Lecture 23 -- NS IX -- Sensory Organs II Flashcards
LO1: sequence the events of sound detection:
1) auricle
2) auditory canal
3) tympanic membrane (eardrum)
4) malleus
5) incus
6) stapes
7) oval window
8) cochlea
LO2: state the role of outer ear structures in sound transmission
list the 3 structures of the outer ear in order:
1) auricle
2) auditory canal
3) tympanic membrane (eardrum)
LO2: state the role of outer ear structures in sound transmission
what is auricle function?
directs sound into auditory canal
LO2: state the role of outer ear structures in sound transmission
what is auditory canal function?
earwax (cerumen) secretion
earwax helps clean and lubricate ear and prevent entry of bacteria
LO2: state the role of outer ear structures in sound transmission
what is tympanic membrane (eardrum) function?
vibrates in response to sound wave
LO3: state the role of middle ear structures in sound transmission
list the 4 structures of the middle ear:
4) malleus
5) incus
6) stapes
7) oval window
LO3: state the role of middle ear structures in sound transmission
what is the function of malleus, incus, stapes, and oval window?
what is the malleus, incus, and stapes collectively referred to as?
vibrations from tympanic membrane get carried to oval window
increases pressure of sound waves before reaching inner ear
ossicles
LO3: state the role of middle ear structures in sound transmission
why do we need to increase pressure of sound waves before reaching inner ear?
inner ear consists of liquid –> vibrations must transfer into liquid
vibrating liquid is hard –> need a lot of pressure to have adequate vibrations
LO3: state the role of middle ear structures in sound transmission
how do middle ear muscles attenuate sound levels by dampening vibration of the ossicular chain?
stapedius –> stiffens attachment of stapes to oval window of cochlea
tensor tympani –> pulls on malleus medially, increases tension of tympanic mb
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
what is the structure of the inner ear and what is special about it?
cochlea – contains the organ for hearing
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
bony labyrinth vs membranous labyrinth:
bony labyrinth –> temporal bone passages that house the inner ear
membranous labyrinth –> continuous system of ducts filled w/ endolymph
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
what does the bony labyrinth contain and what is special about it?
what fluid fills the bony labyrinth?
semicircular canal –> regulates equilibrium
cochlea – contains the organ for hearing
perilymph –> CSF
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
what does the membranous labyrinth contain and what is special about it?
what fluid fills the membranous labyrinth?
semicircular ducts
cochlear duct
endolymph –> intracellular fluid
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
perilymph vs. endolymph
perilymph –> fills bony labyrinth, made of CSF
endolymph –> fills membranous labyrinth, made of intracellular fluid
LO5: identify the structures of the cochlea:
it has ___ ___ chambers separated by ___
3 fluid-filled chambers separated by membranes
LO5: identify the structures of the cochlea:
how many chambers of the cochlea?
what are the chambers filled with?
what are the chambers separated by?
3 fluid-filled chambers separated by membranes
LO5: identify the structures of the cochlea:
what are the 3 cochlear chambers and what are they filled with?
top –> scala vestibuli –> filled w/ perilymph
middle –> scala media (cochlear duct) –> filled w/ endolymph
bottom –> scala tympani –> filled w/ perilymph
LO5: identify the structures of the cochlea:
what are the 3 membranes of the cochlea?
where are they located?
what are their functions?
vestibular membrane – separates off scala vestibuli
- separates endolymph-perilymph and helps to maintain a chemical difference b/n them
tectorial membrane – located above Organ of Corti
basilar membrane – separates off scala tympani, supports the Organ of Corti
LO5: identify the structures of the cochlea:
what is the Organ of Corti?
where is it located?
what is its function?
Organ of Corti == spiral organ
located w/in the cochlear duct, supported on the basilar mb
the receptor organ for hearing
LO6: describe the Organ of Corti:
what is the Organ of Corti?
a sensory epithelium
LO6: describe the Organ of Corti:
what kind of hairs are in the Organ of Corti?
describe the function of the outer cochlear hair cells
outer and inner hairs
receive descending inputs from the brain to assist w/ the modulation of inner hair cell function
LO7: explain how the cochlear hair cells transduce sound-evoked mechanical vibrations into electrical signals that are then relayed to the brain:
1) (cochlea contains liquid). When stapes hits cochlea, liquid in cochlea starts vibrating
2) specialized cells in cochlea convert vibrations into electrical signals –> sent to brain
3) cochlear hair cells (mechanoreceptors in auditory system) will move
4) for both types of cochlear hair cells (IHC, OHC) –> the mechanical bending of stereo cilia opens potassium channels at tips of stereo cilia that allow depolarization of cells
LO7: explain how the cochlear hair cells transduce sound-evoked mechanical vibrations into electrical signals that are then relayed to the brain:
describe mechanotransduction in the hair cell:
what happens in:
- upward movement of basilar mb
- positive mechanical deformation
1) mechanical deformation
–> hair bundle moves toward longer stereovilli
–> opens channels at the tips of the stereovilli
–> allows K+ influx
–> leads to depolarization
2) depolarization activates voltage-sensitive Ca2+ channels
–> causes release of synaptic vesicles
–> stimulation of accompanying sensory neuron
LO7: explain how the cochlear hair cells transduce sound-evoked mechanical vibrations into electrical signals that are then relayed to the brain:
describe mechanotransduction in the hair cell:
what happens in:
- downward movement of basilar mb
- negative mechanical deformation
1) hair bends away from longer stereovilli
–> channels close
–> hyperpolarization
LO8: sequence the auditory projection pathway:
name the 7 steps:
1) stimulation of hair cells activates sensory neurons
2) info carried on cochlear nerve of CN-8 (vestibulocochlear)
3) cochlear nuclei (medulla)
- each ear sends fibers to both sides of the medulla
4) superior olivary nucleus (pons)
- binaural hearing – identify direction of sound source
5) inferior colliculus
- helps locate origin of a sound in space
6) medial geniculate nucleus (on thalamus)
7) auditory cortex (in temporal lobe)
- conscious perception of sound
LO9: list components of vestibular apparatus:
vestibular apparatus maintains ___ and ___ of the body’s ___ ___
consists of:
maintains balance and awareness of body’s spatial orientation
- 3 semicircular ducts
- 2 chambers (otolith organs) –> utricle and saccule
LO10: indicate the functions of the utricle and saccule:
what are they reponsible for? what do they sense?
responsible for static equilibrium
sense head positions
sense linear acceleration