Nervous System - Visual and Hearing Senses Flashcards

1
Q

protective structures of the eye (5)

A
  1. bony orbit
  2. eyebrows
  3. eyelids
  4. eyelashes
  5. lacrimal apparatus
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2
Q

lacrimal apparatus

A
  • lacrimal gland secretes tears which flow through ducts and drain through nasolacrimal duct
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3
Q

conjunctivitis / pink eye

A

inflammation or infection of eye

- vasodilation causes pink colour

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4
Q

structure of eye

A
  • fibrous: outer layer
  • vascular (uvea): middle layer
  • nervous: inner layer
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5
Q

parts of fibrous, vascular, and nervous layers

A
  • sclera, cornea
  • choroid, ciliary body, iris
  • retina
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6
Q

fluid compartments of the eye

A
  1. partition - ciliary body (processes, muscle), suspensory ligaments, lens
  2. aqueous humour and vitreous humor - support the internal pressure, help maintain eye’s shape and size
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7
Q

three sequential processes of visual perception

A
  1. focus light on retina
  2. transduce the light to a nervous signal
  3. process the nervous signals to form conscious perception of objects
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8
Q

refraction

A

bending of light rays

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9
Q

snell’s law of refraction *

A
(n1)sin(X1) = (n2)sin(X2)
n = refractive index of mediums
X = angle formed by incident light ray and a line perpendicular to surface of medium
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10
Q

convex lens

A

converging rays

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11
Q

concave lens

A

diverging rays

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12
Q

focal point (F)

A
  • single point on axis where incident rays of light converge
  • measure of the refractive power of a lens
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13
Q

focal length (f)

A
  • distance from the lens to the focal point

- measure of the refractive power of a lens

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14
Q

refractive power [diopters]

A
  • inverse of focal length

- measure of how much light is bent en route to the retina

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15
Q

accommodation of the eye

A
  • light from close objects must be bent more; the lens rounds up to do this
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16
Q

near point

A

nearest an object can be and still be clearly seen

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17
Q

power of accommodation

A

difference in the refractive power of the relaxed eye and the maximally accommodated eye

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18
Q

presbyopia

A

eye’s natural lenses lose their flexibility as part of the normal aging processes
- hard to see :(

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19
Q

emmetropia

A

eye that has no visual defects

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20
Q

optic disk

A

region where optic nerve leaves the eye

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21
Q

macula luted and fovea centralis

A

contain very high concentration of cones

- get sharpest image here!

22
Q

blind spot

A

no photoreceptors (more)

23
Q

photopic

A

central vision is photopic due to cones (in colour)

24
Q

scotopic

A

peripheral vision is scotopic due to rods (black and white)

25
Q

photoreceptors

A
  1. cones

2. rods

26
Q

refractive errors

A
  • far-sightedness (hypermetropia)

- near-sightedness (myopia)

27
Q

hypermetropia

A

lenses that converge light (+ convex) to correct far-sightedness

28
Q

myopia

A

lenses that diverge light (- concave) to correct for near-sightedness

29
Q

main divisions of ear

A
  1. external (outer) ear
  2. middle ear
  3. ?
30
Q

structure of outer ear

A

external: auricle (pinna)

external auditory meatus (canal)

31
Q

auricle (pinna)

A

collects and directs sound waves to the auditory meaus

32
Q

external auditory meatus (canal)

A
  • channels sound waves to the middle ear
  • contains sebaceous (oil) and ceruminous (wax) glands
  • ends at the tympanic membrane (ear drum)
33
Q

middle ear (tympanic cavity)

A
  1. tympanic membrane
  2. eustachian tubes
  3. auditory ossicles
34
Q

tympanic membrane

A

ear drum

35
Q

Eustachian tubes

A
  • connects the middle ear to the throat

- equalizes pressure on the two sides of the tympanic membrane

36
Q

auditory ossicles

A
  • 3 bones: malleus (hammer), incus (anvil), stapes (stirrup)
    (smallest bones in our body)
  • transmit vibrations to the oval window
  • really amplifies; sound energy can be concentrated 15 fold
37
Q

otitis

A

inflammation of ear

38
Q

structure of the inner ear

A
  1. bony labyrinth
  2. membranous labyrinth
  3. cochlea
39
Q

bony labyrinth

A

interconnecting chambers in the temporal bone

40
Q

membranous labyrinth

A
  • membranous tubes filled with endolymph

- floats in a fluid called perilymph

41
Q

cochlea (coiled structure)

A
  • transduce fluid pressure waves into nerve impulses
  • organ corti: hearing organ
  • produces a tonotopic mapping of sound frequency
42
Q

events in transmission of auditory impulses

A
  1. tympanic membrane vibrates in response to sound waves
  2. auditory ossicles transfer vibrations to the oval window
  3. movement of the oval window starts oscillation in the perilymph in the cochlea
  4. oscillations in the perilymph cause vibrations in the vestibular and basilar membrane
  5. stereocilia on the hair cells in the organ corti rub against the tectorial membrane and bend
  6. bending of the hairs on the hair cells stimulate the formation of the impulses
  7. impulses are transmitted to the auditory cortex
43
Q

auditory sensation

A
  • human auditory system discriminates among tone, timbre, and intensity
44
Q

tones

A

sound waves of a single frequency

- rare in nature

45
Q

timbre

A
  • presence of additional frequencies imposed on a tone constitutes its timbre
  • allows us to discriminate against voice, piano, etc..
46
Q

intensity

A

amplitude of the sound

“loudness”

47
Q

loudness of sound formula *

A

loudness (decibals) = 10log(Isound/Iref)

loudness (dB) = 20log(VPsound/VPref)

48
Q

presbycusis

A

progressive hearing loss with age

49
Q

rods

A
  • sensitive to dim light
  • vision lacks fine details
  • scotopic vision (colour blind)
  • rhodopsin in outer segment
50
Q

cones

A
  • sensitive to bright light
  • vision produces sharp image and fine details
  • photopic vision (colour sensitive)
  • photopigment
51
Q

optic chiasm

A
  • X-shaped structure formed by crossing of the optic nerves in the brain
52
Q

visual cortex

A

primary cortical region of the brain that deals with visual information