Exam #5 ch 15 part 2 Flashcards
what does the inner ear consist of?
a membranous labyrinth containing endolymph in a bony labyrinth containing perilymph
what do both hearing and equilibrium use?
hair cells as sensory receptors
what are hair cells
epithelial cells that function as mechanroceptors
what do hair cells synapse with?
a sensory neuron
what do hair cells have?
about 80 long stereocilia and a longer kinocilium
where does hair cell’s kinocilium project?
into the endolymph
what does the stereocilia contain?
mechanically regulated ion channels
what does bending the stereocilia one direction do?
open ion channels that depolarize the hair cells
what happens when ion channels that depolarize hair cells are open?
it causes more neurotransmitter release that increases the rate of action potentials in the sensory neuron
what does bending the stereocilia in the other direction do?
closes the ion channels, hyperpolarizing the hair cells
what happens when ion channels close, hyperpolarizing the hair cells
it causes less neurotransmitter release that reduces the rate of action potentials in the sensory neuron
what does sound consist of?
pressure waves in the air
what is the frequency (pitch)?
the number of waves per second
what is the amplitude (loudness)?
the height of the pressure waves
what dos the cochlear duct (scala tympani) separate?
the vestibular duct (scala vestibuli) and typanic duct (scala tympani)
where does the vestibular duct begin?
at the oval window
where does the tympanic duct end?
at the round window
where are the tympanic and vestibular ducts connected?
at the end of the cochlea (helicotrema)
where does the hearing organ (spiral organ) sit?
on the basilar membrane
what does the basilar membrane separate?
the cochlear and tympanic ducts
where do hair cells on the basilar membrane project?
up to the overlying tectorial membrane
when the basilar membrane moves what is true of the sterocilia?
the hair cells are bent
what are the inner row of hair cells used for?
hearing
what are the outer row of hair cells used for?
to regulate the tension of the spiral ligament of the basilar membrane
trace a soundwave (3) (VVC)
1) they vibrate the tympanic membrane
2) vibrates the auditory ossicles
3) creates pressure in the vestibular duct
what does the pressure wave cause? (3) (RMB)
1) the round window to bulge out
2) moves the basilar membrane
3) bends the hair cell processes at one location
after the pressure wave what does sound distort?
the basilar membrane at a specific location
what does the location of the sound distortion at the basilar membrane at the specific location depend on?
on the frequency of sound and the width of the basilar membrane
after sound distortion occurs, what does lower frequency sound distort?
the basilar membrane further from the oval window than higher frequencies
what does the sound distortion form?
the basis of pitch discrimination
what does higher amplitude sound stimulate?
more hair cells at a location
what is Timbre?
the quality of sound
why is timbre the quality of the sound?
since most sound areas are complex with several frequencies being produced and several areas of the spiral organ
what do the two muscles attached to the auditory ossicles in the middle ear do?
dampen loud noises
what is the feedback circuits from the superior olivary nucleus to the hair cells used for?
to filter out minor vibrations and noise
where are the sensory neuron cell bodies located?
in the spiral ganglion near the center of the cochlea
what do axons from the spiral ganglia form?
the cochlear branch of the vestibuloochlear nerve (VII)
where do the axons that form the cochlear branch of the vestibuloochlear nerve synapse?
in the cochlear nuclei of the medulla
what happens after the cochlear branch of the vestibuloochlear nerve synapses?
the axons then ascend to the inferior colliculi
what do axons often ascend to the inferior colliculi through?
the superior olivary nucleus
what does the inferior colliculi send?
auditory information to the superior colliculi
what does the inferior colliculi send auditory information to the superior colliculi for?
reflexes and to the medial geniculate nuclei for relaying to the auditory cortex
what detects linear acceleration, rotation and position of the head?
the vestibule and semicircular canals
what detects linear acceleration and position of the head with respect to gravity:?
the static labyrinth (utricle and saccule)
what are the receptors (maculae) in the static labyrinth?
epithelia containing hair cells
where do the hair cell processes of the static labyrinth extend into?
a gelatinous otolith membrane
what does the gelatinous otolith membrane contain?
dense calcium carbonate crystals (otoliths)
when the head tilts or accelerates what happens to the otoliths?
they move gelatinous material bending the hair cell processes
what happens after the otolights move the genlatinous material that bends the hair cell processes?
the rate of neurotransmitter release by hair cell is changed
what does the dynamic labyrinth (semicircular canals) detect?
rotation of the head
what are the receptors (cristae ampullaris) of the dynamic labyrinth?
epithelia containing hair cells
where are the cristae of the dynamic labyrinth?
in the ampulla of each semicircular canal
where does the stereocilia of the hair cells of the dynamic labyrinth extend into?
a gel-like cupula that spans the ampulla
what does each semicircular canal connect to?
the vestibular sacs
what does it mean that the semicircular canal connect to the vestibular sacs?
that they are rendered circular
when the head is rotated what happens?
the inertia of the stationary endolymph in a semicircular duct pushes the cupula which bends the hair cell’s sterocilia the opposite direction of rotation
what is altered when the sterocilia are bent?
the rate of neurotransmitter release by hair cells
what does each semicircular canal detect?
rotation in one of the three planes of space
where are sensory cell bodies located?
in the nearby vestibular ganglia
what do axons continue in the vestibular branch form?
the vestibuloochlear nerve (VII)
where does axons in the vestibular branch synapse?
in the vestibular nuclei in the medulla
what does the vestibular nuclei also receive?
proprioceptive input
what does the vestibular nuclei do? (2) (SA)
1) send motor commands down the vestibulopinal tracts
2) adjust muscle tone to compensate for head and neck movements and to maintain balance
what does the vestibular nuclei relay information to?
the superior colliculi
why does the vestibular nuclei relay information to the superior colliculi?
to keep eyes fixed during head movements
what does the vestibular nuclei send information to the cerebellum for?
about body position and movement for cerebellar function
what type of information does the vestibular nuclei send to the cerebral cortex?
equilibirum information
how does the vestibular nuclei send equillibrium information to the cerebral cortex?
via posterior ventral nucleus of the thalamus
why does the vestibular nuclei send equalibrium information to the cerebral cortex?
to provide a sense of head position and movement
