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PHYSL 212 > Unit 5 - Special Senses > Flashcards

Unit 5 - Special Senses Flashcards

1
Q

How are receptors categorized?

A

By the type of energy required to activate them

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2
Q

What is perception?

A

The organization, identification and interpretation of sensory information in order to represent and understand the environment

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3
Q

Vision involves ________ striking the retina of the eye; and hearing involves _________.

A

Light, pressure waves

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4
Q

What is the adequate stimulus?

A

Sensory endings respond to a particular type of energy applied to them or near them

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5
Q

Energy must be converted to electrochemical energy. This conversion is called:

A

Primary transduction process

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6
Q

What is the primary transduction process for the visual system?

A

Converting photons of light into a change in membrane potential

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7
Q

What is the primary transduction process for hearing?

A

Converting pressure waves in air to pressure waves in a fluid which then bend a hair

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8
Q

What is a receptor potential

A

A type of graded transmembrane potential difference produced by activation of a sensory receptor

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9
Q

How are receptor potentials most often produced?

A

Sensory transduction by depolarization

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10
Q

True or false: receptor potentials can be caused by hyper polarization if K+ leaves the cell

A

True

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11
Q

Humans can detect light with a wavelength between ______ and ______nm.

A

390, 700

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12
Q

Psychophysical experiments with colour discrimination estimate that humans may be able to distinguish between _____ and _____ colours

A

2.3 million and 7.5 million

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13
Q

The tough fibrous part of the eye:

A

Sclera

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14
Q

A thin membrane that covers the inner surface of the eyelid and the sclera

A

Conjunctiva

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15
Q

Inflammation of the conjunctiva is called:

A

Conjunctivitis

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16
Q

Continuous and modified portion of the sclera, and is the most important part of the light focusing power of the eye

A

Cornea

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17
Q

True or false: the lens is more powerful than the cornea in terms of focusing power

A

False

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18
Q

Area of the eye behind the cornea, filled with a clear fluid called the aqueous humor

A

Anterior chamber

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19
Q

Aqueous humor is secreted by the _________ and is drained by the _________ at the cornea-sclera junction

A

Ciliary body, canal of schlemm

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20
Q

True or false: aqueous humor only fills the anterior chamber.

A

False: it also fills the posterior chamber

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21
Q

Has convex surfaces and is elastic, is located immediately behind the anterior chamber

A

Crystalline lens

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22
Q

Large chamber behind the lens filled with a gelatinous substance called the vitreous humor

A

Vitreous chamber

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23
Q

Maintains the shape of the eye because it is very stiff and doesn’t flow well

A

Vitreous humor

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24
Q

Contains several layers of both receptor and processing cells, located at the back of the eye

A

Retina

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25
Q

Pigmented cell layer just outside the neurosensory retina that nourishes retinal visual cells, and is firmly attached to the underlying choroid and overlying retinal visual cells

A

Retinal pigment epithelium (RPE)

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26
Q

Provides oxygen and nourishment to the outer layers of the retina, located behind the RPE

A

Choroid layer

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27
Q

Any light not absorbed by the receptor cells is absorbed by the pigment cells in order to:

A

Prevent light scatter which would blur the image

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28
Q

What is accommodation?

A

The process by which the curvature of the lens is increased?

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29
Q

When does accommodation occur?

A

During near vision

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30
Q

Is the posterior or anterior curvature of the lens most affected by accommodation?

A

Anterior

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31
Q

Holds the lens in place behind the iris

A

Suspensatory ligaments/ zonule fibres

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32
Q

The zonule fibres are attached to a sphincter-like muscle called the:

A

Ciliary muscle

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33
Q

When the ciliary muscle is relaxed, the lens ________, and when the ciliary muscle is contracted the lens _______

A

Flattens, becomes rounder and thicker

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34
Q

The deflection from a straight path undergone by a light ray in passing obliquely from one medium to another in which the velocity is different

A

Refraction

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35
Q

The distance from the refractive surface (cornea) to the point where parallel light rays converge is the:

A

Focal distance

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36
Q

What is the reciprocal of the focal distance?

A

The diopter

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37
Q

The cornea has a refractive power of _______, which means that parallel light rays striking the corneal surface will be focused ________ behind it.

