Lecture 4: Hearing and the Vestibular Senses Flashcards
The scala vestibuli and scala tympani are continous, fluid-filled compartments which contain?
Perilymph
Perilymph is most similar to what kind of fluid and what is its ion content like?
- Most similar to ECF
- High in [Na+] and low [K+]
Where is Endolymph found, what is it most similar to, and what is its ions concentrations like?
- Found in the Scala Media
- Most similar to ICF
- High in [K+] and low in [Na+]
What creates the chamber (scala media) that is isolated from the periymph?
The Basilar and Reissner’s membrane
The composition of the _____ will have a significant effect on the transduction of sound waves into actions potentials?
- Endolymph
- Large electrical gradient (scala media has high positive charge)
What components of the ear transmit and amplify the sound waves from the tympanic membrane to the oval window of the cochlea?
The ossicles
High frequency (short wavelength) sounds cause the maximum vibration of the basilar membrane where?
Closest to the oval window
Low frequency (long wavelength) sounds cause the maximum vibration of the basilar membrane where?
Farthest away from the oval window (towards to helicotrema)
Hair cells of the ear are what kind of receptors and convert what kind of energy?
- Mechanoreceptors
- Convert mechanical signal to an electric signal
What is each hair cell composed of that increase in length; what are they connected to and the function?
- Composed of distinct arrangement of shorter sterocilia that increase in length
- Each stereocilia connected to another at the top by an extracellular filamentous protein, known as the tip link
- This links the stereocilia together, allowing for deflection as a bundle
During transduction, if the stereocilia are bent towards the kinocilium (tallest stereocilia) what occurs?
- K+ ions enter the hair cell
- Hair cell depolarizes and opens voltage-gated Ca2+ channels
- Incoming Ca2+ leads to release of glutamate from synaptic vesicles
During transduction, if the stereocilia are bent away from the kinocilium (tallest stereocilia) what occurs to the hair cell?
Hair cell hyperpolarizes
Deflection of the stereocilia causing depolarization also causes the release of what NT and generates what?
- Release of glutamate
- Generation of AP’s in 8th nerve fibers
Which hair cells are primary source of auditory information and which act as an amplifier?
- One row of inner hair cells = primary source of auditory info
- Three rows of outer hair cells = acts as an amplifier
Hair cells have both afferent and efferent innervation, what type of afferents are the inner hair cells vs. outer hair cells?
- Inner hair cells = type I afferents
- Outer hair cells = type II afferents
The Dorsal (posterior) cochlear nuclei is involved in what process of hearing?
Integrates the acoustic information with somatosensory information for localizing sound (i.e., where the sound is)