Flashcards in 15b. Inner Ear, Hearing, Vestibular Function Deck (48)
What is presbycusis?
Age-related bilateral hearing impairment
Unable to hear frequencies below 1500 Hz
What are the risk factors for presbycusis?
Smoking, hypertension, vascular disease, diabetes
What is sensorineural presbycusis?
Degeneration of the cilia on hair cells of organ of Corti or loss of cochlear nerve fibres
What is conductive presbycusis?
Stiffening of the basilar membrane of the cochlea or ossicles
What is metabolic presbycusis?
Atrophy of the stria vascularis
Loss of resting potential of endolymph
What is the treatment for presbycusis?
Ear protection, avoid loud noises
Amplification devices and cochlear implants
What is the function of hearing aids?
Amplify waves in the outer ear and auditory canal
What are the parts of a hearing aid?
Microphone, amplifier, speaker
What is the use of both a hearing aid and a cochlear implant called?
Electric Acoustic Stimulation
What is the function of a cochlear implant?
Capture and convert sound to electrical signals
Goes to electrode array in cochlea via a stimulator
What type of energy does the vestibular system rely on?
What is the name of the sensory epithelium of the ampulla of the semi-circular canals?
What does the crista ampullaris detect?
Angular acceleration (rotation)
What are the utricle and saccule collectively known as?
What do the otolith organs detect?
Position of the head with respect to gravity (linear acceleration)
What does the superior semi-circular canal detect?
Up and down movements
What does the posterior semi-circular canal detect?
Head tilting to one shoulder
What does the horizontal semi-circular canal detect?
Head turning side to side
What is the name of the gelatinous mass that surrounds the crista ampullaris?
What happens to the endolymph when the semi-circular canals rotate?
Endolymph stays still
Pushes against cupula which bends stereocilia of hair cells
What happens when the stereocilia are pushed against the kinocilium?
Influx of K+ and Ca+ via mechanoceptors causes depolarisation
Release of glutamate activates the vestibular nerve
What happens in the opposite ear to the one with the activated vestibular nerve?
Stereocilia bend away from the kinocilium
Hair cells hyperpolarise
What are the Otolith Organs?
Membranous labyrinths within the vestibule
What is the saccule connected to?
What is the utricle connected to?
What is the name of the sensory epithelium in the otolith organs?
What is the macula composed of?
Supporting cells, sensory hair cells, vestibular dark cells
What surrounds the macula?
Describe the make-up of the otolithic membrane
Contains calcium carbonate crystals (otoliths, otoconia)