitivity and selectivity of the
auditory
system that's all for the video we'll
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