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special senses Flashcards

(58 cards)

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1
Q

hearing, equilibrium & balance

A

mechanical signals
hair cells do not regeneratee

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2
Q

smell & taste

A

chemical signals
sensory cells do regenerate

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3
Q

vision

A

electromagnetic fields
photoreceptors do not regenerate

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4
Q

what structures are in the middle ear

A

tympanic membrane, malleus, incus, stapes, eustachain tube

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5
Q

inner ear structures

A

cochlea - hearing
- organ of corti
vestibular apparatus - balance
- 3 semicircular canals - crista ampullaris
- utricle & saccule - macula

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6
Q

sound

A

changes in air or water pressure produced by a vibrating object
higher amplitude = higher sound/loud

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7
Q

pitch

A

perception of different frequencies
range: 20-20000 Hz
higher frequency = higher pitch (more APs)
- organ of corti hair cells pick up changing vibrations over a 1000 fold frequency range

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8
Q

transmission of sound

A

sound enter the ear & vibrates the tympanic membrane vibrating the ossicles vibrating the oval window, sound passes through cochlear duct (sound transmission) moving stereocilia.

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9
Q

cochlea openings, membranes & lymph

A

scala vestibuli (perilymph)
vestibular membrane - sound pressure = bend
cochlear duct (endolymph) - 160mM K+
Organ of corti
basilar membrane
scala tympani (perilymph)

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10
Q

organ of corti

A

stereocilia stuck to ECM & tectorial membrane
As tectorial membrane vibrates, hair cells are bending, ions flood in = depolarization and release of excitatory NTs. Inner hair cells transmit vibrations to brain

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11
Q

stereocilia

A

protrude into endolymph
longest are connected to gel-like tectorial membrane

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12
Q

stereocilia excitation in organ of corti

A
  1. bending towards kinocilia (tethered to ion channels) opens mechanically gated ion channels, activates K+ & Ca2+ current - depolarization - GP & release of glutamate
  2. bending in the opposite direction closes ion channels, hyperpolarization
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13
Q

endolymph: K+ heavy

A

In hair cells or organ of corti, utricle, saccule, and semicircular canals - K+ move in cells bringing positive charge = depolarization

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14
Q

high sounds

A

high frequency sounds diplace the basiclar membrane near the base

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15
Q

medium sounds

A

medium frequency sounds displace the basilar membrane near the middle

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16
Q

low sounds

A

low frequency sounds displace the basilar membrane near the apex

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17
Q

frequency - fiber strength

A

fibers near the oval window are short & stiff - resonate with high-frequency waves
fibers near apex are longer and more floppy - resonate with low-frequency waves
this mechanically processes sound before signals reach receptors

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18
Q

loudness

A

detected by an increased # of APs in the activated position, louder noise means greater amplitude and stereocilia remain in the activated position for a longer time - cells depolarize = release NTs

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19
Q

sensorineural deafness

A

damage to neural structures at any point from cochlear cells to auditory cortex, gradual hair cell loss

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20
Q

conduction deafness

A

blocked sound to fluids of middle ear
- earwax
- perforated eardrum
- osteosclerosis of ossicles
- otitis media

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21
Q

middle ear inflammation

A

treat with antibitics or tubes through tympanic membrane, interfering with mechanical pathway = inhibit neurons of sensory cells

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22
Q

hearing aids

A

pick up sound & amplify it, send it through middle hear

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23
Q

bone conduction hearing aid

A

lose ability to use middle ear - bypasses outer & middle ear to vibrate temporal bone

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24
Q

linear equilibrium receptor regions

Study These Flashcards
A

macula
- saccule (continuous with cochlear duct)
- utricle (continuous with semicircular canals)