A

42-43 diopters, 0.024m

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38
Q

______% of the refraction of the eye occurs at the cornea, and ______% occurs in the lens

A

70, 30

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39
Q

What is myopia?

A

Near-sightedness

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40
Q

What is hyperopia?

A

Far sightedness

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41
Q

What is presbyopia?

A

Lens becomes stiff due to age, resulting in decreased ability to focus

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42
Q

What is an astigmatism?

A

The corneal surface is more curved in one plane than another, creating a difference in refraction

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43
Q

What is emmetropia?

A

Perfect vision

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44
Q

How is myopia corrected?

A

With a concave lens, which moves the focal point back to the retina

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45
Q

How is hyperopia corrected?

A

A convex lens, which pulls the focal point up to the retina

46
Q

What is the primary choice of correction for people with astigmatism?

A

Eyeglasses

47
Q

How does a cylindrical lens focus light?

A

Into a line

48
Q

How does a spherical lens focus light?

A

Into a point

49
Q

_______ is as transparent possible and appears to be built upside down

A

The retina

50
Q

The first layer of cells that light strikes in the retina are _________, and the last are _________

A

Ganglion cells, receptors

51
Q

In addition to absorbing light not absorbed by photoreceptors, the RPE:

A

Transports nutrients and ions to the photoreceptors

52
Q

What is the daily renewal process of photoreceptors?

A

~10% of their volume (discs) is shed and phagocytoses by the RPE. The discs are replaces from the bottom of the outer segment

53
Q
  • 100-125 million per retina
  • vision in shades of grey
  • high sensitivity
  • low acuity pathways
  • lots of convergence
  • night vision
  • more numerous in retinal periphery
    These are characteristics of:
A

Rods

54
Q
  • 6 million per retina
  • colour vision
  • low sensitivity
  • high acuity
  • little convergence
  • day vision
  • concentrated in fovea
    These are characteristics of:
A

Cones

55
Q

in the dark, a photoreceptor will release _________, which inhibits the ______ bipolar cells and excites the _______ bipolar cells.

A

glutamate, ON, OFF

56
Q

in the light, photons strike the photoreceptors and cause ________ due to activation of opsins which activate all _________, giving energy to stimulate _________ coupled receptors to activate phosphodiesterase which cleaves ________ to _______.

A

inhibition, trans-retinal, G-protein, cGMP, 5’-GMP

57
Q

made of retinal and the protein opsin

A

rhodopsin

58
Q

the aldehyde form of vitamin A

A

retinal

59
Q

an area on the retina which, when stimulated, causes a change in the output of either a particular bipolar cell or ganglion cell

A

receptive field

60
Q

the only retinal cell to generate action potentials and the only cell whose output goes to the brain

A

the ganglion cell

61
Q

the area of the retinal surface, or corresponding region of the visual field, that upon illumination, enhances or inhibits the activity of a bipolar or ganglion cell

A

receptive field

62
Q

true are false: receptor fields have both on and off areas

A

true

63
Q

some ganglion cells are luminous detectors but project to subcortical areas and mediate only unconscious reflexes, and example of this is:

A

pupillary reflexes

64
Q

true or false: receptive fields are not able to overlap

A

false

65
Q

ON channels have their axon terminals in the inner half of the ___________, and the OFF bipolar cells having their terminals in the ___________.

A

inner plexiform layer, outer half

66
Q

OFF bipolar cells express what kind of receptors?

A

AMPA and kainate (ionotropic receptors for glutamate)

67
Q

ON bipolar cells express what type of receptors?

A

mGluR6 (a metabotropic receptor)

68
Q

which bipolar receptor cells hyperpolarize in response to light due to less glutamate arriving from the cone synapse

A

OFF receptors

69
Q

which bipolar cells depolarize in response to less glutamate which opens cation channels

A

ON receptors

70
Q

where is the temporal hemi-retina located?

A

the far right side of the right eye-ball and vice versa

71
Q

where is the nasal hemi-retina located?

A

the far left side of the right eyeball and vice versa

72
Q

in thalamus, the first waystation for visual stimulation

A

lateral geniculate nucleus

73
Q

what is the frequency range of human hearing?

A

between 20-20000Hz

74
Q

how many tones can humans distinguish between?

A

340 000

75
Q

what are the three main functions of the external ear?

