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52 Cards in this Set
- Front
- Back
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___ is associated with hearing.
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Equilibrium
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What are the two types of equilibrium?
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rotational and horizontal & vertical
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What does the vestibular apparatus consist of?
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the utricle, saccule and 3 semicircular canals
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The base of each semicircular canal is expanded into an ___ that contains ___.
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ampulla; sensory hair cells
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The inner ear is encased within the ___ of the temporal lobe.
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petrous portion
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What houses the structures for the senses of equilibrium and hearing?
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inner ear
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bony labyrinth
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• series of curved passages within the skull bones
• it has two distinct regions: cochlea (anterior) for hearing and vestibular apparatus (posterior) for equilibrium |
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membranous labyrinth
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• membranous network that parallels the bony network
• perilymph - fluid between membranous and bony labyrinth • endolymph - fluid contained within the membranous labyrinth • contains sensory hair cells |
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Fluid movement is how we detect ...
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changes in the hair cells.
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Hearing and equilibrium depend on the function of hair cells which are ___ stimulated by the bending of ___.
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mechanoreceptors; their plasma membrane
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The bony labyrinth is filled with ___.
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perilymph (similar to extracellular fluid, high in Na⁺ , low in K⁺
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The membranous labyrinth is filled with ___.
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endolymph (K⁺ rich fluid)
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equilibrium
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changes in position and motion of the head
• balance and coordination of body movement |
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Hair Cells
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• housed within the membranous labyrinth
• possess stereocilia on the surface • single large kinocilium |
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Bending of stereocilia alters ___.
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membrane potential
• bending toward kinocilium opens ion channels, depolarizing membrane • bending away from kinocilium closes ion channels, hyperpolarizing membrane. |
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Where is the stereocilia and kinocilium located?
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utricle, saccule and semicircular canals
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What happens when the hair cells are depolarized?
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it induces more neurotransmitter to be released to associated sensory neurons (greater AP frequency in sensory neurons)
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stereocilia
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processes containing protein filaments surrounded by part of the plasma membrane
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vestibular apparatus
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fluid-filled compartments in the inner ear
• semicircular canals - rotation of the head • otolith organs - linear movement of head and orientation relative to gravity sensory information relayed via the vestibulocochlear nerve (VIII) to the cerebellum and medulla |
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How is sensory information relayed in the vestibular apparatus?
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information relayed via the vestibulocochlear nerve (VIII) to the cerebellum and medulla
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Otolith Organs
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found within two fluid-filled chambers (utricle and saccule)
- Utricle: more sensitive to horizontal acceleration - Saccule: more sensitive to vertical acceleration • Mound of hair cells covered with otolithic membrane - jelly like membrane - otoliths (CaCO₃ crystals) • Linear movement or tilting of the head causes otolithic membrane to sag - bends hair cells - stimulates vestibular neurons |
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Frequency of action potentials is increased when accelerating ___ & decreased when accelerating ___.
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downward; upward
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semicircular canals
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• fluid-filled circular tubes oriented in three planes (anterior, posterior and lateral)
• bell-shaped ampulla at one end of each canal - contains hair cells in mound of supporting cells covered with gel-like cupula • rotation of head in one direction generates inertial pressure in fluid - bends cupula - pushes hair cells in one direction - stimulates vestibular neurons |
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The endolymph can push the cupola so it bends, embedded sterocilia bend as well, stimulating the production of action potentials in the associated sensory neurons of cranial nerve ___.
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VIII
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vertigo
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loss of equilibrium results when the action potential frequency coming from one inner ear is different from the frequency coming from the other
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vestibular nystagmus
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involuntary oscillations of the eyes
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Meniere's disease
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can lead to degeneration of the hair cells in the vestibular apparatus and cochlea. An early symptom is often "ringing in the ears" or tinnitus
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Hearing is ___.
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pressure waves
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pitch
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• frequency of sound waves
• humans can hear frequencies between 20 and 20,000 Hz; hear best at between 2000 and 4000 Hz • ↑ frequency = ↑ pitch |
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Loudness
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• amplitude (size) of sound waves
• measured in decibels: - each 10 dB increase represents a tenfold increase in amplitude • amplitude (size) of sound waves determines the loudness of a sound |
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What is the anatomy of the outer ear?
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• pinna
• external auditory meatus • tympanic membrane |
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pinna
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(auricle)
• collects and channels sound waves • transmits sound waves to the external auditory meatus |
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tympanic membrane
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• vibrates when struck by sound waves
• is much larger than the oval window, the vibrations in response to sound by the tympanic membrane are greatly magnified in the vibrations of the oval window |
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external auditory meatus
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entrance to the skull
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What is the anatomy of the middle ear?
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• air-filled chamber
• auditory tube • three auditory ossicles (malleus, incus and stapes) |
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auditory tube
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connects middle ear to pharynx
• equalizes pressure around your tympanic membrane also helps maintain normal pressure in the middle ear |
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auditory ossicles
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act as sound amplifiers
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stapedius muscle
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attached to stapes, provides protection from loud noises
• can contract & dampen large vibrations • prevents nerve damage in cochlea |
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Where is the most common place to get an earache?
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the middle ear because the infection can come from the throat or pharynx
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Anatomy of the cochlea
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anterior portion of the inner ear
• three snail-shaped tubes filled with fluid 1. scala vestibuli - upper 2. scala tympani - lower 3. cochlear duct |
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scala vestibuli
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upper
leads from the oval window to apex of the spiral • located between bony and membranous labyrinths • contains perilymph |
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scala tympani
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lower
leads from apex of the spiral to the round window • located between bony and membranous labyrinths • contains perilymph |
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cochlear duct
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also called scala media
• inner canal contained within the membranous labyrinth • contains endolymph |
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What is the sensory apparatus of the cochlea?
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organ of Corti
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What are the components of the spiral organ?
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1. basilar membrane
2. hair cells 3. sensory neurons 4. tectorial membrane |
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organ of Corti
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• forms the floor of the cochlear duct
• hair cels embedded in supporting cells • hair cells positioned atop the basilar membrane |
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basilar membrane
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• forms border between cochlea duct and scala tympani
• flexible, vibratory • contains hair cells on its surface |
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tectorial membrane
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• lies top of hair cells
• stereocilia imbedded in membrane • helps cause the bending of stereocilia |
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pitch discrimination
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depends on the region of the basilar membrane that is most affected by a certain frequency of sound
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True/False: Hair cells of our inner ear can regenerate.
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False
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Conduction deafness
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occurs when transmisstion of sound waves to oval window is impaired
• most common hearing problem • impacts all frequencies • helped by hearing aids • damage to the tectorial membrane or middle ear ossicles |
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Sensorineural (perceptive) deafness
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is impaired transmission of nerve impulses
• often impacts some pitches more than others • helped by cochlear implants with stimulate fibers of 8th in response to sounds • works because some sensory dendrites survive and can be stimulated electrically to product action potentials, restoring some perception of speech in affected people |
