Week 3 Flashcards
Cochlear physiology
Cochlea is tonotopically organized and serves as a spectral analyzer of sound
Hair cells, transform hydraulic energy into electrochemical energy
Olivocochlear feedback loop
Most nerve fibers in this pathway cross one side of the brain, stem to the other to control outer hair cells in the opposite cochlea, reducing background noise and improve sound clarity
Signals from the superior olivary nucleus, reduce outer hair cell activity, lowering sound amplification and protecting the ear
Two basic type of CN VIII nerve neurons
Low spontaneous rate neurons
High spontaneous rate neurons
Low spontaneous rate neurons
Respond to very low signal intensities
Display random firing
High spontaneous rate neurons
Require higher level of stimulation
Respond to high intensity signals
Characteristic / best frequency of a neuron
Neuron specialized in 10,000 Hz tones responds Best to that frequency.
Signal frequencies decrease, response rate decreases until 8000 Hz is reached
Vestibular system
Vestibule is entryway to semi circular canals, and the cochlea
It is 5 mm long and 3 mm wide
Houses the sense organs for balance
Vestibular system functions
Provides the brain with proprioceptive feedback about the location and orientation of the body
The information from the vestibular system travels through the vestibular nerve which forms part of CN VIII
Vestibular system balancing mechanism
Semi circular canal contain perilymph
This fluid shakes in response to head motion, however, it slightly lags
This mismatch causes bending of the cilia
The cilia are embedded within a layer of gelatinous substance
This movement allows sensation of very tiny head movements
Vestibular system, dizziness, and nausea
When visual system senses movement and the vestibular does not the result is vertigo
