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NRSC 2000 > Sensory Systems > Flashcards

Sensory Systems Flashcards

1
Q

What visible light colour has the highest frequency? Lowest?

A

blue, red

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2
Q

How much info about our environment comes from our eyes?

A

up to 70%

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3
Q

What converts light energy to biological information?

A

photoreceptors

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4
Q

Where do eyes first develop evolutionarily?

A

jellyfish

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5
Q

Do microbes have eyes?

A

no, but they can sense light

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6
Q

What are the different eye types?

A

simple lens eye, simple corneal eye, compound eye

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7
Q

What is a simple lens eye? What are some examples of things with these eyes?

A

single chamber with retina on one side and lens on the other

vertebrates, squid/octopus, jellyfish

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8
Q

What is a simple corneal eye? What is an example of things with these eyes?

A

no lens, light is focused only by cornea onto retina

arachnids

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9
Q

What is a compound eye? What are some examples of things with these eyes?

A

consists of many identical visual units each with own lens and receptor (like a bunch of mini eyes looking in diff directions)

insects, crustaceans

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10
Q

What is the cornea?

A

clear outer layer of eye, directs light into eyes and focuses it

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11
Q

What is the lens?

A

behind iris, focuses light on retina

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12
Q

What does the iris do?

A

controls the opening and closing of pupil

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13
Q

What is the ciliary muslce?

A

connects to and helps control iris/lens

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14
Q

What is the choroid?

A

network of blood vessels that supplys the retina, runs between retina and sclera

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15
Q

What is the sclera?

A

white outer layer of eye, maintains shape and protects from injury

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16
Q

What is the fovea?

A

small depression in center of retina where visual acuity is the highest

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17
Q

What is the optic disc?

A

where optic nerve connects to retina, blind spot (no photoreceptors)

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18
Q

When looking at the retina with an opthalmoscope how can you tell if its a vein or artery?

A

veins have wider diameters

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19
Q

What is the macula lutea?

A

surrounds the fovea, looks like a yellow ring

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20
Q

What are zonule fibers?

A

fibers that connect ciliary muslce to lens

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21
Q

What is accomodation?

A

automatic adjustment of the eye to focus

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22
Q

What does unaccommodated lens look like?

A

ciliary muslce tense and zonule fibers pull on lens to flatten it

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23
Q

What does accommodated lens look like?

A

ciliary muslce relax and lens thickens

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24
Q

What is emmetropia?

A

normal 20/20 eyes, the light is focused on the retina properly

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25
Q

What is myopia?

A

near sighted, light is focused before it hits the retina so when it actually reaches the retina its not focused

26
Q

What causes myopia?

A

too long eye ball or corneal surface is too curved

27
Q

What is hyperopia?

A

far sighted, light is focused after it hits the retina

28
Q

What causes hyperopia?

A

too short eye ball or weak refractory system

29
Q

What are the three basic layers of the retina?

A

ganglion cell layer, bipolar cell layer, photoreceptor layer

30
Q

Where is the pigment epithelium layer located in retina?

A

outermost layer of retina (beside photoreceptor layer)

31
Q

In what layer does photoreceptors make contact with bipolar cells?

A

outer plexiform layer

32
Q

In what layer do bipolar cells and amacrine cells make contact with ganglion cells?

A

inner plexiform layer

33
Q

What are the types of interneurons found in the retina?

A

horizontal and amacrine

34
Q

What is the purpose of the discs in the outer layer of rod/cone cells?

A

photoreceptor pigments are held, makes more surface area to absorb light

35
Q

What do cilium do in photoreceptor cells?

A

convert light energy to neurological stimulus

36
Q

What are the three sections of photoreceptor cells?

A

outer segment (pigments), inner segment (nucleus), synaptic terminal (synaptic vesicles)

37
Q

What is the traits of rods?

A

low visual acuity, can see in dark, can’t see colour, more of them that cones

38
Q

What is the traits of cones?

A

high visual acuity, can’t see in dark, can see colour, less than rods

39
Q

What is retinitis pigmentosa?

A

hereditary disease caused by cells in the retina breaking down

40
Q

How does retinitis pigmentosa damage photoreceptors?

A

epithelial cells stop regenerating photopigments, and begin to destroy outer segments (discs) of rods/cones

41
Q

What are the steps of damage done by pigment epithelium?

A

discs start to curl, the tip becomes spherical, tip seperates from rod, tip is engulfed by pigment epithelium

42
Q

What are the first symptoms of retinitis pigmentosa?

A

vision loss starting with night vision and peripheral (rods are damaged firs)

43
Q

What is scotopic vision?

A

night vision, poor acuity, no colours, only rods

44
Q

What is mesopic vision?

A

twilight vision, transition between day and night vision, uses cones and rods

45
Q

What is photopic vision?

A

day vision, well light situations, no rods (saturated) only cones, colour vision, good acuity

46
Q

What is opsin?

A

membrane protein found in photoreceptor membrane

47
Q

What allows for phototransduction in rods?

A

rhodopsin

48
Q

What is rhodopsin made up? Where is it found?

A

opsin and 11-cis-retinal, discs of rod cells

49
Q

When 11-cis retinal absorbs a photon what happens?

A

isomerizes to All-trans-retinal

50
Q

What is IRBP? What does it do?

A

made/secreted by photoreceprtors, binds visual retinoids (cis/trans retinal)

51
Q

What happens after All-trans-retinal is made? What does this?

A

converted to All-trans retinyl ester, then to 11-cis retinol, then back to 11-cis retinal

pigment epithelium

52
Q

Do photoreceptors become more positive or negative when activated?

A

negative (opposite of neuron)

53
Q

What does light activation do to sodium/calcium channels?

A

closes them (normally open so there is constant influx of Na, Ca)

54
Q

What are the steps of phototransduction in rods?

A

light enters rhodopsin and makes all-trans retinal, uses transducin to send signal to PDE, which activates the channels (closes them) uses GTP

55
Q

How does cGMP affect phototransduction?

A

high levels in outer segment keep channels open, light causes levels to drop and channels to close causing hyperpolarization

56
Q

What are rhodopsin kinase involved in?

A

deactivation pathwya of phototransduction

57
Q

What happens to the membrane potential of a photoreceptor when there is a very intense flash?

A

more intense means greater hyperpolarization (more negative)

58
Q

What is the difference between rods and cones reactions to same stimulus?

A

rods: activate fast and deactivate slowly

cones: activate fast and deactivate fast

59
Q

Are rods or cones more sensitive to light?

A

rods are (only takes 1 photon to activate)

60
Q

Why are rods more sensitive to light? Why are cones less sensitive?

A

many rods connect to a single bipolar cell

one cone connects to one bipolar cell

61
Q

What is protanopia?

A

red is missing (LWS)

62
Q

What is deuteronopia?

A

green is missing (MWS)

NRSC 2000 (6 decks)

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