ear and hearing Flashcards
function of the outer ear
funnel sounds into ear canal for amplification into inner ear
pina
acts in directing sound further into the ear
blind ending tube
closed by the tympanic membrane with funnel at open end
resonant frequency
natural frequency of vibration determined by the physical parameters of the vibrating object
what is the middle ear connected to
upper respiratory tract via Eustachian tube
function of eustachian tube
equalisation of pressure in ears
oval window
membrane covered opening that leads to vestibule of inner ear
round window
vibrates with opposite phase to vibrations entering inner ear through oval window
what does the middle ear do
transmits vibrational waves from the tympanic membrane into electrical impulses
why is the middle ear succeptible to infections
connected to URT
how is the tympanic membranee connected to the oval window
three bones connected by synovial joints
what are the three bones
malleus
incus
stapes
how to the bones transmit sound
physically move to transmit vibrations from the tympanic membrane to oval window to produce a nerve impulse
where does amplification occur
oval window
muscles found in the middle ear
tensor malleus
stapedius
what is build up of mucus in middle ear called
otitis media
what can chronic forms of otitis media lead to
conductive earring loss
what is in the inner ear
cochlea
what is the cochlea
fluid filler tube coiled
associated with auditory nerve
what are involved in balance
semi circular ducts
what structure transduces the vibrational energy from sound to action potentail
organ of corti (contains hair cells which have sterocilla)
organ of corti
has two types of hair cells (inner and outer)
found on the bacillar membrane
stimulates influx of potassium into hair cells to generate AP
bacillary membrane
becomes wider from the base to apex
narrow for high frequency
wide for low frequency
between ST and SM
how are sound frequencies recieved
vibration at a point on the basilar membrane transferred to hair cells
vibrations picked up by stereo cilia
what are found within sterocilia
potassium channels for depolarisation when bent
where is the auditory cotex
temporal lobe
what causes the generaation of action potentials
to and fro of hair cells by the tectorial memrbane
how is the auditory cortex arranged
tonotopically
4 types of hearing loss
auditory processing disorders
conduct hearing loss
sensorineural hearing loss
mixed hearing loss
what causes auditory processing disorders
brain unable to process information contained in sound from cochlea
cause of conductive heading loss
problem with outer and middle ear interferes passing sound to inner ear
sensorineural hearing loss
cochlea or auditory nerve unable to accurately send electrical information to the brain
mixed hearing loss
conductive and sensorineural hearing loss
arrangement of the coclea
scala vestiboli - top
scala media - middle
scala tympani - bottom
where is the organ of corti found
in the scala media on the bacillar membrane
how is sound transmitted in the inner ear
steps
movement of oval window leads to movement of fluid
movement of fluid in waves causes bacillar membrane conduct waves (different sections relate to different frequencies/sounds)
waves of the bacillary membrane leads to movement of the inner or outer hair cells on the organ of corti (attached to the bacillary membrane)
the hair cells have steriocillla which then move, leads to action potentials due to K+ influx
