Hearing Flashcards
(21 cards)
Describe the role of the tympanic membrane in hearing.
The tympanic membrane vibrates when sound waves enter the external acoustic meatus and strike it, with higher intensity sound waves causing more vibration.
Explain how auditory ossicles contribute to sound transmission.
Auditory ossicles transfer the vibrations from the eardrum to the oval window, facilitating the movement of sound energy into the inner ear.
Define the function of the scala vestibuli in the cochlea.
The scala vestibuli is involved in the transmission of sound waves, where the stapes rocks back and forth on the oval window, creating wave motions in the perilymph.
How do sound waves affect the round window in the ear?
Sound waves end at the round window, causing it to bulge outward into the middle ear cavity.
Describe the helicotrema path in sound wave transmission.
Waves with frequencies below the threshold of hearing travel through the helicotrema and scala tympani to reach the round window.
Explain the basilar membrane path for sounds within the hearing range.
Sounds in the hearing range travel through the cochlear duct, vibrating the basilar membrane at specific locations based on the frequency of the sound.
Define resonance in the context of the basilar membrane.
Resonance refers to the movement of different areas of the basilar membrane in response to a particular frequency of sound.
How does the structure of the basilar membrane change along its length?
The basilar membrane has short and stiff fibers near the oval window that resonate with high-frequency waves, while longer, floppier fibers near the cochlear apex resonate with lower-frequency waves.
Explain the process of sound transduction in the inner ear.
Sound transduction involves the excitation of inner hair cells, where the movement of the basilar membrane deflects the hairs of these cells, leading to the transformation of mechanical energy into neural signals.
Describe the role of stereocilia in cochlear hair cells.
Stereocilia project into K+-rich endolymph, and their bending at the base is the stimulus that excites the hair cells.
What are tip links and their function in hair cells?
Tip links connect the longest hair cells to the shortest hair cells, and when pulled on, they open ion channels, facilitating the transduction of sound.
Describe the effect of bending stereocilia toward shorter ones in hair cells.
Bending of stereocilia toward shorter ones causes tip links to relax, leading to the closure of ion channels.
Explain the process of depolarization in hair cells.
Bending of stereocilia toward the tallest ones pulls on tip links, causing K+ and Ca2+ ion channels in shorter stereocilia to open, resulting in depolarization.
Define the role of outer hair cells in the auditory system.
Outer hair cells can contract and stretch, changing the stiffness of the basilar membrane, which helps fine-tune the responsiveness of inner hair cells and protects them from loud noises.
How does the auditory pathway transmit information to the brain?
The ascending auditory pathway transmits auditory information primarily from cochlear receptors (inner hair cells) to the cerebral cortex, with some fibers crossing over to the other side of the brain.
Explain how the brain perceives pitch based on hair cell activity.
The brain interprets impulses from hair cells in different positions along the basilar membrane as specific pitches, with the location of the cells corresponding to the frequency of sound.
Describe how loudness is detected by the brain.
Detection of loudness is determined by the brain as an increase in the number of action potentials (frequency) that result when hair cells experience larger deflections.
How does sound localization occur in the auditory system?
Localization of sound depends on the relative intensity and timing of sound waves reaching both ears; if timing is increased on one side, the brain interprets the sound as coming from that side.
What is the function of tip links in hair cells?
Tip links connect stereocilia and play a crucial role in opening and closing mechanically gated ion channels in response to bending.
Explain the significance of the basilar membrane’s motion in hearing.
The motion of the basilar membrane is essential for stimulating hair cells, which convert mechanical sound vibrations into neural signals for the brain.
Describe the relationship between action potentials and sound loudness.
The frequency of action potentials generated by hair cells correlates with the perceived loudness of a sound, with higher frequencies indicating louder sounds.
