Karius Special Senses: Hearing Flashcards
Outer ear function
funnel the sound waves into ear
Middle ear
Impedance matching - most sound from air to liquid
Inner ear
cochlea converts sound to action potentials
Scala vestibuli and Scala tympani relationship
continuous, fluid-filled compartments (perilymph)
Helicotrema function
connects the scala tympani and scala vestibuli
Perilymph composition
High Na+, low K+ (similar to ECF)
What separates the scala media from the scala tympani and scala vestibuli
Reissner’s membrane and Basilar membrane
Fluid inside the scala media
endolymph
Endolymph composition
high K+ and low Na+
What is something disrupts the cochlea and perilymph mixes with the endolymph
hearing will be effected profoundly
Head motions
crucial for external ear - helps turn towards noise and improve hearing
Middle ear hearing process
transmit sound waves to aqueous environment of cochlea thru ossicles and oval window
Inner ear hearing process
stapes hits oval window causing basilar membrane to vibrate
High frequency, short wavelength
higher pitch- cause maximum vibration closest to oval window
Low frequency, long wavelength
lower pitch, maximum vibration of basilar membrane farthest away from oval window (towards helicotrema)
Organ of Corti
as basilar membrane moves, organ of corti doesn’t fully connect to basilar membrane so it won’t move with it
Hair cells of basilar membrane and tectorial membrane
dependent on tectorial membrane movement
Tectorial membrane and hair cell movement
doesn’t move when the basilar membrane moves– this causes movement of hair cells (because one side stationary and one side is moving)
Outer hair cells
give us our hearing
Hair cell structure
have shorter stereocilia– get progressively longer and connect at top protein
Tip ink
links tips of each sterocilia so they all move together as 1 hair cell
Kinocilium function
determines whether sound is coming towards or away from it and determines whether to depolarize of hyperpolarize
only present during dvpt then goes away
What causes hair cell depolarization
during transduction, if sterocilia are bent towards kinocilium
What causes hair cell to hyperpolarize
stereocilia move away from kinocilium
What channels open during depolarization (mvnt towards kinocilium)
K+ channels open and K+ enters cell
Two paths in the cochlear nucleus
dorsal and ventral
Ventral pathway
processing of temporal and spectral features of the sound
Dorsal pathway
localizing sound
Medial superior olive
intraaural time difference- how the sound arrived at the two ears differently (where the sound is)
ex. how sound coming from R side reaches the right ear miliseconds before the L ear
Lateral superior olive
Intensity – how the sound arrived at the two ears differently
ex. how sound is slightly reduced compared to what the right ear detected
2 factors in determining where a sound originated from
time and intensity
Inferior colliculus
suppresses information related to echoes and determines location on horizon
Where is it L, R, front, back NOT above or below
Superior colliculus
create spatial map of the sound’s location
tells me above and below
Primary auditory cortex (A1)
tonotopic representation, loudness, volume, rate of frequency
Tonotopic
oriented by tone
Rostral area of primary auditory cortex
Low frequency
Caudal area of primary auditory cortex
high frequency detection
Auditory Association Cortex
area that helps start to interpret the sound
broca’s and wenicke’s
Linear acceleration
motion that occurs in horizontal plane or vertical plane
Angular acceleration
requires rotation around one or more planes
What detects acceleration?
semicircular canals, utricle, saccule
Utricle
detect horizontal plane sound
Saccule
detect vertical accelerations
Rotation acceleration
detected by horizontal (lateral) canal
Falling downward (or being thrown backwards)
detected by posterior semicircular canals
Falling forwards
detected by anterior semicircular canal
Ampulla
detects movement of hair cells in semicircular canals and whether they depolarize or hyperpolarize
Macula
detects movement of hair cells utricle and saccule and whether they depolarize or hyperpolarize
Fluid movement when there is motion of the body
endolymph motion, bending of hair cells in ampulla or macula, and activating the nerves
What muscle is activated with anterior semicircular canal?
superior rectus
What muscle is inhibited with anterior semicircular canal?
inferior rectus
What way do eyes move when I fall forward
Up
What muscle is activated with posterior semicircular canal?
superior oblique
What muscle is inhibited with posterior semicircular canal?
inferior oblique
What way do eyes move when I fall backward
Down
What muscle is activated with horizontal semicircular canal?
medial rectus of ipsilateral eye, lateral rectus of contralateral eye
What muscle is inhibited with horizontal semicircular canal?
lateral rectus of ipsilateral eye, medial rectus of contralateral eye
