Special Senses Flashcards
(99 cards)
1
Q
What is sound?
A
-audible variations in air pressure.
2
Q
Air is compressed (made more dense) when
A
when obj is moving toward a point in space
3
Q
Air is rarefied (made less dense) when
A
an obj is moving away from a point in space.
4
Q
intensity
A
- loudness
- measured in pascals
- human range is from less than a billionth atm pressure (0 decibels) to 10^13 atm pressure (130 decibels)
5
Q
(T/F) Sound waves also have intensity measures as pressure of the wave (Pascals)
A
T
6
Q
Pitch
A
-frequency
-measured in Hz/kHz
-pitch is equal to the number of crests that pass a point in a second (aka cycles per second or Hz)
100 cps = 1 kHz
-incr vibrations, incr pitch
7
Q
auricle
A
- part of outer ear
- cartilage covered by skin
- impt in locating sounds in space
8
Q
auditory canal
A
- aka ear canal
- part of outer ear
9
Q
tympanic membrane
A
- part of outer eat
- outer layer of ear drum
10
Q
ear drum located in
A
middle ear
11
Q
cavity (tympanic cavity)
A
-in middle ear
houses the ossicles: malleus (attached to ear drum), incus, stapes (smallest bone in the body)
12
Q
oval window
A
- part of the middle ear
- connect middle ear to the inner ear
13
Q
semicircular canals
A
- part of inner ear
- filled with fluid attach to cochlea
- sends info about balance and head position
14
Q
cochlea
A
- part of inner ear
- spiral shaped organ where sound transduction takes place
15
Q
eustachian tube
A
part of inner ear
-drains fluid from the inner ear into the throat behind the nose
16
Q
scala media
A
middle chamber of cochlea
-houses the organ of corti that sits on the basilar membrane
17
Q
scale vestibuli
A
- top chamber of the cochlea
- separate by scala media by reissners membrane
18
Q
reissners membrane
A
separates scala media from scala vestibuli
19
Q
scale tympani
A
- bottom chamber of cochlea
- separated by scala media by basilar membrane
20
Q
organ of corti
A
- complex arrangement of cells and accessory xtures that is supported by the basilar membrane
- compromises the sensory cells of the ear
- when basilar membrane vibrates in response to sound, the entire organ or corti moves up and down
21
Q
basilar membrane
A
- separates scale media from scala tymapni
- supports organ of corti
- vibrates in response to sound
- flexible and has unique characteristics that help its ability to respond to sound
22
Q
tectorial membrane
A
-overhanging xture and sits immediately above the organ of corti
23
Q
how does the ear communicate sound
A
basicar membrane vibrates in response to sound. forces organ of corti upward against tectorial membrane. tectorial membrane exerts a sheering force on apical membrane of sensory cells in organ of corti —this communicates sound
24
Q
basicar membrane is wider and more flexible at its
A
apex
25
basilar membrane is narrower and stiffer at its
base
26
(T/F) when sound is transfered to the basilar membrane, the distance it transduced along the length of the membrane does not depend on frequency.
F- it does depend on freq
27
basilar membrane with incr freq
base vibrates a lot and dissipates the energy of the soundwave
28
basilar membrane with decr freq
sound travels to apex
29
(T/F) the tectorial membrane has a tonotopic map
F- the basilar membrane
30
outer hair cells
- 3 of them
- do not contribute to sensory transduction in ear but are important for adjusting the stiffness (tunning) of the basilar membrane
31
inner hair cell
- 1 of them
- completely carries out auditory transduction.
- depolarized cell with a hair bundle
32
Can hair cells fire APs?
cannot fire AP but it's membrane pot fluctuates in response to sound and release NTs onto post syn nerve ending that synapses onto its base
33
Steps in auditory conduction
```
1-bundel deflection
2- transduction current
3-Receptor pot
4-Ca2+ current
5-glutamate release
6-EPSP
7-APs
```
34
tip link
a fine process connect each stereocilia in the hair bundle to the next tallest one
-attached to mechanically gated ion channel
35
How does bundle deflection open gate
when hair bundle is deflected bc of vibration of basilar membrane, the tip-link pulls on a mechanically gates ion channel present on stereocilia, causing it to open.
- cations flow down electrochem gradien
- this cation flow = transduction current
36
transduction current
- when cations flow down electrochem gradient from channels on stereocilia
- transduction current causes receptor potential
37
receptor potential
-caused by transduction current
| activates voltage gated ion channels on basolateral surface of hair cell.
38
why is Ca2+ current impt?
bc this is what supports glutamate NT release from pre syn terminals
39
wavelength is responsible for
perception of color
40
amplitude is responsible for
-intensity-- perception of brightness
41
visible light spectrum
violet-blue-green-yellow-orange-red
400 nm -->700 nm
this is at 10^-6 meters of electromag spectrum
42
electromag spectrum
gamma-xrays-uv-visible light-IR-radar-radiowaves-AC circuits
43
ciliary body and lens
divide the eye into posterior (vitreous) cavity and anterior cavity (which has anterior and posterior chambers)
44
aq humor
- circulates within the eye
- diffuses through walls of anterior chamber
- re enters circulation
45
vitreous humor
- fills posterior cavity
| - not recycled, permanent fluid
46
the lens and how it helps us focus
- light is refracted as it passes through the lens
- closer the light source, the longer the focal distance, flatter the lens
- further the light source, the rounder the lens, the shorter the focal distance
47
retina made up of
rods, cones, pigmented epithelium, bipolar & ganglion cells and horizontal and amocrine cells.
