Auditory Flashcards
The auditory system is designed to ____ and ____ in the environment
Detect; analyze
How is an animals hearing enhanced by
their ability to move ears around
Hearing requires how many ears
1, but localization of sound requires 2
What type of receptor is in the auditory system
mechanrecpetor
What is sound
pressure waves in the air with given frequencies and amplitudes
What produces the sensation of sound
the alternating changes after the the pressure waves strike the tympanic membrane
How does the auditory system perceives sound
Frequency of sound as pitch and amplitude of sound as loudness
What is the intensity of sound quantified?
Decibels
What does the amplitude express?
the energy of the sound relative to the energy of a standard reference sound
What is the frequency of sound?
the number of pressure oscillation cycles per unit occur, expressed in units called Hz`
What is 1Hz
the number of cycles per second
What structures are involved with hearing?
External ear, middle ear, and inner ear
What is the sensory receptor of the ear?
organ of corti?
Where is the organ of corti located?
inner ear
What does the external ear do?
Direct the sound waves into the ear canal
What is the external ear composed of?
Pinna and the ear canal
How is the external ear separated from the middle ear?
by the tympanic memebrane or eardrum
What is the middle ear?
An air filled cavity in the temporal bone
What is the middle ear connected to?
The middle ear is connected to the nasopharynx by the auditory tube
* EUSTHACIAN TUBE
* drains the middle ear cavity
Where are the ossicles
in the middle ear
What are the three ossicles
Malleus
Incus
Stapes
Malleus connect to
eardrum
Incus between
Malleus and stapes
Stapes connect to the
Oval/round window
What is happening the ossicle in terms of vibrations?
Ossicles is transferring the vibration of the ear drum to the oval window, in which there is a significant loss of vibration as the sound wave is transfered
What happnes when the sound wave is being transfered from the ear drum to the oval in terms of amplitude?
Decrease amplitude of sound waves protecting the sensitive sensory cells
Where is the receptor of the auditory located
The inner ear (Labyrinth) contains the sensory organ for both the auditory system and the vestibular system
What is the cochlea
The auditory portion of the inner ear
Spiral shaped and is filled with fluid
The cochlea contains the ____
Organ of Corti - hair cell receptor
Hair cells are what type of receptor
mechanoreceptor
What are important feature of the organ of corti
Sterocilia in there apical surface which are connected by tip links at their tips
Tip links seem to be attached to K channels - open when binding of the sterocillia pulls the tip links apart
Cause of hearing loss
sterocilia do not regenerate, which can damaged from an extensively loud sound (moving them excessively)
What overlies the overlies the sensory cells
the tectorial membrane
What is the floor of the organ of corti
The basilar membrane
What is the transduction of hair wave?
Sound waves are transmitted to the inner ear and cause vibration to the Organ of Corti
The base of the hair cells sits on the basilar membrane and the cilia are embedded in the tectorial membrane
Vibration of the Organ of Corti causes bending of cilia on the hair cells by a shearing force as the cilia push against the tectorial membrane
What happens with bending the cilia
The bending produced a change in K+ conductance of the hair cell membrane
Bending in directions causes
Hyperpolarization and Depolarization
Explain the depolarization in hair cells
Bending causes the cilia to produces a change in K+ conductance of the hair cell membrane
Depolarization is exciting the cell membrane trigging an influx of potassium, which leads to Ca channels opening and release the Glutamate neurotransmitter
What happen when glutamate is release
Glutamate functions as an excitatory neurotransmitter and causes an AP in the afferent cochlear nerves
What is happening in the hyperpolarizatinon stage of bending the cilia
Triggers a potassium efflux and glutamate is not releases and an AP is not formed
What is cochlear microphonic potential (an oscillatory pattern)
When there is an unsteady release of glutamate and unsteady firing of afferent nerves, this
What hair cells respond to higher frequencies?
Hair cells located at the base of the basilar memebrane
What hair cells respond to low frequencies
Hair cells located at the apex layer (Outer cells)
What act as a sound frequency analyzer
The basilar membrane
What does the spatial mapping of frequencies generate
Tonotopic map
Where is the information from hair cells being transmitted to
cochlear nerve
Relays auditory impulses to the cochlear nuclei in the medula oblongata
Axons ascend the brainstem and reach the thalamus
The information is processed in the auditory cerebral cortex
