HEARING PT 1 Flashcards
what are the three major parts of the ear
inner, external, middle
differentiate between external/middle and inner
external and middle are only involved with hearing and inner is involved in hearing and equilibrium (balance)
what are the two structures of the external ear
auricle and external acoustic meatus
describe the auricle
pinna; shell-like projection
what are the three sections of the auricle
Helix (rim)
Lobule (earlobe)
Funnel sounds waves into auditory canal
describe the external acoustic meatus
auditory canal; short tube extending from auricle to eardrum
whats the external acoustic meatus lined with
hairs, sebaceous glands, and modified sweat glands (secrete ear wax)
whats the tympanic membrane
eardrum; boundary between outer and middle ear
what does the tympanic membrane look like
Thin, translucent, connective tissue membrane
what makes the tympanic membrane vibrate
sound waves
what does the tympanic membrane transfer
sound energy to tiny bones of middle ear
→ sets them vibrating
what does the middle ear range from
eardrum to vestibular window
what are the three ossicles in the middle ear
malleus, incus, stapes
what do the malleus, incus, stapes transmit
vibration of eardrum to oval window
what happens after oval window is vibrated
Sets inner ear fluid in motion → Excites hearing receptors
describe shape and location of internal ear
Complicated shape (i.e. labyrinth); Lies deep in temporal bone, behind eye socket
what are the two division of the internal ear
bony labyrinth and membranous labyrinth
whats the bony labyrinth
bony walls that give internal ear cavity-like form
whats the membranous labyrinth
membranous sacs/ducts in the bony labyrinth
what fluids do the membranous and bony labyrinth contain
perilymph (bony) and endolymph (membranous)
what do perilymph and endolymph conduct and respond to
conduct sound vibrations for hearing & respond to mechanical forces from body position changes and acceleration
what are the three regions of the internal ear
vestibule, semicircular canals, and cochlea
whats the shape of the vestibule
central egg-shaped cavity
what does the vestibule contain
saccule (extends to cochlea) and utricle (extends to semicircular canals)
what receptors does the vestibule house
equilibrium receptors: respond to gravity pull and head position changes
what are the semicircular canals
anterior, posterior, and lateral canals
what duct do the semicircular canals contain
semicircular duct (communicates with utricle)
what receptors do the semicircular canals house
equilibrium receptors in ampulla (swelling): respond to rotational head movement
what does the cochlea extend from, contain, and what receptors does it house
Extends from vestibule
Contains cochlear duct
Houses receptor organ (spiral organ) for hearing
what are the three chambers of the cochlea
1) Scala vestibuli 2) Scala media
(cochlear duct) 3) Scala tympani
what does each chamber contain
scala vestibuli (perilymph), scala media (enodymph) scala tympani (perilymph)
what are the other two structures in cochlea
spiral organ and basilar membrane
describe sound
pressure disturbance (alternating areas of high and low pressure) produced by a vibrating object and propagated by molecules of a medium (air)
describe hearing
reception of an air sound wave that is converted to a fluid wave that ultimately stimulates mechanosensitive cochlear hair cells that send impulses to the brain for interpretation
what are sound waves created from
Alternating areas of high- (compressions) and low- (rarefactions) pressures
how does kinetic energy work with sound waves
transferred to air molecules, which then transfer it to other air molecules
Wave energy declines with time and distance
whats frequency
pitch; number of waves that pass a point in a given time
whats amplitude
intensity/volume; height of wave
whats wavelength
distance bw two consecutive crests
how are wavelength and frequency related
Shorter wavelength → Higher frequency
where does sound enter
external acoustic meatus
what happens after sound enters external acoustic meatus
Strikes tympanic membrane
Vibrates at same frequency as sound
what happens after sound strikes tympanic membrane
Vibration transferred to auditory ossicles and amplify vibration
what happens after vibration is amplified from stapes
Stapes hits oval window, which Vibrates perilymph in bony labyrinth
what is the sound we can hear transmitted through
transmitted through cochlear duct to scala tympani
what happens after sound is transmitted to scala tympani
Vibrates basilar membrane
→ Activates hair cells
→ Action potential sent to brain
when do Basilar membrane characteristics changes
across length of basilar membrane
what do sounds at audible frequencies do to basilar membrane
vibrate it
what happens to sound below audible frequencies
sound returned
does Location of basilar membrane vibration and hair cell activation corresponds to specific frequency
yes