A

1) protection
2) pinna funnels sound into the external auditory meatus
3) external auditory meatus gathers sound energy and focusess it on the tympanic membrane

76
Q

has a bactericidal effect on some strains of bacteria

A

cerumen

77
Q

what are the main two features of the external ear that protect the inner membrane from damage

A
  • cerumen
  • hairs in the external auditory meatus
78
Q

by what factor does the external auditory meatus increase sound energy?

A

30-100 fold

79
Q

equalizes pressure on both sides of the tympanic membrane allowing it to vibrate frequently

A

eustachian tube

80
Q

true or false: the middle ear is air filled

A

true

81
Q

what three ossicles connect the tympanic membrane to the inner ear

A

the malleus (hammer), the incus (anvil), and the stapes (stirrup)

82
Q

what is the major function of the middle ear?

A

to match relatively low-impedance airborne sounds to the higher impedance fluid of the inner ear

83
Q

how much acoustic energy is reflected when sound waves travel from air to water?

A

99%

84
Q

in the middle ear, sound energy is boosted 200-fold by these two processes:

A

1) going from a large diameter tympanic membrane to a smaller diameter oval window
2) lever action of the ossicles

85
Q

attached to the malleus and the eustacian tube

A

tensor tympani

86
Q

attached to the wall of the middle ear and the neck of the stapes near the incus

A

stapedius

87
Q

the smallest skeletel muscles in the body

A

tensor tympani and stapdius

88
Q

how do the middle ear muscles provide a noise reduction system?

A

when they contract they dampen the vibration of the ossicles

89
Q

true or false: the middle ear muscles do not increase contraction when vocalization gets louder

A

false

90
Q

what mechanism of the ear allows people to hear others while talking themselves?

A

contraction of the middle ear muscles

91
Q

the middle ear muscle contraction ssytem works fairly well with maintained loud sounds, but not sharp intense sounds which make take __________ to fully contract

A

100-200 msec

92
Q

the inner ear is composed of the _________

A

cochlea

93
Q
  • 10mm in diameter
  • 2.75 turns
  • 35mm long when uncoiled
  • appears to be 3 parallel tubes when cut in a cross section
A

cochlea

94
Q

the _______ and _______ are one tube joined by a hole at the helicotrema, or essentially one tube wrapped around the scala media

A

scala vestibule, scala tympani

95
Q

true or false: the basilar membrane is not a true membrane

A

true

96
Q

composed of fibers which are narrow and stiff near the stapes, and are broader and more limber at the apex

A

basilar membrane

97
Q

rests on the basilar membrane

A

organ of corti

98
Q

in the organ of corti, there are three rows of _________ which have a motor function. there are about ________ per ear

A

outer hair cells, 10 500

99
Q

in the organ of corti, there is a single row of ________ which are sensory cells. there are about ________ per ear

A

inner hair cells, 3500

100
Q

the thin, gelatinous sheet that rests on the outer hair cells

A

tectorial membrane

101
Q

shearing action or stress resulting from applied forces that cause two continguous parts of a body to slide relative to each other in a direction parallel to:

A

their plane of contact

102
Q

hair-like bristles of varying length with the shortest in front and the tallest in back, attached to the tectorial membrane

A

streocilia

103
Q

when inner hair cells move as little as 0.3nm in the direction of ________ a response may be observed

A

the tallest sterocilia

104
Q

has a very high K+ concentration and a very low Na+ concentration

A

endolymph

105
Q

due to its high concentration of positive charged ions, the ______ has a high positive potential

A

endolymph

106
Q

the potential difference from the endolymph to the hair cells is on the order of 150mV, making it the:

A

largest electrical potential difference found in the body

107
Q

what causes the stereocilia to shear against the tectorial membrane?

A

movement of the basilar membrane and Reissner’s membrane

108
Q

when the shear tilts the stereocilia _______ channels open. since the endolymph has a high concentration of _______ it enters the cell and depolarizes it, leading to action potentials

A

K+, K+

109
Q

the point of maximal displacement is determined by the:

A

frequency of the sound

110
Q

high frequencies cause maximal displacement near the _____, and low frequencies cause maximal displacement near the ______

A

stapes, apex

111
Q

what is the purpose of the round window?

A

to absorb any energy that isn’t dissipated and push it into the middle

PHYSL 212 (8 decks)

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