1 - Hearing Flashcards
Structure that marks the end of the external ear.
Tympanic membrane (i.e. eardrum)
Structure of the ear, filled with air, extends from the tympanic membrane to the round and oval windows, also contains the ossicles.
Middle ear
Structure of the ear, contains the bony and membranous labyrinths.
Internal ear
Why does the pressure within the middle normally equal the atomspheric pressure?
The eustachian tube connects the pharynx to the middle ear.
The outer bony framework of the inner ear, forms a maze of passageways “cut” into the temporal bone that forms a cavity that contains the membranous labyrinth.
Bony labyrinth
Divisions/Structures of the bony labyrinth.
Cochlea, vestibule, three semi-circular canals.
Fills the bony labyrinth.
Perilymph
A continuous series of winding, saclike, membranous ducts and sacs within (lining) the bony labyrinth.
Membranous labyrinth
Division/Structures of the membranous labyrinth.
Cochlear duct, utricle, saccule, three semicircular ducts.
Location of the cochlear duct.
Within the cochlea.
Location of the utricle and saccule.
Within the vestibule.
Location of the semicircular ducts.
Within the semicircular canals.
Fluid that surrounds the membranous labyrinth.
Perilymph
Fluid that fills the membranous labyrinth.
Endolymph (i.e. rich in potassium)
Perilymph-filled space “above” the cochlear duct.
Scala vestibuli
Perilymph-filled space “below” below the cochlear duct.
Scala tympani
Membrane-covered opening, where the inner ear’s scala tympani connects to the middle ear.
Round window
Found within localized areas of the membranous labyrinth, generate electricity.
Hair cells
How is sounds transmitted?
Through a medium by producing a vibration of the medium’s molecules
What determines sound’s loudness?
Wave amplitude
What determines sound’s pitch?
Wave frequency
How are vibrations from sounds waves transferred from the tympanic membrane to the oval window?
Tympanic membrane to malleus to incus to stapes to oval window
Why is it important that sound pressure is amplified within the ear?
Liquid is harded to move than air.
Skeletal muscle attached to the malleus, contracts to dampen bone movements thus protecting the cochlea from damage due to continuous loud noises
Tensor tympani
Skeletal muscle attached to the stapes, contracts to dampen bone movements thus protecting the cochlea from damage due to continuous loud noises
Stapedius
When the stapes is vibrating it cause the oval window to bow into the […] and back out rhythmically.
Scala vestibuli
The vestibular membrane is so thin that vibrations in the perilymph within scala vestibuli move easily into the endolymph within the […].
Cochlear duct
A low-frequency sound wave travels all the way down the scala vestibuli, turns the corner, and travels back along scala tympani to the round window (which bulges leftward on the illustration to dissipate the wave). This sound wave is […].
Not heard
The vibrations of audible sound waves are transferred from the scala vestibuli across the cochlear duct (from “top” to “bottom”) and then to the […].
Basilar membrane
Sits atop the basilar membrane, contains inner/outer hair cells (i.e. receptors for hearing).
Organ of corti
Protrude from the hair cell’s border, furthest from the basilar membrane.
Stereocilia
Gel-like structure where stereocilia extend into.
Tectorial membrane
What causes the stereocilia to bend/shear back and forth.
The basilar membrane moves the bulk of the hair cells meanwhile the stereocilia are embedded in a stationary tectorial membrane.
How are hair cells depolarized?
Stereocilia bending in one direction, opens mechanically gated ion channels, K+ from endolymph flows in.
When a hair cell depolarizes, voltage-gated calcium channels open near the cell’s base, Ca++ influx triggers the hair cell to release the transmitter […] onto associated sensory neurons.
Glutamate (i.e. thus the membrane potential of the hair cell oscillates and glutamate is released in bursts)
Glutamate increases action potential production in the sensory neurons, the axons of which are bundled into the cochlear branch of the […] nerve.
Vestibulocochlear (cranial nerve VIII)
How to the volume of sound affect the frequency of action potentials sent to the brain?
Louder sounds = Higher frequency
True/Flase: The basilar membrane contains about 25,000 stiff but elastic fibers that are fixed at one end but not the other, and can thus vibrate like the reeds of a harmonica.
True
Fibers (i.e. of the basilar membrane) near the oval window are […] meanwhile fibers near the cochlea’s apex are […].
Short and stiff; Long and floppy
The stiff fibers (i.e. of the basilar membrane) resonate best at […].
Higher-frequency pressure waves/High-pitch sounds
The floppy fibers (i.e. of the basilar membrane) resonate best with […].
Lower-frequency pressure waves/Low-pitched sounds
States that the brain determines which position along the basilar membrane is most stimulated (by paying attention to which incoming fibers are carrying the most action potentials), and thereby produces the sensation of the pitch of the particular sound.
Place Principles
Where fibers of the sensory neurons (i.e. of the ear) synapse with interneurons.
Brainstem
Sensory input from both ears may converge on the same interneuron, and the different times of input arrival and different intensities of the sound can be used to determine the […] from which the sound came.
Direction
Pathway of sensory information of the ear to brain (i.e. from interneurons).
Interneuron to inferior colliculus (i.e. midbrain) to medial geniculate nucleus (i.e. thalamus) to primary auditory coretex (i.e. temporal lobe)
