Auditory System Flashcards
What bone is the ear found in?
The petrous portion of the temporal bone
What is the function of the outer ear?
Capture sound and focus it on the tympanic membrane
Amplify some frequencies via resonance in the canal
Protect the ear from external threats
What is the function of the middle ear?
Focusing vibrations from large surface area to smaller surface area (this increases pressure)
What is the function of the inner ear? What structure performs these functions?
The cochlea:
Transduces vibration into nervous impulses
Analyses frequencyand intensityof the sound
What are the 3 parts of the cochlea?
Scala vestibuli
Scala tympani
Scala media
What in the cochlea contains perilymph? What are the characteristics of perilymph?
Scala vestibuli and typmani, perilymph is high in sodium
What in the cochlea contains endolymph? What are the characteristics of endolymph?
Scala media, endolymph is high in potassium
Where is the organ of corti located?
In the scala media in the cochlea
What is the basilar membrane?
Where the organ of corti lies
How is the basilar membrane arranged? What does this mean
Arranged tonotopically
It is sensitive to different frequencies at different points along its length
What 2 types of hair cells are found in the organ of corti? How are they arranged?
Inner hair cells arranged in one column
Outer hair cells arranged in 3 columns
How are hairs in the organ of corti deflected?
The tectorial membrane lies above them and allows deflection which then depolarises the cell
What information do the inner hair cells carry and what is their function?
Afferent info
Their function is the transduction of the sound into nerve impulses
What information do the outer hair cells carry and what is their function?
Efferent info
Their function is modulation of the sensitivity of the response.
What hairs of hair cells in the ear called?
Stereocilia
Describe how transduction of sound occours in relation to hair cells?
Stereocilia deflect towards the longest cilium, opening K+ channels
Inflow of K+ depolarises the cell and neurotransmitter is released
Louder sounds causes greater deflection
Describe the auditory pathway
Spiral ganglions from the cochlea project to the ipsilateral cochlear nuclei, the info crosses at the superior olive level then all connections are bilateral