6. 7 Ear Structure and Function Flashcards
CN8: sensory neurons in ______ ganglion for balance or ________ ganglion for hearing
vestibular, auditory
axons from CN8 synapse in the brainstem at the _______ or _______ nuclei
vestibular, cochlear
peripheral components of the auditory system include the _______, _______, and ______ ear, providing info about sound in the environment
external, middle, inner
______ cells are the sensory transducers of the auditory system
hair
afferent info from 8th nerve synapses on _______ nuclei in the brainstem in the auditory system
cochlear
peripheral components of the vestibular system are the _______ ear
inner
vestibular system provides info about _____ and _______, and hair cells are the sensory transducers
motion and gravity
in the vestibular system, afferent info from the 8th nerve synapses on __________ nuclei in the brainstem
vestibular
info from the vestibular system does not reach the _______, but interacts with the motor system
cortex
auditory and vestibular hair cells transduce energy via movement of their ___________
stereocilia
deflection of hair bundle towards its tall side causes ________, whereas deflection toward its short side causes __________
depolarization (excitation) , hyperpolarization (inhibition)
vestibular hair cells are located in the __________ and ________
macular organs (saccule, utricle), semicircular canals (crist ampullaris)
the vestibular hair cells in the macular organs (saccule, utricle) detect _______
linear acceleration (gravity)
the vestibular hair cells in the semicircular canals (crista ampullaris) detect ______________
rotational acceleration
embedded in a glycoprotein matrix and sit on top of hair cell stereocilia?
otoliths
otoliths shift with ________ and bend stereocilia, changing neurotransmitter release by hair cells
gravity
hair cells in ampullae sit on ridge of tissue called __________
crista ampullaris
stereocilia are embedded in the _________, a tall glycoprotein matrix mass
cupula
the cupula is deflected by fluid flowing through the canal when ___________
the head turns
adequate stimulus for kinetic labyrinth (semicircular canals)?
dynamic stimuli (rotational forces) and head acceleratin/deceleration
adequate stimulus for static labyrinth (otolith organs, utricle saccule)?
static stimuli, maintained head position (tilit), translational forces and horizontal displacement
ossicular chain and the size difference between the tympanic membrane and oval window prevents loss of pressure at oval window
impedence matching
eustachian tube connects the middle ear and nasopharynx, allowing for?
pressure equalization
what two muscles can change the stiffness of the tympanic membrane or dampen the movement of the stapes, increasing dynamic range of ear and protecting cochlear hair cells from loud sounds?
tensor tympani and stapedius
shearing force against stereocilia with ____________ movement; change in hair cell membrane potential causes release of neurotransmitter at the base
basilar membrane movement
endolymph has ______ mV endolymphatic potential, and is high in the ion _______
+80, potassium
perilymph has ______ mV hair cell membrane potential, and is high in the ion ______
-40, sodium
the 120 mV membrane potential drives ______ ions into the hair cells
potassium
the _________ secretes K+ ions
stria vascularis (lining of scala media)
the __________ separates endolymph from perilymph
reticular lamina
sound waves enter external auditory canal - tympanic membrane vibrates - _______ vibrate and increase force - _______ window vibrates and sets up motion in perilymph of scala vestibuli - vestibular membrane transfers vibration to scala media - ______ membrane vibrates - hair cells move relative to tectorial membrane - ________ deflect toward long side - channels open and K+ enters through stereocilia tips - ______ membrane depolarizes - voltage gated ______ channels open and enters hair cell - neurotransmitter released - afferent nerves respond with action potential headed for brainstem
ossicles oval basilar stereocilia hair cell calcium
movement of basilar membrane is not uniform along its length- displacement in a given region depends on __________
sound frequency
the apical end of the basilar membrane is most sensitive to _____ frequency sounds, and the base is more sensitive to _______ frequency sounds
low, high
in the cochlea, inner hair cells ______ and outer hair cells modify ____________
transduce, basilar membrane movement
outer hair cells can amplify the transduction of _______ sounds and attenuate the transduction of ______ sounds
low level(faint), and high level (loud)
outer hair cells receive innervation from efferent fibers that originate in the _________ nucleus in the pons
superior olivary
the 8th nerve and cochlear nucleus receive _________ input from the ipsilateral ear
monaural
all other nuclei above the level of the cochlear nucleus receive input from __________
both ears
auditory cortex is located on the lower bank of the _______ sulcus
lateral