48
pigmented epithelium
- epithelial cells that contain melanin
- appears dark in histo prep
- helps prevent light from reflecting back through the retina--> which would lead to image distortion and poor visual acuity
- also a storage for vit A (precursor to the photopigments)
49
bipolar cells & ganglion cells
converge and integrate APs
bipolar cells- transmit their info to the ganglion cells
ganglion cells- extend their axons across the surface of the retina and these fibers make up the optic nerve. these are the output of the retina
50
optic disk
- central pale portion of the retina where the central retinal artery and vein merge
- blind spot-- has no photoreceptors
51
fovea
dense area of retina
| -region of highest acuity
52
which photoreceptors carry out phototransduction?
rods and cones
53
levels cones present
- mostly present in fovea
| - low levels everywhere else (except blind spot_
54
levels rods present
- none in fovea
- increase as we move away from fovea to more periphery of retina and then it falls slowly but still maintained at relatively high levels
55
why are there more stars off center?
focus with rods instead of cones bc better night vision and rods are located on more periphery of retina
56
(T/F) Light only needs to pass through some layers of the retina before it can reach the photo Rs
F- light must pass through all layers of the retina
57
organization of retina from front of the eye back
ganglion cells
- bipolar cells
- rods and cones
- pigmented epithelium
- choriod
58
optic nerve
- perforates the optic disk
- made up of ganglion cell fibers
- transmits the info that was originally transduced by the photoRs to the primary sensory areas of the brain
59
rods
very low spatial acuity
- extremely sensitive to light
- monochromatic night vision
60
cones
- high spatial resolution
- insensitive to light --> specialized for acuity
- color, R,G,B
61
at the lowest level of light what happens
- only rods acivated
- scotopic vision
- sock matching problem
- poor resolution
- no perception of color bc cones not involved
62
scotopic vision
rod mediated vision at lowest level of light, no cones
63
as illumation increases what happens
-cones become more and more dominant
rods decrease = photopic vision
the membrane pot of indiv rods can not longer function bc cell membrane channels are closed
64
photopic vision
when rods decrease because their response to light is saturated with increasing levels of illumination
so no rods, only cones
65
mesopic vision
levels of light which both rods and cones contribute
| ex-twilight
66
macular degeneration
loss of cone function in elderly
| -they are legally blind even though they may have cone
67
(T/F) rods converge on bipolar cells
T
68
Rods or cones exhibit less convergence
cones
69
convergence makes rods better at what? and why
detecting light because small signals from many rods are added together to generate a large response
70
convergence in rods makes them worse at what? and why
spatial resolution and acuity bc the stim the source of a single rod bipolar cell or retinal ganglion cell could come from anywhere within a relatively large area of the retinal surface
71
what are photopigments and which pigments do they contain?
-the outer segments of each photoreceptor is packed with membranous disks that contain the light sensitive pigments which is opsin & retinol (11-cisretinol)
72
rhodopsin
photopigment in rods
| scotopsin + 11-cis retinol
73
retinol
- identical in every photo R but the protein portion of the molecules varies slightly (vary in AA req) and this alters the properties of each photopigment
- comes specialized for B, G or R wavelengths
74
describe the diff in AA between blue and rhodopsin
large difference
75
describe the diff in AA bw G and B
many differences byt not as many as rhodopsin and B
76
describe the diff in AA bw R and G
very similar
77
why do no black bands appear in the rainbow?
because all wavelengths (rods, R, G and B) overlap in the full visible spectrum
78
rod adaptation to light (slow/fast)?
slow
79
cone adaptation to light (slow/fast)?
fast
80
what form of rhodopsin is the only form that fits comfortably in opsin?
11-cis- retinol
81
what happens when a photon is absorbed by retinol?
-changes conf from 11 cis retinal to all trans retinol
82
what does all trans retinal cause?
-bleeching = causes retinol and opsin to dissoc bc all trans can't fit comfortably in opsin molecule
83
the restoration of all trans retinal back to 11 cis retinal is a passive process. (T/F)
F- it is ATP dependent
| it is also enzyme driven
84
what needs to happen in order for us to generate new rhodopsin?
11 cis retinal needs to be restored
85
what is present in outer segment of a rod?
membranous disks and cGMP gated Na+ channels
86
what is present in the inner segment of a rod?
- Na/K ATPase
| - K channels
87
when does a rod experience dark current
when no light present
88
dark current
when Na channels open, Na enters outer segment and K leaves in inner segment.
-this cycle of pos charges entering and leaving creates a flux called dark current.
89
what does incr cGMP do?
keep cGMP gated Na channels open
90
when is the cell depolarized? (dark or light)
in the dark becasue that's when pos charges enter
91
phototransduction in light process
1- light strikes rhodopsin and activates G protein (transducin) and binds GTP
2- alpha subunit activated cGMP PDE
3- PDE breaks down cGMP to 5' cGMP which reduces the conc
4-decr cGMP causes Na channels to close in plasma membrane of outer segment. Inner segment K continues to be pumped out of rod which hyperpolarizes the cell
92
what happens in light basically
-decr conc cGMP in outer segment, closure of cGMP gated Na channels and hyperpolarization of photoR (disrupts dark current)
93
what happens to hyperpolarization as we incr intensity of light?
incr intensity of hyperpolarization
94
(T/F) The depolarization in the dark leads to constitutive release of NT
T
95
when is the release of NT inhibited?
in the light
96
(T/F) the amount of energy a given sensory R responds to in normal function is known as an "adequate stim"
T
97
(T/F) R pots are all in one phenomena
F
98
(T/F) When freq of APs along sensory neurons is const as long as a stim continues, it is called adaptation.
F
99
(T/F) Modality refers to the intensity of a given stim
F
