Special Senses Hearing

Question 1

what is sound

Answer 1

cyclical compression and rarefaction of air molecules causing a cyclical change in air pressure

Question 2

what does the pinna do?

Answer 2

shapes, funnels, and conducts sound toward the meatus and tympanic membrane

Question 3

what is the dual function that pinna has in many species?

Answer 3

hearing and thermoregulation

Question 4

what part of the ear is an air-filled cavity?

Answer 4

middle ear

Question 5

what part of the ear is the fluid-filled cavity?

Answer 5

inner ear

Question 6

what does the choclear duct contain?

Answer 6

endolymph

Question 7

what houses the hair cells that are anchored to the basilar papilla?

Answer 7

organ of corti

Question 8

what is the gel-coated ridge that lies on top of the hair cells?

Answer 8

tectorial membrane

Question 9

what do hair cell synapse onto?

Answer 9

sensory nerves
cochlear nerve -> CN8

Question 10

what happens to sound waves and different frequencies along the basilar papilla?

Answer 10

resonate at different points -> spatial coding along length of membrane -> tonotopic organization

Question 10

how is the organ of corti structured longitudinally?

Answer 10

basilar papilla increases in size and flexibility

Question 11

how is the organ of corti structures in its cross-section?

Answer 11

membranes different in flexibility

Question 12

how is sound energy in air transmitted to vibrations in tissue?

Answer 12

sound waves hit tympanic membrane -> vibrations transferred to oval window -> oval window deformation -> pressure waves in perilymph of cochlea -> pressure waves travels up basilar membrane

Question 13

how many layers of sterocilia does each hair cell have?

Answer 13

3

Question 14

what connects sterocilia?

Answer 14

tip links composed of cell adhesion molecules

Question 15

In what form is mechanical energy transduced to electrical energy?

Answer 15

action potentials

Question 16

map out hairs opening -> signaling cochlear nerve

Answer 16

bent hairs open gated cation channels -> K+ enters hair cell -> hair cell depolarizes -> voltage-gated Ca2+ channels open -> neurotransmitters (glutamate) released -> signaling terminals of cochlear nerve

Question 17

what happens to sensory neurons on hair cells at rest?

Answer 17

transmit AP spontaneously at a specific rate

Question 18

how are quiet noises detected?

Answer 18

1.pinna - funnels and conducts sounds into ear canal
2. meatus - transmits sound
3. middle ear ossicles - transmit and amplify sound 2-3 times
4. cochlear amplifer

Question 19

what do outer hair cells do to amplify quiet noises?

Answer 19

change length in response to movements of basilar membrane -> amplification of signal

Question 20

what is the function of outer hair cells?

Answer 20

increase sensitivity of inner hair cells

Question 21

where does information originating in one cochlea reach?

Answer 21

both sides

Question 22

where does information from one cochlea travel?

Answer 22

predominantly up the contralateral side

Question 23

what does the superior olivary complex do?

Answer 23

sound localization

Question 24

what does the medial geniculate nucleus & inferior colliculus do?

Answer 24

specialized to detect certain frequency combinations and timing among sounds

Question 25

what does the auditory cortex do?

Answer 25

conscious perception of sound

Question 26

Map the auditory NS system

Answer 26

CN8 -> cochlear nuclei -> superior olivary complex -> inferior colliculus -> medial geniculate nucleus -> auditory cortex

Question 27

what can cause phase delay between ipsilateral and contralateral ear?

Answer 27

time difference and intensity differences

Question 28

what receives input from both cochlear nuclei?

Answer 28

superior olivary complex

Question 29

what is the term for louder in one ear?

Answer 29

interaurel intensity difference

Question 30

what is the term for sound reaching one ear first?

Answer 30

interaural timing differences

Question 31

what do lateral superior olive cells measure?

Answer 31

interaural intensity differences by integrating ipsilateral excitatory and contralateral inhibitory inputs

Question 32

what do medial superior olive cells measure?

Answer 32

interaurel time differences using excitatory inputs from both sides

Question 33

which olive cells measure using excitatory and inhibitory inputs?

Answer 33

lateral superior olive

Question 34

which olive cells measure using only excitatory inputs?

Answer 34

medial superior

Question 35

map the auditory pathway with sounds at different frequencies

Answer 35

detect sounds at different frequencies -> bipolar neurons that connect hair cells to cochlear nuclei -> acoustic filtering -> pathway splits to right/left olive -> directionality and sound localization -> tonotopic organization; information routed to vestibulo-ocular reflex and startle response -> awarness of a sound relay to auditory cortex -> conscious localization and perception of sound

Question 36

what is BAER testing?

Answer 36

brainstem auditory evoked response

Question 37

how and where can auditory evoked potentials be detected?

Answer 37

detected at surface of skin in response to clicks or certain tones from a speaker

Question 38

what is required to boost the signal and remove noise in the BAER test?

Answer 38

differential amplification

Question 39

what calculates the mean value of the clicks to reveal the pattern in a BAER test?

Answer 39

signal averger

Question 40

what does wave I-VII reflect?

Answer 40

I - cochlea, spiral gangli, CN8 II - cochlear nuclei III - superior olivary complex IV & V - lateral lemniscus & lemniscal nuceli, and causal colliculus VI - medial geniculate body VII - auditory radiations

Question 41

which ear can each puppy hear in?

Answer 41

1 - both ears 2 - right ear 3 - left ear 4 - neither ear

Question 42

what is acquired deafness

Answer 42

hearing loss due to an infection, injury, gradual or sudden hearing loss due to age, noise exposure, drugs

Question 43

what do ototoxic drugs do?

Answer 43

kill hair cells -> hearing loss

Question 44

what do aminoglycosides first target and then spread to?

Answer 44

first - hair cells in basal portion of cochlear spiral spread - outer spiral then nerve

Question 45

what sounds do aminoglycosides have the most affect on?

Answer 45

high frequency

Question 46

what coat color is linked to deafness in dog, cat, horse, cow, pig, sheep, ferret, mink, camelid, and rabbit?

Answer 46

white

Question 47

when does deafness develop due to the loss of melanocyte-dependent blood supply to cochlea?

Answer 47

3-4 weeks

Question 48

what does binaurel hearing do?

Answer 48

allow for comparing signal from both ears to determine location of a sound in space

Question 49

where is the binaurel input recieved from both cochlea?

Answer 49

olivary complex

Question 50

what protects the ear from excessive noise?

Answer 50

two skeletal muscles attached to malleus and stapes