25
cochlear implant
lose stereocilia - in temporal bone connected to neurons that were to be synapsing with hair cells.
26
moniter rotational equilibrium
semicircular canals receptor region = crista ampullaris
27
structure of macula
stereocilia are embedded in the otolith membrane and studded with otoliths (CaCO3). On utricle - stereocilia point up & down to move forwards/backwards ON saccule - stereocilia point sideways to move up or down these hair cells synapse with vestibular nerve fibers
28
gravitational pull on a macular receptor in the utricle
at rest, macular stereocilia release NT continuously, head tilted toward kinocilia 0 higher frequency of APs - depolarization. Head tilted away from kinocilia - lower frequency - hyperpolarization
29
crista ampullaris location & structure
one in ampulla of each canal. each crista has supporting cells and hair cells that extend into gel-like mass (cupula) and synapse with vestibular nerve fibers.
30
crista ampullaris during movement
At rest, the cupula stickers out straight into the endolymph During rotational accel. relatively stational endolymph bends the cupula in the opposite direction of rotation and depolarizes. After gaining inertia, a rapid stop causes endolymph to keep moving in the direction of rotation & the cupula bends in the opposite direction
31
olfactory receptors
make use of g protein coupled receptors sensitive to strong smells - higher NT release
32
smell receptor steps
1. Odorant binds to its receptor 2. Activated receptor activates a G protein 3. G protein activates adenylate cyclase 4. Adenylate cyclase converts ATP to cAMP (mono-phosphate) by cutting 2 phosphates and cycling the other 1 5. cAMP opens a channel, causing Na+ and Ca2+ influx - depolarization - exocytosis of glutamate
33
structure of taste bud
gustatory cells - epithelial cells that are sensory and have microvilli (receptors, increase SA)/ release 5 NTs - excitatory basal epithelial cells - stem cells that replace gustatory cells every 7-10 days
34
5 taste sensations
salty - metal ions (inorganic salts) sour - H+ in solution (malic, ascorbic, citric acids) sweet - sugars, alcohol, some amino acids bitter - alkaloids (quinine, nicotine, aspirin) umami - amino acids, glutamate, aspartate
35
activation of taste receptors
food chemical binds to gustatory cell/receptor, depolarizes taste cell membrane - NT release - APs on sensory neurons
36
how does salty taste depolarize
Na+ influx to directly cause depolarization (NT - unknown)
37
how does sour taste depolarize
H+ donation which blocks Ka+ channels or opens Na+/Ca2+ channels (NT - serotonin, GABA, NE)
38
how does sweet/bitter/umami taste depolarize
are couple to the G protein gustducin which depolarizes the membrane (NT - ATP or AceCoH)
39
light
packets of energy (photons) that travel in wavelike fashion. white objects/lights reflects/transmits all colors
40
refraction
bending of light rays due to change in speed of light when it passes from one transparent medium to another. Occurs when light meets the surface of a different medium at other than a 90 angle
41
refraction by a biconvex lens
light refracted 3 times as it goes through fluids of the eye 1. entering cornea 2. entering lens 3. leaving lens
42
retina layers
1. retinal pigmented epithelium 2. Inner neural layer
43
retinal pigmented epithelium
absorbs light and prevents its scattering cannot regenerate photoreceptors so phagocytosis of cell fragments recycles vitamin A/chromophores
44
inner neural layer
transparent layer with 3 main neurons 1. photoreceptors 2. bipolar cells 3. ganglion cells - axons act on optic n.
45
photoreceptors to bipolar cell ratio
3 rods : 1 bipolar cell 1 cone : 1 bipolar cell
46
functional anatomy of photoreceptors
outer segments are receptive regions that contain photopigments - rods - rhodopsin, 500 nm - cones - 3 phoropsins, R (560 nm), G (530 nm), & B (420 nm) inner segment connects to bipolar cells
47
rhodopsin =
opsin (protein) + 11-cis-retinal
48
11-cis-retinal
in form before light hits it (dark) active - reduction or 2 H+- vit A - oxidation of 2 H+ - inactive opsin doesn't absorb light. when light hits rhodopsin, 11-cis-retinal binds to photon & activates G-protein
49
photoprotein activation rate
photoprotein cannot bind to another photon after activated GPCR, must lose protein first be diffusing across retinal pigmented epithelium and simple diffusing back
50
sensing light/phototransduction
1. Retinal (11-cis-retinal) absorbs light & changes shape (all-trans-retinal), visual pigment (opsin) activates 2. Visual pigment activates transducin (G protein) 3. Transducin activates phosphodiesterase (PDE) 4. PDE convert cGMP into GMP causing cGMP levels to fall (PDE cuts the cyclic nucleotide & inactivates it) 5. As cGMP levels fall, cGMP-gated cation channels close - hyperpolarization (inhibits inhibitory NT), depolarize by release inhibitory NTs) in the dark
51
photoreceptor light on pathway in light
cGMP breaks down, channels close and photoreceptors hyperpolarize & stop releasing NT glutamate (ON signal)
52
photoreceptor light on pathway in dark
cGMP increases & holds channels of outer segment open - Na+ & Ca2+ depolarize cell - release NT glutamate which is inhibitory for bipolar cells, excitatory for ganglion cells which generate more APs to occur
53
light adaptation
rods & cones strongly stimulated, pupils constrict to reduce light. Burnout of photopigments visual acuity improves over 5-10 min as: 1. rod system turns off 2. retinal sensitivity decreases 3. cones and neurons rapidly adapt
54
dark adaptation
cones stop functioning, pupils dilate rhodopsin accumulates on rods retinal sensitivity increases within 20-30 min
55
can the olfactory sensory cell produce its own action potential
Yes, as soon as odorant binds to receptor, olfactory cascade begins
56
what are the major determinants of refraction
changes in speed, angle of incident
57
distant objects
ciliary m.s relax sus ligs tight lens is flat
58
near objects
ciliary m.s tight sus ligs relax lens is thicker/rounder

physiology (9 decks)

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