EQUILIBRIUM AND AUDITION Flashcards
What part of the ear is the cochlea?
inner ear
What is the pinna?
visible part of the outer ear
What structures does the middle ear consist of?
tiny bones that connect tympanic membrane to inner ear
Where is the tympanic membrane located?
separates outer and middle ear
How is membrane potential defined?
inside relative to outside
What are the two things that affect flow of ions across membranes?
- concentration gradient
- membrane potential
What side of the hair cell does endolymph touch?
apical side of hair cells, where stereocilia are
What is a key player in depolarization and repolarization of hair cells?
K+
People can hear sounds up to how many Hz?
20,000
Bats can hear sounds up to how many Hz?
100,000
What is the stapes?
structure on oval window that include the last of 3 bones that vibrate against cochlea, near its base
What is the cochlear base?
thinner, less flexible part of basilar membrane tuned for high frequencies
What is the apex?
thicker, floppier part of basilar membrane tuned for low frequencies
What type of coding does audition employ?
- labelled line coding
- temporal coding
- rate coding
What does the shape of the ear give information about?
gives information on whether sound is in front or behind you – changes shape of sound wave as it enters ear canal, depending on whether sound is coming from the front or back
Are pulses highly directional?
yes
Have moths co-evolved with bats?
yes, and they have developed ears that can hear ultrasound
Visual information is processed broadly in the brain – from retina to areas of the brain.
- eyes are part of central nervous system (CNS)
- lateral geniculate nucleus (LGN)
- striate cortex (V1 or primary visual cortex)
Where are photoreceptors that respond to different colours?
intermingled in retina
What is protanopia?
missing long (red) cone – cannot detect redness, red and green look very similar
medium (green) and long (red) cones have absorbance spectra that are fairly overlapping (they work together a lot) – if one of them is missing, can’t discriminate between colours in that range
What is scotopic vision?
very lowest levels of light
- only rods are active – more sensitive
- below cone threshold
What is mesotopic vision?
some ability to detect colours because cones are activated above this threshold – but it’s not great
What is photopic vision?
indoor levels of light
- rods are saturated ∴ not giving much information
- relying much more heavily on cones ∴ have better colour vision
Visual input is not evaluated on blank slate.
everything we see is process through frameworks that already exist in brain (ie. shadow affects overall brightness, but more importantly brain has evolved circuits to understand shadows)
Which type of hair cell is more common?
stereocilia
What do sounds consist of?
sinusoidal waves of air pressure changes – ie. tuning fork produces rippling changes in air pressure
Flow into hair cells: endolymph vs. inner hair cells
- apical membrane potential of hair cells is -125 mV
- both have high K+ ∴ concentration gradient won’t do much
- large membrane potential ∴ K+ flows toward negative side into hair cells
Flow out of hair cells: perilymph vs. inner hair cells
- basal membrane potential is -45 mV (lower electrical strength)
- large K+ concentration gradient drives K+ out of cell into perilymph, even if it’s against the electrical gradient
Why isn’t loss of ability to hear high frequencies as we age not that important?
communication and much of what we use auditory system for is only a very small part of the range we can actually hear ∴ loss of high frequency detection in older adults does not affect day-to-day a lot
What does the shape of the ear do?
gives info on if sound is in front or behind you – changes shape of sound wave as it enters ear canal
What is the left LSO excited and inhibited by?
- excited by sound from left side
- inhibited by sound from right side
What is the right LSO excited and inhibited by?
- excited by sound from right side
- inhibited by sound from left side
How do bats escape bat echolocation?
moths often hear loud ultrasound pulses before bats can hear returning echoes ∴ can react with escape behaviour
moths jam bat sonar – produce high-pitched clicking sounds that interfere with echolocation
- as bat gets closer to moth, call frequency gets higher
- when far away from moth, bat just needs to know the general direction of moth location
- when closer to moth, bat needs to know exact moth location ∴ they increase call frequency to get more and updated information
clicking sounds from moth interfere with bat call frequencies
- bat call frequencies no longer increase reliably (speed varying) because bat is confused and unsure of target location
